Merge pull request #507 from CelticMinstrel/lua-vconfig

Lua vconfig iteration

data/lua/helper.lua

@@ -39,9 +39,7 @@ end
 --! If @a id is not nil, the "id" attribute of the subtag has to match too.
 --! The function also returns the index of the subtag in the array.
 function helper.get_child(cfg, name, id)
-	-- ipairs cannot be used on a vconfig object
-	for i = 1, #cfg do
-		local v = cfg[i]
+	for i,v in ipairs(cfg) do
 		if v[1] == name then
 			local w = v[2]
 			if not id or w.id == id then return w, i end
@@ -49,19 +47,50 @@ function helper.get_child(cfg, name, id)
 	end
 end
 
+--! Returns the nth subtag of @a cfg with the given @a name.
+--! (Indices start at 1, as always with Lua.)
+--! The function also returns the index of the subtag in the array.
+function helper.get_nth_child(cfg, name, n)
+	for i,v in ipairs(cfg) do
+		if v[1] == name then
+			n = n - 1
+			if n == 0 then return v[2], i end
+		end
+	end
+end
+
+--! Returns the number of subtags of @a with the given @a name.
+function helper.child_count(cfg, name)
+	local n = 0
+	for i,v in ipairs(cfg) do
+		if v[1] == name then
+			n = n + 1
+		end
+	end
+	return n
+end
+
 --! Returns an iterator over all the subtags of @a cfg with the given @a name.
 function helper.child_range(cfg, tag)
+	local iter, state, i = ipairs(cfg)
 	local function f(s)
 		local c
 		repeat
-			local i = s.i
-			c = cfg[i]
+			i,c = iter(s,i)
 			if not c then return end
-			s.i = i + 1
 		until c[1] == tag
 		return c[2]
 	end
-	return f, { i = 1 }
+	return f, state
+end
+
+--! Returns an array from the subtags of @a cfg with the given @a name
+function helper.child_array(cfg, tag)
+	local result = {}
+	for val in helper.child_range(cfg, tag) do
+		table.insert(result, val)
+	end
+	return result
 end
 
 --! Modifies all the units satisfying the given @a filter.

src/scripting/lua_common.cpp

@@ -42,6 +42,8 @@
 
 static const char * gettextKey = "gettext";
 static const char * vconfigKey = "vconfig";
+static const char * vconfigpairsKey = "vconfig pairs";
+static const char * vconfigipairsKey = "vconfig ipairs";
 const char * tstringKey = "translatable string";
 
 namespace lua_common {
@@ -227,10 +229,105 @@ static int impl_vconfig_size(lua_State *L)
 static int impl_vconfig_collect(lua_State *L)
 {
 	vconfig *v = static_cast<vconfig *>(lua_touserdata(L, 1));
-	v->vconfig::~vconfig();
+	v->~vconfig();
 	return 0;
 }
 
+/**
+ * Iterate through the attributes of a vconfig
+ */
+static int impl_vconfig_pairs_iter(lua_State *L)
+{
+	vconfig vcfg = luaW_checkvconfig(L, 1);
+	void* p = luaL_checkudata(L, lua_upvalueindex(1), vconfigpairsKey);
+	config::const_attr_itors& range = *static_cast<config::const_attr_itors*>(p);
+	if (range.first == range.second) {
+		return 0;
+	}
+	config::attribute value = *range.first++;
+	lua_pushlstring(L, value.first.c_str(), value.first.length());
+	luaW_pushscalar(L, vcfg[value.first]);
+	return 2;
+}
+
+/**
+ * Destroy a vconfig pairs iterator
+ */
+static int impl_vconfig_pairs_collect(lua_State *L)
+{
+	typedef config::const_attr_itors const_attr_itors;
+	void* p = lua_touserdata(L, 1);
+	const_attr_itors* cai = static_cast<const_attr_itors*>(p);
+	cai->~const_attr_itors();
+	return 0;
+}
+
+/**
+ * Construct an iterator to iterate through the attributes of a vconfig
+ */
+static int impl_vconfig_pairs(lua_State *L)
+{
+	static const size_t sz = sizeof(config::const_attr_itors);
+	vconfig vcfg = luaW_checkvconfig(L, 1);
+	new(lua_newuserdata(L, sz)) config::const_attr_itors(vcfg.get_config().attribute_range());
+	luaL_newmetatable(L, vconfigpairsKey);
+	lua_setmetatable(L, -2);
+	lua_pushcclosure(L, &impl_vconfig_pairs_iter, 1);
+	lua_pushvalue(L, 1);
+	return 2;
+}
+
+typedef std::pair<vconfig::all_children_iterator, vconfig::all_children_iterator> vconfig_child_range;
+
+/**
+ * Iterate through the subtags of a vconfig
+ */
+static int impl_vconfig_ipairs_iter(lua_State *L)
+{
+	luaW_checkvconfig(L, 1);
+	int i = luaL_checkinteger(L, 2);
+	void* p = luaL_checkudata(L, lua_upvalueindex(1), vconfigipairsKey);
+	vconfig_child_range& range = *static_cast<vconfig_child_range*>(p);
+	if (range.first == range.second) {
+		return 0;
+	}
+	std::pair<std::string, vconfig> value = *range.first++;
+	lua_pushinteger(L, i + 1);
+	lua_createtable(L, 2, 0);
+	lua_pushlstring(L, value.first.c_str(), value.first.length());
+	lua_rawseti(L, -2, 1);
+	luaW_pushvconfig(L, value.second);
+	lua_rawseti(L, -2, 2);
+	return 2;
+}
+
+/**
+ * Destroy a vconfig ipairs iterator
+ */
+static int impl_vconfig_ipairs_collect(lua_State *L)
+{
+	void* p = lua_touserdata(L, 1);
+	vconfig_child_range* vcr = static_cast<vconfig_child_range*>(p);
+	vcr->~vconfig_child_range();
+	return 0;
+}
+
+/**
+ * Construct an iterator to iterate through the subtags of a vconfig
+ */
+static int impl_vconfig_ipairs(lua_State *L)
+{
+	static const size_t sz = sizeof(vconfig_child_range);
+	vconfig cfg = luaW_checkvconfig(L, 1);
+	new(lua_newuserdata(L, sz)) vconfig_child_range(cfg.ordered_begin(), cfg.ordered_end());
+	luaL_newmetatable(L, vconfigipairsKey);
+	lua_setmetatable(L, -2);
+	lua_pushcclosure(L, &impl_vconfig_ipairs_iter, 1);
+	lua_pushvalue(L, 1);
+	lua_pushinteger(L, 0);
+	return 3;
+}
+
 /**
  * Creates a vconfig containing the WML table.
  * - Arg 1: WML table.
@@ -294,12 +391,29 @@ std::string register_vconfig_metatable(lua_State *L)
 		{ "__gc",           &impl_vconfig_collect},
 		{ "__index",        &impl_vconfig_get},
 		{ "__len",          &impl_vconfig_size},
+		{ "__pairs",        &impl_vconfig_pairs},
+		{ "__ipairs",       &impl_vconfig_ipairs},
 		{ NULL, NULL }
 	};
 	luaL_setfuncs(L, callbacks, 0);
 
 	lua_pushstring(L, "wml object");
 	lua_setfield(L, -2, "__metatable");
+	
+	// Metatables for the iterator userdata
+	
+	// I don't bother setting __metatable because this
+	// userdata is only ever stored in the iterator's
+	// upvalues, so it's never visible to the user.
+	luaL_newmetatable(L, vconfigpairsKey);
+	lua_pushstring(L, "__gc");
+	lua_pushcfunction(L, &impl_vconfig_pairs_collect);
+	lua_rawset(L, -3);
+	
+	luaL_newmetatable(L, vconfigipairsKey);
+	lua_pushstring(L, "__gc");
+	lua_pushcfunction(L, &impl_vconfig_ipairs_collect);
+	lua_rawset(L, -3);
 
 	return "Adding vconfig metatable...\n";
 }