[Boost-commit] svn:boost r85120 - trunk/boost/xpressive/detail/utility

Subject: [Boost-commit] svn:boost r85120 - trunk/boost/xpressive/detail/utility
From: eric_at_[hidden]
Date: 2013-07-23 00:03:37

Author: eric_niebler
Date: 2013-07-23 00:03:37 EDT (Tue, 23 Jul 2013)
New Revision: 85120
URL: http://svn.boost.org/trac/boost/changeset/85120

Log:
use RAII instead of try/catch in sequence_stack.hpp, refs #8882

Text files modified: 
   trunk/boost/xpressive/detail/utility/sequence_stack.hpp |    33 ++++++++++++++++++++-------------       
   1 files changed, 20 insertions(+), 13 deletions(-)

Modified: trunk/boost/xpressive/detail/utility/sequence_stack.hpp
==============================================================================
--- trunk/boost/xpressive/detail/utility/sequence_stack.hpp	Mon Jul 22 23:26:30 2013	(r85119)
+++ trunk/boost/xpressive/detail/utility/sequence_stack.hpp	2013-07-23 00:03:37 EDT (Tue, 23 Jul 2013)	(r85120)
@@ -31,22 +31,29 @@
 template<typename T>
 struct sequence_stack
 {
+    struct allocate_guard_t;
+    friend struct allocate_guard_t;
+    struct allocate_guard_t
+    {
+        std::size_t i;
+        T *p;
+        bool dismissed;
+        ~allocate_guard_t()
+        {
+            if(!this->dismissed)
+                sequence_stack::deallocate(this->p, this->i);
+        }
+    };
 private:
     static T *allocate(std::size_t size, T const &t)
     {
-        std::size_t i = 0;
-        T *p = (T *)::operator new(size * sizeof(T));
-        try
-        {
-            for(; i < size; ++i)
-                ::new((void *)(p+i)) T(t);
-        }
-        catch(...)
-        {
-            deallocate(p, i);
-            throw;
-        }
-        return p;
+        allocate_guard_t guard = {0, (T *)::operator new(size * sizeof(T)), false};
+
+        for(; guard.i < size; ++guard.i)
+            ::new((void *)(guard.p + guard.i)) T(t);
+        guard.dismissed = true;
+
+        return guard.p;
     }
 
     static void deallocate(T *p, std::size_t i)