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