1 files changed, 97 insertions, 0 deletions
diff --git a/util/template.lua b/util/template.lua
new file mode 100644
index 00000000..66d4fca7
--- /dev/null
+++ b/util/template.lua
@@ -0,0 +1,97 @@
+
+local stanza_mt = require "util.stanza".stanza_mt;
+local setmetatable = setmetatable;
+local pairs = pairs;
+local ipairs = ipairs;
+local error = error;
+local loadstring = loadstring;
+local debug = debug;
+local t_remove = table.remove;
+local parse_xml = require "util.xml".parse;
+
+module("template")
+
+local function trim_xml(stanza)
+	for i=#stanza,1,-1 do
+		local child = stanza[i];
+		if child.name then
+			trim_xml(child);
+		else
+			child = child:gsub("^%s*", ""):gsub("%s*$", "");
+			stanza[i] = child;
+			if child == "" then t_remove(stanza, i); end
+		end
+	end
+end
+
+local function create_string_string(str)
+	str = ("%q"):format(str);
+	str = str:gsub("{([^}]*)}", function(s)
+		return '"..(data["'..s..'"]or"").."';
+	end);
+	return str;
+end
+local function create_attr_string(attr, xmlns)
+	local str = '{';
+	for name,value in pairs(attr) do
+		if name ~= "xmlns" or value ~= xmlns then
+			str = str..("[%q]=%s;"):format(name, create_string_string(value));
+		end
+	end
+	return str..'}';
+end
+local function create_clone_string(stanza, lookup, xmlns)
+	if not lookup[stanza] then
+		local s = ('setmetatable({name=%q,attr=%s,tags={'):format(stanza.name, create_attr_string(stanza.attr, xmlns));
+		-- add tags
+		for i,tag in ipairs(stanza.tags) do
+			s = s..create_clone_string(tag, lookup, stanza.attr.xmlns)..";";
+		end
+		s = s..'};';
+		-- add children
+		for i,child in ipairs(stanza) do
+			if child.name then
+				s = s..create_clone_string(child, lookup, stanza.attr.xmlns)..";";
+			else
+				s = s..create_string_string(child)..";"
+			end
+		end
+		s = s..'}, stanza_mt)';
+		s = s:gsub('%.%.""', ""):gsub('([=;])""%.%.', "%1"):gsub(';"";', ";"); -- strip empty strings
+		local n = #lookup + 1;
+		lookup[n] = s;
+		lookup[stanza] = "_"..n;
+	end
+	return lookup[stanza];
+end
+local function create_cloner(stanza, chunkname)
+	local lookup = {};
+	local name = create_clone_string(stanza, lookup, "");
+	local f = "local setmetatable,stanza_mt=...;return function(data)";
+	for i=1,#lookup do
+		f = f.."local _"..i.."="..lookup[i]..";";
+	end
+	f = f.."return "..name..";end";
+	local f,err = loadstring(f, chunkname);
+	if not f then error(err); end
+	return f(setmetatable, stanza_mt);
+end
+
+local template_mt = { __tostring = function(t) return t.name end };
+local function create_template(templates, text)
+	local stanza, err = parse_xml(text);
+	if not stanza then error(err); end
+	trim_xml(stanza);
+
+	local info = debug.getinfo(3, "Sl");
+	info = info and ("template(%s:%d)"):format(info.short_src:match("[^\\/]*$"), info.currentline) or "template(unknown)";
+
+	local template = setmetatable({ apply = create_cloner(stanza, info), name = info, text = text }, template_mt);
+	templates[text] = template;
+	return template;
+end
+
+local templates = setmetatable({}, { __mode = 'k', __index = create_template });
+return function(text)
+	return templates[text];
+end;