From c56f32eb5e0b88ef8297a691f5286ba4aa4aa8b4 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 16 Aug 2010 11:45:23 +0200
Subject: Add pointer guard for naked pointer

---
 odb/database.txx       |  2 +-
 odb/pointer-traits.hxx | 41 +++++++++++++++++++++++++++++++++++++++++
 odb/result.hxx         | 25 +++++++++++++++++++++----
 odb/traits.hxx         | 12 ++++++------
 4 files changed, 69 insertions(+), 11 deletions(-)

(limited to 'odb')

diff --git a/odb/database.txx b/odb/database.txx
index a120afa..bec3234 100644
--- a/odb/database.txx
+++ b/odb/database.txx
@@ -32,7 +32,7 @@ namespace odb
 
     typename traits::pointer_type r (find<T> (id));
 
-    if (traits::pointer_ops::null_ptr (r))
+    if (traits::pointer_traits::null_ptr (r))
       throw object_not_persistent ();
 
     return r;
diff --git a/odb/pointer-traits.hxx b/odb/pointer-traits.hxx
index a715a9d..26f8b90 100644
--- a/odb/pointer-traits.hxx
+++ b/odb/pointer-traits.hxx
@@ -16,6 +16,24 @@ namespace odb
   template <typename P>
   class pointer_traits;
 
+  // No-op pointer guard for smart pointers.
+  //
+  template <typename P>
+  class nop_guard
+  {
+  public:
+    nop_guard () {}
+
+    explicit
+    nop_guard (P) {}
+
+    void
+    release () {}
+
+    void
+    reset (P) {}
+  };
+
   // Default implementation that should work for any sensible smart
   // pointer with one template argument (object type). The only
   // assumptions that we make are the availability of operator-> and
@@ -28,6 +46,7 @@ namespace odb
   public:
     typedef T type;
     typedef P<T> pointer;
+    typedef nop_guard<pointer> guard;
 
     // Return underlying pointer, including NULL.
     //
@@ -77,12 +96,33 @@ namespace odb
 
   // Specialization for naked pointer.
   //
+  template <typename P>
+  class nptr_guard
+  {
+  public:
+    ~nptr_guard () {delete p_;}
+    nptr_guard (): p_ (0) {}
+
+    explicit
+    nptr_guard (P p): p_ (p) {}
+
+    void
+    release () {p_ = 0;}
+
+    void
+    reset (P p) {delete p_; p_ = p;}
+
+  private:
+    P p_;
+  };
+
   template <typename T>
   class pointer_traits<T*>
   {
   public:
     typedef T type;
     typedef T* pointer;
+    typedef nptr_guard<pointer> guard;
 
     static type*
     get_ptr (pointer p)
@@ -126,6 +166,7 @@ namespace odb
   public:
     typedef T type;
     typedef odb::shared_ptr<T> pointer;
+    typedef nop_guard<pointer> guard;
 
     static type*
     get_ptr (const pointer& p)
diff --git a/odb/result.hxx b/odb/result.hxx
index 87374e5..0323b66 100644
--- a/odb/result.hxx
+++ b/odb/result.hxx
@@ -32,12 +32,19 @@ namespace odb
     friend class result<T>;
     friend class result_iterator<T>;
 
-    typename object_traits<T>::pointer_type
-    current (bool /*release*/)
+    typedef object_traits<T> traits;
+    typedef typename traits::pointer_type pointer_type;
+    typedef typename traits::pointer_traits pointer_traits;
+
+    pointer_type
+    current (bool release)
     {
-      if (object_traits<T>::pointer_ops::null_ptr (current_) && !end_)
+      if (pointer_traits::null_ptr (current_) && !end_)
         current ();
 
+      if (release)
+        guard_.release ();
+
       return current_;
     }
 
@@ -58,8 +65,18 @@ namespace odb
     next () = 0;
 
   protected:
+    void
+    current (pointer_type p)
+    {
+      current_ = p;
+      guard_.reset (current_);
+    }
+
     bool end_;
-    typename object_traits<T>::pointer_type current_;
+
+  private:
+    pointer_type current_;
+    typename pointer_traits::guard guard_;
   };
 
   template <typename T>
diff --git a/odb/traits.hxx b/odb/traits.hxx
index d38ee41..e5c9eed 100644
--- a/odb/traits.hxx
+++ b/odb/traits.hxx
@@ -67,16 +67,16 @@ namespace odb
     create ()
     {
       void* v (pointer_traits<P>::allocate (sizeof (object_type)));
-      guard g (v);
+      mem_guard g (v);
       P p (new (v) object_type);
       g.release ();
       return p;
     }
   private:
-    struct guard
+    struct mem_guard
     {
-      guard (void* p): p_ (p) {}
-      ~guard () {if (p_) pointer_traits<P>::free (p_);}
+      mem_guard (void* p): p_ (p) {}
+      ~mem_guard () {if (p_) pointer_traits<P>::free (p_);}
       void release () {p_ = 0;}
       void* p_;
     };
@@ -86,8 +86,8 @@ namespace odb
   struct object_traits: access::object_traits<T>
   {
     typedef
-    pointer_traits<typename access::object_traits<T>::pointer_type>
-    pointer_ops;
+    odb::pointer_traits<typename access::object_traits<T>::pointer_type>
+    pointer_traits;
   };
 }
 
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