From 0881c95bef812d94d8086225c2736b4f15b4c8dc Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 19 Apr 2020 17:30:36 +0300
Subject: [PATCH] Support custom action maps in loader classes

This makes it possible to implement a persistent action map which is
only initialized once the first time a particular class is used.
---
 source/loader.cpp | 42 ++++++++++++++++++++++++++++++++++--------
 source/loader.h   | 11 +++++++++--
 2 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/source/loader.cpp b/source/loader.cpp
index 55492b6..51e22ed 100644
--- a/source/loader.cpp
+++ b/source/loader.cpp
@@ -48,6 +48,7 @@ namespace Msp {
 namespace DataFile {
 
 Loader::Loader():
+	actions(0),
 	cur_st(0),
 	direct(false),
 	check_sub_loads(false)
@@ -55,12 +56,15 @@ Loader::Loader():
 
 Loader::~Loader()
 {
-	for(ActionMap::iterator i=actions.begin(); i!=actions.end(); ++i)
+	for(ActionMap::iterator i=local_actions.begin(); i!=local_actions.end(); ++i)
 		delete i->second;
 }
 
 void Loader::load(Parser &p)
 {
+	if(!actions)
+		throw logic_error("no actions");
+
 	while(p)
 	{
 		if(p.peek(0))
@@ -78,6 +82,9 @@ void Loader::load(Parser &p)
 
 void Loader::load(const Statement &st)
 {
+	if(!actions)
+		throw logic_error("no actions");
+
 	for(list<Statement>::const_iterator i=st.sub.begin(); i!=st.sub.end(); ++i)
 		load_statement(*i);
 	finish();
@@ -156,17 +163,30 @@ void Loader::load_sub_with(Loader &ldr)
 		throw logic_error("no current statement");
 }
 
+void Loader::set_actions(ActionMap &a)
+{
+	if(actions)
+		throw logic_error("actions already set");
+
+	actions = &a;
+	if(a.empty())
+		init_actions();
+}
+
 void Loader::add(const string &kwd, LoaderAction *act)
 {
+	if(!actions)
+		actions = &local_actions;
+
 	StatementKey key(kwd, (act ? act->get_signature() : "*"));
-	ActionMap::iterator i = actions.find(key);
-	if(i!=actions.end())
+	ActionMap::iterator i = actions->find(key);
+	if(i!=actions->end())
 	{
 		delete i->second;
 		i->second = act;
 	}
 	else
-		actions[key] = act;
+		(*actions)[key] = act;
 }
 
 void Loader::add_auxiliary_loader(Loader &ldr)
@@ -176,8 +196,11 @@ void Loader::add_auxiliary_loader(Loader &ldr)
 
 bool Loader::has_action(const StatementKey &key) const
 {
-	ActionMap::const_iterator i = actions.lower_bound(StatementKey(key.keyword, string()));
-	for(; (i!=actions.end() && i->first.keyword==key.keyword); ++i)
+	if(!actions)
+		return false;
+
+	ActionMap::const_iterator i = actions->lower_bound(StatementKey(key.keyword, string()));
+	for(; (i!=actions->end() && i->first.keyword==key.keyword); ++i)
 		if(signature_match(key.signature, i->first.signature))
 			return true;
 	return false;
@@ -185,8 +208,11 @@ bool Loader::has_action(const StatementKey &key) const
 
 LoaderAction *Loader::find_action(const StatementKey &key) const
 {
-	ActionMap::const_iterator begin = actions.lower_bound(StatementKey(key.keyword, string()));
-	ActionMap::const_iterator end = actions.upper_bound(StatementKey(key.keyword, "~"));
+	if(!actions)
+		return 0;
+
+	ActionMap::const_iterator begin = actions->lower_bound(StatementKey(key.keyword, string()));
+	ActionMap::const_iterator end = actions->upper_bound(StatementKey(key.keyword, "~"));
 
 	if(begin==end)
 		throw unknown_keyword(key.keyword);
diff --git a/source/loader.h b/source/loader.h
index 7799a7e..5dac2e6 100644
--- a/source/loader.h
+++ b/source/loader.h
@@ -35,10 +35,12 @@ See also classes ObjectLoader and CollectionObjectLoader in objectloader.h.
 */
 class Loader
 {
-private:
+protected:
 	typedef std::map<StatementKey, LoaderAction *> ActionMap;
 
-	ActionMap actions;
+private:
+	ActionMap local_actions;
+	ActionMap *actions;
 	Parser *cur_parser;
 	unsigned cur_level;
 	const Statement *cur_st;
@@ -88,6 +90,11 @@ protected:
 	/** Processes the current statement's substatements with another Loader. */
 	void load_sub_with(Loader &);
 
+	/** Sets the actions to be used when loading.  If the map is empty,
+	init_actions will be called. */
+	void set_actions(ActionMap &);
+	virtual void init_actions() { }
+
 	/** Adds a keyword that is loaded by calling a function. */
 	template<typename L>
 	void add(const std::string &k, void (L::*func)())
-- 
2.43.0