add shared_object.hpp, the base for shared string and tstring

projectfiles/CodeBlocks-SCons/wesnoth.cbp

@@ -420,7 +420,8 @@
 		<Unit filename="..\..\src\gui\dialogs\..\..\settings.hpp" />
         <Unit filename="..\..\src\sha1.cpp" />
         <Unit filename="..\..\src\sha1.hpp" />
-        <Unit filename="..\..\src\show_dialog.cpp" />
+		<Unit filename="..\..\src\shared_object.hpp" />
+		<Unit filename="..\..\src\show_dialog.cpp" />
         <Unit filename="..\..\src\show_dialog.hpp" />
         <Unit filename="..\..\src\sound.cpp" />
         <Unit filename="..\..\src\sound.hpp" />

projectfiles/CodeBlocks/wesnoth.cbp

@@ -451,6 +451,7 @@
 		<Unit filename="..\..\src\gui\dialogs\..\..\settings.hpp" />
 		<Unit filename="..\..\src\sha1.cpp" />
 		<Unit filename="..\..\src\sha1.hpp" />
+		<Unit filename="..\..\src\shared_object.hpp" />
 		<Unit filename="..\..\src\show_dialog.cpp" />
 		<Unit filename="..\..\src\show_dialog.hpp" />
 		<Unit filename="..\..\src\sound.cpp" />

projectfiles/VC9/wesnoth.vcproj

@@ -674,6 +674,10 @@
 				RelativePath="..\..\src\statistics_dialog.cpp"
 				>
 			</File>
+			<File
+				RelativePath="..\..\src\shared_object.hpp"
+				>
+			</File>
 			<File
 				RelativePath="..\..\src\team.cpp"
 				>

src/shared_object.hpp

@@ -0,0 +1,146 @@
+#include <climits>
+#include <cassert>
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/hashed_index.hpp>
+#include <boost/multi_index/member.hpp>
+
+template <typename T>
+struct shared_node {
+	T val;
+	unsigned long count;
+	shared_node() : val(), count(0) { }
+	shared_node(const T& o) : val(o), count(0) { }
+	static const unsigned long max_count = ULONG_MAX;
+};
+
+struct increment_count {
+	template <typename T>
+	void operator()(T& o) {
+		++o.count;
+	}
+};
+
+struct decrement_count {
+	template <typename T>
+	void operator()(T& o) {
+		--o.count;
+	}
+};
+
+template <typename T>
+struct hasher {
+	size_t operator()(const T& o) {
+		return hash_value(o.val);
+	}
+};
+
+template <typename T, typename node = shared_node<T> >
+class shared_object {
+public:
+	typedef T type;
+
+	shared_object() : val_(0) { set(T()); }
+
+	template <typename U>
+	shared_object(const U& o) : val_(0) { set(o); }
+	
+	shared_object(const shared_object& o) : val_(o.val_) { 
+		assert(valid()); 
+		index().modify(index().iterator_to(*val_), increment_count());
+	}
+
+	operator T() const {
+		assert(valid());
+		return val_->val;
+	}
+
+	shared_object& operator=(const shared_object& o) {
+		if (val_ == o.val_) return *this;
+		shared_object tmp(o);
+		swap(tmp);
+		return *this;
+	}
+
+	~shared_object() { clear(); }
+
+	void set(const T& o) {
+		if (val_ && o == get()) return;
+		clear();
+
+		val_ = &*index().insert(node(o)).first;
+		index().modify(index().iterator_to(*val_), increment_count());
+
+		assert((val_->count) < (node::max_count));
+	}
+
+	const T& get() const {
+		assert(valid());
+		return val_->val;
+	}
+
+	void swap(shared_object& o) {
+		std::swap(val_, o.val_);
+	}
+
+	bool valid() const {
+		return val_;
+	}
+
+	const node* ptr() const {
+		return val_;
+	}
+
+protected:
+
+	typedef boost::multi_index_container<
+		node,
+		boost::multi_index::indexed_by<
+			boost::multi_index::hashed_unique<
+				BOOST_MULTI_INDEX_MEMBER(node, T, val)
+			>
+		>
+	> hash_map;
+
+	typedef typename hash_map::template nth_index<0>::type hash_index;
+
+	static hash_map& map() { static hash_map* map = new hash_map; return *map; }
+	static hash_index& index() { return map().template get<0>(); }
+
+	const node* val_;
+	
+	void clear() {
+		if (!val_) return;
+		index().modify(index().iterator_to(*val_), decrement_count());
+
+		if (val_->count == 0) index().erase(index().iterator_to(*val_));
+		val_ = 0;
+	}
+
+};
+
+template <typename T>
+bool operator==(const shared_object<T>& a, const shared_object<T>& b) {
+	return a.ptr() == b.ptr() ? true : a.get() == b.get();
+}
+
+template <typename T>
+bool operator<(const shared_object<T>& a, const shared_object<T>& b) {
+	assert(a.valid());
+	assert(b.valid());
+	return a.get() < b.get();
+}
+
+template <typename T>
+std::ostream& operator<<(std::ostream& stream, const shared_object<T>& o) {
+	assert(o.valid());
+	return stream << o.get();
+}
+
+template <typename T>
+std::istream& operator>>(std::istream& stream, shared_object<T>& o) {
+	T t;
+	std::istream& ret = stream >> t;
+	o.set(t);
+	return ret;
+}
+