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/**
* @fileoverview Rule to flag the use of empty character classes in regular expressions
* @author Ian Christian Myers
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const { RegExpParser, visitRegExpAST } = require("@eslint-community/regexpp");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
const parser = new RegExpParser();
const QUICK_TEST_REGEX = /\[\]/u;
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "problem",
docs: {
description: "Disallow empty character classes in regular expressions",
recommended: true,
url: "https://eslint.org/docs/latest/rules/no-empty-character-class"
},
schema: [],
messages: {
unexpected: "Empty class."
}
},
create(context) {
return {
"Literal[regex]"(node) {
const { pattern, flags } = node.regex;
if (!QUICK_TEST_REGEX.test(pattern)) {
return;
}
let regExpAST;
try {
regExpAST = parser.parsePattern(pattern, 0, pattern.length, {
unicode: flags.includes("u"),
unicodeSets: flags.includes("v")
});
} catch {
// Ignore regular expressions that regexpp cannot parse
return;
}
visitRegExpAST(regExpAST, {
onCharacterClassEnter(characterClass) {
if (!characterClass.negate && characterClass.elements.length === 0) {
context.report({ node, messageId: "unexpected" });
}
}
});
}
};
}
};