util.template: Initial commit. A template library for XML stanzas.

1 files changed, 112 insertions, 0 deletions

diff --git a/util/template.lua b/util/template.lua
new file mode 100644
index 00000000..c143a216
--- /dev/null
+++ b/util/template.lua
@@ -0,0 +1,112 @@
+
+local t_insert = table.insert;
+local st = require "util.stanza";
+local lxp = require "lxp";
+local setmetatable = setmetatable;
+local pairs = pairs;
+local error = error;
+local s_gsub = string.gsub;
+
+local print = print;
+
+module("template")
+
+local function process_stanza(stanza, ops)
+	-- process attrs
+	for key, val in pairs(stanza.attr) do
+		if val:match("{[^}]*}") then
+			t_insert(ops, {stanza.attr, key, val});
+		end
+	end
+	-- process children
+	local i = 1;
+	while i <= #stanza do
+		local child = stanza[i];
+		if child.name then
+			process_stanza(child, ops);
+		elseif child:match("{[^}]*}") then -- text
+			t_insert(ops, {stanza, i, child});
+		end
+		i = i + 1;
+	end
+end
+
+local parse_xml = (function()
+	local ns_prefixes = {
+		["http://www.w3.org/XML/1998/namespace"] = "xml";
+	};
+	local ns_separator = "\1";
+	local ns_pattern = "^([^"..ns_separator.."]*)"..ns_separator.."?(.*)$";
+	return function(xml)
+		local handler = {};
+		local stanza = st.stanza("root");
+		function handler:StartElement(tagname, attr)
+			local curr_ns,name = tagname:match(ns_pattern);
+			if name == "" then
+				curr_ns, name = "", curr_ns;
+			end
+			if curr_ns ~= "" then
+				attr.xmlns = curr_ns;
+			end
+			for i=1,#attr do
+				local k = attr[i];
+				attr[i] = nil;
+				local ns, nm = k:match(ns_pattern);
+				if nm ~= "" then
+					ns = ns_prefixes[ns]; 
+					if ns then 
+						attr[ns..":"..nm] = attr[k];
+						attr[k] = nil;
+					end
+				end
+			end
+			stanza:tag(name, attr);
+		end
+		function handler:CharacterData(data)
+			data = data:gsub("^%s*", ""):gsub("%s*$", "");
+			stanza:text(data);
+		end
+		function handler:EndElement(tagname)
+			stanza:up();
+		end
+		local parser = lxp.new(handler, "\1");
+		local ok, err, line, col = parser:parse(xml);
+		if ok then ok, err, line, col = parser:parse(); end
+		--parser:close();
+		if ok then
+			return stanza.tags[1];
+		else
+			return ok, err.." (line "..line..", col "..col..")";
+		end
+	end;
+end)();
+
+local function create_template(text)
+	local stanza, err = parse_xml(text);
+	if not stanza then error(err); end
+	local ops = {};
+	process_stanza(stanza, ops);
+	ops.stanza = stanza;
+	
+	local template = {};
+	function template.apply(data)
+		local newops = st.clone(ops);
+		for i=1,#newops do
+			local op = newops[i];
+			local t, k, v = op[1], op[2], op[3];
+			t[k] = s_gsub(v, "{([^}]*)}", data);
+		end
+		return newops.stanza;
+	end
+	return template;
+end
+
+local templates = setmetatable({}, { __mode = 'k' });
+return function(text)
+	local template = templates[text];
+	if not template then
+		template = create_template(text);
+		templates[text] = template;
+	end
+	return template;
+end;