var utils = {

/* Like Python's |range|, but without |step|. */
range: function(start, stop) {
  if (stop === undefined) {
    stop = start;
    start = 0;
  }

  var result = new Array(Math.max(0, stop - start));
  for (var i = 0, j = start; j < stop; i++, j++) {
    result[i] = j;
  }
  return result;
},

find: function(array, callback) {
  var length = array.length;
  for (var i = 0; i < length; i++) {
    if (callback(array[i])) {
      return array[i];
    }
  }
},

indexOf: function(array, callback) {
  var length = array.length;
  for (var i = 0; i < length; i++) {
    if (callback(array[i])) {
      return i;
    }
  }
  return -1;
},

contains: function(array, value) {
  /*
   * Stupid IE does not have Array.prototype.indexOf, otherwise this function
   * would be a one-liner.
   */
  var length = array.length;
  for (var i = 0; i < length; i++) {
    if (array[i] === value) {
      return true;
    }
  }
  return false;
},

each: function(array, callback) {
  var length = array.length;
  for (var i = 0; i < length; i++) {
    callback(array[i], i);
  }
},

map: function(array, callback) {
  var result = [];
  var length = array.length;
  for (var i = 0; i < length; i++) {
    result[i] = callback(array[i], i);
  }
  return result;
},

pluck: function(array, key) {
  return utils.map(array, function (e) { return e[key]; });
},

keys: function(object) {
  var result = [];
  for (var key in object) {
    if (object.hasOwnProperty(key)) {
      result.push(key);
    }
  }
  return result;
},

values: function(object) {
  var result = [];
  for (var key in object) {
    if (object.hasOwnProperty(key)) {
      result.push(object[key]);
    }
  }
  return result;
},

clone: function(object) {
  var result = {};
  for (var key in object) {
    if (object.hasOwnProperty(key)) {
      result[key] = object[key];
    }
  }
  return result;
},

defaults: function(object, defaults) {
  for (var key in defaults) {
    if (defaults.hasOwnProperty(key)) {
      if (!(key in object)) {
        object[key] = defaults[key];
      }
    }
  }
},

/*
 * The code needs to be in sync with the code template in the compilation
 * function for "action" nodes.
 */
subclass: function(child, parent) {
  function ctor() { this.constructor = child; }
  ctor.prototype = parent.prototype;
  child.prototype = new ctor();
},

/*
 * Returns a string padded on the left to a desired length with a character.
 *
 * The code needs to be in sync with the code template in the compilation
 * function for "action" nodes.
 */
padLeft: function(input, padding, length) {
  var result = input;

  var padLength = length - input.length;
  for (var i = 0; i < padLength; i++) {
    result = padding + result;
  }

  return result;
},

/*
 * Returns an escape sequence for given character. Uses \x for characters <=
 * 0xFF to save space, \u for the rest.
 *
 * The code needs to be in sync with the code template in the compilation
 * function for "action" nodes.
 */
escape: function(ch) {
  var charCode = ch.charCodeAt(0);
  var escapeChar;
  var length;

  if (charCode <= 0xFF) {
    escapeChar = 'x';
    length = 2;
  } else {
    escapeChar = 'u';
    length = 4;
  }

  return '\\' + escapeChar + utils.padLeft(charCode.toString(16).toUpperCase(), '0', length);
},

/*
 * Surrounds the string with quotes and escapes characters inside so that the
 * result is a valid JavaScript string.
 *
 * The code needs to be in sync with the code template in the compilation
 * function for "action" nodes.
 */
quote: function(s) {
  /*
   * ECMA-262, 5th ed., 7.8.4: All characters may appear literally in a string
   * literal except for the closing quote character, backslash, carriage
   * return, line separator, paragraph separator, and line feed. Any character
   * may appear in the form of an escape sequence.
   *
   * For portability, we also escape all control and non-ASCII characters.
   * Note that "\0" and "\v" escape sequences are not used because JSHint does
   * not like the first and IE the second.
   */
  return '"' + s
    .replace(/\\/g, '\\\\')  // backslash
    .replace(/"/g, '\\"')    // closing quote character
    .replace(/\x08/g, '\\b') // backspace
    .replace(/\t/g, '\\t')   // horizontal tab
    .replace(/\n/g, '\\n')   // line feed
    .replace(/\f/g, '\\f')   // form feed
    .replace(/\r/g, '\\r')   // carriage return
    .replace(/[\x00-\x07\x0B\x0E-\x1F\x80-\uFFFF]/g, utils.escape)
    + '"';
},

/*
 * Escapes characters inside the string so that it can be used as a list of
 * characters in a character class of a regular expression.
 */
quoteForRegexpClass: function(s) {
  /*
   * Based on ECMA-262, 5th ed., 7.8.5 & 15.10.1.
   *
   * For portability, we also escape all control and non-ASCII characters.
   */
  return s
    .replace(/\\/g, '\\\\')  // backslash
    .replace(/\//g, '\\/')   // closing slash
    .replace(/\]/g, '\\]')   // closing bracket
    .replace(/\^/g, '\\^')   // caret
    .replace(/-/g,  '\\-')   // dash
    .replace(/\0/g, '\\0')   // null
    .replace(/\t/g, '\\t')   // horizontal tab
    .replace(/\n/g, '\\n')   // line feed
    .replace(/\v/g, '\\x0B') // vertical tab
    .replace(/\f/g, '\\f')   // form feed
    .replace(/\r/g, '\\r')   // carriage return
    .replace(/[\x01-\x08\x0E-\x1F\x80-\uFFFF]/g, utils.escape);
},

/*
 * Builds a node visitor -- a function which takes a node and any number of
 * other parameters, calls an appropriate function according to the node type,
 * passes it all its parameters and returns its value. The functions for
 * various node types are passed in a parameter to |buildNodeVisitor| as a
 * hash.
 */
buildNodeVisitor: function(functions) {
  return function(node) {
    return functions[node.type].apply(null, arguments);
  };
},

findRuleByName: function(ast, name) {
  return utils.find(ast.rules, function(r) { return r.name === name; });
},

indexOfRuleByName: function(ast, name) {
  return utils.indexOf(ast.rules, function(r) { return r.name === name; });
}

};

module.exports = utils;