mustache.js/mustache.js

/*!
 * mustache.js - Logic-less {{mustache}} templates with JavaScript
 * http://github.com/janl/mustache.js
 */
var Mustache = (typeof module !== "undefined" && module.exports) || {};

(function (exports) {

  exports.name = "mustache.js";
  exports.version = "0.5.0-dev";
  exports.tags = ["{{", "}}"];
  exports.parse = parse;
  exports.compile = compile;
  exports.render = render;
  exports.clearCache = clearCache;

  exports.to_html = render; // keep backwards compatibility

  var _toString = Object.prototype.toString;
  var _isArray = Array.isArray;
  var _forEach = Array.prototype.forEach;
  var _trim = String.prototype.trim;

  var isArray;
  if (_isArray) {
    isArray = _isArray;
  } else {
    isArray = function (obj) {
      return _toString.call(obj) === "[object Array]";
    };
  }

  var forEach;
  if (_forEach) {
    forEach = function (obj, callback, scope) {
      return _forEach.call(obj, callback, scope);
    };
  } else {
    forEach = function (obj, callback, scope) {
      for (var i = 0, len = obj.length; i < len; ++i) {
        callback.call(scope, obj[i], i, obj);
      }
    };
  }

  var spaceRe = /^\s*$/;

  function isWhitespace(string) {
    return spaceRe.test(string);
  }

  var trim;
  if (_trim) {
    trim = function (string) {
      return string == null ? "" : _trim.call(string);
    };
  } else {
    var trimLeft, trimRight;

    if (isWhitespace("\xA0")) {
      trimLeft = /^\s+/;
      trimRight = /\s+$/;
    } else {
      // IE doesn't match non-breaking spaces with \s, thanks jQuery.
      trimLeft = /^[\s\xA0]+/;
      trimRight = /[\s\xA0]+$/;
    }

    trim = function (string) {
      return string == null ? "" :
        String(string).replace(trimLeft, "").replace(trimRight, "");
    };
  }

  var escapeMap = {
    "&": "&amp;",
    "<": "&lt;",
    ">": "&gt;",
    '"': '&quot;',
    "'": '&#39;'
  };

  function escapeHTML(string) {
    return String(string).replace(/&(?!\w+;)|[<>"']/g, function (s) {
      return escapeMap[s] || s;
    });
  }

  /**
   * Adds the `template`, `line`, and `file` properties to the given error
   * object and alters the message to provide more useful debugging information.
   */
  function debug(e, template, line, file) {
    file = file || "<template>";

    var lines = template.split("\n"),
        start = Math.max(line - 3, 0),
        end = Math.min(lines.length, line + 3),
        context = lines.slice(start, end);

    var c;
    for (var i = 0, len = context.length; i < len; ++i) {
      c = i + start + 1;
      context[i] = (c === line ? " >> " : "    ") + context[i];
    }

    e.template = template;
    e.line = line;
    e.file = file;
    e.message = [file + ":" + line, context.join("\n"), "", e.message].join("\n");

    return e;
  }

  /**
   * Looks up the value of the given `name` in the given context `stack`.
   */
  function findName(name, stack) {
    var names = name.split(".");
    var lastIndex = names.length - 1;
    var target = names[lastIndex];

    var value, context, i = stack.length, j, localStack;
    while (i) {
      localStack = stack.slice(0);
      context = stack[--i];

      j = 0;
      while (j < lastIndex) {
        context = context[names[j++]];

        if (context == null) {
          break;
        }

        localStack.push(context);
      }

      if (context && target in context) {
        value = context[target];
        break;
      }
    }

    // If the value is a function, call it in the current context.
    if (typeof value === "function") {
      value = value.call(localStack[localStack.length - 1]);
    }

    return value == null ? "" : value;
  }

  function sendSection(send, value, callback, stack, inverted) {
    if (inverted) {
      // From the spec: inverted sections may render text once based on the
      // inverse value of the key. That is, they will be rendered if the key
      // doesn't exist, is false, or is an empty list.
      if (value == null || value === false || (isArray(value) && value.length === 0)) {
        send(callback());
      }
    } else if (isArray(value)) {
      forEach(value, function (value) {
        stack.push(value);
        send(callback());
        stack.pop();
      });
    } else if (typeof value === "object") {
      stack.push(value);
      send(callback());
      stack.pop();
    } else if (typeof value === "function") {
      var scope = stack[stack.length - 1];
      var scopedRender = function (template) {
        return render(template, scope);
      };
      send(value.call(scope, callback(), scopedRender) || "");
    } else if (value) {
      send(callback());
    }
  }

  /**
   * Parses the given `template` and returns the source of a function that,
   * with the proper arguments, will render the template. Recognized options
   * include the following:
   *
   *   - file     The name of the file the template comes from (displayed in
   *              error messages)
   *   - tags     An array of open and close tags the `template` uses. Defaults
   *              to the value of Mustache.tags
   *   - debug    Set `true` to log the body of the generated function to the
   *              console
   *   - space    Set `true` to preserve whitespace from lines that otherwise
   *              contain only a {{tag}}. Defaults to `false`
   */
  function parse(template, options) {
    options = options || {};

    var tags = options.tags || exports.tags,
        openTag = tags[0],
        closeTag = tags[tags.length - 1];

    var code = [
      "var line = 1;", // keep track of source line number
      "\ntry {",
      '\nsend("'
    ];

    var spaces = [],      // indices of whitespace in code for the current line
        nonSpace = false; // is there a non-space char on the current line?

    // Strips all space characters from the code array for the current line
    // if there was a {{tag}} on it and otherwise only spaces.
    var stripSpace = function () {
      if (!nonSpace && !options.space) {
        while (spaces.length) {
          code.splice(spaces.pop(), 1);
        }
      } else {
        spaces = [];
      }

      nonSpace = false;
    };

    // Returns a bit of code that can be used to find the given `name`.
    var findFor = function (name) {
      return name === "." ? "stack[stack.length - 1]" : 'find("' + name + '")';
    };

    var sectionStack = [], updateLine, nextOpenTag, nextCloseTag;

    var setTags = function (source) {
      tags = trim(source).split(/\s+/);
      nextOpenTag = tags[0];
      nextCloseTag = tags[tags.length - 1];
    };

    var includePartial = function (source) {
      code.push(
        '");',
        updateLine,
        '\nvar partial = partials["' + trim(source) + '"];',
        '\nif (partial) {',
        '\n  send(render(partial, stack[stack.length - 1], partials));',
        '\n}',
        '\nsend("'
      );
    };

    var openSection = function (source, inverted) {
      var name = trim(source);

      if (name === "") {
        throw debug(new Error("Section name may not be empty"), template, line, options.file);
      }

      sectionStack.push({name: name, inverted: inverted});

      code.push(
        '");',
        updateLine,
        '\nvar value = ' + findFor(name) + ';',
        '\nvar callback = (function () {',
        '\n  var buffer, send = function (chunk) { buffer.push(chunk); };',
        '\n  return function () {',
        '\n    buffer = [];',
        '\nsend("'
      );
    };

    var openInvertedSection = function (source) {
      openSection(source, true);
    };

    var closeSection = function (source) {
      var name = trim(source);
      var openName = sectionStack.length != 0 && sectionStack[sectionStack.length - 1].name;

      if (!openName || name != openName) {
        throw debug(new Error('Section named "' + name + '" was never opened'), template, line, file);
      }

      var section = sectionStack.pop();

      code.push(
        '");',
        '\n    return buffer.join("");',
        '\n  };',
        '\n})();'
      );

      if (section.inverted) {
        code.push("\nsendSection(send,value,callback,stack,true);");
      } else {
        code.push("\nsendSection(send,value,callback,stack);");
      }

      code.push('\nsend("');
    };

    var sendPlain = function (source) {
      code.push(
        '");',
        updateLine,
        '\nsend(' + findFor(trim(source)) + ');',
        '\nsend("'
      );
    };

    var sendEscaped = function (source) {
      code.push(
        '");',
        updateLine,
        '\nsend(escapeHTML(' + findFor(trim(source)) + '));',
        '\nsend("'
      );
    };

    var line = 1, c, callback;
    for (var i = 0, len = template.length; i < len; ++i) {
      if (template.slice(i, i + openTag.length) === openTag) {
        i += openTag.length;
        c = template.substr(i, 1);
        updateLine = '\nline = ' + line + ';';
        nextOpenTag = openTag;
        nextCloseTag = closeTag;

        switch (c) {
        case "!": // comment
          i++;
          callback = null;
          break;
        case "=": // change open/close tags, e.g. {{=<% %>=}}
          i++;
          closeTag = "=" + closeTag;
          callback = setTags;
          break;
        case ">": // include partial
          i++;
          callback = includePartial;
          break;
        case "#": // start section
          i++;
          callback = openSection;
          break;
        case "^": // start inverted section
          i++;
          callback = openInvertedSection;
          break;
        case "/": // end section
          i++;
          callback = closeSection;
          break;
        case "{": // plain variable
          closeTag = "}" + closeTag;
          // fall through
        case "&": // plain variable
          i++;
          nonSpace = true;
          callback = sendPlain;
          break;
        default: // escaped variable
          nonSpace = true;
          callback = sendEscaped;
        }

        var end = template.indexOf(closeTag, i);

        if (end === -1) {
          throw debug(new Error('Tag "' + openTag + '" was not closed properly'), template, line, options.file);
        }

        var source = template.substring(i, end);

        if (callback) {
          callback(source);
        }

        // Maintain line count for \n in source.
        var n = 0;
        while (~(n = source.indexOf("\n", n))) {
          line++;
          n++;
        }

        i = end + closeTag.length - 1;
        openTag = nextOpenTag;
        closeTag = nextCloseTag;
      } else {
        c = template.substr(i, 1);

        switch (c) {
        case '"':
        case "\\":
          nonSpace = true;
          code.push("\\" + c);
          break;
        case "\n":
          spaces.push(code.length);
          code.push("\\n");
          stripSpace(); // Check for whitespace on the current line.
          line++;
          break;
        default:
          if (isWhitespace(c)) {
            spaces.push(code.length);
          } else {
            nonSpace = true;
          }

          code.push(c);
        }
      }
    }

    if (sectionStack.length != 0) {
      throw debug(new Error('Section "' + sectionStack[sectionStack.length - 1].name + '" was not closed properly'), template, line, options.file);
    }

    // Clean up any whitespace from a closing {{tag}} that was at the end
    // of the template without a trailing \n.
    stripSpace();

    code.push(
      '");',
      "\nsend(null);", // Send null as the last operation.
      "\n} catch (e) { throw {error: e, line: line}; }"
    );

    // Ignore empty send("") statements.
    var body = code.join("").replace(/send\(""\);\n/g, "");

    if (options.debug) {
      if (typeof console != "undefined" && console.log) {
        console.log(body);
      } else if (typeof print === "function") {
        print(body);
      }
    }

    return body;
  }

  /**
   * Used by `compile` to generate a reusable function for the given `template`.
   */
  function _compile(template, options) {
    var args = "view,partials,send,stack,find,escapeHTML,sendSection,render";
    var body = parse(template, options);
    var fn = new Function(args, body);

    // This anonymous function wraps the generated function so we can do
    // argument coercion, setup some variables, and handle any errors
    // encountered while executing it.
    return function (view, partials, callback) {
      if (typeof partials === "function") {
        callback = partials;
        partials = {};
      }

      partials = partials || {};

      var buffer = []; // output buffer

      var send = callback || function (chunk) {
        buffer.push(chunk);
      };

      var stack = [view]; // context stack

      var find = function (name) {
        return findName(name, stack);
      };

      try {
        fn(view, partials, send, stack, find, escapeHTML, sendSection, render);
      } catch (e) {
        throw debug(e.error, template, e.line, options.file);
      }

      return buffer.join("");
    };
  }

  // Cache of pre-compiled templates.
  var _cache = {};

  /**
   * Clear the cache of compiled templates.
   */
  function clearCache() {
    _cache = {};
  }

  /**
   * Compiles the given `template` into a reusable function using the given
   * `options`. In addition to the options accepted by Mustache.parse,
   * recognized options include the following:
   *
   *   - cache    Set `false` to bypass any pre-compiled version of the given
   *              template. Otherwise, a given `template` string will be cached
   *              the first time it is parsed
   */
  function compile(template, options) {
    options = options || {};

    // Use a pre-compiled version from the cache if we have one.
    if (options.cache !== false) {
      if (!_cache[template]) {
        _cache[template] = _compile(template, options);
      }

      return _cache[template];
    }

    return _compile(template, options);
  }

  /**
   * High-level function that renders the given `template` using the given
   * `view`, `partials`, and `callback`. The `callback` is used to return the
   * output piece by piece, as it is rendered. When finished, the callback will
   * receive `null` as its argument, after which it will not be called any more.
   * If no callback is given, the complete rendered template will be used as the
   * return value for the function.
   *
   * Note: If no partials are needed, the third argument may be the callback.
   * If you need to use any of the template options (see `compile` above), you
   * must compile in a separate step, and then call that compiled function.
   */
  function render(template, view, partials, callback) {
    return compile(template)(view, partials, callback);
  }

})(Mustache);