#i105938# Provides simplistic pool memory from a std::vector

1 files changed, 132 insertions, 0 deletions

diff --git a/o3tl/inc/o3tl/vector_pool.hxx b/o3tl/inc/o3tl/vector_pool.hxx
new file mode 100644
index 000000000000..19fc3d6d74c4
--- /dev/null
+++ b/o3tl/inc/o3tl/vector_pool.hxx
@@ -0,0 +1,132 @@
+/*************************************************************************
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * Copyright 2008 by Sun Microsystems, Inc.
+ *
+ * OpenOffice.org - a multi-platform office productivity suite
+ *
+ * $RCSfile: lazy_update.hxx,v $
+ * $Revision: 1.3 $
+ *
+ * This file is part of OpenOffice.org.
+ *
+ * OpenOffice.org is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3
+ * only, as published by the Free Software Foundation.
+ *
+ * OpenOffice.org is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License version 3 for more details
+ * (a copy is included in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * version 3 along with OpenOffice.org.  If not, see
+ * <http://www.openoffice.org/license.html>
+ * for a copy of the LGPLv3 License.
+ *
+ ************************************************************************/
+
+#ifndef INCLUDED_O3TL_VECTOR_POOL_HXX
+#define INCLUDED_O3TL_VECTOR_POOL_HXX
+
+#include <sal/types.h>
+#include <vector>
+
+namespace o3tl
+{
+    namespace detail
+    {
+        template<typename ValueType, class Container> class simple_pool_impl :
+            public Container
+        {
+            typedef typename Container::value_type value_type;
+            std::ptrdiff_t mnFirstFreeIndex;
+
+        public:
+            simple_pool_impl() :
+                mnFirstFreeIndex(-1)
+            {}
+
+            std::ptrdiff_t alloc()
+            {
+                return store(ValueType());
+            }
+
+            std::ptrdiff_t store(const ValueType& rCopy)
+            {
+                if( mnFirstFreeIndex != -1 )
+                {
+                    std::ptrdiff_t nIdx=mnFirstFreeIndex;
+                    mnFirstFreeIndex = this->at(mnFirstFreeIndex).nextFree;
+                    this->at(nIdx).value = rCopy;
+                    this->at(nIdx).nextFree = -1;
+
+                    return nIdx;
+                }
+                else
+                {
+                    push_back(value_type(rCopy));
+                    return this->size()-1;
+                }
+            }
+
+            void free( std::ptrdiff_t nIdx )
+            {
+                this->at(nIdx).nextFree = mnFirstFreeIndex;
+                mnFirstFreeIndex = nIdx;
+            }
+
+            const ValueType& get( std::ptrdiff_t nIdx ) const
+            {
+                return this->operator[](nIdx).value;
+            }
+            ValueType& get( std::ptrdiff_t nIdx )
+            {
+                return this->operator[](nIdx).value;
+            }
+        };
+
+        template< typename ValueType > struct struct_from_value
+        {
+            struct type
+            {
+                type() :
+                    value(),
+                    nextFree(-1)
+                {}
+                explicit type( const ValueType& val ) :
+                    value(val),
+                    nextFree(-1)
+                {}
+
+                ValueType      value;
+                std::ptrdiff_t nextFree;
+            };
+        };
+    }
+
+    /** Simple vector-based memory pool allocator
+
+        This template can be used to provide simple pooled memory
+        allocation from a container class that adheres to the stl
+        random access container concept. Note that alloc/free works
+        with _indices_ into the container!
+
+        @example
+        <pre>
+vector_pool<type> myPool;
+int nIdx=myPool.alloc();
+myPool[nIdx] = myVal;
+ ... do stuff ...
+myPool.free(nIdx);
+        </pre>
+     */
+    template<typename ValueType> struct vector_pool :
+        public detail::simple_pool_impl<ValueType,
+                                       std::vector<typename detail::struct_from_value<ValueType>::type > >
+    {};
+}
+
+#endif /* INCLUDED_O3TL_VECTOR_POOL_HXX */