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JavaScript

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