src/web/html.lua


local s_gsub = string.gsub;

local html_escape_table = { ["'"] = "&apos;", ["\""] = "&quot;", ["<"] = "&lt;", [">"] = "&gt;", ["&"] = "&amp;" };
local function html_escape(str) return (s_gsub(str, "['&<>\"]", html_escape_table)); end

local html_unescape_table = {}; for k,v in pairs(html_escape_table) do html_unescape_table[v] = k; end
local function html_unescape(str) return (s_gsub(str, "&%a+;", html_unescape_table)); end

local tags = {
	em = "/"; strong = "*"; small = ""; s = ""; cite = "";
	q = "\""; dfn = ""; code = "`"; var = "`"; samp = "`"; kbd = "`";
	sub = "~"; sup = "^"; i = "/"; b = "*"; u = "_"; mark = "";
};

local function formatted(text)
	return html_escape(text):gsub(html_escape("<(%a+)([^>]*)>(.-)</%1>"), function (tag, attrs, content)
		tag = tag:lower();
		if tags[tag] then
			return ("<%s>%s</%s>"):format(tag, content, tag);
		end
	end);
end

local function html2md(text)
	return text:gsub("<(%a+)([^>]*)>(.-)</%1>", function (tag, attrs, content)
		tag = tags[tag];
		if tag then
			return tag .. content .. tag;
		end
	end);
end

local par = { ["("] = ")", ["<"] = ">", ["["] = "]", ["{"] = "}", [";"] = "&", };

local function linkify(text)
	return text:gsub("(%S?)(https?://%S+)", function (p, url)
		local extra = "";
		-- Attempt to get rid of trailing parenthesis from found URLs
		if par[p] and url:find(par[p], 1, true) then
			extra = url:sub(url:find(par[p], 1, true), -1);
			url = url:sub(1, url:find(par[p], 1, true) - 1);
		end
		return ("%s<a rel=\"nofollow\" href=\"%s\">%s</a>%s"):format(p, url, url, extra);
	end);
end

return {
	escape = html_escape;
	html2md = html2md;
	formatted = formatted;
	linkify = linkify;
	unescape = html_unescape;
};