From 9bafeadb554fd4dfc11ce5c2b036a937008455f9 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 10 Aug 2010 13:16:47 +0200
Subject: Make result copy-assignable

Return result from database::query instead of pointer to impl
---
 odb/database.hxx |  6 +++---
 odb/database.txx |  6 +++---
 odb/result.hxx   | 48 ++++++++++++++++++++++++------------------------
 3 files changed, 30 insertions(+), 30 deletions(-)

(limited to 'odb')

diff --git a/odb/database.hxx b/odb/database.hxx
index 1b3a6d6..0a993d5 100644
--- a/odb/database.hxx
+++ b/odb/database.hxx
@@ -71,15 +71,15 @@ namespace odb
     // Object query API.
     //
     template <typename T>
-    shared_ptr<result_impl<T> >
+    result<T>
     query ();
 
     template <typename T>
-    shared_ptr<result_impl<T> >
+    result<T>
     query (const std::string&);
 
     template <typename T>
-    shared_ptr<result_impl<T> >
+    result<T>
     query (const odb::query<T>&);
 
     // Transaction API.
diff --git a/odb/database.txx b/odb/database.txx
index 7440127..a120afa 100644
--- a/odb/database.txx
+++ b/odb/database.txx
@@ -94,21 +94,21 @@ namespace odb
   }
 
   template <typename T>
-  shared_ptr<result_impl<T> > database::
+  result<T> database::
   query ()
   {
     return query (odb::query<T> ());
   }
 
   template <typename T>
-  shared_ptr<result_impl<T> > database::
+  result<T> database::
   query (const std::string& q)
   {
     return query (odb::query<T> (q));
   }
 
   template <typename T>
-  shared_ptr<result_impl<T> > database::
+  result<T> database::
   query (const odb::query<T>& q)
   {
     if (!transaction::has_current ())
diff --git a/odb/result.hxx b/odb/result.hxx
index 979988a..7356395 100644
--- a/odb/result.hxx
+++ b/odb/result.hxx
@@ -31,14 +31,9 @@ namespace odb
     typedef std::input_iterator_tag iterator_category;
 
   public:
-    result_iterator ()
-        : res_ (0)
-    {
-    }
-
     explicit
-    result_iterator (result_impl<T>& res)
-        : res_ (&res)
+    result_iterator (result_impl<T>* res = 0)
+        : res_ (res)
     {
     }
 
@@ -140,24 +135,41 @@ namespace odb
     typedef std::ptrdiff_t difference_type;
 
   public:
+    result ()
+    {
+    }
+
+    explicit
     result (shared_ptr<result_impl<T> > impl)
         : impl_ (impl)
     {
     }
 
-    /*
+    // Copying or assignment of a result object leads to one instance
+    // being an alias for another. Think of copying a result as copying
+    // a file handle -- the file you access through either of them is
+    // still the same.
+    //
+  public:
+    result (const result& r)
+        : impl_ (r.impl_)
+    {
+    }
+
     result&
-    operator= (shared_ptr<result_impl<T> > impl)
+    operator= (const result& r)
     {
-      impl_ = impl;
+      if (impl_ != r.impl_)
+        impl_ = r.impl_;
+
+      return *this;
     }
-    */
 
   public:
     iterator
     begin ()
     {
-      return iterator (*impl_);
+      return iterator (impl_.get ());
     }
 
     iterator
@@ -166,18 +178,6 @@ namespace odb
       return iterator ();
     }
 
-  public:
-    operator shared_ptr<result_impl<T> > ()
-    {
-      return impl_;
-    }
-
-    // Copying or assignment of results is not supported.
-    //
-  private:
-    result (const result&);
-    result& operator= (const result&);
-
   private:
     shared_ptr<result_impl<T> > impl_;
   };
-- 
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