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Documentation License, version 1.2</a>; with no Invariant Sections, + no Front-Cover Texts and no Back-Cover Texts. + </p> + + <p>This document is available in the following formats: + <a href="http://www.codesynthesis.com/projects/xsde/documentation/cxx/serializer/guide/index.xhtml">XHTML</a>, + <a href="http://www.codesynthesis.com/projects/xsde/documentation/cxx/serializer/guide/cxx-serializer-e-guide.pdf">PDF</a>, and + <a href="http://www.codesynthesis.com/projects/xsde/documentation/cxx/serializer/guide/cxx-serializer-e-guide.ps">PostScript</a>.</p> + + </div> + + <h1>Table of Contents</h1> + + <table class="toc"> + <tr> + <th></th><td><a href="#0">Preface</a> + <table class="toc"> + <tr><th></th><td><a href="#0.1">About This Document</a></td></tr> + <tr><th></th><td><a href="#0.2">More Information</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>1</th><td><a href="#1">Introduction</a> + <table class="toc"> + <tr><th>1.1</th><td><a href="#1.1">Mapping Overview</a></td></tr> + <tr><th>1.2</th><td><a href="#1.2">Benefits</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>2</th><td><a href="#2">Hello World Example</a> + <table class="toc"> + <tr><th>2.1</th><td><a href="#2.1">Writing Schema</a></td></tr> + <tr><th>2.2</th><td><a href="#2.2">Translating Schema to C++</a></td></tr> + <tr><th>2.3</th><td><a href="#2.3">Implementing Application Logic</a></td></tr> + <tr><th>2.4</th><td><a href="#2.4">Compiling and Running</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>3</th><td><a href="#3">Serializer Skeletons</a> + <table class="toc"> + <tr><th>3.1</th><td><a href="#3.1">Implementing the Gender Serializer</a></td></tr> + <tr><th>3.2</th><td><a href="#3.2">Implementing the Person Serializer</a></td></tr> + <tr><th>3.3</th><td><a href="#3.3">Implementing the People Serializer</a></td></tr> + <tr><th>3.4</th><td><a href="#3.4">Connecting the Serializers Together</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>4</th><td><a href="#4">Type Maps</a> + <table class="toc"> + <tr><th>4.1</th><td><a href="#4.1">Object Model</a></td></tr> + <tr><th>4.2</th><td><a href="#4.2">Type Map File Format</a></td></tr> + <tr><th>4.3</th><td><a href="#4.3">Serializer Implementations</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>5</th><td><a href="#5">Serializer Callbacks</a> + <table class="toc"> + <tr><th>5.1</th><td><a href="#5.1">Optional Callback</a></td></tr> + <tr><th>5.2</th><td><a href="#5.2">Sequence Callback</a></td></tr> + <tr><th>5.3</th><td><a href="#5.3">Choice Callback</a></td></tr> + <tr><th>5.4</th><td><a href="#5.4">Element Wildcard Callbacks</a></td></tr> + <tr><th>5.5</th><td><a href="#5.5">Attribute Wildcard Callbacks</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>6</th><td><a href="#6">Mapping Configuration</a> + <table class="toc"> + <tr><th>6.1</th><td><a href="#6.1">Standard Template Library</a></td></tr> + <tr><th>6.2</th><td><a href="#6.2">Input/Output Stream Library</a></td></tr> + <tr><th>6.3</th><td><a href="#6.3">C++ Exceptions</a></td></tr> + <tr><th>6.4</th><td><a href="#6.4">XML Schema Validation</a></td></tr> + <tr><th>6.5</th><td><a href="#6.5">64-bit Integer Type</a></td></tr> + <tr><th>6.6</th><td><a href="#6.6">Serializer Reuse</a></td></tr> + <tr><th>6.7</th><td><a href="#6.7">Support for Polymorphism</a></td></tr> + <tr><th>6.8</th><td><a href="#6.8">A Minimal Example</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>7</th><td><a href="#7">Built-In XML Schema Type Serializers</a> + <table class="toc"> + <tr><th>7.1</th><td><a href="#7.1">Floating-Point Type Serializers</a></td></tr> + <tr><th>7.2</th><td><a href="#7.2">String-Based Type Serializers</a></td></tr> + <tr><th>7.3</th><td><a href="#7.3"><code>QName</code> Serializer</a></td></tr> + <tr><th>7.4</th><td><a href="#7.4"><code>NMTOKENS</code> and <code>IDREFS</code> Serializers</a></td></tr> + <tr><th>7.5</th><td><a href="#7.5"><code>base64Binary</code> and <code>hexBinary</code> Serializers</a></td></tr> + <tr><th>7.6</th><td><a href="#7.6">Time Zone Representation</a></td></tr> + <tr><th>7.7</th><td><a href="#7.7"><code>date</code> Serializer</a></td></tr> + <tr><th>7.8</th><td><a href="#7.8"><code>dateTime</code> Serializer</a></td></tr> + <tr><th>7.9</th><td><a href="#7.9"><code>duration</code> Serializer</a></td></tr> + <tr><th>7.10</th><td><a href="#7.10"><code>gDay</code> Serializer</a></td></tr> + <tr><th>7.11</th><td><a href="#7.11"><code>gMonth</code> Serializer</a></td></tr> + <tr><th>7.12</th><td><a href="#7.12"><code>gMonthDay</code> Serializer</a></td></tr> + <tr><th>7.13</th><td><a href="#7.13"><code>gYear</code> Serializer</a></td></tr> + <tr><th>7.14</th><td><a href="#7.14"><code>gYearMonth</code> Serializer</a></td></tr> + <tr><th>7.15</th><td><a href="#7.15"><code>time</code> Serializer</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th>8</th><td><a href="#8">Document Serializer and Error Handling</a> + <table class="toc"> + <tr><th>8.1</th><td><a href="#8.1">Document Serializer</a></td></tr> + <tr><th>8.2</th><td><a href="#8.2">Exceptions</a></td></tr> + <tr><th>8.3</th><td><a href="#8.3">Error Codes</a></td></tr> + <tr><th>8.4</th><td><a href="#8.4">Reusing Serializers after an Error</a></td></tr> + </table> + </td> + </tr> + + <tr> + <th></th><td><a href="#A">Appendix A — Supported XML Schema Constructs</a></td> + </tr> + + </table> + </div> + + <h1><a name="0">Preface</a></h1> + + <h2><a name="0.1">About This Document</a></h2> + + <p>The goal of this document is to provide you with an + understanding of the C++/Serializer programming model and allow you + to efficiently evaluate XSD/e against your project's technical + requirements. As such, this document is intended for embedded + C++ developers and software architects who are looking for an + embedded XML processing solution. Prior experience with XML + and C++ is required to understand this document. Basic + understanding of XML Schema is advantageous but not expected + or required. + </p> + + + <h2><a name="0.2">More Information</a></h2> + + <p>Beyond this guide, you may also find the following sources of + information useful:</p> + + <ul class="list"> + <li><a href="http://www.codesynthesis.com/projects/xsde/documentation/xsde.xhtml">XSD/e + Compiler Command Line Manual</a></li> + + <li>The <code>INSTALL</code> file in the XSD/e distribution provides + build instructions for various platforms.</li> + + <li>The <code>examples/cxx/serializer/</code> directory in the XSD/e + distribution contains a collection of examples and a README + file with an overview of each example.</li> + + <li>The <a href="http://www.codesynthesis.com/mailman/listinfo/xsde-users">xsde-users</a> + mailing list is the place to ask technical questions about XSD/e and the + Embedded C++/Serializer mapping. Furthermore, the + <a href="http://www.codesynthesis.com/pipermail/xsde-users/">archives</a> + may already have answers to some of your questions.</li> + + </ul> + + <!-- Introduction --> + + <h1><a name="1">1 Introduction</a></h1> + + <p>Welcome to CodeSynthesis XSD/e and the Embedded C++/Serializer mapping. + XSD/e is a validating XML parser/serializer generator for mobile and + embedded systems. Embedded C++/Serializer is a W3C XML Schema to C++ + mapping that represents an XML vocabulary as a set of serializer + skeletons which you can implement to perform XML serialization as + required by your application logic. + </p> + + <h2><a name="1.1">1.1 Mapping Overview</a></h2> + + <p>The Embedded C++/Serializer mapping provides event-driven, + stream-oriented XML serialization, XML Schema validation, + and C++ data binding. It was specifically designed and + optimized for mobile and embedded systems where hardware + constraints require high efficiency and economical use of + resources. As a result, the generated serializers are 2-10 + times faster than general-purpose validating XML serializers + while at the same time maintaining extremely low static and + dynamic memory footprints. For example, a validating serializer + executable can be as small as 60KB in size. The size can be + further reduced by disabling support for XML Schema validation. + </p> + + <p>The generated code and the runtime library are also highly-portable + and, in their minimal configuration, can be used without STL, RTTI, + iostream, C++ exceptions, and C++ templates.</p> + + <p>To speed up application development, the C++/Serializer mapping + can be instructed to generate sample serializer implementations + and a test driver which can then be filled with the application + logic code. The mapping also provides a wide range of + mechanisms for controlling and customizing the generated code.</p> + + <p>The next chapter shows how to create a simple application + that uses the Embedded C++/Serializer mapping to validate + and serialize simple data to an XML document. The following + chapters describe the Embedded C++/Serializer mapping in more + detail.</p> + + <h2><a name="1.2">1.2 Benefits</a></h2> + + <p>Traditional XML serialization APIs such as Document Object Model (DOM) + or XML Writer as well as general-purpose XML Schema validators have + a number of drawbacks that make them less suitable for creating + mobile and embedded XML processing applications. These drawbacks + include: + </p> + + <ul class="list"> + <li>Text-based representation results in inefficient use of + resources.</li> + + <li>Extra validation code that is not used by the application.</li> + + <li>Generic representation of XML in terms of elements, attributes, + and text forces an application developer to write a substantial + amount of bridging code that identifies and transforms pieces + of information produced by the application logic to the text + encoding used in XML.</li> + + <li>Resulting applications are hard to debug, change, and + maintain.</li> + </ul> + + <p>In contrast, statically-typed, vocabulary-specific serializer + skeletons produced by the Embedded C++/Serializer mapping use + native data types (for example, integers are passed as + integers, not as text) and include validation code only for + XML Schema constructs that are used in the application. This + results in efficient use of resources and compact object code.</p> + + <p>Furthermore, the serializer skeletons allow you to operate in your + domain terms instead of the generic elements, attributes, and + text. Automatic code generation frees you for more + interesting tasks (such as doing something useful with the + information that needs to be stored in XML) and + minimizes the effort needed to adapt your applications to changes + in the document structure. To summarize, the C++/Serializer mapping + has the following key advantages over generic XML serialization APIs:</p> + + <ul class="list"> + <li><b>Ease of use.</b> The generated code hides all the complexity + associated with recreating the document structure, maintaining the + state, and converting the data from types suitable for + manipulation by the application logic to the text representation + used in XML.</li> + + <li><b>Natural representation.</b> The generated serializer skeletons + implement serializer callbacks as virtual functions with names + corresponding to elements and attributes in XML. As a result, + you serialize the data using your domain vocabulary instead + of generic elements, attributes, and text. + </li> + + <li><b>Concise code.</b> With a separate serializer skeleton for each + XML Schema type, the application implementation is simpler + and thus easier to read and understand.</li> + + <li><b>Safety.</b> The data is passed by serializer callbacks as + statically typed objects. The serializer callbacks themselves + are virtual functions. This helps catch programming errors + at compile-time rather than at runtime.</li> + + <li><b>Maintainability.</b> Automatic code generation minimizes the + effort needed to adapt the application to changes in the + document structure. With static typing, the C++ compiler + can pin-point the places in the application code that need to be + changed.</li> + + <li><b>Efficiency.</b> The generated serializer skeletons use native + data types and combine validation and data-to-text + conversion in a single step. This makes them much more efficient + than traditional architectures with separate stages for validation + and data conversion.</li> + </ul> + + + <!-- Hello World Example --> + + + <h1><a name="2">2 Hello World Example</a></h1> + + <p>In this chapter we will examine how to create a very simple XML + document using the XSD/e-generated C++/Serializer skeletons. + + All the code presented in this chapter is based on the <code>hello</code> + example which can be found in the <code>examples/cxx/serializer/</code> + directory of the XSD/e distribution.</p> + + <h2><a name="2.1">2.1 Writing Schema</a></h2> + + <p>First, we need to get an idea about the structure of the XML + document that we are going to create. The sample XML that + we will try to produce with our Hello application looks like + this:</p> + + <pre class="xml"> +<hello> + + <greeting>Hello</greeting> + + <name>sun</name> + <name>earth</name> + <name>world</name> + +</hello> + </pre> + + <p>Then we can write a description of the above XML in the + XML Schema language and save it into <code>hello.xsd</code>:</p> + + <pre class="xml"> +<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> + + <xs:complexType name="hello"> + <xs:sequence> + <xs:element name="greeting" type="xs:string"/> + <xs:element name="name" type="xs:string" maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <xs:element name="hello" type="hello"/> + +</xs:schema> + </pre> + + <p>Even if you are not familiar with the XML Schema language, it + should be easy to connect declarations in <code>hello.xsd</code> + to elements in the sample XML document above. The <code>hello</code> + type is defined as a sequence of the nested <code>greeting</code> + and <code>name</code> elements. Note that the term sequence in XML + Schema means that elements should appear in a particular order + as opposed to appearing multiple times. The <code>name</code> + element has its <code>maxOccurs</code> property set to + <code>unbounded</code> which means it can appear multiple times + in an XML document. Finally, the globally-defined <code>hello</code> + element prescribes the root element for our vocabulary. For an + easily-approachable introduction to XML Schema refer to + <a href="http://www.w3.org/TR/xmlschema-0/">XML Schema Part 0: + Primer</a>.</p> + + <p>The above schema is a specification of our vocabulary; it tells + everybody what valid XML instances of our vocabulary should look + like. The next step is to compile this schema to generate C++ + serializer skeletons.</p> + + <h2><a name="2.2">2.2 Translating Schema to C++</a></h2> + + <p>Now we are ready to translate our <code>hello.xsd</code> to C++ + serializer skeletons. To do this we invoke the XSD/e compiler + from a terminal (UNIX) or a command prompt (Windows): + </p> + + <pre class="terminal"> +$ xsde cxx-serializer hello.xsd + </pre> + + <p>The XSD/e compiler produces two C++ files: <code>hello-sskel.hxx</code> + and <code>hello-sskel.cxx</code>. The following code fragment is taken + from <code>hello-sskel.hxx</code>; it should give you an idea about what + gets generated: + </p> + +<pre class="c++"> +class hello_sskel +{ +public: + // Serializer callbacks. Override them in your implementation. + // + virtual void + pre (); + + virtual std::string + greeting () = 0; + + virtual bool + name_next () = 0; + + virtual std::string + name () = 0; + + virtual void + post (); + + // Serializer construction API. + // + void + greeting_serializer (xml_schema::string_sskel&); + + void + name_serializer (xml_schema::string_sskel&); + + void + serializers (xml_schema::string_sskel& /* greeting */, + xml_schema::string_sskel& /* name */); + +private: + ... +}; + </pre> + + <p>The first five member functions shown above are called serializer + callbacks. You would normally override them in your implementation + of the serializer. Let's go through all of them one by one.</p> + + <p>The <code>pre()</code> function is an initialization callback. It is + called when a new element of type <code>hello</code> is about + to be serialized. You would normally use this function to initialize + data structures, such as iterators, which will be used during + serialization. As we will see in subsequent chapters, there is + also a way to pass an argument to this function which may be + useful if you are serializing an in-memory data structure + to XML. The default implementation of the initialization callback + does nothing.</p> + + <p>The <code>post()</code> function is a finalization callback. It is + called when serialization of the element is completed. If necessary, + you can use this function to perform cleanups of data structures + initialized in <code>pre()</code> or during serialization. + The default implementation of the finalization callback also does + nothing. + </p> + + <p>The <code>greeting()</code> and <code>name()</code> functions are + called when the <code>greeting</code> and <code>name</code> elements + are about to be serialized and the values for these elements need + to be provided. Because the <code>name</code> element can be + repeated several times (note the <code>maxOccurs="unbounded"</code> + attribute in the schema), the serializer skeleton also has the + <code>name_next()</code> function which is called before + <code>name()</code> to check if another <code>name</code> element + needs to be serialized.</p> + + <p>The last three functions are for connecting serializers to each other. + For example, there is a predefined serializer for built-in XML Schema + type <code>string</code> in the XSD/e runtime. We will be using it to + serialize the values of <code>greeting</code> and <code>name</code> + elements, as shown in the next section.</p> + + <h2><a name="2.3">2.3 Implementing Application Logic</a></h2> + + <p>At this point we have all the parts we need to create our + sample XML document. The first step is to implement the + serializer: + </p> + + <pre class="c++"> +#include <string> +#include <vector> +#include "hello-sskel.hxx" + +struct hello_simpl: hello_sskel +{ + hello_simpl () + { + names_.push_back ("sun"); + names_.push_back ("moon"); + names_.push_back ("world"); + } + + virtual void + pre () + { + i_ = names_.begin (); + } + + virtual std::string + greeting () + { + return "Hello"; + } + + virtual bool + name_next () + { + return i_ != names_.end (); + } + + virtual std::string + name () + { + return *i_++; + } + +private: + typedef std::vector<std::string> names; + + names names_; + names::iterator i_; +}; + </pre> + + <p>We use the <code>hello_simpl</code>'s constructor to initialize + a vector of names. Then, in the <code>pre()</code> initialization + callback, we initialize an iterator to point to the beginning of the + names vector. The <code>greeting()</code> callback + simply returns the string representing our greeting. The + <code>name_next()</code> callback checks if we reached the + end of the names vector and returns <code>false</code> + if that's the case. The <code>name()</code> callback returns + the next name from the names vector and advances the iterator. + Note that <code>name()</code> is not called if <code>name_next()</code> + returned false. Finally, we left <code>post()</code> with the + default implementations since we don't have anything to cleanup.</p> + + <p>Now it is time to put this serializer implementation to work:</p> + + <pre class="c++"> +#include <iostream> + +using namespace std; + +int +main () +{ + try + { + // Construct the serializer. + // + xml_schema::string_simpl string_s; + hello_simpl hello_s; + + hello_s.greeting_serializer (string_s); + hello_s.name_serializer (string_s); + + // Create the XML document. + // + xml_schema::document_simpl doc_s (hello_s, "hello"); + + hello_s.pre (); + doc_s.serialize (cout); + hello_s.post (); + } + catch (const xml_schema::serializer_exception& e) + { + cerr << "error: " << e.text () << endl; + return 1; + } +} + </pre> + + <p>The first part of this code snippet instantiates individual serializers + and assembles them into a complete vocabulary serializer. + <code>xml_schema::string_simpl</code> is an implementation of a + serializer for built-in XML Schema type <code>string</code>. It is + provided by the XSD/e runtime along with serializers for other built-in + types (for more information on the built-in serializers see + <a href="#7">Chapter 7, "Built-In XML Schema Type Serializers"</a>). + We use <code>string_simpl</code> to serialize the <code>greeting</code> + and <code>name</code> elements as indicated by the calls to + <code>greeting_serializer()</code> and <code>name_serializer()</code>. + </p> + + <p>Then we instantiate a document serializer (<code>doc_s</code>). The + first argument to its constructor is the serializer for the root + element (<code>hello_s</code> in our case). The second argument is + the root element name. + </p> + + <p>The final piece is the calls to <code>pre()</code>, + <code>serialize()</code>, and <code>post()</code>. The call to + <code>serialize()</code> performs the actual XML serialization + with the result written to <code>std::cout</code>. The calls + to <code>pre()</code> and <code>post()</code> make sure that + the serializer for the root element can perform proper + initialization and cleanup.</p> + + <p>While our serializer implementation and test driver are pretty small and + easy to write by hand, for bigger XML vocabularies it can be a + substantial effort. To help with this task XSD/e can automatically + generate sample serializer implementations and a test driver from your + schemas. To request the generation of a sample implementation with + empty function bodies specify the <code>--generate-empty-impl</code> + option. To request the generation of a test driver you can use the + <code>--generate-test-driver</code> option. For more information + on these options refer to the + <a href="http://www.codesynthesis.com/projects/xsde/documentation/xsde.xhtml">XSD/e + Compiler Command Line Manual</a>.</p> + + <h2><a name="2.4">2.4 Compiling and Running</a></h2> + + <p>After saving all the parts from the previous section in + <code>driver.cxx</code>, we are ready to compile and run + our first application. On UNIX this can be done with the + following commands: + </p> + + <pre class="terminal"> +$ c++ -I.../libxsde -c driver.cxx hello-sskel.cxx +$ c++ -o driver driver.o hello-sskel.o .../libxsde/xsde/libxsde.a +$ ./driver +<hello> + <greeting>Hello</greeting> + <name>sun</name> + <name>moon</name> + <name>world</name> +</hello> + </pre> + + <p>Here <code>.../libxsde</code> represents the path to the + <code>libxsde</code> directory in the XSD/e distribution.</p> + + <p> + We can also test XML Schema validation. We can "forget" to + add any names to the vector so that <code>name_next()</code> + returns <code>false</code> on the first call:</p> + +<pre class="c++"> +struct hello_simpl: hello_sskel +{ + hello_simpl () + { + /* + names_.push_back ("sun"); + names_.push_back ("moon"); + names_.push_back ("world"); + */ + } + ... +}; + </pre> + + <p>This will violate our vocabulary specification which requires + at least one <code>name</code> element to be present. If we + make the above change and recompile our application, we will + get the following output:</p> + + <pre class="terminal"> +$ ./driver +error: expected element not encountered + </pre> + + + <!-- Chapater 3 --> + + + <h1><a name="3">3 Serializer Skeletons</a></h1> + + <p>As we have seen in the previous chapter, the XSD/e compiler generates + a serializer skeleton class for each type defined in XML Schema. In + this chapter we will take a closer look at different functions + that comprise a serializer skeleton as well as the way to connect + our implementations of these serializer skeletons to create a complete + vocabulary serializer.</p> + + <p>In this and subsequent chapters we will use the following + schema that describes a collection of person records. We + save it in <code>people.xsd</code>:</p> + + <pre class="xml"> +<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> + + <xs:simpleType name="gender"> + <xs:restriction base="xs:string"> + <xs:enumeration value="male"/> + <xs:enumeration value="female"/> + </xs:restriction> + </xs:simpleType> + + <xs:complexType name="person"> + <xs:sequence> + <xs:element name="first-name" type="xs:string"/> + <xs:element name="last-name" type="xs:string"/> + <xs:element name="gender" type="gender"/> + <xs:element name="age" type="xs:short"/> + </xs:sequence> + </xs:complexType> + + <xs:complexType name="people"> + <xs:sequence> + <xs:element name="person" type="person" maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <xs:element name="people" type="people"/> + +</xs:schema> + </pre> + + <p>A sample XML instance to go along with this schema could look like + this:</p> + + <pre class="xml"> +<people> + <person> + <first-name>John</first-name> + <last-name>Doe</last-name> + <gender>male</gender> + <age>32</age> + </person> + <person> + <first-name>Jane</first-name> + <last-name>Doe</last-name> + <gender>female</gender> + <age>28</age> + </person> +</people> + </pre> + + <p>Compiling <code>people.xsd</code> with the XSD/e compiler results + in three serializer skeletons being generated: <code>gender_sskel</code>, + <code>person_sskel</code>, and <code>people_sskel</code>. We are going + to examine and implement each of them in the subsequent sections.</p> + + <p>In the previous chapter we used pre-initialized, static data to + create an XML document. In this chapter we will use the standard + input (<code>std::cin</code>) as the source of data. This approach + reflects a common design theme where the data to be serialized is + computed on the fly instead of being stored in, for example, an + in-memory object model. The next chapter will examine mechanisms + provided by the C++/Serializer mapping for serializing in-memory + object models.</p> + + <h2><a name="3.1">3.1 Implementing the Gender Serializer</a></h2> + + <p>The generated <code>gender_sskel</code> serializer skeleton looks + like this:</p> + + <pre class="c++"> +class gender_sskel: public xml_schema::string_sskel +{ +public: + gender_sskel (xml_schema::string_sskel* base_impl) + + // Serializer callbacks. Override them in your implementation. + // + virtual void + pre (); + + virtual void + post (); +}; + </pre> + + <p>Notice that <code>gender_sskel</code> inherits from + <code>xml_schema::string_sskel</code> which is a serializer + skeleton for built-in XML Schema type <code>string</code> + and is predefined in the XSD/e runtime library. This is an example + of the general rule that serializer skeletons follow: if a type + in XML Schema inherits from another then there will be an + equivalent inheritance between the corresponding serializer + skeleton classes. The <code>gender_sskel</code> class also + declares a constructor which expects a pointer to the base + serializer skeleton. We will discuss the purpose of this + constructor shortly.</p> + + <p>The <code>pre()</code> and <code>post()</code> callbacks should look + familiar from the previous chapter. Let's now implement this + serializer. Our implementation will simply query the gender + value from the standard input stream (<code>std::cin</code>):</p> + + + <pre class="c++"> +#include <string> +#include <iostream> + +using namespace std; + +class gender_simpl: public gender_sskel +{ +public: + gender_simpl () + : gender_sskel (&base_impl_) + { + } + + virtual void + pre () + { + string g; + cerr << "gender (male/female): "; + getline (cin, g); + base_impl_.pre (g); + } + +private: + xml_schema::string_simpl base_impl_; +}; + </pre> + + <p>While the code is quite short, there is a lot going on. First, + notice that we define a member variable <code>base_impl_</code> + of type <code>xml_schema::string_simpl</code> and then pass + it to the <code>gender_sskel</code>'s constructor. We have + encountered <code>xml_schema::string_simpl</code> already; it is an + implementation of the <code>xml_schema::string_sskel</code> serializer + skeleton for built-in XML Schema type <code>string</code>. By + passing <code>base_impl_</code> to the <code>gender_sskel</code>'s + constructor we provide an implementation for the part of the + serializer skeleton that is inherited from <code>string_sskel</code>.</p> + + <p>This is another common theme in the C++/Serializer programming model: + reusing implementations of the base serializers in the derived ones. + In our case, <code>string_simpl</code> will do all the dirty work of + serializing the data which we pass to it with the call to + <code>base_impl_.pre()</code>. For more information on serializer + implementation reuse refer to <a href="#6.6">Section 6.6, + "Serializer Reuse"</a>.</p> + + <p>In case you are curious, here are the definitions for + <code>xml_schema::string_sskel</code> and + <code>xml_schema::string_simpl</code>:</p> + + <pre class="c++"> +namespace xml_schema +{ + class string_sskel: public serializer_simple_content + { + public: + virtual void + pre (const std::string&) = 0; + }; + + class string_simpl: public string_sskel + { + public: + virtual void + pre (const std::string&); + + virtual void + _serialize_content (); + + protected: + std::string value_; + }; +} + </pre> + + <p>There are two new pieces in this code that we haven't seen yet. + Those are the <code>xml_schema::serializer_simple_content</code> + class and the <code>_serialize_content()</code> function. + The <code>serializer_simple_content</code> class is defined in + the XSD/e runtime and is a base class for all serializer skeletons + that conform to the simple content model in XML Schema. Types with + the simple content model cannot have nested elements—only + text and attributes. There is also the + <code>xml_schema::serializer_complex_content</code> class which + corresponds to the complex content mode (types with nested elements, + for example, <code>person</code> from <code>people.xsd</code>).</p> + + <p>The <code>_serialize_content()</code> function is a low-level + serializer callback that is called to perform actual content + serialization (that is to output text or nested elements). There + is also the <code>_serialize_attributes()</code> callback which + is called to serialize attributes in complex types. You will seldom + need to use these callbacks directly. Using implementations for the + built-in serializers provided by the XSD/e runtime is usually a + simpler and more convenient alternative.</p> + + <p>Another bit of information that is useful to know about is + the <code>_pre()</code> and <code>_post()</code> serialization + callbacks. Remember we talked about the <code>pre()</code> and + <code>post()</code> callbacks in the previous chapter? The + <code>_pre()</code> and <code>_post</code> have very + similar but somewhat different roles. As a result, each + serializer skeleton has four special callbacks:</p> + + <pre class="c++"> + virtual void + pre (); + + virtual void + _pre (); + + virtual void + _post (); + + virtual void + post (); + </pre> + + <p><code>pre()</code> and <code>_pre()</code> are initialization + callbacks. They get called in that order before a new instance of the type + is about to be serialized. The difference between <code>pre()</code> and + <code>_pre()</code> is conventional: <code>pre()</code> can + be completely overridden by a derived serializer. The derived + serializer can also override <code>_pre()</code> but has to always call + the original version. This allows you to partition initialization + into customizable and required parts.</p> + + <p>Similarly, <code>_post()</code> and <code>post()</code> are + finalization callbacks with exactly the same semantics: + <code>post()</code> can be completely overridden by the derived + serializer while the original <code>_post()</code> should always be + called. + </p> + + <p>At this point you might be wondering why some <code>pre()</code> + callbacks, for example <code>string_sskel::pre()</code>, have an + argument with which they receive the data they need to serialize while + others, for example <code>gender_sskel::pre()</code>, have no such + argument. This is a valid concern and it will be addressed in the + next chapter.</p> + + <h2><a name="3.2">3.2 Implementing the Person Serializer</a></h2> + + <p>The generated <code>person_sskel</code> serializer skeleton looks like + this:</p> + + <pre class="c++"> +class person_sskel: public xml_schema::serializer_complex_content +{ +public: + // Serializer callbacks. Override them in your implementation. + // + virtual void + pre (); + + virtual std::string + first_name () = 0; + + virtual std::string + last_name () = 0; + + virtual void + gender (); + + virtual short + age () = 0; + + virtual void + post (); + + // Serializer construction API. + // + void + first_name_serializer (xml_schema::string_sskel&); + + void + last_name_serializer (xml_schema::string_sskel&); + + void + gender_serializer (gender_sskel&); + + void + age_serializer (xml_schema::short_sskel&); + + void + serializers (xml_schema::string_sskel& /* first-name */, + xml_schema::string_sskel& /* last-name */, + gender_sskel& /* gender */, + xml_schema::short_sskel& /* age */); +}; + </pre> + + + <p>As you can see, we have a serializer callback for each of the nested + elements found in the <code>person</code> XML Schema type. + The implementation of this serializer is straightforward:</p> + + <pre class="c++"> +class person_simpl: public person_sskel +{ +public: + virtual string + first_name () + { + string fn; + cerr << "first name: "; + getline (cin, fn); + return fn; + } + + virtual std::string + last_name () + { + string ln; + cerr << "last name: "; + getline (cin, ln); + return ln; + } + + virtual short + age () + { + short a; + cerr << "age: "; + cin >> a; + return a; + } +}; + </pre> + + <p>Notice that we didn't need to override the <code>gender()</code> + callback because all the work is done by <code>gender_simpl</code>.</p> + + <h2><a name="3.3">3.3 Implementing the People Serializer</a></h2> + + <p>The generated <code>people_sskel</code> serializer skeleton looks like + this:</p> + + <pre class="c++"> +class people_sskel: public xml_schema::serializer_complex_content +{ +public: + // Serializer callbacks. Override them in your implementation. + // + virtual void + pre (); + + virtual bool + person_next () = 0; + + virtual void + person (); + + virtual void + post (); + + // Serializer construction API. + // + void + person_serializer (person_sskel&); + + void + serializers (person_sskel& /* person */); +}; + </pre> + + <p>The <code>person_next()</code> callback will be called before serializing + each <code>person</code> element. Our implementation of + <code>person_next()</code> asks the user whether to serialize + another person record:</p> + + <pre class="c++"> +class people_simpl: public people_sskel +{ +public: + virtual bool + person_next () + { + string s; + cerr << "serialize another person record (y/n): "; + cin >> ws; // Skip leading whitespaces. + getline (cin, s); + return s == "y"; + } +}; + </pre> + + <p>Now it is time to put everything together.</p> + + + <h2><a name="3.4">3.4 Connecting the Serializers Together</a></h2> + + <p>At this point we have all the individual serializers implemented + and can proceed to assemble them into a complete serializer + for our XML vocabulary. The first step is to instantiate + all the individual serializers that we will need:</p> + + <pre class="c++"> +xml_schema::short_simpl short_s; +xml_schema::string_simpl string_s; + +gender_simpl gender_s; +person_simpl person_s; +people_simpl people_s; + </pre> + + <p>Notice that our schema uses two built-in XML Schema types: + <code>string</code> for the <code>first-name</code> and + <code>last-name</code> elements as well as <code>short</code> + for <code>age</code>. We will use predefined serializers that + come with the XSD/e runtime to serialize these types. The next + step is to connect all the individual serializers. We do this + with the help of functions defined in the serializer + skeletons and marked with the "Serializer Construction API" + comment. One way to do it is to connect each individual + serializers by calling the <code>*_serializer()</code> functions:</p> + + <pre class="c++"> +person_s.first_name_serializer (string_s); +person_s.last_name_serializer (string_s); +person_s.gender_serializer (gender_s); +person_s.age_serializer (short_s); + +people_s.person_serializer (person_s); + </pre> + + <p>You might be wondering what happens if you do not provide + a serializer by not calling one of the <code>*_serializer()</code> + functions. In that case the corresponding XML fragment will be + skipped.</p> + + <p>An alternative, shorter, way to connect the serializers is by using + the <code>serializers()</code> functions which connects all the + serializers for a given type at once:</p> + + <pre class="c++"> +person_s.serializers (string_s, string_s, gender_s, short_s); +people_s.serializers (person_s); + </pre> + + <p>The following figure illustrates the resulting connections. Notice + the correspondence between return types of element callbacks and + argument types of the <code>pre()</code> functions that are connected + by the arrows.</p> + + <!-- align=center is needed for html2ps --> + <div class="img" align="center"><img src="figure-1.png"/></div> + + <p>The last step is the construction of the document serializer and + invocation of the complete serializer to produce an XML + document:</p> + + <pre class="c++"> +xml_schema::document_simpl doc_s (people_s, "people"); + +std::ostringstream os; + +people_s.pre (); +doc_s.serialize (os); +people_s.post (); + +cout << os.str (); + </pre> + + <p>Note that we first serialize the document into an + <code>std::ostringstream</code> object and then write + the result to the standard output stream. This is done + to prevent the input prompts and output XML from interleaving. + However, writing XML directly to <code>std::cout</code> in + this example is a great way to observe the moments in the XML + document construction process at which serializer callbacks are + being called.</p> + + <p>Let's consider <code>xml_schema::document_simpl</code> in + more detail. While the exact definition of this class + varies depending on the mapping configuration, here is + the part relevant to our example:</p> + + <pre class="c++"> +namespace xml_schema +{ + class document_simpl + { + public: + document_simpl (xml_schema::serializer_base&, + const std::string& root_element_name); + + document_simpl (xml_schema::serializer_base&, + const std::string& root_element_namespace, + const std::string& root_element_name); + + void + serialize (std::ostream&); + }; +} + </pre> + + <p><code>xml_schema::document_simpl</code> is a root serializer for + the vocabulary. The first argument to its constructors is the + serializer for the type of the root element (<code>people_simpl</code> + in our case). Because a type serializer is only concerned with + the element's content and not with the element's name, we need + to specify the root element name somewhere. That's + what is passed as the second and third arguments to the + <code>document_simpl</code>'s constructors.</p> + + <p>There is also a number of overloaded <code>serialize()</code> + function defined in the <code>document_simpl</code> class. + At the moment we are only interested in the version that + writes XML to a standard output stream. For more information + on the <code>xml_schema::document_simpl</code> class + refer to <a href="#8">Chapter 8, "Document Serializer and Error + Handling"</a>.</p> + + <p>Let's now consider a step-by-step list of actions that happen + as we serialize the following sample XML document:</p> + + <pre class="xml"> +<people> + <person> + <first-name>John</first-name> + <last-name>Doe</last-name> + <gender>male</gender> + <age>32</age> + </person> +</people> + </pre> + + + <ol class="steps"> + <li><code>people_s.pre()</code> is called from + <code>main()</code>. We did not provide any implementation + for this callback so this call is a no-op.</li> + + <li><code>doc_s.serialize(os)</code> is called from + <code>main()</code>. The document serializer + writes out the <code><people></code> opening tag + and calls <code>_pre()</code> on the root element + type serializer (<code>people_s</code>) which is + also a no-op. Serialization is delegated to + <code>people_s</code>.</li> + + <li>The <code>people_s</code> serializer calls <code>person_next()</code> + to determine if another <code>person</code> element + needs to be serialized. Our implementation ask the user + (who answers <code>"y"</code>) and returns <code>true</code>.</li> + + <li>The <code>people_s</code> serializer calls <code>person()</code> + which is a no-op. It then calls <code>pre()</code> on + <code>person_s</code> (no-op), writes out the + <code><person></code> opening tag, and calls <code>_pre()</code> + on <code>person_s</code> (no-op). Serialization is delegated to + <code>person_s</code>.</li> + + <li>The <code>person_s</code> serializer calls <code>first_name()</code> + that returns a first name which it asks the user to enter. + <code>person_s</code> then calls <code>pre()</code> on + <code>string_s</code> and passes the name returned from + <code>first_name()</code> as its argument. It then writes + out the <code><first-name></code> opening tag and calls + <code>_pre()</code> on <code>string_s</code>. Serialization + is delegated to <code>string_s</code>.</li> + + <li>The <code>_serialize_content()</code> callback is called on + <code>string_s</code> which writes out the string passed + to it in the <code>pre()</code> call.</li> + + <li>Control is returned to <code>person_s</code> which + calls <code>_post()</code> on <code>string_s</code>, writes + out the <code></first-name></code> closing tag, and calls + <code>post()</code> on <code>string_s</code>.</li> + + <li>Steps analogous to 5-7 are performed for the <code>last-name</code>, + <code>gender</code>, and <code>age</code> elements.</li> + + <li>Control is returned to <code>people_s</code> + which calls <code>_post()</code> on <code>person_s</code> (no-op), + writes out the <code></person></code> closing tag, and calls + <code>post()</code> on <code>person_s</code> (no-op).</li> + + <li>The <code>people_s</code> serializer calls <code>person_next()</code> + to determine if another <code>person</code> element + needs to be serialized. Our implementation ask the user + (who answers <code>"n"</code>) and returns <code>false</code>.</li> + + <li>Control is returned to <code>doc_s</code> which calls + <code>_post()</code> on <code>people_s</code> (no-op) and + writes out the <code></people></code> closing tag.</li> + + <li>Control is returned to <code>main()</code> which + calls <code>post()</code> on <code>people_s</code> (no-op).</li> + </ol> + + + <!-- Chpater 4 --> + + + <h1><a name="4">4 Type Maps</a></h1> + + <p>There are many useful things you can do inside serializer callbacks as they + are right now. There are, however, times when you want to propagate + some information from one serializer to another or from the caller of + the serializer. One common task that would greatly benefit from such a + possibility is serializing a tree-like in-memory object model to XML. + During execution, each individual serializer would be responsible + for disaggregating and serializing a specific portion of the tree + and delegating the rest to its sub-serializers.</p> + + <p>In this chapter we will discuss the mechanisms offered by the + C++/Serializer mapping for passing information between individual + serializers and see how to use them to serialize a sample object + model for our people vocabulary.</p> + + <h2><a name="4.1">4.1 Object Model</a></h2> + + <p>An object model for our person record example could + look like this (saved in the <code>people.hxx</code> file):</p> + + <pre class="c++"> +#include <string> +#include <vector> + +enum gender +{ + male, + female +}; + +class person +{ +public: + person (const std::string& first, + const std::string& last, + ::gender gender, + short age) + : first_ (first), last_ (last), + gender_ (gender), age_ (age) + { + } + + const std::string& + first () const + { + return first_; + } + + const std::string& + last () const + { + return last_; + } + + ::gender + gender () const + { + return gender_; + } + + short + age () const + { + return age_; + } + +private: + std::string first_; + std::string last_; + ::gender gender_; + short age_; +}; + +typedef std::vector<person> people; + </pre> + + <p>While it is clear which serializer is responsible for which part of + the object model, it is not exactly clear how, for + example, <code>person_simpl</code> will pass <code>gender</code> + to <code>gender_simpl</code>. You might have noticed that + <code>string_simpl</code> manages to receive its value from the + <code>first_name()</code> callback. Let's + see how we can utilize the same mechanism to propagate our + own data.</p> + + <p>There is a way to tell the XSD/e compiler that you want to + exchange data between serializers. More precisely, for each + type defined in XML Schema, you can tell the compiler two things. + First, the argument type of the <code>pre()</code> callback + in the serializer skeleton generated for this type. And, second, + the return type for callbacks corresponding to elements and + attributes of this type. For example, for XML Schema type + <code>gender</code> we can specify the argument type for + <code>pre()</code> in the <code>gender_sskel</code> + skeleton and the return type for the <code>gender()</code> callback + in the <code>person_sskel</code> skeleton. As you might have guessed, + the generated code will then pass the return value from an + element or attribute callback (<code>person_sskel::gender()</code> + in our case) to the <code>pre()</code> callback of the corresponding + serializer skeleton (<code>gender_sskel::pre()</code> in our case).</p> + + <p>The way to tell the XSD/e compiler about these XML Schema to + C++ mappings is with type map files. Here is a simple type + map for the <code>gender</code> type from the previous paragraph.</p> + + <pre class="type-map"> +include "people.hxx"; +gender ::gender ::gender; + </pre> + + <p>The first line indicates that the generated code must include + <code>people.hxx</code> in order to get the definition for the + <code>gender</code> type. The second line specifies that both + argument and return types for the <code>gender</code> + XML Schema type should be the <code>::gender</code> C++ enum + (we use fully-qualified C++ names to avoid name clashes). + The next section will describe the type map format in more detail. + We save this type map in <code>people.map</code> and + then translate our schemas with the <code>--type-map</code> + option to let the XSD/e compiler know about our type map:</p> + + <pre class="terminal"> +$ xsde cxx-serializer --type-map people.map people.xsd + </pre> + + <p>If we now look at the generated <code>people-sskel.hxx</code>, + we will see the following changes in the <code>gender_sskel</code> and + <code>person_sskel</code> skeletons:</p> + + <pre class="c++"> +#include "people.hxx" + +class gender_sskel: public xml_schema::string_sskel +{ + virtual void + pre (::gender) = 0; + + ... +}; + +class person_sskel: public xml_schema::serializer_complex_content +{ + virtual ::gender + gender () = 0; + + ... +}; + </pre> + + <p>Notice that <code>#include "people.hxx"</code> was added to + the generated header file from the type map to provide the + definition for the <code>gender</code> enum.</p> + + <h2><a name="4.2">4.2 Type Map File Format</a></h2> + + <p>Type map files are used to define a mapping between XML Schema + and C++ types. The compiler uses this information + to determine argument types of <code>pre()</code> + callbacks in serializer skeletons corresponding to XML Schema + types as well as return types for callbacks corresponding + to elements and attributes of these types.</p> + + <p>The compiler has a set of predefined mapping rules that map + the built-in XML Schema types to suitable C++ types (discussed + below) and all other types to <code>void</code>. + By providing your own type maps you can override these predefined + rules. The format of the type map file is presented below: + </p> + + <pre class="type-map"> +namespace <schema-namespace> [<cxx-namespace>] +{ + (include <file-name>;)* + ([type] <schema-type> <cxx-ret-type> [<cxx-arg-type>];)* +} + </pre> + + <p>Both <code><i><schema-namespace></i></code> and + <code><i><schema-type></i></code> are regex patterns while + <code><i><cxx-namespace></i></code>, + <code><i><cxx-ret-type></i></code>, and + <code><i><cxx-arg-type></i></code> are regex pattern + substitutions. All names can be optionally enclosed in + <code>" "</code>, for example, to include white-spaces.</p> + + <p><code><i><schema-namespace></i></code> determines XML + Schema namespace. Optional <code><i><cxx-namespace></i></code> + is prefixed to every C++ type name in this namespace declaration. + <code><i><cxx-ret-type></i></code> is a C++ type name that is + used as a return type for the element and attribute callbacks corresponding + to this schema type. Optional <code><i><cxx-arg-type></i></code> + is an argument type for the <code>pre()</code> callback in the serializer + skeleton for this schema type. If <code><i><cxx-arg-type></i></code> + is not specified, it defaults to <code><i><cxx-ret-type></i></code> + if <code><i><cxx-ret-type></i></code> ends with <code>*</code> or + <code>&</code> (that is, it is a pointer or a reference) and + <code>const <i><cxx-ret-type></i>&</code> + otherwise. + <code><i><file-name></i></code> is a file name either in the + <code>" "</code> or <code>< ></code> format + and is added with the <code>#include</code> directive to + the generated code.</p> + + <p>The <code><b>#</b></code> character starts a comment that ends + with a new line or end of file. To specify a name that contains + <code><b>#</b></code> enclose it in <code><b>" "</b></code>. + For example:</p> + + <pre> +namespace http://www.example.com/xmlns/my my +{ + include "my.hxx"; + + # Pass apples by value. + # + apple apple; + + # Pass oranges as pointers. + # + orange orange_t*; +} + </pre> + + <p>In the example above, for the + <code>http://www.example.com/xmlns/my#orange</code> + XML Schema type, the <code>my::orange_t*</code> C++ type will + be used as both return and argument types.</p> + + <p>Several namespace declarations can be specified in a single + file. The namespace declaration can also be completely + omitted to map types in a schema without a namespace. For + instance:</p> + + <pre class="type-map"> +include "my.hxx"; +apple apple; + +namespace http://www.example.com/xmlns/my +{ + orange "const orange_t*"; +} + </pre> + + <p>The compiler has a number of predefined mapping rules for + the built-in XML Schema types which can be presented as the + following map files:</p> + + <pre class="type-map"> +namespace http://www.w3.org/2001/XMLSchema +{ + boolean bool bool; + + byte "signed char" "signed char"; + unsignedByte "unsigned char" "unsigned char"; + + short short short; + unsignedShort "unsigned short" "unsigned short"; + + int int int; + unsignedInt "unsigned int" "unsigned int"; + + long "long long" "long long"; + unsignedLong "unsigned long long" "unsigned long long"; + + integer long long; + + negativeInteger long long; + nonPositiveInteger long long; + + positiveInteger "unsigned long" "unsigned long"; + nonNegativeInteger "unsigned long" "unsigned long"; + + float float float; + double double double; + decimal double double; + + NMTOKENS "const xml_schema::string_sequence*"; + IDREFS "const xml_schema::string_sequence*"; + + base64Binary "const xml_schema::buffer*"; + hexBinary "const xml_schema::buffer*"; + + date xml_schema::date; + dateTime xml_schema::date_time; + duration xml_schema::duration; + gDay xml_schema::gday; + gMonth xml_schema::gmonth; + gMonthDay xml_schema::gmonth_day; + gYear xml_schema::gyear; + gYearMonth xml_schema::gyear_month; + time xml_schema::time; +} + </pre> + + <p>If STL is enabled (<a href="#6.1">Section 6.1, "Standard Template + Library"</a>), the following mapping is used for the string-based + XML Schema built-in types:</p> + + <pre class="type-map"> +namespace http://www.w3.org/2001/XMLSchema +{ + include <string>; + + string std::string; + normalizedString std::string; + token std::string; + Name std::string; + NMTOKEN std::string; + NCName std::string; + ID std::string; + IDREF std::string; + language std::string; + anyURI std::string; + + QName xml_schema::qname; +} + </pre> + + <p>Otherwise, a C string-based mapping is used:</p> + + <pre class="type-map"> +namespace http://www.w3.org/2001/XMLSchema +{ + string "const char*"; + normalizedString "const char*"; + token "const char*"; + Name "const char*"; + NMTOKEN "const char*"; + NCName "const char*"; + ID "const char*"; + IDREF "const char*"; + language "const char*"; + anyURI "const char*"; + + QName "const xml_schema::qname*"; +} + </pre> + + <p>For more information about the mapping of the built-in XML Schema types + to C++ types refer to <a href="#7">Chapter 7, "Built-In XML Schema Type + Serializers"</a>. The last predefined rule maps anything that wasn't + mapped by previous rules to <code>void</code>:</p> + + <pre class="type-map"> +namespace .* +{ + .* void void; +} + </pre> + + + <p>When you provide your own type maps with the + <code>--type-map</code> option, they are evaluated first. This + allows you to selectively override any + of the predefined rules. Note also that if you change the mapping + of a built-in XML Schema type then it becomes your responsibility + to provide the corresponding serializer skeleton and implementation + in the <code>xml_schema</code> namespace. You can include the + custom definitions into the generated header file using the + <code>--hxx-prologue-*</code> options.</p> + + <h2><a name="4.3">4.3 Serializer Implementations</a></h2> + + <p>With the knowledge from the previous section, we can proceed + with creating a type map that maps types in the <code>people.xsd</code> + schema to our object model classes in + <code>people.hxx</code>. In fact, we already have the beginning + of our type map file in <code>people.map</code>. Let's extend + it with the rest of the types:</p> + + <pre class="type-map"> +include "people.hxx"; + +gender ::gender ::gender; +person "const ::person&"; +people "const ::people&"; + </pre> + + <p>A few things to note about this type map. We decided to pass + the <code>person</code> and <code>people</code> objects by + constant references in order to avoid unnecessary copying. + We can do this because we know that our object model is + present for the duration of serialization. We also did not + provide any mappings for built-in XML Schema types + <code>string</code> and <code>short</code> because they + are handled by the predefined rules and we are happy with + the result. Note also that all C++ types are fully qualified. + This is done to avoid potential name conflicts in the generated + code. Now we can recompile our schema and move on to implementing + the serializers:</p> + + <pre class="terminal"> +$ xsde cxx-serializer --type-map people.map people.xsd + </pre> + + <p>Here is the implementation of our three serializers in full. One + way to save typing when implementing your own serializers is + to open the generated code and copy the signatures of serializer + callbacks into your code. Or you could always auto generate the + sample implementations and fill them with your code.</p> + + <pre class="c++"> +#include "people-sskel.hxx" + +const char* gender_strings[] = {"male", "female"}; + +class gender_simpl: public gender_sskel +{ +public: + gender_simpl () + : gender_sskel (&base_impl_) + { + } + + virtual void + pre (gender g) + { + base_impl_.pre (gender_strings[g]); + } + +private: + xml_schema::string_simpl base_impl_; +}; + +class person_simpl: public person_sskel +{ +public: + virtual void + pre (const person& p) + { + p_ = &p; + } + + virtual std::string + first_name () + { + return p_->first (); + } + + virtual std::string + last_name () + { + return p_->last (); + } + + virtual ::gender + gender () + { + return p_->gender (); + } + + virtual short + age () + { + return p_->age (); + } + +private: + const person* p_; +}; + +class people_simpl: public people_sskel +{ +public: + virtual void + pre (const people& p) + { + p_ = &p; + i_ = p_->begin (); + } + + virtual bool + person_next () + { + return i_ != p_->end (); + } + + virtual const ::person& + person () + { + return *i_++; + } + +private: + const people* p_; + people::const_iterator i_; +}; + </pre> + + <p>This code fragment should look familiar by now. Just note that + all the <code>pre()</code> callbacks now have arguments. Here is the + implementation of the test driver for this example:</p> + + <pre class="c++"> +#include <iostream> + +using namespace std; + +int +main () +{ + // Create a sample object model. + // + people ppl; + + ppl.push_back (person ("John", "Doe", male, 32)); + ppl.push_back (person ("Jane", "Doe", female, 28)); + + // Construct the serializer. + // + xml_schema::short_simpl short_s; + xml_schema::string_simpl string_s; + + gender_simpl gender_s; + person_simpl person_s; + people_simpl people_s; + + person_s.serializers (string_s, string_s, gender_s, short_s); + people_s.serializers (person_s); + + // Create the XML document. + // + xml_schema::document_simpl doc_s (people_s, "people"); + + people_s.pre (ppl); + doc_s.serialize (cout); + people_s.post (); +} + </pre> + + <p>The serializer creation and assembly part is exactly the same as in + the previous chapter. The serialization part is a bit different: + <code>people_simpl::pre()</code> now has an argument which is the + complete object model. Also we write the resulting XML directly + to the standard output stream instead of first storing it in a string. + We can now save the last two code fragments to <code>driver.cxx</code> + and proceed to compile and test our new application:</p> + + + <pre class="terminal"> +$ c++ -I.../libxsde -c driver.cxx people-sskel.cxx +$ c++ -o driver driver.o people-sskel.o .../libxsde/xsde/libxsde.a +$ ./driver +<people> + <person> + <first-name>John</first-name> + <last-name>Doe</last-name> + <gender>male</gender> + <age>32</age> + </person> + <person> + <first-name>Jane</first-name> + <last-name>Doe</last-name> + <gender>female</gender> + <age>28</age> + </person> +</people> + </pre> + + + <!-- Serializer Callbacks --> + + <h1><a name="5">5 Serializer Callbacks</a></h1> + + <p>In previous chapters we have learned that for each attribute + and element in a schema type there is a callback in a serializer + skeleton with the same name and which optionally returns + this element's or attribute's value. We've also seen that + elements that can appear multiple times + (<code>maxOccurs="unbounded"</code>) have an additional + serializer callback in the form:</p> + + <pre class="c++"> +virtual bool +<name>_next (); + </pre> + + <p>Where <code><name></code> stands for the element's name. In + this chapter we will discuss other additional serializer + callbacks that are generated for certain XML Schema constructs. + We will also learn that besides elements and attributes, serializer + callback can be generated for the <code>all</code>, <code>choice</code>, + and <code>sequence</code> compositors as well as the <code>any</code> + and <code>anyAttribute</code> wildcards.</p> + + <p>When additional serializer callback are generated for elements + and attributes, their names are derived from element's and + attribute's names. Compositors and wildcards, on the other + hand, do not have names and as a result the serializer + callback names for these constructs are based on synthesized + names in the form: <code>all</code> for the <code>all</code> + compositor, <code>sequence</code>, <code>sequence1</code>, + etc., for the <code>sequence</code> compositors, <code>choice</code>, + <code>choice1</code>, etc., for the <code>choice</code> compositors, + <code>any</code>, <code>any1</code>, etc., for the <code>any</code> + wildcards, and <code>any_attribute</code>, <code>any_attribute1</code>, + etc., for the <code>anyAttribute</code> wildcards. For example:</p> + + <pre> +<xs:complexType name="coordinates"> + <xs:sequence maxOccurs="unbounded"> + <xs:element name="lat" type="xs:float"/> + <xs:element name="lon" type="xs:float"/> + </xs:sequence> +</xs:complexType> + </pre> + + <p>The above schema fragment, when compiled, results in the following + serializer skeleton:</p> + + <pre class="c++"> +class coordinates_sskel: public xml_schema::serializer_complex_content +{ +public: + virtual void + pre (); + + virtual bool + sequence_next (); + + virtual float + lan () = 0; + + virtual float + lon () = 0; + + virtual void + post (); + + ... +}; + </pre> + + + <h2><a name="5.1">5.1 Optional Callback</a></h2> + + <p>For elements, compositors, and element wildcards with the minimal + occurrence constraint equals <code>0</code> (<code>minOccurs="0"</code>) + and the maximum occurrence constraint equals <code>1</code> + (<code>maxOccurs="1"</code>) as well as for optional attributes, the + optional callback is generated in the form:</p> + + <pre class="c++"> +virtual bool +<name>_present (); + </pre> + + <p>This callback is called before any other callbacks for this schema + construct and if it returns <code>false</code> no further callback + calls corresponding to this construct are made and the corresponding + XML fragment is omitted. For example:</p> + + <pre> +<xs:complexType name="name"> + <xs:sequence minOccurs="0"> + <xs:element name="first" type="xs:string"/> + <xs:element name="initial" type="xs:string" minOccurs="0"/> + <xs:element name="last" type="xs:string"/> + </xs:sequence> + <xs:attribute name="lang" type="xs:language"/> +</xs:complexType> + </pre> + + <p>The above schema fragment, when compiled, results in the following + serializer skeleton:</p> + + <pre class="c++"> +class name_sskel: public xml_schema::serializer_complex_content +{ +public: + virtual void + pre (); + + virtual bool + lang_present (); + + virtual std::string + lang () = 0; + + virtual bool + sequence_present (); + + virtual std::string + first () = 0; + + virtual bool + initial_present (); + + virtual std::string + initial () = 0; + + virtual std::string + last () = 0; + + virtual void + post (); + + ... +}; + </pre> + + <h2><a name="5.2">5.2 Sequence Callback</a></h2> + + <p>For elements, compositors, and element wildcards with the the maximum + occurrence constraint greater than <code>1</code> (for example, + <code>maxOccurs="unbounded"</code>) the sequence callback is + generated in the form:</p> + + <pre class="c++"> +virtual bool +<name>_next (); + </pre> + + <p>This callback is called before each new item of the sequence is + about to be serialized. Returning <code>false</code> from this + callback indicates that no more items in the sequence need to + be serialized. For example:</p> + + <pre> +<xs:complexType name="names"> + <xs:sequence maxOccurs="unbounded"> + <xs:element name="first" type="xs:string"/> + <xs:element name="last" type="xs:string"/> + <xs:element name="pseudonym" type="xs:string" maxOccurs="3"/> + </xs:sequence> +</xs:complexType> + </pre> + + <p>The above schema fragment, when compiled, results in the following + serializer skeleton:</p> + + <pre class="c++"> +class names_sskel: public xml_schema::serializer_complex_content +{ +public: + virtual void + pre (); + + virtual bool + sequence_next () = 0; + + virtual std::string + first () = 0; + + virtual std::string + last () = 0; + + virtual bool + pseudonym_next () = 0; + + virtual std::string + pseudonym () = 0; + + virtual void + post (); +}; + </pre> + + <h2><a name="5.3">5.3 Choice Callback</a></h2> + + <p>The choice compositor allows an XML document to contain one + of several element or compositor options. In the Embedded + C++/Serializer mapping, these options are called <em>choice + arms</em> and are identified by the <em>arm tags</em>. For + example:</p> + + <pre> +<xs:complexType name="name"> + <xs:choice> + <xs:element name="full-name" type="xs:string"/> + <xs:sequence> + <xs:element name="first-name" type="xs:string"/> + <xs:element name="last-name" type="xs:string"/> + </xs:sequence> + </xs:choice> +</xs:complexType> + </pre> + + <p>The above schema fragment, when compiled, results in the following + serializer skeleton:</p> + + <pre class="c++"> +class name_sskel: public xml_schema::serializer_complex_content +{ +public: + virtual void + pre (); + + enum choice_arm_tag + { + full_name_tag, + sequence_tag + }; + + virtual choice_arm_tag + choice_arm () = 0; + + virtual std::string + full_name () = 0; + + virtual std::string + first_name () = 0; + + virtual std::string + last_name () = 0; + + virtual void + post (); +}; + </pre> + + <p>The arm tags enum name (<code>choice_arm_tag</code> above) is derived + from the choice compositor name (that is, <code>choice</code>, + <code>choice1</code>, etc.) by adding the <code>_arm_tag</code> + suffix. The tag names themselves are derived from the corresponding + elements, compositors, or element wildcards.</p> + + <p>The choice compositor callback has a name in the form + <code>choice_tag()</code> (or <code>choice1_tag()</code>, etc., for + subsequent <code>choice</code> compositors in the type). It returns + the arm tag which identifies the choice arm that should be + serialized. For example, if a <code>name_sskel</code> implementation + returns <code>full_name_tag</code> from the <code>choice_arm()</code> + callback, then the first choice arm is chosen and + the <code>full_name()</code> callback is then called. Otherwise + the <code>first_name</code> and <code>last_name()</code> callbacks + are called.</p> + + + <h2><a name="5.4">5.4 Element Wildcard Callbacks</a></h2> + + <p>An element wildcard allows an arbitrary element from the specified + namespace list to be present in an XML instance. Element wildcards + can have the same cardinality constraints as elements and, as as a + result, the optional or sequence callbacks can be generated. For + example:</p> + + <pre> +<xs:complexType name="name"> + <xs:sequence> + <xs:element name="first" type="xs:string"/> + <xs:element name="last" type="xs:string"/> + <xs:any namespace="##other" processContents="skip" minOccurs="0"/> + </xs:sequence> +</xs:complexType> + </pre> + + <p>The above schema fragment, when compiled, results in the following + serializer skeleton:</p> + + <pre class="c++"> +class name_sskel: public xml_schema::serializer_complex_content +{ +public: + virtual void + pre (); + + virtual std::string + first () = 0; + + virtual std::string + last () = 0; + + virtual bool + any_present (); + + virtual void + any (std::string& ns, std::string& name); + + virtual void + serialize_any (); + + virtual void + post (); +}; + </pre> + + <p>The <code>any()</code> callback is called to obtain the element + name and namespace. If validation is enabled, the namespace is + checked against the allowed list. Then an element with these name + and namespace is created and the <code>serialize_any()</code> + callback is called to allow you to serialize the element's attributes + and content. There are two common ways to serialize a wildcard + element. The first approach is to use a serializer implementation. + This approach is shown in the <code>wildcard</code> example which + is part of the XSD/e distribution. The other approach is to use + the low-level XML serialization API that is available to every + serializer implementation via the + <code>xml_schema::serializer_base</code> base serializer:</p> + + <pre class="c++"> +namespace xml_schema +{ + class serializer_base + { + public: + void + _start_element (const char* name); + + void + _start_element (const char* ns, const char* name); + + void + _end_element (); + + void + _start_attribute (const char* name); + + void + _start_attribute (const char* ns, const char* name); + + void + _end_attribute (); + + void + _attribute (const char* name, const char* value); + + void + _attribute (const char* ns, const char* name, const char* value); + + void + _characters (const char*); + + void + _characters (const char*, size_t); + + void + _declare_namespace (const char* ns, const char* prefix); + + void + _declare_default_namespace (const char* ns); + + void + _clear_default_namespace (); + }; +} + </pre> + + <p>The following example shows how we could implement the + <code>name_sskel</code> skeleton using this approach:</p> + + <pre class="c++"> +class name_simpl: public name_sskel +{ +public: + virtual std::string + first () + { + return "John"; + } + + virtual ::std::string + last () + { + return "Doe"; + } + + virtual bool + any_present () + { + return true; + } + + virtual void + any (std::string& ns, std::string& name) + { + ns = "http://www.example.com/extension"; + name = "pseudonyms"; + } + + virtual void + serialize_any () + { + _attribute ("id", "jd"); + + _start_element ("pseudonym"); + _characters ("Johnny Doer"); + _end_element (); + + _start_element ("pseudonym"); + _characters ("Johnty Doo"); + _end_element (); + } +}; + </pre> + + + <h2><a name="5.5">5.5 Attribute Wildcard Callbacks</a></h2> + + <p>An attribute wildcard allows an arbitrary number of attributes from + the specified namespace list to be present in an XML instance. As a + result, the serializer callbacks for an attribute wildcard resemble + those of an element with <code>maxOccurs="unbounded"</code>. For + example:</p> + + <pre> +<xs:complexType name="name"> + <xs:sequence> + <xs:element name="first" type="xs:string"/> + <xs:element name="last" type="xs:string"/> + </xs:sequence> + <xs:anyAttribute namespace="##any" processContents="skip"/> +</xs:complexType> + </pre> + + <p>The above schema fragment, when compiled, results in the following + serializer skeleton:</p> + + <pre class="c++"> +class name_sskel: public xml_schema::serializer_complex_content +{ +public: + virtual void + pre (); + + virtual bool + any_attribute_next (); + + virtual void + any_attribute (std::string& ns, std::string& name); + + virtual void + serialize_any_attribute (); + + virtual std::string + first () = 0; + + virtual std::string + last () = 0; + + virtual void + post (); +}; + </pre> + + <p>Every time the <code>any_attribute_next()</code> callback returns + <code>true</code>, <code>any_attribute()</code> is called to obtain + the attribute name and namespace. If validation is enabled, the + namespace is checked against the allowed list. Then an attribute + with these name and namespace is created and the + <code>serialize_any_attribute()</code> callback is called to allow + you to write the attribute value, for example using one of the + serializer implementations (see the <code>wildcard</code> example + on how to do it) or the low-level <code>_characters()</code> function + (for more information about the low-level XML serialization + API see the previous section). The following example show + how we could implement the <code>name_sskel</code> skeleton + using the latter approach:</p> + + <pre class="c++"> +class name_simpl: public name_sskel +{ +public: + virtual void + pre () + { + id_written_ = false; + } + + virtual bool + any_attribute_next () + { + return !id_written_; + } + + virtual void + any_attribute (std::string& ns, std::string& name) + { + ns = ""; + name = "id"; + } + + virtual void + serialize_any_attribute () + { + _characters ("jd"); + id_written_ = true; + } + + virtual std::string + first () + { + return "John"; + } + + virtual ::std::string + last () + { + return "Doe"; + } + +private: + bool id_written_; +}; + </pre> + + + <!-- Mapping Configuration --> + + + <h1><a name="6">6 Mapping Configuration</a></h1> + + <p>The Embedded C++/Serializer mapping has a number of configuration + parameters that determine the overall properties and behavior + of the generated code, such as the use of Standard Template + Library (STL), Input/Output Stream Library (iostream), C++ + exceptions, XML Schema validation, 64-bit integer types, serializer + implementation reuse styles, and support for XML Schema polymorphism. + Previous chapters assumed that the use of STL, iostream, C++ + exceptions, and XML Schema validation were enabled. + This chapter will discuss the changes in the Embedded C++/Serializer + programming model that result from the changes to these configuration + parameters. A complete example that uses the minimal mapping + configuration is presented at the end of this chapter.</p> + + <p>In order to enable or disable a particular feature, the corresponding + configuration parameter should be set accordingly in the XSD/e runtime + library as well as specified during schema compilation with the XSD/e + command line options as described in the + <a href="http://www.codesynthesis.com/projects/xsde/documentation/xsde.xhtml">XSD/e + Compiler Command Line Manual</a>. + </p> + + <p>The Embedded C++/Serializer mapping always expects character data + supplied by the application to be in the UTF-8 encoding. The + underlying XML serializer used by the Embedded C++/Serializer + mapping produces the resulting XML in the UTF-8 encoding as + well.</p> + + <h2><a name="6.1">6.1 Standard Template Library</a></h2> + + <p>To disable the use of STL you will need to configure the XSD/e + runtime without support for STL as well as pass the + <code>--no-stl</code> option to the XSD/e compiler when + translating your schemas. When STL is disabled, all string-based + XML Schema types are mapped to C-style <code>const char*</code> + instead of <code>std::string</code>, as described in + <a href="#4.2">Section 4.2, "Type Map File Format"</a>. The + following code fragment shows changes in the + signatures of the <code>first_name()</code> and <code>last_name()</code> + callbacks from the person record example.</p> + + <pre class="c++"> +class person_sskel +{ +public: + virtual const char* + first_name (); + + virtual const char* + last_name (); + + ... +}; + </pre> + + <p>When STL is disabled, the serializer implementations for the string-based + built-in XML Schema types can be instructed to release the string + after serialization using operator <code>delete[]</code>. For more + information on how to do this refer to <a href="#7.2">Section 7.2, + "String-Based Type Serializers"</a>. + </p> + + <h2><a name="6.2">6.2 Input/Output Stream Library</a></h2> + + <p>To disable the use of iostream you will need to configure the + XSD/e runtime library without support for iostream as well as + pass the <code>--no-iostream</code> option to the XSD/e compiler + when translating your schemas. When iostream is disabled, the + following <code>serialize()</code> function in the + <code>xml_schema::document_simpl</code> class become unavailable:</p> + + <pre class="c++"> +void +serialize (std::ostream&); + </pre> + + <p>See <a href="#8.1">Section 8.1, "Document Serializer"</a> + for more information.</p> + + <h2><a name="6.3">6.3 C++ Exceptions</a></h2> + + <p>To disable the use of C++ exceptions, you will need to configure + the XSD/e runtime without support for exceptions as well as pass + the <code>--no-exceptions</code> option to the XSD/e compiler + when translating your schemas. When C++ exceptions are disabled, + the error conditions are indicated with error codes instead of + exceptions, as described in <a href="#8.3">Section 8.3, + "Error Codes"</a>. + </p> + + <h2><a name="6.4">6.4 XML Schema Validation</a></h2> + + <p>To disable support for XML Schema validation, you will need to + configure the XSD/e runtime accordingly as well as pass + the <code>--suppress-validation</code> option to the XSD/e compiler + when translating your schemas. Disabling XML Schema validation + allows to further increase the serialization performance and + reduce footprint in cases where the data being serialized is + known to be valid. + </p> + + <h2><a name="6.5">6.5 64-bit Integer Type</a></h2> + + <p>By default the 64-bit <code>long</code> and <code>unsignedLong</code> + XML Schema built-in types are mapped to the 64-bit <code>long long</code> + and <code>unsigned long long</code> fundamental C++ types. To + disable the use of these types in the mapping you will need to + configure the XSD/e runtime accordingly as well as pass + the <code>--no-long-long</code> option to the XSD/e compiler + when translating your schemas. When the use of 64-bit integral + C++ types is disabled the <code>long</code> and + <code>unsignedLong</code> XML Schema built-in types are mapped + to <code>long</code> and <code>unsigned long</code> fundamental + C++ types.</p> + + <h2><a name="6.6">6.6 Serializer Reuse</a></h2> + + <p>When one type in XML Schema inherits from another, it is + often desirable to be able to reuse the serializer implementation + corresponding to the base type in the serializer implementation + corresponding to the derived type. XSD/e provides support + for two serializer reuse styles: the so-called <em>mixin</em> + (generated when the <code>--reuse-style-mixin</code> option + is specified) and <em>tiein</em> (generated by default) styles.</p> + + <p>The compiler can also be instructed not to generate any support + for serializer reuse with the <code>--reuse-style-none</code> option. + This is mainly useful to further reduce the generated code size + when your vocabulary does not use inheritance or when you plan + to implement each serializer from scratch. Note also that the + XSD/e runtime should be configured in accordance with the + serializer reuse style used in the generated code. The remainder + of this section discusses the mixin and tiein serializer reuse + styles in more detail.</p> + + + <p>To provide concrete examples for each reuse style we will use the + following schema fragment:</p> + + <pre class="xml"> +<xs:complexType name="person"> + <xs:sequence> + <xs:element name="first-name" type="xs:string"/> + <xs:element name="last-name" type="xs:string"/> + <xs:element name="age" type="xs:short"/> + </xs:sequence> +</xs:complexType> + +<xs:complexType name="emplyee"> + <complexContent> + <extension base="person"> + <xs:sequence> + <xs:element name="position" type="xs:string"/> + <xs:element name="salary" type="xs:unsignedLong"/> + </xs:sequence> + </extension> + </complexContent> +</xs:complexType> + </pre> + + <p>The mixin serializer reuse style uses the C++ mixin idiom that + relies on multiple and virtual inheritance. Because + virtual inheritance can result in a significant object + code size increase, this reuse style should be considered + when such an overhead is acceptable and/or the vocabulary + consists of only a handful of types. When the mixin reuse + style is used, the generated serializer skeletons use virtual + inheritance, for example:</p> + + <pre class="c++"> +class person_sskel: public virtual serializer_complex_content +{ + ... +}; + +class employee_sskel: public virtual person_sskel +{ + ... +}; + </pre> + + + <p>When you implement the base serializer you also need to use + virtual inheritance. The derived serializer is implemented + by inheriting from both the derived serializer skeleton and + the base serializer implementation (that is, <em>mixing in</em> + the base serializer implementation), for example:</p> + + <pre class="c++"> +class person_simpl: public virtual person_sskel +{ + ... +}; + +class employee_simpl: public employee_sskel, + public person_simpl +{ + ... +}; + </pre> + + + <p>The tiein serializer reuse style uses delegation and normally + results in a significantly smaller object code while being + almost as convenient to use as the mixin style. When the + tiein reuse style is used, the generated derived serializer + skeleton declares a constructor which allows you to specify + the implementation of the base serializer:</p> + + <pre class="c++"> +class person_sskel: public serializer_complex_content +{ + ... +}; + +class employee_sskel: public person_sskel +{ +public: + employee_sskel (person_sskel* base_impl) + + ... +}; + </pre> + + <p>If you pass the implementation of the base serializer to this + constructor then the generated code will transparently + forward all the callbacks corresponding to the base serializer + skeleton to this implementation. You can also pass + <code>0</code> to this constructor in which case you will + need to implement the derived serializer from scratch. The + following example shows how we could implement the + <code>person</code> and <code>employee</code> serializers + using the tiein style:</p> + + <pre class="c++"> +class person_simpl: public person_sskel +{ + ... +}; + +class employee_simpl: public employee_sskel +{ +public: + employee_simpl () + : employee_sskel (&base_impl_) + { + } + + ... + +private: + person_simpl base_impl_; +}; + </pre> + + <p>Note that you cannot use the <em>tied in</em> base serializer + instance (<code>base_impl_</code> in the above code) for + serializing anything except the derived type.</p> + + <p>The ability to override the base serializer callbacks in the + derived serializer is also available in the tiein style. For + example, the following code fragment shows how we can + override the <code>age()</code> callback if we didn't + like the implementation provided by the base serializer:</p> + + <pre class="c++"> +class employee_simpl: public employee_sskel +{ +public: + employee_simpl () + : employee_sskel (&base_impl_) + { + } + + virtual short + age () + { + ... + } + + ... + +private: + person_simpl base_impl_; +}; + </pre> + + <p>In the above example the <code>age</code> element will be + handled by <code>emplyee_simpl</code> while the <code>first-name</code> + and <code>last-name</code> callbacks will still go to + <code>base_impl_</code>.</p> + + <p>It is also possible to inherit from the base serializer implementation + instead of declaring it as a member variable. This can be useful + if you need to access protected members in the base implementation + or need to override a virtual function that is not part of + the serializer skeleton interface. Note, however, that in this case + you will need to resolve a number of ambiguities with explicit + qualifications or using-declarations. For example:</p> + + + <pre class="c++"> +class person_simpl: public person_sskel +{ +public: + virtual void + pre (person* p) + { + person_ = p; + } + + ... + +protected: + person* person_; +}; + +class employee_simpl: public employee_sskel, + public person_simpl +{ +public: + employee_simpl () + : employee_sskel (static_cast<person_simpl*> (this)) + { + } + + // Resolve ambiguities. + // + using emplyee_sskel::serializers; + + virtual void + pre (employee* e) + { + person_simpl::pre (e); + } + + virtual std::string + position () + { + return static_cast<employee*> (person_)->position (); + } + + virtual unsigned int + salary () + { + return static_cast<employee*> (person_)->salary (); + } +}; + </pre> + + <h2><a name="6.7">6.7 Support for Polymorphism</a></h2> + + <p>By default the XSD/e compiler generates non-polymorphic code. If your + vocabulary uses XML Schema polymorphism in the form of <code>xsi:type</code> + and/or substitution groups, then you will need to configure the XSD/e + runtime with support for polymorphism, compile your schemas with the + <code>--generate-polymorphic</code> option to produce polymorphism-aware + code, as well as pass <code>true</code> as the last argument to the + <code>xml_schema::document</code>'s constructors. If some of your + schemas do not require support for polymorphism then you can compile + them with the <code>--runtime-polymorphic</code> option and still + use the XSD/e runtime configured with polymorphism support. + </p> + + <p>When using the polymorphism-aware generated code, you can specify + several serializers for a single element by passing a serializer map + instead of an individual serializer to the serializer connection function + for the element. One of the serializers will then be looked up and used + depending on the user-provided type information that can optionally be + set in the callback function for the element. Consider the following + schema as an example:</p> + + <pre class="xml"> +<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> + + <xs:complexType name="person"> + <xs:sequence> + <xs:element name="name" type="xs:string"/> + </xs:sequence> + </xs:complexType> + + <!-- substitution group root --> + <xs:element name="person" type="person"/> + + <xs:complexType name="superman"> + <xs:complexContent> + <xs:extension base="person"> + <xs:attribute name="can-fly" type="xs:boolean"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + <xs:element name="superman" + type="superman" + substitutionGroup="person"/> + + <xs:complexType name="batman"> + <xs:complexContent> + <xs:extension base="superman"> + <xs:attribute name="wing-span" type="xs:unsignedInt"/> + </xs:extension> + </xs:complexContent> + </xs:complexType> + + <xs:complexType name="supermen"> + <xs:sequence> + <xs:element ref="person" maxOccurs="unbounded"/> + </xs:sequence> + </xs:complexType> + + <xs:element name="supermen" type="supermen"/> + +</xs:schema> + </pre> + + <p>Conforming XML documents can use the <code>superman</code> + and <code>batman</code> types in place of the <code>person</code> + type either by specifying the type with the <code>xsi:type</code> + attributes or by using the elements from the substitution + group, for instance:</p> + + <pre class="xml"> +<supermen xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> + + <person> + <name>John Doe</name> + </person> + + <superman can-fly="false"> + <name>James "007" Bond</name> + </superman> + + <person can-fly="true" wing-span="10" xsi:type="batman"> + <name>Bruce Wayne</name> + </person> + +</supermen> + </pre> + + <p>The C++ object model for this vocabulary might look as follows:</p> + + <pre class="c++"> +#include <string> +#include <vector> + +enum type_id +{ + person_type, + superman_type, + batman_type +}; + +class person +{ +public: + virtual + ~person () {} + + person (const std::string& name) + : name_ (name) + { + } + + const std::string& + name () const + { + return name_; + } + + void + name (const std::string& n) + { + name_ = n; + } + + virtual type_id + type () const + { + return person_type; + } + +private: + std::string name_; +}; + +class superman: public person +{ +public: + superman (const std::string& name, bool can_fly) + : person (name), can_fly_ (can_fly) + { + } + + bool + can_fly () const + { + return can_fly_; + } + + void + can_fly (bool cf) + { + can_fly_ = cf; + } + + virtual type_id + type () const + { + return superman_type; + } + +private: + bool can_fly_; +}; + +class batman: public superman +{ +public: + batman (const std::string& name, unsigned int wing_span) + : superman (name, true), wing_span_ (wing_span) + { + } + + unsigned int + wing_span () const + { + return wing_span_; + } + + void + wing_span (unsigned int ws) + { + wing_span_ = ws; + } + + virtual type_id + type () const + { + return batman_type; + } + +private: + unsigned int wing_span_; +}; + +// Poor man's polymorphic sequence which also assumes ownership +// of the elements. +// +class supermen: public std::vector<person*> +{ +public: + ~supermen () + { + for (iterator i = begin (); i != end (); ++i) + delete *i; + } +}; + </pre> + + <p>Here we choose to provide our own type information. We can instead + use the standard C++ <code>typeid</code>/<code>type_info</code> + mechanism if it is available. The type map corresponding to this + object model is presented below. Notice that the <code>superman</code> + and <code>batman</code> objects are passed as a reference to + <code>person</code>:</p> + + <pre> +person "const ::person&"; +superman "const ::person&"; +batman "const ::person&"; +supermen "const ::supermen&"; + </pre> + + <p>The serializer implementations that serialize the above + C++ object model to XML are presented next:</p> + + <pre class="c++"> +class person_simpl: public person_sskel +{ +public: + virtual void + pre (const person& p) + { + person_ = &p; + } + + virtual std::string + name () + { + return person_->name (); + } + + // Derived serializer implementations need access to this + // member variable. + // +public: + const person* person_; +}; + +class superman_simpl: public superman_sskel +{ +public: + superman_simpl () + : superman_sskel (&base_impl_) + { + } + + virtual bool + can_fly () + { + return superman_ ().can_fly (); + } + + const superman& + superman_ () + { + return *static_cast<const superman*> (base_impl_.person_); + } + +private: + person_simpl base_impl_; +}; + +class batman_simpl: public batman_sskel +{ +public: + batman_simpl () + : batman_sskel (&base_impl_) + { + } + + virtual unsigned int + wing_span () + { + return batman_ ().wing_span (); + } + + const batman& + batman_ () + { + return static_cast<const batman&> (base_impl_.superman_ ()); + } + +private: + superman_simpl base_impl_; +}; + +class supermen_simpl: public supermen_sskel +{ +public: + virtual void + pre (const supermen& s) + { + supermen_ = &s; + i_ = s.begin (); + } + + virtual bool + person_next () + { + return i_ != supermen_->end (); + } + + virtual const ::person& + person () + { + const ::person& p = **i_++; + xml_schema::serializer_context& ctx = _context (); + + switch (p.type ()) + { + case person_type: + { + ctx.type_id (person_sskel::_static_type ()); + break; + } + case superman_type: + { + ctx.type_id (superman_sskel::_static_type ()); + break; + } + case batman_type: + { + ctx.type_id (batman_sskel::_static_type ()); + break; + } + } + + return p; + } + +private: + const supermen* supermen_; + supermen::const_iterator i_; +}; + </pre> + + <p>Most of the code in these serializer implementations is the same + as in the non-polymorphic case. The only part that explicitly deals + with polymorphism is the <code>person()</code> callback in the + <code>superman_simpl</code> class. In it we are translating + the type information as provided by the C++ object mode to + the type information used in the default implementation of + the serializer map (we will talk more about serializer maps + as well as the <code>_static_type()</code> function shortly). + The <code>type_id()</code> function from + <code>xml_schema::serializer_context</code> allows you to + specify optional type information which is used to look up + the corresponding serializer. Its argument is of type + <code>const void*</code> which allows you to pass + application-specific type information as an opaque pointer.</p> + + <p>The following code fragment shows how to connect the serializers + together and then use them to serialize a sample object model. + Notice that for the <code>person</code> element in the + <code>instance_s</code> serializer we specify a serializer map + instead of a specific serializer and we pass <code>true</code> as + the last argument to the document serializer constructor to indicate + that we are serializing potentially-polymorphic XML documents:</p> + + <pre class="c++"> +int +main () +{ + // Create a sample supermen catalog. To keep things simple + // the following code is not exception-safe. + // + supermen sm; + + sm.push_back (new person ("John Doe")); + sm.push_back (new superman ("James 007 Bond", false)); + sm.push_back (new batman ("Bruce Wayne", 10)); + + // Construct the serializer. + // + xml_schema::string_simpl string_s; + xml_schema::boolean_simpl boolean_s; + xml_schema::unsigned_int_simpl unsigned_int_s; + + person_simpl person_s; + superman_simpl superman_s; + batman_simpl batman_s; + + xml_schema::serializer_map_impl person_map (5); // 5 hashtable buckets + supermen_simpl supermen_s; + + person_s.serializers (string_s); + superman_s.serializers (string_s, boolean_s); + batman_s.serializers (string_s, boolean_s, unsigned_int_s); + + // Here we are specifying several serializers that can be + // used to serialize the person element. + // + person_map.insert (person_s); + person_map.insert (superman_s); + person_map.insert (batman_s); + + supermen_s.person_serializer (person_map); + + // Create the XML instance document. The last argument to the + // document's constructor indicates that we are serializing + // polymorphic XML documents. + // + xml_schema::document_simpl doc_s (supermen_s, "supermen", true); + + supermen_s.pre (sm); + doc_s.serialize (std::cout); + supermen_s.post (); +} + </pre> + + <p>When polymorphism-aware code is generated, each element's + <code>*_serializer()</code> function is overloaded to also accept + an object of the <code>xml_schema::serializer_map</code> type. + For example, the <code>supermen_sskel</code> class from the + above example looks like this:</p> + + <pre class="c++"> +class supermen_sskel: public xml_schema::serializer_complex_content +{ +public: + + ... + + // Serializer construction API. + // + void + serializers (person_sskel&); + + // Individual element serializers. + // + void + person_serializer (person_sskel&); + + void + person_serializer (xml_schema::serializer_map&); + + ... +}; + </pre> + + <p>Note that you can specify both the individual (static) serializer and + the serializer map. The individual serializer will be used when the static + element type and the dynamic type of the object being serialized are + the same. This is the case when the <code>type_id()</code> function + hasn't been called or the type information pointer is set to + <code>0</code>. Because the individual serializer for an element + is cached and no map lookup is necessary, it makes sense to specify + both the individual serializer and the serializer map when most of + the objects being serialized are of the static type and optimal + performance is important. The following code fragment shows how + to change the above example to set both the individual serializer + and the serializer map:</p> + + <pre class="c++"> +int +main () +{ + ... + + // Here we are specifying several serializers that can be + // used to serialize the person element. + // + person_map.insert (superman_s); + person_map.insert (batman_s); + + supermen_s.person_serializer (person_s); + supermen_s.person_serializer (person_map); + + ... +} + </pre> + + + <p>The <code>xml_schema::serializer_map</code> interface and its + default implementation, <code>xml_schema::serializer_map_impl</code>, + are presented below:</p> + + <pre class="c++"> +namespace xml_schema +{ + class serializer_map + { + public: + virtual serializer_base* + find (const void* type_id) const = 0; + + virtual void + reset () const = 0; + }; + + class serializer_map_impl: public serializer_map + { + public: + serializer_map_impl (size_t buckets); + + // Note that the type_id string is not copied so it should + // be valid for the lifetime of the map. + // + void + insert (const char* type_id, serializer_base&); + + // This version of insert is a shortcut that uses the string + // returned by the serializer's _dynamic_type() function. + // + void + insert (serializer_base&); + + virtual serializer_base* + find (const void* type_id) const; + + virtual void + reset () const; + + private: + serializer_map_impl (const serializer_map_impl&); + + serializer_map_impl& + operator= (const serializer_map_impl&); + + ... + }; +} + </pre> + + <p>The <code>type_id</code> argument in the <code>find()</code> virtual + function is the application-specific type information for the object + being serialized that is specified using the <code>type_id()</code> + function in the element callback. It is passed as an opaque + <code>const void*</code>. The <code>reset()</code> virtual function + is used to reset the serializers contained in the map (as opposed to + resetting or clearing the map itself). For more information on serializer + resetting refer to <a href="#8.4">Section 8.4, "Reusing Serializers + after an Error"</a>.</p> + + <p>The XSD/e runtime provided the default implementation for the + <code>xml_schema::serializer_map</code> interface, + <code>xml_schema::serializer_map_impl</code>, which uses a C string + (<code>const char*</code>) as type information. One way to + obtain a serializer's dynamic type in the form + <code>"<name> <namespace>"</code> with the space and the + namespace part absent if the type does not have a namespace + is to call the <code>_dynamic_type()</code> function on this + serializer. The static type can be obtained by calling the static + <code>_static_type()</code> function, for example + <code>person_sskel::_static_type()</code>. Both functions return + a C string (<code>const char*</code>) which is valid for as long + as the application is running.</p> + + <p>The default serializer map implementation is a hashmap. It requires + that you specify the number of buckets it will contain and it does + not support automatic table resizing. To obtain good performance the + elements to buckets ratio should be between 0.7 and 0.9. It is also + recommended to use prime numbers for bucket counts: + 53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593, 49157, 98317, + 196613, 393241. + </p> + + <p>If C++ exceptions are disabled (<a href="#5.3">Section 5.3, + "C++ Exceptions"</a>), the <code>xml_schema::serializer_map_impl</code> + class has the following additional error querying API. It can be used + to detect the out of memory errors after calls to the + <code>serializer_map_impl</code>'s constructor and <code>insert()</code> + functions.</p> + + <pre class="c++"> +namespace xml_schema +{ + class serializer_map_impl: public serializer_map + { + public: + enum error + { + error_none, + error_no_memory + }; + + error + _error () const; + + ... + }; +} + </pre> + + <p>You can also provide your own serializer map implementation which uses + custom type information. The following example shows how we can + implement our own serializer map for the above example that uses + the type information provided by the C++ object model:</p> + + <pre class="c++"> +#include <map> + +class person_serializer_map: public xml_schema::serializer_map +{ +public: + void + insert (person_sskel& p) + { + const char* dt = p._dynamic_type (); + type_id ti; + + if (strcmp (dt, person_sskel::_static_type ()) == 0) + ti = person_type; + else if (strcmp (dt, superman_sskel::_static_type ()) == 0) + ti = superman_type; + else if (strcmp (dt, batman_sskel::_static_type ()) == 0) + ti = batman_type; + else + return; + + map_[ti] = &p; + } + + virtual xml_schema::serializer_base* + find (const char* x) const + { + const person* p = static_cast<const person*> (x); + map::const_iterator i = map_.find (p->type ()); + return i != map_.end () ? i->second : 0; + } + + virtual void + reset () const + { + for (map::const_iterator i (map_.begin ()), e (map_.end ()); + i != e; ++i) + { + person_sskel* s = i->second; + s->_reset (); + } + } + +private: + typedef std::map<type_id, person_sskel*> map; + map map_; +}; + </pre> + + <p>Our custom implementation of the serializer map expects that + we pass the actual object to the <code>find()</code> function. + To account for this will need to change the + <code>supermen_simpl::person()</code> callback as follows:</p> + + <pre class="c++"> + virtual const ::person& + person () + { + const ::person& p = **i_++; + _context ().type_id (&p); + return p; + } + </pre> + + + <p>To support polymorphic serialization the XSD/e runtime and generated + code maintain a number of hashmaps that contain substitution and, if + XML Schema validation is enabled (<a href="#5.4">Section 5.4, + "XML Schema Validation"</a>), inheritance information. Because + the number of elements in these hashmaps depends on the schemas + being compiled and thus is fairly static, these hashmaps do not + perform automatic table resizing and instead the number of buckets + is specified when the XSD/e runtime is configured. To obtain good + performance the elements to buckets ratio in these hashmaps should + be between 0.7 and 0.9. The recommended way to ensure this range + is to add diagnostics code to your application as shown in the + following example:</p> + + <pre class="c++"> +int +main () +{ + // Check that the load in substitution and inheritance hashmaps + // is not too high. + // +#ifndef NDEBUG + float load = xml_schema::serializer_smap_elements (); + load /= xml_schema::serializer_smap_buckets (); + + if (load > 0.8) + { + cerr << "substitution hashmap load is " << load << endl; + cerr << "time to increase XSDE_SERIALIZER_SMAP_BUCKETS" << endl; + } + + load = xml_schema::serializer_smap_bucket_elements (); + load /= xml_schema::serializer_smap_bucket_buckets (); + + if (load > 0.8) + { + cerr << "substitution inner hashmap load is " << load << endl; + cerr << "time to increase XSDE_SERIALIZER_SMAP_BUCKET_BUCKETS" << endl; + } + + load = xml_schema::serializer_imap_elements (); + load /= xml_schema::serializer_imap_buckets (); + + if (load > 0.8) + { + cerr << "inheritance hashmap load is " << load << endl; + cerr << "time to increase XSDE_SERIALIZER_IMAP_BUCKETS" << endl; + } +#endif + + ... +} + </pre> + + <p>Most of the code presented in this section is taken from the + <code>polymorphism</code> example which can be found in the + <code>examples/cxx/serializer/</code> directory of the XSD/e distribution. + Handling of <code>xsi:type</code> and substitution groups when used + on root elements requires a number of special actions as shown in + the <code>polyroot</code> example.</p> + + <h2><a name="6.8">6.8 A Minimal Example</a></h2> + + <p>The following example is a re-implementation of the person + records example presented in <a href="#4">Chapter 4, + "Type Maps"</a>. It is intended to work without STL, + iostream, and C++ exceptions. It can be found in the + <code>examples/cxx/serializer/minimal/</code> directory of the + XSD/e distribution. The <code>people.xsd</code> schema is + compiled with the <code>--no-stl</code>, <code>--no-iostream</code>, + and <code>--no-exceptions</code> options. The object model + types in <code>people.hxx</code> have also been reimplemented + in order not to use STL types:</p> + + <pre class="c++"> +#include <stddef.h> // size_t + +enum gender +{ + male, + female +}; + +struct person +{ + const char* first_name_; + const char* last_name_; + gender gender_; + unsigned short age_; +}; + +struct people +{ + person* people_; + size_t size_; +}; + </pre> + + + <p>The following listing presents the implementation of serializer + skeletons and the test driver in full:</p> + + <pre class="c++"> +#include <stdio.h> +#include "people-sskel.hxx" + +const char* gender_strings[] = {"male", "female"}; + +class gender_simpl: public gender_sskel +{ +public: + gender_simpl () + : gender_sskel (&base_impl_) + { + } + + virtual void + pre (gender g) + { + base_impl_.pre (gender_strings[g]); + } + +private: + public xml_schema::string_simpl base_impl_; +}; + +class person_simpl: public person_sskel +{ +public: + virtual void + pre (const person& p) + { + person_ = &p; + } + + virtual const char* + first_name () + { + return person_->first_name_; + } + + virtual const char* + last_name () + { + return person_->last_name_; + } + + virtual ::gender + gender () + { + return person_->gender_; + } + + virtual unsigned short + age () + { + return person_->age_; + } + +private: + const person* person_; +}; + +class people_simpl: public people_sskel +{ +public: + virtual void + pre (const people& p) + { + i_ = 0; + people_ = &p; + } + + virtual bool + person_next () + { + return i_ < people_->size_; + } + + virtual const ::person& + person () + { + return people_->people_[i_++]; + } + +private: + size_t i_; + const people* people_; +}; + +class writer: public xml_schema::writer +{ +public: + virtual bool + write (const char* s, size_t n) + { + return fwrite (s, n, 1, stdout) == 1; + } + + virtual bool + flush () + { + return fflush (stdout) == 0; + } +}; + +int +main () +{ + // Create a sample person list. + // + people p; + + p.size_ = 2; + p.people_ = new person[p.size_]; + + if (p.people_ == 0) + { + fprintf (stderr, "error: no memory\n"); + return 1; + } + + p.people_[0].first_name_ = "John"; + p.people_[0].last_name_ = "Doe"; + p.people_[0].gender_ = male; + p.people_[0].age_ = 32; + + p.people_[1].first_name_ = "Jane"; + p.people_[1].last_name_ = "Doe"; + p.people_[1].gender_ = female; + p.people_[1].age_ = 28; + + // Construct the serializer. + // + xml_schema::unsigned_short_simpl unsigned_short_s; + xml_schema::string_simpl string_s; + + gender_simpl gender_s; + person_simpl person_s; + people_simpl people_s; + + person_s.serializers (string_s, string_s, gender_s, unsigned_short_s); + people_s.serializers (person_s); + + // Serialize. + // + typedef xml_schema::serializer_error error; + + error e; + writer w; + + do + { + xml_schema::document_simpl doc_s (people_s, "people"); + + if (e = doc_s._error ()) + break; + + people_s.pre (p); + + if (e = people_s._error ()) + break; + + doc_s.serialize (w); + + if (e = doc_s._error ()) + break; + + people_s.post (); + + e = people_s._error (); + + } while (false); + + delete[] p.people_; + + // Handle errors. + // + if (e) + { + switch (e.type ()) + { + case error::sys: + { + fprintf (stderr, "error: %s\n", e.sys_text ()); + break; + } + case error::xml: + { + fprintf (stderr, "error: %s\n", e.xml_text ()); + break; + } + case error::schema: + { + fprintf (stderr, "error: %s\n", e.schema_text ()); + break; + } + case error::app: + { + fprintf (stderr, "application error: %d\n", e.app_code ()); + break; + } + default: + break; + } + + return 1; + } + + return 0; +} + </pre> + + + <!-- Built-in XML Schema Type Serializers --> + + + <h1><a name="7">7 Built-In XML Schema Type Serializers</a></h1> + + <p>The XSD/e runtime provides serializer implementations for all built-in + XML Schema types as summarized in the following table. Declarations + for these types are automatically included into each generated + header file. As a result you don't need to include any headers + to gain access to these serializer implementations.</p> + + <!-- border="1" is necessary for html2ps --> + <table id="builtin" border="1"> + <tr> + <th>XML Schema type</th> + <th>Serializer implementation in the <code>xml_schema</code> namespace</th> + <th>Serializer argument type</th> + </tr> + + <tr> + <th colspan="3">anyType and anySimpleType types</th> + </tr> + <tr> + <td><code>anyType</code></td> + <td><code>any_type_simpl</code></td> + <td><code>void</code></td> + </tr> + <tr> + <td><code>anySimpleType</code></td> + <td><code>any_simple_type_simpl</code></td> + <td><code>void</code></td> + </tr> + + <tr> + <th colspan="3">fixed-length integral types</th> + </tr> + <!-- 8-bit --> + <tr> + <td><code>byte</code></td> + <td><code>byte_simpl</code></td> + <td><code>signed char</code></td> + </tr> + <tr> + <td><code>unsignedByte</code></td> + <td><code>unsigned_byte_simpl</code></td> + <td><code>unsigned char</code></td> + </tr> + + <!-- 16-bit --> + <tr> + <td><code>short</code></td> + <td><code>short_simpl</code></td> + <td><code>short</code></td> + </tr> + <tr> + <td><code>unsignedShort</code></td> + <td><code>unsigned_short_simpl</code></td> + <td><code>unsigned short</code></td> + </tr> + + <!-- 32-bit --> + <tr> + <td><code>int</code></td> + <td><code>int_simpl</code></td> + <td><code>int</code></td> + </tr> + <tr> + <td><code>unsignedInt</code></td> + <td><code>unsigned_int_simpl</code></td> + <td><code>unsigned int</code></td> + </tr> + + <!-- 64-bit --> + <tr> + <td><code>long</code></td> + <td><code>long_simpl</code></td> + <td><code>long long</code> or <code>long</code><br/> + <a href="#6.5">Section 6.5, "64-bit Integer Type"</a></td> + </tr> + <tr> + <td><code>unsignedLong</code></td> + <td><code>unsigned_long_simpl</code></td> + <td><code>unsigned long long</code> or + <code>unsigned long</code><br/> + <a href="#6.5">Section 6.5, "64-bit Integer Type"</a></td> + </tr> + + <tr> + <th colspan="3">arbitrary-length integral types</th> + </tr> + <tr> + <td><code>integer</code></td> + <td><code>integer_simpl</code></td> + <td><code>long</code></td> + </tr> + <tr> + <td><code>nonPositiveInteger</code></td> + <td><code>non_positive_integer_simpl</code></td> + <td><code>long</code></td> + </tr> + <tr> + <td><code>nonNegativeInteger</code></td> + <td><code>non_negative_integer_simpl</code></td> + <td><code>unsigned long</code></td> + </tr> + <tr> + <td><code>positiveInteger</code></td> + <td><code>positive_integer_simpl</code></td> + <td><code>unsigned long</code></td> + </tr> + <tr> + <td><code>negativeInteger</code></td> + <td><code>negative_integer_simpl</code></td> + <td><code>long</code></td> + </tr> + + <tr> + <th colspan="3">boolean types</th> + </tr> + <tr> + <td><code>boolean</code></td> + <td><code>boolean_simpl</code></td> + <td><code>bool</code></td> + </tr> + + <tr> + <th colspan="3">fixed-precision floating-point types</th> + </tr> + <tr> + <td><code>float</code></td> + <td><code>float_simpl</code></td> + <td><code>float</code><br/> + <a href="#7.1">Section 7.1, "Floating-Point Type Serializers"</a></td> + </tr> + <tr> + <td><code>double</code></td> + <td><code>double_simpl</code></td> + <td><code>double</code><br/> + <a href="#7.1">Section 7.1, "Floating-Point Type Serializers"</a></td> + </tr> + + <tr> + <th colspan="3">arbitrary-precision floating-point types</th> + </tr> + <tr> + <td><code>decimal</code></td> + <td><code>decimal_simpl</code></td> + <td><code>double</code><br/> + <a href="#7.1">Section 7.1, "Floating-Point Type Serializers"</a></td> + </tr> + + <tr> + <th colspan="3">string-based types</th> + </tr> + <tr> + <td><code>string</code></td> + <td><code>string_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + <tr> + <td><code>normalizedString</code></td> + <td><code>normalized_string_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + <tr> + <td><code>token</code></td> + <td><code>token_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + <tr> + <td><code>Name</code></td> + <td><code>name_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + <tr> + <td><code>NMTOKEN</code></td> + <td><code>nmtoken_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + <tr> + <td><code>NCName</code></td> + <td><code>ncname_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + + <tr> + <td><code>language</code></td> + <td><code>language_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + + <tr> + <th colspan="3">qualified name</th> + </tr> + <tr> + <td><code>QName</code></td> + <td><code>qname_simpl</code></td> + <td><code>const xml_schema::qname&</code> or<br/> + <code>const xml_schema::qname*</code><br/> + <a href="#7.3">Section 7.3, "<code>QName</code> Serializer"</a></td> + </tr> + + <tr> + <th colspan="3">ID/IDREF types</th> + </tr> + <tr> + <td><code>ID</code></td> + <td><code>id_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + <tr> + <td><code>IDREF</code></td> + <td><code>idref_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + + <tr> + <th colspan="3">list types</th> + </tr> + <tr> + <td><code>NMTOKENS</code></td> + <td><code>nmtokens_simpl</code></td> + <td><code>const xml_schema::string_sequence*</code><br/><a href="#7.4">Section + 7.4, "<code>NMTOKENS</code> and <code>IDREFS</code> Serializers"</a></td> + </tr> + <tr> + <td><code>IDREFS</code></td> + <td><code>idrefs_simpl</code></td> + <td><code>const xml_schema::string_sequence*</code><br/><a href="#7.4">Section + 7.4, "<code>NMTOKENS</code> and <code>IDREFS</code> Serializers"</a></td> + </tr> + + <tr> + <th colspan="3">URI types</th> + </tr> + <tr> + <td><code>anyURI</code></td> + <td><code>uri_simpl</code></td> + <td><code>const std::string&</code> or<br/> <code>const char*</code><br/> + <a href="#7.2">Section 7.2, "String-Based Type Serializers"</a></td> + </tr> + + <tr> + <th colspan="3">binary types</th> + </tr> + <tr> + <td><code>base64Binary</code></td> + <td><code>base64_binary_simpl</code></td> + <td><code>const xml_schema::buffer*</code><br/> + <a href="#7.5">Section 7.5, "<code>base64Binary</code> and + <code>hexBinary</code> Serializers"</a></td> + </tr> + <tr> + <td><code>hexBinary</code></td> + <td><code>hex_binary_simpl</code></td> + <td><code>const xml_schema::buffer*</code><br/> + <a href="#7.5">Section 7.5, "<code>base64Binary</code> and + <code>hexBinary</code> Serializers"</a></td> + </tr> + + <tr> + <th colspan="3">date/time types</th> + </tr> + <tr> + <td><code>date</code></td> + <td><code>date_simpl</code></td> + <td><code>const xml_schema::date&</code><br/> + <a href="#7.7">Section 7.7, "<code>date</code> Serializer"</a></td> + </tr> + <tr> + <td><code>dateTime</code></td> + <td><code>date_time_simpl</code></td> + <td><code>const xml_schema::date_time&</code><br/> + <a href="#7.8">Section 7.8, "<code>dateTime</code> Serializer"</a></td> + </tr> + <tr> + <td><code>duration</code></td> + <td><code>duration_simpl</code></td> + <td><code>const xml_schema::duration&</code><br/> + <a href="#7.9">Section 7.9, "<code>duration</code> Serializer"</a></td> + </tr> + <tr> + <td><code>gDay</code></td> + <td><code>gday_simpl</code></td> + <td><code>const xml_schema::gday&</code><br/> + <a href="#7.10">Section 7.10, "<code>gDay</code> Serializer"</a></td> + </tr> + <tr> + <td><code>gMonth</code></td> + <td><code>gmonth_simpl</code></td> + <td><code>const xml_schema::gmonth&</code><br/> + <a href="#7.11">Section 7.11, "<code>gMonth</code> Serializer"</a></td> + </tr> + <tr> + <td><code>gMonthDay</code></td> + <td><code>gmonth_day_simpl</code></td> + <td><code>const xml_schema::gmonth_day&</code><br/> + <a href="#7.12">Section 7.12, "<code>gMonthDay</code> Serializer"</a></td> + </tr> + <tr> + <td><code>gYear</code></td> + <td><code>gyear_simpl</code></td> + <td><code>const xml_schema::gyear&</code><br/> + <a href="#7.13">Section 7.13, "<code>gYear</code> Serializer"</a></td> + </tr> + <tr> + <td><code>gYearMonth</code></td> + <td><code>gyear_month_simpl</code></td> + <td><code>const xml_schema::gyear_month&</code><br/> + <a href="#7.14">Section 7.14, "<code>gYearMonth</code> Serializer"</a></td> + </tr> + <tr> + <td><code>time</code></td> + <td><code>time_simpl</code></td> + <td><code>const xml_schema::time&</code><br/> + <a href="#7.15">Section 7.15, "<code>time</code> Serializer"</a></td> + </tr> + + </table> + + <h2><a name="7.1">7.1 Floating-Point Type Serializers</a></h2> + + <p>The serializer implementations for the <code>float</code>, + <code>double</code>, and <code>decimal</code> built-in + XML Schema types allow you to specify the resulting + notation (fixed or scientific) as well as precision. + This is done by passing the corresponding arguments + to their constructors:</p> + + <pre class="c++"> +namespace xml_schema +{ + class float_simpl: public float_sskel + { + enum notation + { + notation_auto, + notation_fixed, + notation_scientific + }; + + float_simpl (notation = notation_auto, + unsigned int precision = FLT_DIG); + + virtual void + pre (float); + + ... + }; + + class double_simpl: public double_sskel + { + enum notation + { + notation_auto, + notation_fixed, + notation_scientific + }; + + double_simpl (notation = notation_auto, + unsigned int precision = DBL_DIG); + + virtual void + pre (double); + + ... + }; + + class decimal_simpl: public decimal_sskel + { + decimal_simpl (unsigned int precision = DBL_DIG); + + virtual void + pre (double); + + ... + }; +} + </pre> + + <p>By default the notation for the <code>float</code> and <code>double</code> + types is automatically selected to produce the shortest representation. + Note that the <code>decimal</code> values are always serialized in + the fixed-point notation.</p> + + <h2><a name="7.2">7.2 String-Based Type Serializers</a></h2> + + <p>When STL is enabled (<a href="#6.1">Section 6.1, "Standard Template + Library"</a>), the serializer argument type for the <code>string</code>, + <code>normalizedString</code>, <code>token</code>, + <code>Name</code>, <code>NMTOKEN</code>, <code>NCName</code>, + <code>ID</code>, <code>IDREF</code>, <code>language</code>, + and <code>anyURI</code> built-in XML Schema types is + <code>const std::string&</code>. When STL is disabled, the value + is passed as a constant C-string: <code>const char*</code>. + In this case, you can also instruct the serializer + implementations for string-based types to release the + string with operator <code>delete[]</code> by passing + <code>true</code> to their constructors. For instance, + using the person records example from the previous chapter:</p> + + <pre class="c++"> +class person_simpl: public person_sskel +{ +public: + virtual const char* + first_name () + { + char* r = new char[5]; + strcpy (r, "John"); + return r; + } + + virtual const char* + last_name () + { + char* r = new char[4]; + strcpy (r, "Doe"); + return r; + } + + ... +}; + +int +main () +{ + // Construct the serializer. + // + xml_schema::unsigned_short_simpl unsigned_short_s; + xml_schema::string_simpl string_s (true); // Release the string passed. + + gender_simpl gender_s; + person_simpl person_s; + people_simpl people_s; + + person_s.serializers (string_s, string_s, gender_s, unsigned_short_s); + + ... +} + </pre> + + <h2><a name="7.3">7.3 <code>QName</code> Serializer</a></h2> + + <p>The argument type of the <code>qname_simpl</code> serializer + implementation is either <code>const xml_schema::qname&</code> + when STL is enabled (<a href="#6.1">Section 6.1, "Standard Template + Library"</a>) or <code>const xml_schema::qname*</code> when STL + is disabled. The <code>qname</code> class represents an XML + qualified name. When the argument type is <code>const + xml_schema::qname*</code>, you can optionally instruct the + serializer to release the <code>qname</code> object with operator + <code>delete</code> by passing <code>true</code> to its + constructor.</p> + + <p>With STL enabled, the <code>qname</code> type has the following + interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class qname + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + qname (); + + explicit + qname (const std::string& name); + qname (const std::string& prefix, const std::string& name); + + void + swap (qname&); + + const std::string& + prefix () const; + + std::string& + prefix (); + + void + prefix (const std::string&); + + const std::string& + name () const; + + std::string& + name (); + + void + name (const std::string&); + }; + + bool + operator== (const qname&, const qname&); + + bool + operator!= (const qname&, const qname&); +} + </pre> + + <p>When STL is disabled and C++ exceptions are enabled + (<a href="#6.3">Section 6.3, "C++ Exceptions"</a>), the + <code>qname</code> type has the following interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class qname + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + qname (); + + explicit + qname (char* name); + qname (char* prefix, char* name); + + void + swap (qname&); + + private: + qname (const qname&); + + qname& + operator= (const qname&); + + public: + char* + prefix (); + + const char* + prefix () const; + + void + prefix (char*); + + void + prefix_copy (const char*); + + char* + prefix_detach (); + + public: + char* + name (); + + const char* + name () const; + + void + name (char*); + + void + name_copy (const char*); + + char* + name_detach (); + }; + + bool + operator== (const qname&, const qname&); + + bool + operator!= (const qname&, const qname&); +} +</pre> + + <p>The modifier functions and constructors that have the <code>char*</code> + argument assume ownership of the passed strings which should be allocated + with operator <code>new char[]</code> and will be deallocated with + operator <code>delete[]</code> by the <code>qname</code> object. + If you detach the underlying prefix or name strings, then they + should eventually be deallocated with operator <code>delete[]</code>. + </p> + + <p>Finally, if both STL and C++ exceptions are disabled, the + <code>qname</code> type has the following interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class qname + { + public: + enum error + { + error_none, + error_no_memory + }; + + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + qname (); + + explicit + qname (char* name); + qname (char* prefix, char* name); + + void + swap (qname&); + + private: + qname (const qname&); + + qname& + operator= (const qname&); + + public: + char* + prefix (); + + const char* + prefix () const; + + void + prefix (char*); + + error + prefix_copy (const char*); + + char* + prefix_detach (); + + public: + char* + name (); + + const char* + name () const; + + void + name (char*); + + error + name_copy (const char*); + + char* + name_detach (); + }; + + bool + operator== (const qname&, const qname&); + + bool + operator!= (const qname&, const qname&); +} + </pre> + + <h2><a name="7.4">7.4 <code>NMTOKENS</code> and <code>IDREFS</code> Serializers</a></h2> + + <p>The argument type of the <code>nmtokens_simpl</code> and + <code>idrefs_simpl</code> serializer implementations is + <code>const xml_schema::string_sequence*</code>. You can + optionally instruct these serializers to release the + <code>string_sequence</code> object with operator <code>delete</code> + by passing <code>true</code> to their constructors. With STL and C++ exceptions enabled + (<a href="#6.1">Section 6.1, "Standard Template Library"</a>, + <a href="#6.3">Section 6.3, "C++ Exceptions"</a>), the + <code>string_sequence</code> type has the following interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class string_sequence + { + public: + typedef std::string value_type; + typedef std::string* pointer; + typedef const std::string* const_pointer; + typedef std::string& reference; + typedef const std::string& const_reference; + + typedef size_t size_type; + typedef ptrdiff_t difference_type; + + typedef std::string* iterator; + typedef const std::string* const_iterator; + + public: + string_sequence (); + + void + swap (string_sequence&); + + private: + string_sequence (string_sequence&); + + string_sequence& + operator= (string_sequence&); + + public: + iterator + begin (); + + const_iterator + begin () const; + + iterator + end (); + + const_iterator + end () const; + + std::string& + front (); + + const std::string& + front () const; + + std::string& + back (); + + const std::string& + back () const; + + std::string& + operator[] (size_t); + + const std::string& + operator[] (size_t) const; + + public: + bool + empty () const; + + size_t + size () const; + + size_t + capacity () const; + + size_t + max_size () const; + + public: + void + clear (); + + void + pop_back (); + + iterator + erase (iterator); + + void + push_back (const std::string&); + + iterator + insert (iterator, const std::string&); + + void + reserve (size_t); + }; + + bool + operator== (const string_sequence&, const string_sequence&); + + bool + operator!= (const string_sequence&, const string_sequence&); +} + </pre> + + <p>When STL is enabled and C++ exceptions are disabled, the signatures + of the <code>push_back()</code>, <code>insert()</code>, and + <code>reserve()</code> functions change as follows:</p> + + <pre class="c++"> +namespace xml_schema +{ + class string_sequence + { + public: + enum error + { + error_none, + error_no_memory + }; + + ... + + public: + error + push_back (const std::string&); + + error + insert (iterator, const std::string&); + + error + insert (iterator, const std::string&, iterator& result); + + error + reserve (size_t); + }; +} + </pre> + + <p>When STL is disabled and C++ exceptions are enabled, the + <code>string_sequence</code> type has the following interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class string_sequence + { + public: + typedef char* value_type; + typedef char** pointer; + typedef const char** const_pointer; + typedef char* reference; + typedef const char* const_reference; + + typedef size_t size_type; + typedef ptrdiff_t difference_type; + + typedef char** iterator; + typedef const char* const* const_iterator; + + string_sequence (); + + void + swap (string_sequence&); + + private: + string_sequence (string_sequence&); + + string_sequence& + operator= (string_sequence&); + + public: + iterator + begin (); + + const_iterator + begin () const; + + iterator + end (); + + const_iterator + end () const; + + char* + front (); + + const char* + front () const; + + char* + back (); + + const char* + back () const; + + char* + operator[] (size_t); + + const char* + operator[] (size_t) const; + + public: + bool + empty () const; + + size_t + size () const; + + size_t + capacity () const; + + size_t + max_size () const; + + public: + void + clear (); + + void + pop_back (); + + iterator + erase (iterator); + + void + push_back (char*); + + void + push_back_copy (const char*); + + iterator + insert (iterator, char*); + + void + reserve (size_t); + + // Detach a string from the sequence at a given position. + // The string pointer at this position in the sequence is + // set to 0. + // + char* + detach (iterator); + }; + + bool + operator== (const string_sequence&, const string_sequence&); + + bool + operator!= (const string_sequence&, const string_sequence&); +} + </pre> + + <p>The <code>push_back()</code> and <code>insert()</code> functions + assume ownership of the passed string which should be allocated + with operator <code>new char[]</code> and will be deallocated + with operator <code>delete[]</code> by the <code>string_sequence</code> + object. These two functions free the passed object if the reallocation + of the underlying sequence buffer fails. The <code>push_back_copy()</code> + function makes a copy of the passed string. + If you detach the underlying element string, then it should + eventually be deallocated with operator <code>delete[]</code>.</p> + + <p>When both STL and C++ exceptions are disabled, the signatures + of the <code>push_back()</code>, <code>push_back_copy()</code>, + <code>insert()</code>, and <code>reserve()</code> functions change + as follows:</p> + + <pre class="c++"> +namespace xml_schema +{ + class string_sequence + { + public: + enum error + { + error_none, + error_no_memory + }; + + ... + + public: + error + push_back (char*); + + error + push_back_copy (const char*); + + error + insert (iterator, char*); + + error + insert (iterator, char*, iterator& result); + + error + reserve (size_t); + }; +} + </pre> + + + <h2><a name="7.5">7.5 <code>base64Binary</code> and <code>hexBinary</code> Serializers</a></h2> + + <p>The argument type of the <code>base64_binary_simpl</code> and + <code>hex_binary_simpl</code> serializer implementations is + <code>const xml_schema::buffer*</code>. You can optionally + instruct these serializers to release the <code>buffer</code> + object with operator <code>delete</code> by passing <code>true</code> + to their constructors. With C++ exceptions enabled (<a href="#6.3">Section + 6.3, "C++ Exceptions"</a>), the <code>buffer</code> type has the + following interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class buffer + { + public: + class bounds {}; // Out of bounds exception. + + public: + buffer (); + + explicit + buffer (size_t size); + buffer (size_t size, size_t capacity); + buffer (const void* data, size_t size); + buffer (const void* data, size_t size, size_t capacity); + + enum ownership_value { assume_ownership }; + + // This constructor assumes ownership of the memory passed. + // + buffer (void* data, size_t size, size_t capacity, ownership_value); + + private: + buffer (const buffer&); + + buffer& + operator= (const buffer&); + + public: + void + attach (void* data, size_t size, size_t capacity); + + void* + detach (); + + void + swap (buffer&); + + public: + size_t + capacity () const; + + bool + capacity (size_t); + + public: + size_t + size () const; + + bool + size (size_t); + + public: + const char* + data () const; + + char* + data (); + + const char* + begin () const; + + char* + begin (); + + const char* + end () const; + + char* + end (); + }; + + bool + operator== (const buffer&, const buffer&); + + bool + operator!= (const buffer&, const buffer&); +} + </pre> + + <p>The last constructor and the <code>attach()</code> member function + make the <code>buffer</code> instance assume the ownership of the + memory block pointed to by the <code>data</code> argument and + eventually release it by calling <code>operator delete()</code>. + The <code>detach()</code> member function detaches and returns the + underlying memory block which should eventually be released by + calling <code>operator delete()</code>. + </p> + + <p>The <code>capacity()</code> and <code>size()</code> modifier functions + return <code>true</code> if the underlying buffer has moved. The + <code>bounds</code> exception is thrown if the constructor or + <code>attach()</code> member function arguments violate the + <code>(size <= capacity)</code> constraint.</p> + + <p>If C++ exceptions are disabled, the <code>buffer</code> type has + the following interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class buffer + { + public: + enum error + { + error_none, + error_bounds, + error_no_memory + }; + + buffer (); + + private: + buffer (const buffer&); + + buffer& + operator= (const buffer&); + + public: + error + attach (void* data, size_t size, size_t capacity); + + void* + detach (); + + void + swap (buffer&); + + public: + size_t + capacity () const; + + error + capacity (size_t); + + error + capacity (size_t, bool& moved); + + public: + size_t + size () const; + + error + size (size_t); + + error + size (size_t, bool& moved); + + public: + const char* + data () const; + + char* + data (); + + const char* + begin () const; + + char* + begin (); + + const char* + end () const; + + char* + end (); + }; + + bool + operator== (const buffer&, const buffer&); + + bool + operator!= (const buffer&, const buffer&); +} + </pre> + + <h2><a name="7.6">7.6 Time Zone Representation</a></h2> + + <p>The <code>date</code>, <code>dateTime</code>, <code>gDay</code>, + <code>gMonth</code>, <code>gMonthDay</code>, <code>gYear</code>, + <code>gYearMonth</code>, and <code>time</code> XML Schema built-in + types all include an optional time zone component. The following + <code>xml_schema::time_zone</code> base class is used to represent + this information:</p> + + <pre class="c++"> +namespace xml_schema +{ + class time_zone + { + public: + time_zone (); + time_zone (short hours, short minutes); + + bool + zone_present () const; + + void + zone_reset (); + + short + zone_hours () const; + + void + zone_hours (short); + + short + zone_minutes () const; + + void + zone_minutes (short); + }; + + bool + operator== (const time_zone&, const time_zone&); + + bool + operator!= (const time_zone&, const time_zone&); +} + </pre> + + <p>The <code>zone_present()</code> accessor function returns <code>true</code> + if the time zone is specified. The <code>zone_reset()</code> modifier + function resets the time zone object to the <em>not specified</em> + state. If the time zone offset is negative then both hours and + minutes components are represented as negative integers.</p> + + <h2><a name="7.7">7.7 <code>date</code> Serializer</a></h2> + + <p>The argument type of the <code>date_simpl</code> serializer implementation + is <code>const xml_schema::date&</code>. The <code>date</code> class + represents a year, a day, and a month with an optional time zone. Its + interface is presented below. For more information on the base + <code>xml_schema::time_zone</code> class refer to <a href="#7.6">Section + 7.6, "Time Zone Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class date: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + date (); + + date (int year, unsigned short month, unsigned short day); + + date (int year, unsigned short month, unsigned short day, + short zone_hours, short zone_minutes); + + int + year () const; + + void + year (int); + + unsigned short + month () const; + + void + month (unsigned short); + + unsigned short + day () const; + + void + day (unsigned short); + }; + + bool + operator== (const date&, const date&); + + bool + operator!= (const date&, const date&); +} + </pre> + + <h2><a name="7.8">7.8 <code>dateTime</code> Serializer</a></h2> + + <p>The argument type of the <code>date_time_simpl</code> serializer + implementation is <code>const xml_schema::date_time&</code>. + The <code>date_time</code> class represents a year, a month, a day, + hours, minutes, and seconds with an optional time zone. Its interface + is presented below. For more information on the base + <code>xml_schema::time_zone</code> class refer to <a href="#7.6">Section + 7.6, "Time Zone Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class date_time: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + date_time (); + + date_time (int year, unsigned short month, unsigned short day, + unsigned short hours, unsigned short minutes, + double seconds); + + date_time (int year, unsigned short month, unsigned short day, + unsigned short hours, unsigned short minutes, + double seconds, short zone_hours, short zone_minutes); + + int + year () const; + + void + year (int); + + unsigned short + month () const; + + void + month (unsigned short); + + unsigned short + day () const; + + void + day (unsigned short); + + unsigned short + hours () const; + + void + hours (unsigned short); + + unsigned short + minutes () const; + + void + minutes (unsigned short); + + double + seconds () const; + + void + seconds (double); + }; + + bool + operator== (const date_time&, const date_time&); + + bool + operator!= (const date_time&, const date_time&); +} + </pre> + + <h2><a name="7.9">7.9 <code>duration</code> Serializer</a></h2> + + <p>The argument type of the <code>duration_simpl</code> serializer + implementation is <code>const xml_schema::duration&</code>. + The <code>duration</code> class represents a potentially + negative duration in the form of years, months, days, hours, minutes, + and seconds. Its interface is presented below.</p> + + <pre class="c++"> +namespace xml_schema +{ + class duration + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + duration (); + + duration (bool negative, + unsigned int years, unsigned int months, unsigned int days, + unsigned int hours, unsigned int minutes, double seconds); + + bool + negative () const; + + void + negative (bool); + + unsigned int + years () const; + + void + years (unsigned int); + + unsigned int + months () const; + + void + months (unsigned int); + + unsigned int + days () const; + + void + days (unsigned int); + + unsigned int + hours () const; + + void + hours (unsigned int); + + unsigned int + minutes () const; + + void + minutes (unsigned int); + + double + seconds () const; + + void + seconds (double); + }; + + bool + operator== (const duration&, const duration&); + + bool + operator!= (const duration&, const duration&); +} + </pre> + + + <h2><a name="7.10">7.10 <code>gDay</code> Serializer</a></h2> + + <p>The argument type of the <code>gday_simpl</code> serializer + implementation is <code>const xml_schema::gday&</code> The + <code>gday</code> class represents a day of the month with + an optional time zone. Its interface is presented below. For + more information on the base <code>xml_schema::time_zone</code> + class refer to <a href="#7.6">Section 7.6, "Time Zone + Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class gday: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + gday (); + + explicit + gday (unsigned short day); + + gday (unsigned short day, short zone_hours, short zone_minutes); + + unsigned short + day () const; + + void + day (unsigned short); + }; + + bool + operator== (const gday&, const gday&); + + bool + operator!= (const gday&, const gday&); +} + </pre> + + <h2><a name="7.11">7.11 <code>gMonth</code> Serializer</a></h2> + + <p>The argument type of the <code>gmonth_simpl</code> serializer + implementation is <code>const xml_schema::gmonth&</code>. The + <code>gmonth</code> class represents a month of the year with + an optional time zone. Its interface is presented below. For + more information on the base <code>xml_schema::time_zone</code> + class refer to <a href="#7.6">Section 7.6, "Time Zone + Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class gmonth: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + gmonth (); + + explicit + gmonth (unsigned short month); + + gmonth (unsigned short month, + short zone_hours, short zone_minutes); + + unsigned short + month () const; + + void + month (unsigned short); + }; + + bool + operator== (const gmonth&, const gmonth&); + + bool + operator!= (const gmonth&, const gmonth&); +} + </pre> + + <h2><a name="7.12">7.12 <code>gMonthDay</code> Serializer</a></h2> + + <p>The argument type of the <code>gmonth_day_simpl</code> serializer + implementation is <code>const xml_schema::gmonth_day&</code>. + The <code>gmonth_day</code> class represents a day and a month of + the year with an optional time zone. Its interface is presented below. + For more information on the base <code>xml_schema::time_zone</code> + class refer to <a href="#7.6">Section 7.6, "Time Zone + Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class gmonth_day: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + gmonth_day (); + + gmonth_day (unsigned short month, unsigned short day); + + gmonth_day (unsigned short month, unsigned short day, + short zone_hours, short zone_minutes); + + unsigned short + month () const; + + void + month (unsigned short); + + unsigned short + day () const; + + void + day (unsigned short); + }; + + bool + operator== (const gmonth_day&, const gmonth_day&); + + bool + operator!= (const gmonth_day&, const gmonth_day&); +} + </pre> + + <h2><a name="7.13">7.13 <code>gYear</code> Serializer</a></h2> + + <p>The argument type of the <code>gyear_simpl</code> serializer + implementation is <code>const xml_schema::gyear&</code>. The + <code>gyear</code> class represents a year with an optional + time zone. Its interface is presented below. For more information + on the base <code>xml_schema::time_zone</code> class refer to + <a href="#7.6">Section 7.6, "Time Zone Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class gyear: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + gyear (); + + explicit + gyear (int year); + + gyear (int year, short zone_hours, short zone_minutes); + + int + year () const; + + void + year (int); + }; + + bool + operator== (const gyear&, const gyear&); + + bool + operator!= (const gyear&, const gyear&); +} + </pre> + + <h2><a name="7.14">7.14 <code>gYearMonth</code> Serializer</a></h2> + + <p>The argument type of the <code>gyear_month_simpl</code> serializer + implementation is <code>const xml_schema::gyear_month&</code>. + The <code>gyear_month</code> class represents a year and a month + with an optional time zone. Its interface is presented below. + For more information on the base <code>xml_schema::time_zone</code> + class refer to <a href="#7.6">Section 7.6, "Time Zone + Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class gyear_month: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + gyear_month (); + + gyear_month (int year, unsigned short month); + + gyear_month (int year, unsigned short month, + short zone_hours, short zone_minutes); + + int + year () const; + + void + year (int); + + unsigned short + month () const; + + void + month (unsigned short); + }; + + bool + operator== (const gyear_month&, const gyear_month&); + + bool + operator!= (const gyear_month&, const gyear_month&); +} + </pre> + + + <h2><a name="7.15">7.15 <code>time</code> Serializer</a></h2> + + <p>The argument type of the <code>time_simpl</code> serializer implementation + is <code>const xml_schema::time&</code>. The <code>time</code> class + represents hours, minutes, and seconds with an optional time zone. Its + interface is presented below. For more information on the base + <code>xml_schema::time_zone</code> class refer to <a href="#7.6">Section + 7.6, "Time Zone Representation"</a>.</p> + + <pre class="c++"> +namespace xml_schema +{ + class time: public time_zone + { + public: + // The default constructor creates an uninitialized object. + // Use modifiers to initialize it. + // + time (); + + time (unsigned short hours, unsigned short minutes, double seconds); + + time (unsigned short hours, unsigned short minutes, double seconds, + short zone_hours, short zone_minutes); + + unsigned short + hours () const; + + void + hours (unsigned short); + + unsigned short + minutes () const; + + void + minutes (unsigned short); + + double + seconds () const; + + void + seconds (double); + }; + + bool + operator== (const time&, const time&); + + bool + operator!= (const time&, const time&); +} + </pre> + + + <!-- Error Handling --> + + + <h1><a name="8">8 Document Serializer and Error Handling</a></h1> + + <p>In this chapter we will discuss the <code>xml_schema::document_simpl</code> + type, the error handling mechanisms provided by the mapping, as well as + how to reuse a serializer after an error has occurred.</p> + + <p>There are four categories of errors that can result from running + a serializer to produce an XML instance: system, xml, schema, and + application. The system category contains memory allocation and + input/output operation errors. The xml category is for XML serialization + and well-formedness checking errors. Similarly, the schema category is + for XML Schema validation errors. Finally, the application category + is for application logic errors that you may want to propagate + from serializer implementations to the caller of the serializer. + </p> + + <p>The C++/Serializer mapping supports two methods of reporting errors: + using C++ exceptions and with error codes. The method used depends + on whether or not you have configured the XSD/e runtime and + the generated code with C++ exceptions enabled, as described + in <a href="#6.3">Section 6.3, "C++ Exceptions"</a>.</p> + + <h2><a name="8.1">8.1 Document Serializer</a></h2> + + <p>The <code>xml_schema::document_simpl</code> serializer is a root + serializer for the vocabulary. As mentioned in <a href="#3.4">Section + 3.4, "Connecting the Serializer Together"</a>, its interface varies + depending on the mapping configuration (<a href="#6">Chapter 6, "Mapping + Configuration"</a>). When STL, C++ exceptions, and the iostream library + are enabled, the <code>xml_schema::document_simpl</code> class has the + following interface:</p> + + <pre class="c++"> +namespace xml_schema +{ + class serializer_base; + + class writer + { + public: + // The first write function is called to write a '\0'-terminated + // string. Its default implementation calls the second versions: + // write (s, strlen (s)). These functions use exceptions to + // indicate a write failure. + // + virtual void + write (const char* s); + + virtual void + write (const char* s, size_t n) = 0; + + virtual void + flush () = 0; + }; + + class document_simpl + { + public: + document_simpl (serializer_base&, + const char* root_element_name); + + document_simpl (serializer_base&, + const char* root_element_namespace, + const char* root_element_name); + + document_simpl (serializer_base&, + const std::string& root_element_name); + + document_simpl (serializer_base&, + const std::string& root_element_namespace, + const std::string& root_element_name); + + public: + void + add_prefix (const char* prefix, const char* namespace_); + + void + add_default_prefix (const char* namespace_); + + void + add_schema (const char* namespace_, const char* location); + + void + add_no_namespace_schema (const char* location); + + void + add_prefix (const std::string& prefix, + const std::string& namespace_); + + void + add_default_prefix (const std::string& namespace_); + + void + add_schema (const std::string& namespace_, + const std::string& location); + + void + add_no_namespace_schema (const std::string& location); + + public: + // Serialize to std::ostream. The std::ios_base::failure + // exception is used to report io errors (badbit and failbit) + // if C++ exceptions are enabled. Otherwise error codes are + // used. + // + void + serialize (std::ostream&); + + public: + // Serialize by calling writer::write() and writer::flush() to + // output XML. + // + void + serialize (writer&); + + // Serialize by calling the write and flush functions. If the + // unbounded write function is not provided, the bounded version + // is called: write_bound_func (s, strlen (s)). user_data is + // passed as a first argument to these functions. These functions + // use exceptions to indicate a write failure. + // + typedef void (*write_func) (void*, const char*); + typedef void (*write_bound_func) (void*, const char*, size_t); + typedef void (*flush_func) (void*); + + void + serialize (write_bound_func, flush_func, void* user_data); + + void + serialize (write_func, write_bound_func, flush_func, void* user_data); + + public: + // Low-level, genx-specific serialization. With this method + // it is your responsibility to call genxStartDoc*() and + // genxEndDocument(). + // + void + serialize (genxWriter); + }; +} + </pre> + + <p>When the use of STL is disabled, the constructors, as well as + the <code>add_prefix()</code> and <code>add_schema()</code> + functions that use <code>std::string</code> in their signatures + are not available. When the use of iostream is disabled, the + <code>serialize()</code> functions that serializes to + <code>std::ostream</code> is not available.</p> + + <p>When C++ exceptions are disabled, the <code>write()</code> and + <code>flush()</code> virtual functions in the <code>writer</code> + interface as well as <code>write_func</code>, + <code>write_bound_func</code>, and <code>flush_func</code> + function pointers use <code>bool</code> return type + for error reporting. These functions should return <code>true</code> + if the operation was successful and <code>false</code> otherwise. + The relevant parts in the <code>writer</code> and + <code>document_simpl</code> interfaces change as follows:</p> + + <pre class="c++"> +namespace xml_schema +{ + class serializer_base; + + class writer + { + public: + // The first write function is called to write a '\0'-terminated + // string. Its default implementation calls the second versions: + // write (s, strlen (s)). These functions return true if the + // operation was successful and false otherwise. + // + // indicate a write failure. + // + virtual bool + write (const char* s); + + virtual bool + write (const char* s, size_t n) = 0; + + virtual bool + flush () = 0; + }; + + class document_simpl + { + ... + + // Serialize by calling the write and flush functions. If the + // unbounded write function is not provided, the bounded version + // is called: write_bound_func (s, strlen (s)). user_data is + // passed as a first argument to these functions. These functions + // return true if the operation was successful and false otherwise. + // + typedef bool (*write_func) (void*, const char*); + typedef bool (*write_bound_func) (void*, const char*, size_t); + typedef bool (*flush_func) (void*); + + ... + + public: + const serializer_error& + _error () const; + }; +} + </pre> + + <p>For more information on error handling with C++ exceptions and + error codes see <a href="#8.2">Section 8.2, "Exceptions"</a> + and <a href="#8.3">Section 8.3, "Error Codes"</a> below.</p> + + <p>When support for XML Schema polymorphism is enabled, the + overloaded <code>document_simpl</code> constructors have + additional arguments which control polymorphic serialization. + For more information refer to <a href="#6.7">Section 6.7, + "Support for Polymorphism"</a>. + </p> + + <p>The first argument to all overloaded constructors is the + serializer for the type of the root element. The + <code>serializer_base</code> class is the base type for all + serializer skeletons. The second and third arguments to the + <code>document_simpl</code>'s constructors are the root element's + name and namespace.</p> + + <p>The <code>add_prefix()</code> and <code>add_default_prefix()</code> + functions allow you to establish custom prefixes for XML + namespaces. If none is provided, and namespaces are used + by your vocabulary, the serializer will automatically + assign namespace prefixes in an implementation-specific + manner. For example:</p> + + <pre class="c++"> +xml_schema::document_simpl doc_s ( + root_s, + "http://www.example.com/example", + "root"); + +doc_s.add_prefix ("ex", "http://www.example.com/example"); + </pre> + + <p>The resulting XML will have the following namespace declaration:</p> + + <pre class="xml"> +<ex:root xmlns:ex="http://www.example.com/example" ...> + ... +</ex:root> + </pre> + + <p>Similarly, the <code>add_schema()</code> and + <code>add_no_namespace_schema()</code> functions allow you to embed + schema location information for a particular namespace into resulting + XML. The schema location information is placed into the + <code>xsi:schemaLocation</code> and + <code>xsi:noNamespaceSchemaLocation</code> attributes. For example:</p> + + <pre class="c++"> +xml_schema::document_simpl doc_s ( + root_s, + "http://www.example.com/example", + "root"); + +doc_s.add_prefix ("ex", "http://www.example.com/example"); +doc_s.add_schema ("http://www.example.com/example", "example.xsd"); + </pre> + + <p>The resulting XML will have the following namespace declaration:</p> + + <pre class="xml"> +<ex:root + xmlns:ex="http://www.example.com/example" + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:schemaLocation="http://www.example.com/example example.xsd" ...> + ... +</ex:root> + </pre> + + <h2><a name="8.2">8.2 Exceptions</a></h2> + + <p>When C++ exceptions are used for error reporting, the system + errors are mapped to the standard exceptions. The out of memory + condition is indicated by throwing an instance + of <code>std::bad_alloc</code>. The stream operation errors + are reported by throwing an instance of + <code>std::ios_base::failure</code>.</p> + + <p>The xml and schema errors are reported by throwing the + <code>xml_schema::serializer_xml</code> and + <code>xml_schema::serializer_schema</code> + exceptions, respectively. These two exceptions derive from + <code>xml_schema::serializer_exception</code> which, in turn, derives + from <code>std::exception</code>. As a result, you can handle + any error from these two categories by either catching + <code>std::exception</code>, <code>xml_schema::serializer_exception</code>, + or individual exceptions. The further down the hierarchy you go + the more detailed error information is available to you. The + following listing shows the definitions of these exceptions:</p> + + <pre class="c++"> +namespace xml_schema +{ + class serializer_exception: public std::exception + { + public: + virtual const char* + text () const = 0; + + ... + }; + + std::ostream& + operator<< (std::ostream&, const serializer_exception&); + + + typedef <implementation-details> serializer_xml_error; + + class serializer_xml: public serializer_exception + { + public: + serializer_xml_error + code () const; + + virtual const char* + text () const; + + virtual const char* + what () const throw (); + + ... + }; + + + typedef <implementation-details> serializer_schema_error; + + class serializer_schema: public serializer_exception + { + public: + serializer_schema_error + code () const; + + virtual const char* + text () const; + + virtual const char* + what () const throw (); + + ... + }; +} + </pre> + + <p>The <code>serializer_xml_error</code> and + <code>serializer_schema_error</code> are implementation-specific error + code types. The <code>operator<<</code> defined for the + <code>serializer_exception</code> class simply prints the error + description as returned by the <code>text()</code> function. The + following example shows how we can catch these exceptions:</p> + + <pre class="c++"> +int +main () +{ + try + { + // Serialize. + } + catch (const xml_schema::serializer_exception& e) + { + cout << "error: " << e.text () << endl; + return 1; + } +} + </pre> + + <p>Finally, for reporting application errors from serializer callbacks, + you can throw any exceptions of your choice. They are propagated + to the caller of the serializer without any alterations.</p> + + <h2><a name="8.3">8.3 Error Codes</a></h2> + + <p>When C++ exceptions are not available, error codes are used to + report error conditions. Each serializer skeleton and the root + <code>document_simpl</code> serializer have the following member + function for querying the error status:</p> + + <pre class="c++"> +xml_schema::serializer_error +_error () const; + </pre> + + <p>To handle all possible error conditions, you will need to obtain + the error status after calls to: the <code>document_simpl</code>'s + constructor (it performs memory allocations which may fail), + calls to <code>add_prefix()</code> and <code>add_schema()</code> + functions if any, the call to the root serializer <code>pre()</code> + callback, the call to the <code>serialize()</code> function, and, + finally, the call to the root serializer <code>post()</code> callback. + The definition of <code>xml_schema::serializer_error</code> class + is presented below:</p> + + <pre class="c++"> +namespace xml_schema +{ + class sys_error + { + public: + enum value + { + none, + no_memory, + open_failed, + read_failed, + write_failed + }; + + sys_error (value); + + operator value () const; + + static const char* + text (value); + + ... + }; + + typedef <implementation-details> serializer_xml_error; + typedef <implementation-details> serializer_schema_error; + + class serializer_error + { + public: + enum error_type + { + none, + sys, + xml, + schema, + app + }; + + error_type + type () const; + + // Returns true if there is an error so that you can write + // if (s.error ()) or if (error e = s.error ()). + // + typedef void (error::*bool_convertible) (); + operator bool_convertible () const; + + // system + // + sys_error + sys_code () const; + + const char* + sys_text () const; + + // xml + // + serializer_xml_error + xml_code () const; + + const char* + xml_text () const; + + // schema + // + serializer_schema_error + schema_code () const; + + const char* + schema_text () const; + + // app + // + int + app_code () const; + + ... + }; +} + </pre> + + <p>The <code>serializer_xml_error</code> and + <code>serializer_schema_error</code> are implementation-specific + error code types. The <code>serializer_error</code> class incorporates + four categories of errors which you can query by calling the + <code>type()</code> function. The following example shows how to + handle error conditions with error codes. It is based on the + person record example presented in <a href="#3">Chapter 3, "Serializer + Skeletons"</a>.</p> + + <pre class="c++"> +int +main () +{ + // Construct the serializer. + // + xml_schema::short_simpl short_s; + xml_schema::string_simpl string_s; + + gender_simpl gender_s; + person_simpl person_s; + people_simpl people_s; + + person_s.serializers (string_s, string_s, gender_s, short_s); + people_s.serializers (person_s); + + // Serialize. + // + using xml_schema::serializer_error; + serializer_error e; + + do + { + xml_schema::document_simpl doc_s (people_s, "people"); + if (e = doc_s._error ()) + break; + + people_s.pre (); + if (e = people_s._error ()) + break; + + doc_s.serialize (cout); + if (e = doc_s._error ()) + break; + + people_s.post (); + e = people_s._error (); + + } while (false); + + // Handle errors. + // + if (e) + { + switch (e.type ()) + { + case serializer_error::sys: + { + cerr << "system error: " << e.sys_text () << endl; + break; + } + case serializer_error::xml: + { + cerr << "xml error: " << e.xml_text () << endl; + break; + } + case serializer_error::schema: + { + cerr << "schema error: " << e.schema_text () << endl; + break; + } + case serializer_error::app: + { + cerr << "application error: " << e.app_code () << endl; + break; + } + } + return 1; + } +} + </pre> + + <p>The error type for application errors is <code>int</code> with + the value <code>0</code> indicated the absence of error. You can + set the application error by calling the <code>_app_error()</code> + function inside a serializer callback. For example, if it was invalid + to have a person younger than 18 in our people catalog, then we + could have implemented this check as follows: </p> + + <pre class="c++"> +class person_simpl: public person_sskel +{ +public: + virtual short + age () + { + short a = ...; + + if (a < 18) + _app_error (1); + + return a; + } +}; + </pre> + + <p>You can also set a system error by calling the <code>_sys_error()</code> + function inside a serializer callback. This function has one argument of + type <code>xml_schema::sys_error</code> which was presented above. + For example:</p> + + <pre class="c++"> +class person_simpl: public person_sskel +{ +public: + virtual const char* + first_name () + { + char* r = new char[5]; + + if (r == 0) + { + _sys_error (xml_schema::sys_error::no_memory); + return 0; + } + + strcpy (r, "John"); + return r; + } +}; + </pre> + + <h2><a name="8.4">8.4 Reusing Serializers after an Error</a></h2> + + <p>After a successful execution a serializer returns into the initial + state and can be used to serialize another document without any + extra actions. On the other hand, if an error occurred during + serialization and you would like to reuse the serializer to serialize another + document, you need to explicitly reset it into the initial + state as shown in the following code fragment:</p> + + <pre class="c++"> +int +main () +{ + ... + + xml_schema::document_simpl doc_s (people_s, "people"); + + for (size_t i = 0; i < 4; ++i) + { + try + { + people_s.pre (); + doc_s.serialize (cout); + people_s.post (); + } + catch (const xml_schema::serializer_exception&) + { + doc_s.reset (); + } + } +} + </pre> + + <p>If you do not need to reuse serializers after an error for example + because your application terminates or you create a new serializer + instance in such situations, then you can avoid generating + serializer reset code by specifying the <code>--suppress-reset</code> + XSD/e compiler option.</p> + + <p>Your individual serializer implementations may also require extra + actions in order to bring them into a usable state after an + error. To accomplish this you can override the <code>_reset()</code> + virtual function as shown below. Notice that when you override the + <code>_reset()</code> function in your implementation, you should + always call the base skeleton version to allow it to reset + its state:</p> + +<pre class="c++"> +class person_simpl: public person_sskel +{ +public: + virtual void + pre (person* p) + { + p_ = p; + } + + virtual void + post () + { + delete p_; + p_ = 0; + } + + virtual void + _reset () + { + person_sskel::_reset (); + delete p_; + p_ = 0; + } + + ... + +private: + person* p_; +}; + </pre> + + <p>Note also that the <code>_reset()</code> mechanism is used only when + an error has occurred. To make sure that your serializer implementations + arrive at the initial state during successful execution, use the + initialization (<code>pre()</code> and <code>_pre()</code>) and + finalization (<code>post_*()</code> and <code>_post()</code>) + callbacks.</p> + + + <!-- Appendix A --> + + + <h1><a name="A">Appendix A — Supported XML Schema Constructs</a></h1> + + <p>The Embedded C++/Serializer mapping supports validation of the following + W3C XML Schema constructs in the generated code.</p> + + <!-- border="1" is necessary for html2ps --> + <table id="features" border="1"> + <tr><th>Construct</th><th>Notes</th></tr> + <tr><th colspan="2">Structure</th></tr> + + <tr><td>element</td><td></td></tr> + <tr><td>attribute</td><td></td></tr> + + <tr><td>any</td><td></td></tr> + <tr><td>anyAttribute</td><td></td></tr> + + <tr><td>all</td><td></td></tr> + <tr><td>sequence</td><td></td></tr> + <tr><td>choice</td><td></td></tr> + + <tr><td>complex type, empty content</td><td></td></tr> + <tr><td>complex type, mixed content</td><td></td></tr> + <tr><td>complex type, simple content extension</td><td></td></tr> + <tr><td>complex type, simple content restriction</td> + <td>Simple type facets are not validated.</td></tr> + <tr><td>complex type, complex content extension</td><td></td></tr> + <tr><td>complex type, complex content restriction</td><td></td></tr> + + <tr><td>list</td><td></td></tr> + + <tr><th colspan="2">Datatypes</th></tr> + + <tr><td>byte</td><td></td></tr> + <tr><td>unsignedByte</td><td></td></tr> + <tr><td>short</td><td></td></tr> + <tr><td>unsignedShort</td><td></td></tr> + <tr><td>int</td><td></td></tr> + <tr><td>unsignedInt</td><td></td></tr> + <tr><td>long</td><td></td></tr> + <tr><td>unsignedLong</td><td></td></tr> + <tr><td>integer</td><td></td></tr> + <tr><td>nonPositiveInteger</td><td></td></tr> + <tr><td>nonNegativeInteger</td><td></td></tr> + <tr><td>positiveInteger</td><td></td></tr> + <tr><td>negativeInteger</td><td></td></tr> + + <tr><td>boolean</td><td></td></tr> + + <tr><td>float</td><td></td></tr> + <tr><td>double</td><td></td></tr> + <tr><td>decimal</td><td></td></tr> + + <tr><td>string</td><td></td></tr> + <tr><td>normalizedString</td><td></td></tr> + <tr><td>token</td><td></td></tr> + <tr><td>Name</td><td></td></tr> + <tr><td>NMTOKEN</td><td></td></tr> + <tr><td>NCName</td><td></td></tr> + <tr><td>language</td><td></td></tr> + <tr><td>anyURI</td><td></td></tr> + + <tr><td>ID</td><td>Identity constraint is not enforced.</td></tr> + <tr><td>IDREF</td><td>Identity constraint is not enforced.</td></tr> + + <tr><td>NMTOKENS</td><td></td></tr> + <tr><td>IDREFS</td><td>Identity constraint is not enforced.</td></tr> + + <tr><td>QName</td><td></td></tr> + + <tr><td>base64Binary</td><td></td></tr> + <tr><td>hexBinary</td><td></td></tr> + + <tr><td>date</td><td></td></tr> + <tr><td>dateTime</td><td></td></tr> + <tr><td>duration</td><td></td></tr> + <tr><td>gDay</td><td></td></tr> + <tr><td>gMonth</td><td></td></tr> + <tr><td>gMonthDay</td><td></td></tr> + <tr><td>gYear</td><td></td></tr> + <tr><td>gYearMonth</td><td></td></tr> + <tr><td>time</td><td></td></tr> + </table> + + </div> +</div> + + +</body> +</html> |