function parseTemplate()

in luigi/static/visualiser/lib/mustache.js [360:467]
67 lines of code
26 McCabe index (conditional complexity)

  function parseTemplate(template, tags) {
    template = template || '';
    tags = tags || mustache.tags;

    if (typeof tags === 'string') tags = tags.split(spaceRe);
    if (tags.length !== 2) throw new Error('Invalid tags: ' + tags.join(', '));

    var tagRes = escapeTags(tags);
    var scanner = new Scanner(template);

    var sections = [];     // Stack to hold section tokens
    var tokens = [];       // Buffer to hold the tokens
    var spaces = [];       // Indices of whitespace tokens on the current line
    var hasTag = false;    // Is there a {{tag}} on the current line?
    var nonSpace = false;  // Is there a non-space char on the current line?

    // Strips all whitespace tokens array for the current line
    // if there was a {{#tag}} on it and otherwise only space.
    function stripSpace() {
      if (hasTag && !nonSpace) {
        while (spaces.length) {
          delete tokens[spaces.pop()];
        }
      } else {
        spaces = [];
      }

      hasTag = false;
      nonSpace = false;
    }

    var start, type, value, chr, token;
    while (!scanner.eos()) {
      start = scanner.pos;

      // Match any text between tags.
      value = scanner.scanUntil(tagRes[0]);
      if (value) {
        for (var i = 0, len = value.length; i < len; ++i) {
          chr = value.charAt(i);

          if (isWhitespace(chr)) {
            spaces.push(tokens.length);
          } else {
            nonSpace = true;
          }

          tokens.push(['text', chr, start, start + 1]);
          start += 1;

          // Check for whitespace on the current line.
          if (chr == '\n') stripSpace();
        }
      }

      // Match the opening tag.
      if (!scanner.scan(tagRes[0])) break;
      hasTag = true;

      // Get the tag type.
      type = scanner.scan(tagRe) || 'name';
      scanner.scan(whiteRe);

      // Get the tag value.
      if (type === '=') {
        value = scanner.scanUntil(eqRe);
        scanner.scan(eqRe);
        scanner.scanUntil(tagRes[1]);
      } else if (type === '{') {
        value = scanner.scanUntil(new RegExp('\\s*' + escapeRegExp('}' + tags[1])));
        scanner.scan(curlyRe);
        scanner.scanUntil(tagRes[1]);
        type = '&';
      } else {
        value = scanner.scanUntil(tagRes[1]);
      }

      // Match the closing tag.
      if (!scanner.scan(tagRes[1])) throw new Error('Unclosed tag at ' + scanner.pos);

      token = [type, value, start, scanner.pos];
      tokens.push(token);

      if (type === '#' || type === '^') {
        sections.push(token);
      } else if (type === '/') {
        // Check section nesting.
        if (sections.length === 0) throw new Error('Unopened section "' + value + '" at ' + start);
        var openSection = sections.pop();
        if (openSection[1] !== value) throw new Error('Unclosed section "' + openSection[1] + '" at ' + start);
      } else if (type === 'name' || type === '{' || type === '&') {
        nonSpace = true;
      } else if (type === '=') {
        // Set the tags for the next time around.
        tags = value.split(spaceRe);
        if (tags.length !== 2) throw new Error('Invalid tags at ' + start + ': ' + tags.join(', '));
        tagRes = escapeTags(tags);
      }
    }

    // Make sure there are no open sections when we're done.
    var openSection = sections.pop();
    if (openSection) throw new Error('Unclosed section "' + openSection[1] + '" at ' + scanner.pos);

    tokens = squashTokens(tokens);

    return nestTokens(tokens);
  }