local utils = require "../utils"
return function (template, params, pattern)
	local content = string.gsub(template, pattern or "{{([%w_]+)}}", function (s)
		if params[s] == nil then
			utils.expect_nil("No variable "..s)
		end
		if params[s] == true then
			return "true"
		end
		if params[s] == false then
			return "false"
		end
		return params[s]
	end)
	return content
end