no-empty-character-class.js
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/**
* @fileoverview Rule to flag the use of empty character classes in regular expressions
* @author Ian Christian Myers
*/
"use strict";
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/*
plain-English description of the following regexp:
0. `^` fix the match at the beginning of the string
1. `\/`: the `/` that begins the regexp
2. `([^\\[]|\\.|\[([^\\\]]|\\.)+\])*`: regexp contents; 0 or more of the following
2.0. `[^\\[]`: any character that's not a `\` or a `[` (anything but escape sequences and character classes)
2.1. `\\.`: an escape sequence
2.2. `\[([^\\\]]|\\.)+\]`: a character class that isn't empty
3. `\/` the `/` that ends the regexp
4. `[gimuy]*`: optional regexp flags
5. `$`: fix the match at the end of the string
*/
var regex = /^\/([^\\[]|\\.|\[([^\\\]]|\\.)+\])*\/[gimuy]*$/;
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = function(context) {
return {
"Literal": function(node) {
var token = context.getFirstToken(node);
if (token.type === "RegularExpression" && !regex.test(token.value)) {
context.report(node, "Empty class.");
}
}
};
};
module.exports.schema = [];