libs/web: add support for string templates to luci.template module

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

modules/base/luasrc/template.lua

@@ -50,6 +50,13 @@ function render(name, scope)
 	return Template(name):render(scope or getfenv(2))
 end
 
+--- Render a template from a string.
+-- @param template	Template string
+-- @param scope		Scope to assign to template (optional)
+function render_string(template, scope)
+	return Template(nil, template):render(scope or getfenv(2))
+end
+
 
 -- Template class
 Template = util.class()
@@ -59,11 +66,14 @@ Template.cache = setmetatable({}, {__mode = "v"})
 
 
 -- Constructor - Reads and compiles the template on-demand
-function Template.__init__(self, name)	
+function Template.__init__(self, name, template)
+	if name then
+		self.template = self.cache[name]
+		self.name = name
+	else
+		self.name = "[string]"
+	end
 
-	self.template = self.cache[name]
-	self.name = name
-	
 	-- Create a new namespace for this template
 	self.viewns = context.viewns
 	
@@ -72,16 +82,22 @@ function Template.__init__(self, name)
 
 		-- Compile template
 		local err
-		local sourcefile = viewdir .. "/" .. name .. ".htm"
+		local sourcefile
 
-		self.template, _, err = tparser.parse(sourcefile)
+		if name then
+			sourcefile = viewdir .. "/" .. name .. ".htm"
+			self.template, _, err = tparser.parse(sourcefile)
+		else
+			sourcefile = "[string]"
+			self.template, _, err = tparser.parse_string(template)
+		end
 
 		-- If we have no valid template throw error, otherwise cache the template
 		if not self.template then
 			error("Failed to load template '" .. name .. "'.\n" ..
 			      "Error while parsing template '" .. sourcefile .. "':\n" ..
 			      (err or "Unknown syntax error"))
-		else
+		elseif name then
 			self.cache[name] = self.template
 		end
 	end