Function createSimpleLexer

docs/assets/js/prettify.js:662–788

Given triples of [style, pattern, context] returns a lexing function, * The lexing function interprets the patterns to find token boundaries and * returns a decoration list of the form * [index_0, style_0, index_1, style_1, ..., index_n, style_n] * where index_n is an index into the

(shortcutStylePatterns, fallthroughStylePatterns)

    *   function that takes source code and returns a list of decorations.
    */
  function createSimpleLexer(shortcutStylePatterns, fallthroughStylePatterns) {
    var shortcuts = {};
    var tokenizer;
    (function () {
      var allPatterns = shortcutStylePatterns.concat(fallthroughStylePatterns);
      var allRegexs = [];
      var regexKeys = {};
      for (var i = 0, n = allPatterns.length; i < n; ++i) {
        var patternParts = allPatterns[i];
        var shortcutChars = patternParts[3];
        if (shortcutChars) {
          for (var c = shortcutChars.length; --c >= 0;) {
            shortcuts[shortcutChars.charAt(c)] = patternParts;
          }
        }
        var regex = patternParts[1];
        var k = '' + regex;
        if (!regexKeys.hasOwnProperty(k)) {
          allRegexs.push(regex);
          regexKeys[k] = null;
        }
      }
      allRegexs.push(/[\0-\uffff]/);
      tokenizer = combinePrefixPatterns(allRegexs);
    })();

    var nPatterns = fallthroughStylePatterns.length;

    /**
     * Lexes job.sourceCode and produces an output array job.decorations of
     * style classes preceded by the position at which they start in
     * job.sourceCode in order.
     *
     * @param {Object} job an object like <pre>{
     *    sourceCode: {string} sourceText plain text,
     *    basePos: {int} position of job.sourceCode in the larger chunk of
     *        sourceCode.
     * }</pre>
     */
    var decorate = function (job) {
      var sourceCode = job.sourceCode, basePos = job.basePos;
      /** Even entries are positions in source in ascending order.  Odd enties
        * are style markers (e.g., PR_COMMENT) that run from that position until
        * the end.
        * @type {Array.<number|string>}
        */
      var decorations = [basePos, PR_PLAIN];
      var pos = 0;  // index into sourceCode
      var tokens = sourceCode.match(tokenizer) || [];
      var styleCache = {};

      for (var ti = 0, nTokens = tokens.length; ti < nTokens; ++ti) {
        var token = tokens[ti];
        var style = styleCache[token];
        var match = void 0;

        var isEmbedded;
        if (typeof style === 'string') {