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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/* $Rev$ $Date$ */
+
+#ifndef tuscany_gc_hpp
+#define tuscany_gc_hpp
+
+/**
+ * Garbage collected memory management, using APR memory pools.
+ */
+
+#include <stdlib.h>
+#include <apr_general.h>
+#include <apr_pools.h>
+#include <assert.h>
+#include <new>
+#include "config.hpp"
+
+namespace tuscany
+{
+
+/**
+ * Pointer to a value.
+ */
+template<typename T> class gc_ptr {
+public:
+    gc_ptr(T* ptr = NULL) throw() : ptr(ptr) {
+    }
+
+    ~gc_ptr() throw() {
+    }
+
+    gc_ptr(const gc_ptr& r) throw() : ptr(r.ptr) {
+    }
+
+    gc_ptr& operator=(const gc_ptr& r) throw() {
+        if(this == &r)
+            return *this;
+        ptr = r.ptr;
+        return *this;
+    }
+
+    const bool operator==(const gc_ptr& r) const throw() {
+        if (this == &r)
+            return true;
+        return ptr == r.ptr;
+    }
+
+    const bool operator!=(const gc_ptr& r) const throw() {
+        return !this->operator==(r);
+    }
+
+    T& operator*() const throw() {
+        return *ptr;
+    }
+
+    T* operator->() const throw() {
+        return ptr;
+    }
+
+    operator T*() const throw() {
+        return ptr;
+    }
+
+    T* ptr;
+};
+
+/**
+ * Garbage collected APR memory pool.
+ */
+class gc_pool {
+public:
+    gc_pool() : apr_pool(NULL) {
+    }
+
+    gc_pool(apr_pool_t* p) : apr_pool(p) {
+    }
+
+    gc_pool(const gc_pool& pool) : apr_pool(pool.apr_pool) {
+    }
+
+    gc_pool& operator=(const gc_pool& pool) {
+        if (this == &pool)
+            return *this;
+        apr_pool = pool.apr_pool;
+        return *this;
+    }
+
+private:
+    friend apr_pool_t* pool(const gc_pool& pool);
+    friend class gc_global_pool_t;
+    friend class gc_scoped_pool;
+
+    apr_pool_t* apr_pool;
+};
+
+/**
+ * Return APR pool used by a gc_pool.
+ */
+apr_pool_t* pool(const gc_pool& pool) {
+    return pool.apr_pool;
+}
+
+/**
+ * Destroy a memory pool.
+ */
+const bool destroy(const gc_pool& p) {
+    apr_pool_destroy(pool(p));
+    return true;
+}
+
+/**
+ * Initialize APR.
+ */
+class gc_apr_context_t {
+public:
+    gc_apr_context_t() {
+        apr_initialize();
+    }
+} gc_apr_context;
+
+/**
+ * Maintain a stack of memory pools.
+ */
+#ifdef WANT_THREADS
+__thread
+#endif
+apr_pool_t* gc_pool_stack = NULL;
+
+/**
+ * Return the current memory pool.
+ */
+apr_pool_t* gc_current_pool() {
+    apr_pool_t* apr_pool = gc_pool_stack;
+    if (apr_pool != NULL)
+        return apr_pool;
+
+    // Create a parent pool for the current thread
+    apr_pool_create(&apr_pool, NULL);
+    assert(apr_pool != NULL);
+    gc_pool_stack = apr_pool;
+    return apr_pool;
+}
+
+/**
+ * Push a pool onto the stack.
+ */
+apr_pool_t* gc_push_pool(apr_pool_t* pool) {
+    apr_pool_t* p = gc_pool_stack;
+    gc_pool_stack = pool;
+    return p;
+}
+
+/**
+ * Pop a pool from the stack.
+ */
+apr_pool_t* gc_pop_pool(apr_pool_t* pool) {
+    apr_pool_t* p = gc_pool_stack;
+    gc_pool_stack = pool;
+    return p;
+}
+
+/**
+ * A memory pool scope, used to setup a scope in which a particular pool
+ * will be used for all allocations.
+ */
+class gc_scoped_pool : public gc_pool {
+public:
+
+    gc_scoped_pool() : gc_pool(NULL), prev(gc_current_pool()), owner(true) {
+        apr_pool_create(&apr_pool, NULL);
+        assert(apr_pool != NULL);
+        gc_push_pool(apr_pool);
+    }
+
+    gc_scoped_pool(apr_pool_t* pool) : gc_pool(pool), prev(gc_current_pool()), owner(false) {
+        gc_push_pool(apr_pool);
+    }
+
+    ~gc_scoped_pool() {
+        if (owner)
+            apr_pool_destroy(apr_pool);
+        gc_pop_pool(prev);
+    }
+
+private:
+    gc_scoped_pool(const unused gc_scoped_pool& pool) : gc_pool(pool.apr_pool), prev(NULL), owner(false) {
+    }
+
+    apr_pool_t* prev;
+    bool owner;
+};
+
+/**
+ * Allocates a pointer to an object allocated from a memory pool and
+ * register a cleanup callback for it.
+ */
+template<typename T> apr_status_t gc_pool_cleanup(void* v) {
+    T* t = static_cast<T*>(v);
+    t->~T();
+    return APR_SUCCESS;
+}
+
+template<typename T> T* gc_new(apr_pool_t* p) {
+    void* gc_new_ptr = apr_palloc(p, sizeof(T));
+    assert(gc_new_ptr != NULL);
+    apr_pool_cleanup_register(p, gc_new_ptr, gc_pool_cleanup<T>, apr_pool_cleanup_null) ;
+    return static_cast<T*>(gc_new_ptr);
+}
+
+template<typename T> T* gc_new(const gc_pool& p) {
+    return gc_new<T>(pool(p));
+}
+
+template<typename T> T* gc_new() {
+    return gc_new<T>(gc_current_pool());
+}
+
+template<typename T> apr_status_t gc_pool_acleanup(void* v) {
+    int* m = static_cast<int*>(v);
+    int n = *m;
+    T* t = (T*)(m + 1);
+    for (int i = 0; i < n; i++, t++)
+        t->~T();
+    return APR_SUCCESS;
+}
+
+template<typename T> T* gc_anew(apr_pool_t* p, int n) {
+    int* gc_anew_ptr = static_cast<int*>(apr_palloc(p, sizeof(int) + sizeof(T[n])));
+    assert(gc_anew_ptr != NULL);
+    *gc_anew_ptr = n;
+    apr_pool_cleanup_register(p, gc_anew_ptr, gc_pool_acleanup<T>, apr_pool_cleanup_null) ;
+    return (T*)(gc_anew_ptr + 1);
+}
+
+template<typename T> T* gc_anew(const gc_pool& p, int n) {
+    return gc_anew<T>(pool(p), n);
+}
+
+template<typename T> T* gc_anew(int n) {
+    return gc_anew<T>(gc_current_pool(), n);
+}
+
+/**
+ * Allocate an array of chars.
+ */
+char* gc_cnew(apr_pool_t* p, int n) {
+    char* gc_cnew_ptr = static_cast<char*>(apr_palloc(p, n));
+    assert(gc_cnew_ptr != NULL);
+    return gc_cnew_ptr;
+}
+
+char* gc_cnew(int n) {
+    return gc_cnew(gc_current_pool(), n);
+}
+
+}
+
+#endif /* tuscany_gc_hpp */