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codeql-action/node_modules/eslint/lib/rules/no-useless-escape.js
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/** | |
* @fileoverview Look for useless escapes in strings and regexes | |
* @author Onur Temizkan | |
*/ | |
"use strict"; | |
const astUtils = require("./utils/ast-utils"); | |
const { RegExpParser, visitRegExpAST } = require("@eslint-community/regexpp"); | |
/** | |
* @typedef {import('@eslint-community/regexpp').AST.CharacterClass} CharacterClass | |
* @typedef {import('@eslint-community/regexpp').AST.ExpressionCharacterClass} ExpressionCharacterClass | |
*/ | |
//------------------------------------------------------------------------------ | |
// Rule Definition | |
//------------------------------------------------------------------------------ | |
/** | |
* Returns the union of two sets. | |
* @param {Set} setA The first set | |
* @param {Set} setB The second set | |
* @returns {Set} The union of the two sets | |
*/ | |
function union(setA, setB) { | |
return new Set(function *() { | |
yield* setA; | |
yield* setB; | |
}()); | |
} | |
const VALID_STRING_ESCAPES = union(new Set("\\nrvtbfux"), astUtils.LINEBREAKS); | |
const REGEX_GENERAL_ESCAPES = new Set("\\bcdDfnpPrsStvwWxu0123456789]"); | |
const REGEX_NON_CHARCLASS_ESCAPES = union(REGEX_GENERAL_ESCAPES, new Set("^/.$*+?[{}|()Bk")); | |
/* | |
* Set of characters that require escaping in character classes in `unicodeSets` mode. | |
* ( ) [ ] { } / - \ | are ClassSetSyntaxCharacter | |
*/ | |
const REGEX_CLASSSET_CHARACTER_ESCAPES = union(REGEX_GENERAL_ESCAPES, new Set("q/[{}|()-")); | |
/* | |
* A single character set of ClassSetReservedDoublePunctuator. | |
* && !! ## $$ %% ** ++ ,, .. :: ;; << == >> ?? @@ ^^ `` ~~ are ClassSetReservedDoublePunctuator | |
*/ | |
const REGEX_CLASS_SET_RESERVED_DOUBLE_PUNCTUATOR = new Set("!#$%&*+,.:;<=>?@^`~"); | |
/** @type {import('../shared/types').Rule} */ | |
module.exports = { | |
meta: { | |
type: "suggestion", | |
docs: { | |
description: "Disallow unnecessary escape characters", | |
recommended: true, | |
url: "https://eslint.org/docs/latest/rules/no-useless-escape" | |
}, | |
hasSuggestions: true, | |
messages: { | |
unnecessaryEscape: "Unnecessary escape character: \\{{character}}.", | |
removeEscape: "Remove the `\\`. This maintains the current functionality.", | |
removeEscapeDoNotKeepSemantics: "Remove the `\\` if it was inserted by mistake.", | |
escapeBackslash: "Replace the `\\` with `\\\\` to include the actual backslash character." | |
}, | |
schema: [] | |
}, | |
create(context) { | |
const sourceCode = context.sourceCode; | |
const parser = new RegExpParser(); | |
/** | |
* Reports a node | |
* @param {ASTNode} node The node to report | |
* @param {number} startOffset The backslash's offset from the start of the node | |
* @param {string} character The uselessly escaped character (not including the backslash) | |
* @param {boolean} [disableEscapeBackslashSuggest] `true` if escapeBackslash suggestion should be turned off. | |
* @returns {void} | |
*/ | |
function report(node, startOffset, character, disableEscapeBackslashSuggest) { | |
const rangeStart = node.range[0] + startOffset; | |
const range = [rangeStart, rangeStart + 1]; | |
const start = sourceCode.getLocFromIndex(rangeStart); | |
context.report({ | |
node, | |
loc: { | |
start, | |
end: { line: start.line, column: start.column + 1 } | |
}, | |
messageId: "unnecessaryEscape", | |
data: { character }, | |
suggest: [ | |
{ | |
// Removing unnecessary `\` characters in a directive is not guaranteed to maintain functionality. | |
messageId: astUtils.isDirective(node.parent) | |
? "removeEscapeDoNotKeepSemantics" : "removeEscape", | |
fix(fixer) { | |
return fixer.removeRange(range); | |
} | |
}, | |
...disableEscapeBackslashSuggest | |
? [] | |
: [ | |
{ | |
messageId: "escapeBackslash", | |
fix(fixer) { | |
return fixer.insertTextBeforeRange(range, "\\"); | |
} | |
} | |
] | |
] | |
}); | |
} | |
/** | |
* Checks if the escape character in given string slice is unnecessary. | |
* @private | |
* @param {ASTNode} node node to validate. | |
* @param {string} match string slice to validate. | |
* @returns {void} | |
*/ | |
function validateString(node, match) { | |
const isTemplateElement = node.type === "TemplateElement"; | |
const escapedChar = match[0][1]; | |
let isUnnecessaryEscape = !VALID_STRING_ESCAPES.has(escapedChar); | |
let isQuoteEscape; | |
if (isTemplateElement) { | |
isQuoteEscape = escapedChar === "`"; | |
if (escapedChar === "$") { | |
// Warn if `\$` is not followed by `{` | |
isUnnecessaryEscape = match.input[match.index + 2] !== "{"; | |
} else if (escapedChar === "{") { | |
/* | |
* Warn if `\{` is not preceded by `$`. If preceded by `$`, escaping | |
* is necessary and the rule should not warn. If preceded by `/$`, the rule | |
* will warn for the `/$` instead, as it is the first unnecessarily escaped character. | |
*/ | |
isUnnecessaryEscape = match.input[match.index - 1] !== "$"; | |
} | |
} else { | |
isQuoteEscape = escapedChar === node.raw[0]; | |
} | |
if (isUnnecessaryEscape && !isQuoteEscape) { | |
report(node, match.index, match[0].slice(1)); | |
} | |
} | |
/** | |
* Checks if the escape character in given regexp is unnecessary. | |
* @private | |
* @param {ASTNode} node node to validate. | |
* @returns {void} | |
*/ | |
function validateRegExp(node) { | |
const { pattern, flags } = node.regex; | |
let patternNode; | |
const unicode = flags.includes("u"); | |
const unicodeSets = flags.includes("v"); | |
try { | |
patternNode = parser.parsePattern(pattern, 0, pattern.length, { unicode, unicodeSets }); | |
} catch { | |
// Ignore regular expressions with syntax errors | |
return; | |
} | |
/** @type {(CharacterClass | ExpressionCharacterClass)[]} */ | |
const characterClassStack = []; | |
visitRegExpAST(patternNode, { | |
onCharacterClassEnter: characterClassNode => characterClassStack.unshift(characterClassNode), | |
onCharacterClassLeave: () => characterClassStack.shift(), | |
onExpressionCharacterClassEnter: characterClassNode => characterClassStack.unshift(characterClassNode), | |
onExpressionCharacterClassLeave: () => characterClassStack.shift(), | |
onCharacterEnter(characterNode) { | |
if (!characterNode.raw.startsWith("\\")) { | |
// It's not an escaped character. | |
return; | |
} | |
const escapedChar = characterNode.raw.slice(1); | |
if (escapedChar !== String.fromCodePoint(characterNode.value)) { | |
// It's a valid escape. | |
return; | |
} | |
let allowedEscapes; | |
if (characterClassStack.length) { | |
allowedEscapes = unicodeSets ? REGEX_CLASSSET_CHARACTER_ESCAPES : REGEX_GENERAL_ESCAPES; | |
} else { | |
allowedEscapes = REGEX_NON_CHARCLASS_ESCAPES; | |
} | |
if (allowedEscapes.has(escapedChar)) { | |
return; | |
} | |
const reportedIndex = characterNode.start + 1; | |
let disableEscapeBackslashSuggest = false; | |
if (characterClassStack.length) { | |
const characterClassNode = characterClassStack[0]; | |
if (escapedChar === "^") { | |
/* | |
* The '^' character is also a special case; it must always be escaped outside of character classes, but | |
* it only needs to be escaped in character classes if it's at the beginning of the character class. To | |
* account for this, consider it to be a valid escape character outside of character classes, and filter | |
* out '^' characters that appear at the start of a character class. | |
*/ | |
if (characterClassNode.start + 1 === characterNode.start) { | |
return; | |
} | |
} | |
if (!unicodeSets) { | |
if (escapedChar === "-") { | |
/* | |
* The '-' character is a special case, because it's only valid to escape it if it's in a character | |
* class, and is not at either edge of the character class. To account for this, don't consider '-' | |
* characters to be valid in general, and filter out '-' characters that appear in the middle of a | |
* character class. | |
*/ | |
if (characterClassNode.start + 1 !== characterNode.start && characterNode.end !== characterClassNode.end - 1) { | |
return; | |
} | |
} | |
} else { // unicodeSets mode | |
if (REGEX_CLASS_SET_RESERVED_DOUBLE_PUNCTUATOR.has(escapedChar)) { | |
// Escaping is valid if it is a ClassSetReservedDoublePunctuator. | |
if (pattern[characterNode.end] === escapedChar) { | |
return; | |
} | |
if (pattern[characterNode.start - 1] === escapedChar) { | |
if (escapedChar !== "^") { | |
return; | |
} | |
// If the previous character is a `negate` caret(`^`), escape to caret is unnecessary. | |
if (!characterClassNode.negate) { | |
return; | |
} | |
const negateCaretIndex = characterClassNode.start + 1; | |
if (negateCaretIndex < characterNode.start - 1) { | |
return; | |
} | |
} | |
} | |
if (characterNode.parent.type === "ClassIntersection" || characterNode.parent.type === "ClassSubtraction") { | |
disableEscapeBackslashSuggest = true; | |
} | |
} | |
} | |
report( | |
node, | |
reportedIndex, | |
escapedChar, | |
disableEscapeBackslashSuggest | |
); | |
} | |
}); | |
} | |
/** | |
* Checks if a node has an escape. | |
* @param {ASTNode} node node to check. | |
* @returns {void} | |
*/ | |
function check(node) { | |
const isTemplateElement = node.type === "TemplateElement"; | |
if ( | |
isTemplateElement && | |
node.parent && | |
node.parent.parent && | |
node.parent.parent.type === "TaggedTemplateExpression" && | |
node.parent === node.parent.parent.quasi | |
) { | |
// Don't report tagged template literals, because the backslash character is accessible to the tag function. | |
return; | |
} | |
if (typeof node.value === "string" || isTemplateElement) { | |
/* | |
* JSXAttribute doesn't have any escape sequence: https://facebook.github.io/jsx/. | |
* In addition, backticks are not supported by JSX yet: https://github.com/facebook/jsx/issues/25. | |
*/ | |
if (node.parent.type === "JSXAttribute" || node.parent.type === "JSXElement" || node.parent.type === "JSXFragment") { | |
return; | |
} | |
const value = isTemplateElement ? sourceCode.getText(node) : node.raw; | |
const pattern = /\\[^\d]/gu; | |
let match; | |
while ((match = pattern.exec(value))) { | |
validateString(node, match); | |
} | |
} else if (node.regex) { | |
validateRegExp(node); | |
} | |
} | |
return { | |
Literal: check, | |
TemplateElement: check | |
}; | |
} | |
}; |