index.js

/**
 * Expose `render()`.`
 */

exports = module.exports = render;

/**
 * Expose `compile()`.
 */

exports.compile = compile;

/**
 * Render the given mustache `str` with `obj`.
 *
 * @param {String} str
 * @param {Object} obj
 * @return {String}
 * @api public
 */

function render(str, obj) {
  obj = obj || {};
  var fn = compile(str);
  return fn(obj);
}

/**
 * Compile the given `str` to a `Function`.
 *
 * @param {String} str
 * @return {Function}
 * @api public
 */

function compile(str) {
  var js = [];
  var toks = parse(str);
  var tok;

  for (var i = 0; i < toks.length; ++i) {
    tok = toks[i];
    if (i % 2 == 0) {
      js.push('"' + tok.replace(/"/g, '\\"') + '"');
    } else {
      switch (tok[0]) {
        case '/':
          tok = tok.slice(1);
          js.push(' }) + ');
          break;
        case '^':
          tok = tok.slice(1);
          assertProperty(tok);
          js.push(' + section(obj, "' + tok + '", true, function(obj){ return ');
          break;
        case '#':
          tok = tok.slice(1);
          assertProperty(tok);
          js.push(' + section(obj, "' + tok + '", false, function(obj){ return ');
          break;
        case '!':
          tok = tok.slice(1);
          assertProperty(tok);
          js.push(' + obj.' + tok + ' + ');
          break;
        default:
          assertProperty(tok);
          js.push(' + escape(obj.' + tok + ') + ');
      }
    }
  }

  js = '\n'
    + indent(escape.toString()) + ';\n\n'
    + indent(section.toString()) + ';\n\n'
    + '  return ' + js.join('').replace(/\n/g, '\\n');

  return new Function('obj', js);
}

/**
 * Assert that `prop` is a valid property.
 *
 * @param {String} prop
 * @api private
 */

function assertProperty(prop) {
  if (!prop.match(/^[\w.]+$/)) throw new Error('invalid property "' + prop + '"');
}

/**
 * Parse `str`.
 *
 * @param {String} str
 * @return {Array}
 * @api private
 */

function parse(str) {
  return str.split(/\{\{|\}\}/);
}

/**
 * Indent `str`.
 *
 * @param {String} str
 * @return {String}
 * @api private
 */

function indent(str) {
  return str.replace(/^/gm, '  ');
}

/**
 * Section handler.
 *
 * @param {Object} context obj
 * @param {String} prop
 * @param {Function} thunk
 * @param {Boolean} negate
 * @api private
 */

function section(obj, prop, negate, thunk) {
  var val = obj[prop];
  if (Array.isArray(val)) return val.map(thunk).join('');
  if ('function' == typeof val) return val.call(obj, thunk(obj));
  if (negate) val = !val;
  if (val) return thunk(obj);
  return '';
}

/**
 * Escape the given `html`.
 *
 * @param {String} html
 * @return {String}
 * @api private
 */

function escape(html) {
  return String(html)
    .replace(/&/g, '&amp;')
    .replace(/"/g, '&quot;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;');
}