Add support for object sections

Sections are an optimization mechanism that allows the partitioning of
data members of a persistent class into groups that can be separately
loaded and/or updated.

7 files changed, 523 insertions, 1 deletions

diff --git a/README b/README
index bbaea80..0c35ecd 100644
--- a/README
+++ b/README
@@ -44,6 +44,10 @@ inheritance/reuse
 inheritance/polymorphism
   Shows how to use polymorphism inheritance with ODB.
 
+section
+  Shows how to use object sections to implement lazy-loading and change-
+  updating of a subset of data members in a persistent class.
+
 view
   Shows how to define and use object, table, mixed, and native views.
 
diff --git a/makefile b/makefile
index 1b99343..fb9aa3f 100644
--- a/makefile
+++ b/makefile
@@ -16,7 +16,8 @@ mapping                  \
 optimistic               \
 pimpl                    \
 prepared                 \
-schema/embedded
+schema/embedded          \
+section
 
 tr1_dirs   := relationship inverse schema/custom view
 cxx11_dirs := c++11
diff --git a/section/README b/section/README
new file mode 100644
index 0000000..34be589
--- /dev/null
+++ b/section/README
@@ -0,0 +1,63 @@
+This example shows how to use object sections to implement lazy-loading
+and change-updating of a subset of data members in a persistent class.
+
+The example consists of the following files:
+
+person.hxx
+  Header file defining the 'person' persistent class. It contains a number of
+  data members some of which are made to belong to a section.
+
+person-odb.hxx
+person-odb.ixx
+person-odb.cxx
+person.sql
+  The first three files contain the database support code and the last file
+  contains the database schema for the person.hxx header.
+
+  These files are generated by the ODB compiler from person.hxx using the
+  following command line:
+
+  odb -d <database> --generate-schema person.hxx
+
+  Where <database> stands for the database system we are using, for example,
+  'mysql'.
+
+database.hxx
+  Contains the create_database() function which instantiates the concrete
+  database class corresponding to the database system we are using.
+
+driver.cxx
+  Driver for the example. It includes the person.hxx and person-odb.hxx
+  headers to gain access to the persistent classes and their database support
+  code. It also includes database.hxx for the create_database() function
+  declaration.
+
+  In main() the driver first calls create_database() to obtain the database
+  instance. It then persists a 'person' object, loads it back, including
+  the section, and prints the contents of its members. Finally, the driver
+  shows how to update the state of the section data members in various ways,
+  then re-loads and prints the object to verify that the changes have been
+  made persistent.
+
+To compile and link the example manually from the command line we can use
+the following commands (using  MySQL as an example; replace 'c++' with your
+C++ compiler name):
+
+c++ -c person-odb.cxx
+c++ -DDATABASE_MYSQL -c driver.cxx
+c++ -o driver driver.o person-odb.o -lodb-mysql -lodb
+
+To run the example we may first need to create the database schema (for some
+database systems, such as SQLite, the schema is embedded into the generated
+code which makes this step unnecessary). Using MySQL as an example, this
+can be achieved with the following command:
+
+mysql --user=odb_test --database=odb_test < person.sql
+
+Here we use 'odb_test' as the database login and also 'odb_test' as the
+database name.
+
+Once the database schema is ready, we can run the example (using MySQL as
+the database):
+
+./driver --user odb_test --database odb_test
diff --git a/section/database.hxx b/section/database.hxx
new file mode 100644
index 0000000..4a1a350
--- /dev/null
+++ b/section/database.hxx
@@ -0,0 +1,94 @@
+// file      : section/database.hxx
+// copyright : not copyrighted - public domain
+
+//
+// Create concrete database instance based on the DATABASE_* macros.
+//
+
+#ifndef DATABASE_HXX
+#define DATABASE_HXX
+
+#include <string>
+#include <memory>   // std::auto_ptr
+#include <cstdlib>  // std::exit
+#include <iostream>
+
+#include <odb/database.hxx>
+
+#if defined(DATABASE_MYSQL)
+#  include <odb/mysql/database.hxx>
+#elif defined(DATABASE_SQLITE)
+#  include <odb/connection.hxx>
+#  include <odb/transaction.hxx>
+#  include <odb/schema-catalog.hxx>
+#  include <odb/sqlite/database.hxx>
+#elif defined(DATABASE_PGSQL)
+#  include <odb/pgsql/database.hxx>
+#elif defined(DATABASE_ORACLE)
+#  include <odb/oracle/database.hxx>
+#elif defined(DATABASE_MSSQL)
+#  include <odb/mssql/database.hxx>
+#else
+#  error unknown database; did you forget to define the DATABASE_* macros?
+#endif
+
+inline std::auto_ptr<odb::database>
+create_database (int& argc, char* argv[])
+{
+  using namespace std;
+  using namespace odb::core;
+
+  if (argc > 1 && argv[1] == string ("--help"))
+  {
+    cout << "Usage: " << argv[0] << " [options]" << endl
+         << "Options:" << endl;
+
+#if defined(DATABASE_MYSQL)
+    odb::mysql::database::print_usage (cout);
+#elif defined(DATABASE_SQLITE)
+    odb::sqlite::database::print_usage (cout);
+#elif defined(DATABASE_PGSQL)
+    odb::pgsql::database::print_usage (cout);
+#elif defined(DATABASE_ORACLE)
+    odb::oracle::database::print_usage (cout);
+#elif defined(DATABASE_MSSQL)
+    odb::mssql::database::print_usage (cout);
+#endif
+
+    exit (0);
+  }
+
+#if defined(DATABASE_MYSQL)
+  auto_ptr<database> db (new odb::mysql::database (argc, argv));
+#elif defined(DATABASE_SQLITE)
+  auto_ptr<database> db (
+    new odb::sqlite::database (
+      argc, argv, false, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE));
+
+  // Create the database schema. Due to bugs in SQLite foreign key
+  // support for DDL statements, we need to temporarily disable
+  // foreign keys.
+  //
+  {
+    connection_ptr c (db->connection ());
+
+    c->execute ("PRAGMA foreign_keys=OFF");
+
+    transaction t (c->begin ());
+    schema_catalog::create_schema (*db);
+    t.commit ();
+
+    c->execute ("PRAGMA foreign_keys=ON");
+  }
+#elif defined(DATABASE_PGSQL)
+  auto_ptr<database> db (new odb::pgsql::database (argc, argv));
+#elif defined(DATABASE_ORACLE)
+  auto_ptr<database> db (new odb::oracle::database (argc, argv));
+#elif defined(DATABASE_MSSQL)
+  auto_ptr<database> db (new odb::mssql::database (argc, argv));
+#endif
+
+  return db;
+}
+
+#endif // DATABASE_HXX
diff --git a/section/driver.cxx b/section/driver.cxx
new file mode 100644
index 0000000..b01454e
--- /dev/null
+++ b/section/driver.cxx
@@ -0,0 +1,133 @@
+// file      : section/driver.cxx
+// copyright : not copyrighted - public domain
+
+#include <memory>   // std::auto_ptr
+#include <iostream>
+
+#include <odb/database.hxx>
+#include <odb/transaction.hxx>
+
+#include "database.hxx" // create_database
+
+#include "person.hxx"
+#include "person-odb.hxx"
+
+using namespace std;
+using namespace odb::core;
+
+int
+main (int argc, char* argv[])
+{
+  try
+  {
+    auto_ptr<database> db (create_database (argc, argv));
+
+    unsigned long id;
+
+    // Create a persistent person object.
+    //
+    {
+      person joe ("Joe", "Dirt");
+      joe.bio ("Joe Dirt is a very strange man indeed...");
+      joe.nicknames ().push_back ("JD");
+
+      // At this point the state of a section is undefined since the
+      // object is transient.
+
+      transaction t (db->begin ());
+      id = db->persist (joe);
+      t.commit ();
+
+      // Now, since the object is persistent, the state of the section
+      // is loaded and unchanged.
+    }
+
+    // Load the object and print what we've got. Then update the bio.
+    //
+    {
+      transaction t (db->begin ());
+      auto_ptr<person> p (db->load<person> (id));
+
+      // Now, while the object is loaded, the section is not. If (and
+      // when) we need to access the section data members, we have to
+      // load them explicitly.
+
+      cout << p->first () << " " << p->last () << endl;
+
+      db->load (*p, p->extras_section ());
+
+      // Now the section is loaded and unchanged.
+
+      cout << "  " << p->bio () << endl
+           << "  " << p->nicknames ().size () << " nickname(s)" << endl;
+
+      // Update the bio.
+      //
+      p->bio ("Joe Dirt is a very clean man indeed...");
+
+      // Now, the section is marked changed by the bio() modifier.
+      // Because of that, the following object update will also
+      // update the section.
+      //
+      db->update (*p);
+
+      t.commit ();
+    }
+
+    // Add a new nickname.
+    //
+    {
+      transaction t (db->begin ());
+
+      auto_ptr<person> p (db->load<person> (id));
+      db->load (*p, p->extras_section ());
+
+      // Add a new nickname. The nicknames container is now marked
+      // changed.
+      //
+      p->nicknames ().push_back ("Squeaky Clean");
+
+      // While the section hasn't been marked as changed, a change-
+      // tracking container that belongs to it has been. As a result,
+      // the following object update call will automatically mark the
+      // section as changed and update its state in the database.
+      //
+      db->update (*p);
+
+      t.commit ();
+    }
+
+    // We can also update just the section if we know the rest of
+    // the object hasn't changed.
+    //
+    {
+      transaction t (db->begin ());
+
+      auto_ptr<person> p (db->load<person> (id));
+      db->load (*p, p->extras_section ());
+
+      p->nicknames ().push_back ("Dirty Joe");
+      db->update (*p, p->extras_section ());
+
+      t.commit ();
+    }
+
+    // Load and print the updated object.
+    //
+    {
+      transaction t (db->begin ());
+      auto_ptr<person> p (db->load<person> (id));
+      db->load (*p, p->extras_section ());
+      t.commit ();
+
+      cout << p->first () << " " << p->last () << endl
+           << "  " << p->bio () << endl
+           << "  " << p->nicknames ().size () << " nickname(s)" << endl;
+    }
+  }
+  catch (const odb::exception& e)
+  {
+    cerr << e.what () << endl;
+    return 1;
+  }
+}
diff --git a/section/makefile b/section/makefile
new file mode 100644
index 0000000..abbb9c9
--- /dev/null
+++ b/section/makefile
@@ -0,0 +1,122 @@
+# file      : section/makefile
+# copyright : Copyright (c) 2009-2013 Code Synthesis Tools CC
+# license   : GNU GPL v2; see accompanying LICENSE file
+
+include $(dir $(lastword $(MAKEFILE_LIST)))../build/bootstrap.make
+
+cxx_tun := driver.cxx
+odb_hdr := person.hxx
+cxx_obj := $(addprefix $(out_base)/,$(cxx_tun:.cxx=.o) $(odb_hdr:.hxx=-odb.o))
+cxx_od  := $(cxx_obj:.o=.o.d)
+
+driver  := $(out_base)/driver
+dist    := $(out_base)/.dist
+test    := $(out_base)/.test
+clean   := $(out_base)/.clean
+
+# Import.
+#
+$(call import,\
+  $(scf_root)/import/odb/stub.make,\
+  odb: odb,odb-rules: odb_rules)
+
+$(call import,\
+  $(scf_root)/import/libodb/stub.make,\
+  l: odb.l,cpp-options: odb.l.cpp-options)
+
+ifdef db_id
+$(call import,\
+  $(scf_root)/import/libodb-$(db_id)/stub.make,\
+  l: odb_db.l,cpp-options: odb_db.l.cpp-options)
+endif
+
+ifeq ($(odb_db.l.cpp-options),)
+odb_db.l.cpp-options := $(out_base)/.unbuildable
+endif
+
+# Build.
+#
+$(driver): $(cxx_obj) $(odb_db.l) $(odb.l)
+$(cxx_obj) $(cxx_od): cpp_options := -I$(out_base) -I$(src_base) -D$(db_macro)
+$(cxx_obj) $(cxx_od): $(odb.l.cpp-options) $(odb_db.l.cpp-options)
+
+genf := $(addprefix $(odb_hdr:.hxx=-odb),.hxx .ixx .cxx) $(odb_hdr:.hxx=.sql)
+gen  := $(addprefix $(out_base)/,$(genf))
+
+$(gen): $(odb)
+$(gen): odb := $(odb)
+$(gen) $(dist): export odb_options += --generate-schema --table-prefix section_
+$(gen): cpp_options := -I$(src_base)
+$(gen): $(odb.l.cpp-options)
+
+$(gen): odb_options += --database $(db_id)
+
+$(call include-dep,$(cxx_od),$(cxx_obj),$(gen))
+
+# Alias for default target.
+#
+$(out_base)/: $(driver)
+
+# Dist
+#
+name := $(subst /,-,$(subst $(src_root)/,,$(src_base)))
+
+$(dist): sources := $(cxx_tun)
+$(dist): headers := $(odb_hdr)
+$(dist): export name := $(name)
+$(dist): export odb_header_stem := $(basename $(odb_hdr))
+$(dist): export extra_dist := README $(call vc8projs,$(name)) \
+$(call vc9projs,$(name)) $(call vc10projs,$(name)) $(call vc11projs,$(name))
+$(dist):
+	$(call dist-data,$(sources) $(headers) README database.hxx)
+	$(call meta-automake,../template/Makefile.am)
+	$(call meta-vc8projs,../template/template,$(name))
+	$(call meta-vc9projs,../template/template,$(name))
+	$(call meta-vc10projs,../template/template,$(name))
+	$(call meta-vc11projs,../template/template,$(name))
+
+# Test.
+#
+$(test): header := $(odb_hdr)
+$(test): $(driver)
+	$(call schema)
+	$(call message,test $<,$< --options-file $(dcf_root)/$(db_id).options)
+
+# Clean.
+#
+$(clean):                            \
+  $(driver).o.clean                  \
+  $(addsuffix .cxx.clean,$(cxx_obj)) \
+  $(addsuffix .cxx.clean,$(cxx_od))  \
+  $(addprefix $(out_base)/,$(odb_hdr:.hxx=-odb.cxx.hxx.clean))
+
+# Generated .gitignore.
+#
+ifeq ($(out_base),$(src_base))
+$(driver): | $(out_base)/.gitignore
+
+$(out_base)/.gitignore: files := driver $(genf)
+$(clean): $(out_base)/.gitignore.clean
+
+$(call include,$(bld_root)/git/gitignore.make)
+endif
+
+# How to.
+#
+$(call include,$(bld_root)/dist.make)
+$(call include,$(bld_root)/meta/vc8proj.make)
+$(call include,$(bld_root)/meta/vc9proj.make)
+$(call include,$(bld_root)/meta/vc10proj.make)
+$(call include,$(bld_root)/meta/vc11proj.make)
+$(call include,$(bld_root)/meta/automake.make)
+
+$(call include,$(bld_root)/cxx/standard.make) # cxx_standard
+ifdef cxx_standard
+$(gen): odb_options += --std $(cxx_standard)
+$(call include,$(odb_rules))
+endif
+
+$(call include,$(bld_root)/cxx/cxx-d.make)
+$(call include,$(bld_root)/cxx/cxx-o.make)
+$(call include,$(bld_root)/cxx/o-e.make)
+
diff --git a/section/person.hxx b/section/person.hxx
new file mode 100644
index 0000000..996fc19
--- /dev/null
+++ b/section/person.hxx
@@ -0,0 +1,105 @@
+// file      : section/person.hxx
+// copyright : not copyrighted - public domain
+
+#ifndef PERSON_HXX
+#define PERSON_HXX
+
+#include <string>
+
+#include <odb/core.hxx>
+#include <odb/vector.hxx>
+#include <odb/section.hxx>
+
+#pragma db object
+class person
+{
+public:
+  person (const std::string& first, const std::string& last)
+      : first_ (first), last_ (last)
+  {
+  }
+
+  const std::string&
+  first () const
+  {
+    return first_;
+  }
+
+  const std::string&
+  last () const
+  {
+    return last_;
+  }
+
+  // Biography.
+  //
+  const std::string&
+  bio () const
+  {
+    return bio_;
+  }
+
+  void
+  bio (const std::string& bio)
+  {
+    bio_ = bio;
+    extras_.change (); // Mark the section as changed.
+  }
+
+  // Nicknames.
+  //
+  typedef odb::vector<std::string> names;
+
+  const names&
+  nicknames () const
+  {
+    return nicknames_;
+  }
+
+  names&
+  nicknames ()
+  {
+    // Because we are using a change-tracking container (odb::vector),
+    // ODB will automatically mark the section as changed if we update
+    // the nicknames.
+    //
+    return nicknames_;
+  }
+
+  // The extras section accessor and modifier. Notice that they are
+  // by-reference.
+  //
+  const odb::section&
+  extras_section () const
+  {
+    return extras_;
+  }
+
+  odb::section&
+  extras_section ()
+  {
+    return extras_;
+  }
+
+private:
+  friend class odb::access;
+
+  person () {}
+
+  #pragma db id auto
+  unsigned long id_;
+
+  std::string first_;
+  std::string last_;
+
+  #pragma db section(extras_)
+  std::string bio_;
+
+  #pragma db section(extras_)
+  names nicknames_;
+
+  #pragma db load(lazy) update(change)
+  odb::section extras_;
+};
+
+#endif // PERSON_HXX