Made load dialog faster when there are many saved games.

1. Added a child_range_index member function to config to generate an index

2. Changed the load dialog from the O(N^2) search for saved games to a
O(N) listing.

src/config.cpp

@@ -422,8 +422,7 @@ void config::merge_children_by_attribute(const t_token& key, const t_token& attr
 void config::merge_children_by_attribute(const std::string& key, const std::string& attribute){
 	merge_children_by_attribute(t_token(key), t_token(attribute));}
 
-config::child_itors config::child_range(const t_token& key)
-{
+config::child_itors config::child_range(const t_token& key) {
 	check_valid();
 
 	child_map::iterator i = children.find(key);
@@ -437,8 +436,7 @@ config::child_itors config::child_range(const t_token& key)
 }
 config::child_itors config::child_range(const std::string& key){ return child_range( t_token(key) );}
 
-config::const_child_itors config::child_range(const t_token& key) const
-{
+config::const_child_itors config::child_range(const t_token& key) const {
 	check_valid();
 
 	child_map::const_iterator i = children.find(key);
@@ -452,8 +450,7 @@ config::const_child_itors config::child_range(const t_token& key) const
 }
 
 config::const_child_itors config::child_range(const std::string& key) const { return child_range(t_token(key));}  
-unsigned config::child_count(const t_token &key) const
-{
+unsigned config::child_count(const t_token &key) const {
 	check_valid();
 
 	child_map::const_iterator i = children.find(key);
@@ -463,6 +460,25 @@ unsigned config::child_count(const t_token &key) const
 	return 0;
 }
 
+config::t_child_range_index config::child_range_index(config::t_token const & key, config::t_token const & name) {
+	t_child_range_index index;
+
+	child_map::iterator irange = children.find(key);
+	if (irange != children.end()) {
+		foreach(config * c, irange->second) {
+			index.insert(std::make_pair((*c)[name].token(), c)); } }
+		return index; }
+
+config::t_const_child_range_index config::const_child_range_index(config::t_token const & key, config::t_token const & name) const {
+	t_const_child_range_index index;
+
+	child_map::const_iterator irange = children.find(key);
+	if (irange != children.end()) {
+		foreach(config const * c, irange->second){
+			index.insert(std::make_pair((*c)[name].token(), c)); } }
+		return index; }
+
+
 unsigned config::child_count(const std::string &key) const { return child_count(t_token(key)); }  
 config &config::child(const t_token& key, int n)
 {

src/config.hpp

@@ -117,6 +117,9 @@ public:
 	//typedef std::map<t_token,child_list> child_map;
 	typedef boost::unordered_map<t_token,child_list> child_map;
 
+	typedef boost::unordered_map<config::t_token, config *> t_child_range_index;
+	typedef boost::unordered_map<config::t_token, config const *> t_const_child_range_index;
+
 	struct const_child_iterator;
 
 	struct child_iterator
@@ -298,6 +301,19 @@ public:
 	typedef std::pair<const_attribute_iterator,const_attribute_iterator> const_attr_itors;
 	child_itors child_range(const t_token& key);
 	const_child_itors child_range(const t_token& key) const;
+
+	/** Creates an index into the child range to allow for quick searches.
+		key is the key for the child range and name is the column to index.
+		i.e. if the list of save games is stored in a child called save with titles 
+		then to create a container indexed by titles do
+
+		child_range_index(z_save, z_title);
+		@Note the index is not stored in the config and is intended for 
+		repeated searches of large child ranges.
+	 */
+	t_child_range_index child_range_index(const t_token& key, config::t_token const & name);
+	t_const_child_range_index const_child_range_index(const t_token& key, config::t_token const & name) const;
+
 	unsigned child_count(const t_token &key) const;
 
 	child_itors child_range(const std::string& key);

src/dialogs.cpp

@@ -578,14 +578,20 @@ std::string load_game_dialog(display& disp, const config& game_config, bool* sho
 		return "";
 	}
 
+	config::t_child_range_index index = savegame::save_index::indexed_summaries();
+
 	std::vector<config*> summaries;
 	std::vector<savegame::save_info>::const_iterator i;
 	//FIXME: parent_to_child is not used yet
 	std::map<std::string,std::string> parent_to_child;
 	for(i = games.begin(); i != games.end(); ++i) {
-		config& cfg = savegame::save_index::save_summary(i->name);
-		parent_to_child[cfg["parent"]] = i->name;
-		summaries.push_back(&cfg);
+		config::t_token iname(i->name);
+		config::t_child_range_index::iterator xcfgi = index.find( iname);
+		if(xcfgi != index.end()){
+			config& cfg = *xcfgi->second;
+			parent_to_child[cfg["parent"]] = iname;
+			summaries.push_back(&cfg);
+		}
 	}
 
 	const events::event_context context;

src/savegame.cpp

@@ -126,6 +126,13 @@ static lg::log_domain log_engine("engine");
 	}
 #endif /* _WIN32 */
 
+
+
+namespace {
+	//Static tokens are replacements for string literals in code
+	//They allow for fast comparison, copying and hashing operations.
+	static const config::t_token z_save("save", false);
+}
 namespace savegame {
 
 const std::string save_info::format_time_local() const{
@@ -374,14 +381,18 @@ config& save_index::save_summary(std::string save)
 	}
 
 	config& cfg = load();
-	if (config &sv = cfg.find_child("save", "save", save))
+	if (config &sv = cfg.find_child(z_save, z_save, save))
 		return sv;
 
-	config &res = cfg.add_child("save");
-	res["save"] = save;
+	config &res = cfg.add_child(z_save);
+	res[z_save] = save;
 	return res;
 }
 
+config::t_child_range_index save_index::indexed_summaries(){
+	return load().child_range_index(z_save, z_save);
+}
+
 void save_index::write_save_index()
 {
 	log_scope("write_save_index()");

src/savegame.hpp

@@ -80,6 +80,8 @@ public:
 	static config& save_summary(std::string save);
 	/** Update the save_index file with changed savegame information. */
 	static void write_save_index();
+	/** Create an index to the save summaries. */
+	static config::t_child_range_index indexed_summaries();
 
 private:
 	/** Default-Constructor (don't instantiate this class) */