--- /dev/null
+'use strict';
+
+var decode = require('parse-entities');
+var whitespace = require('is-whitespace-character');
+var locate = require('../locate/url');
+
+module.exports = url;
+url.locator = locate;
+url.notInLink = true;
+
+var C_BRACKET_OPEN = '[';
+var C_BRACKET_CLOSE = ']';
+var C_PAREN_OPEN = '(';
+var C_PAREN_CLOSE = ')';
+var C_LT = '<';
+var C_AT_SIGN = '@';
+
+var HTTP_PROTOCOL = 'http://';
+var HTTPS_PROTOCOL = 'https://';
+var MAILTO_PROTOCOL = 'mailto:';
+
+var PROTOCOLS = [
+ HTTP_PROTOCOL,
+ HTTPS_PROTOCOL,
+ MAILTO_PROTOCOL
+];
+
+var PROTOCOLS_LENGTH = PROTOCOLS.length;
+
+function url(eat, value, silent) {
+ var self = this;
+ var subvalue;
+ var content;
+ var character;
+ var index;
+ var position;
+ var protocol;
+ var match;
+ var length;
+ var queue;
+ var parenCount;
+ var nextCharacter;
+ var exit;
+
+ if (!self.options.gfm) {
+ return;
+ }
+
+ subvalue = '';
+ index = -1;
+ length = PROTOCOLS_LENGTH;
+
+ while (++index < length) {
+ protocol = PROTOCOLS[index];
+ match = value.slice(0, protocol.length);
+
+ if (match.toLowerCase() === protocol) {
+ subvalue = match;
+ break;
+ }
+ }
+
+ if (!subvalue) {
+ return;
+ }
+
+ index = subvalue.length;
+ length = value.length;
+ queue = '';
+ parenCount = 0;
+
+ while (index < length) {
+ character = value.charAt(index);
+
+ if (whitespace(character) || character === C_LT) {
+ break;
+ }
+
+ if (
+ character === '.' ||
+ character === ',' ||
+ character === ':' ||
+ character === ';' ||
+ character === '"' ||
+ character === '\'' ||
+ character === ')' ||
+ character === ']'
+ ) {
+ nextCharacter = value.charAt(index + 1);
+
+ if (!nextCharacter || whitespace(nextCharacter)) {
+ break;
+ }
+ }
+
+ if (character === C_PAREN_OPEN || character === C_BRACKET_OPEN) {
+ parenCount++;
+ }
+
+ if (character === C_PAREN_CLOSE || character === C_BRACKET_CLOSE) {
+ parenCount--;
+
+ if (parenCount < 0) {
+ break;
+ }
+ }
+
+ queue += character;
+ index++;
+ }
+
+ if (!queue) {
+ return;
+ }
+
+ subvalue += queue;
+ content = subvalue;
+
+ if (protocol === MAILTO_PROTOCOL) {
+ position = queue.indexOf(C_AT_SIGN);
+
+ if (position === -1 || position === length - 1) {
+ return;
+ }
+
+ content = content.substr(MAILTO_PROTOCOL.length);
+ }
+
+ /* istanbul ignore if - never used (yet) */
+ if (silent) {
+ return true;
+ }
+
+ exit = self.enterLink();
+ content = self.tokenizeInline(content, eat.now());
+ exit();
+
+ return eat(subvalue)({
+ type: 'link',
+ title: null,
+ url: decode(subvalue),
+ children: content
+ });
+}