source: imaps-frontend/node_modules/eslint/lib/rules/no-useless-escape.js

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Last change on this file was d565449, checked in by stefan toskovski <stefantoska84@…>, 4 weeks ago

Update repo after prototype presentation
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1/**
2 * @fileoverview Look for useless escapes in strings and regexes
3 * @author Onur Temizkan
4 */
5
6"use strict";
7
8const astUtils = require("./utils/ast-utils");
9const { RegExpParser, visitRegExpAST } = require("@eslint-community/regexpp");
10
11/**
12 * @typedef {import('@eslint-community/regexpp').AST.CharacterClass} CharacterClass
13 * @typedef {import('@eslint-community/regexpp').AST.ExpressionCharacterClass} ExpressionCharacterClass
14 */
15//------------------------------------------------------------------------------
16// Rule Definition
17//------------------------------------------------------------------------------
18
19/**
20 * Returns the union of two sets.
21 * @param {Set} setA The first set
22 * @param {Set} setB The second set
23 * @returns {Set} The union of the two sets
24 */
25function union(setA, setB) {
26 return new Set(function *() {
27 yield* setA;
28 yield* setB;
29 }());
30}
31
32const VALID_STRING_ESCAPES = union(new Set("\\nrvtbfux"), astUtils.LINEBREAKS);
33const REGEX_GENERAL_ESCAPES = new Set("\\bcdDfnpPrsStvwWxu0123456789]");
34const REGEX_NON_CHARCLASS_ESCAPES = union(REGEX_GENERAL_ESCAPES, new Set("^/.$*+?[{}|()Bk"));
35
36/*
37 * Set of characters that require escaping in character classes in `unicodeSets` mode.
38 * ( ) [ ] { } / - \ | are ClassSetSyntaxCharacter
39 */
40const REGEX_CLASSSET_CHARACTER_ESCAPES = union(REGEX_GENERAL_ESCAPES, new Set("q/[{}|()-"));
41
42/*
43 * A single character set of ClassSetReservedDoublePunctuator.
44 * && !! ## $$ %% ** ++ ,, .. :: ;; << == >> ?? @@ ^^ `` ~~ are ClassSetReservedDoublePunctuator
45 */
46const REGEX_CLASS_SET_RESERVED_DOUBLE_PUNCTUATOR = new Set("!#$%&*+,.:;<=>?@^`~");
47
48/** @type {import('../shared/types').Rule} */
49module.exports = {
50 meta: {
51 type: "suggestion",
52
53 docs: {
54 description: "Disallow unnecessary escape characters",
55 recommended: true,
56 url: "https://eslint.org/docs/latest/rules/no-useless-escape"
57 },
58
59 hasSuggestions: true,
60
61 messages: {
62 unnecessaryEscape: "Unnecessary escape character: \\{{character}}.",
63 removeEscape: "Remove the `\\`. This maintains the current functionality.",
64 removeEscapeDoNotKeepSemantics: "Remove the `\\` if it was inserted by mistake.",
65 escapeBackslash: "Replace the `\\` with `\\\\` to include the actual backslash character."
66 },
67
68 schema: []
69 },
70
71 create(context) {
72 const sourceCode = context.sourceCode;
73 const parser = new RegExpParser();
74
75 /**
76 * Reports a node
77 * @param {ASTNode} node The node to report
78 * @param {number} startOffset The backslash's offset from the start of the node
79 * @param {string} character The uselessly escaped character (not including the backslash)
80 * @param {boolean} [disableEscapeBackslashSuggest] `true` if escapeBackslash suggestion should be turned off.
81 * @returns {void}
82 */
83 function report(node, startOffset, character, disableEscapeBackslashSuggest) {
84 const rangeStart = node.range[0] + startOffset;
85 const range = [rangeStart, rangeStart + 1];
86 const start = sourceCode.getLocFromIndex(rangeStart);
87
88 context.report({
89 node,
90 loc: {
91 start,
92 end: { line: start.line, column: start.column + 1 }
93 },
94 messageId: "unnecessaryEscape",
95 data: { character },
96 suggest: [
97 {
98
99 // Removing unnecessary `\` characters in a directive is not guaranteed to maintain functionality.
100 messageId: astUtils.isDirective(node.parent)
101 ? "removeEscapeDoNotKeepSemantics" : "removeEscape",
102 fix(fixer) {
103 return fixer.removeRange(range);
104 }
105 },
106 ...disableEscapeBackslashSuggest
107 ? []
108 : [
109 {
110 messageId: "escapeBackslash",
111 fix(fixer) {
112 return fixer.insertTextBeforeRange(range, "\\");
113 }
114 }
115 ]
116 ]
117 });
118 }
119
120 /**
121 * Checks if the escape character in given string slice is unnecessary.
122 * @private
123 * @param {ASTNode} node node to validate.
124 * @param {string} match string slice to validate.
125 * @returns {void}
126 */
127 function validateString(node, match) {
128 const isTemplateElement = node.type === "TemplateElement";
129 const escapedChar = match[0][1];
130 let isUnnecessaryEscape = !VALID_STRING_ESCAPES.has(escapedChar);
131 let isQuoteEscape;
132
133 if (isTemplateElement) {
134 isQuoteEscape = escapedChar === "`";
135
136 if (escapedChar === "$") {
137
138 // Warn if `\$` is not followed by `{`
139 isUnnecessaryEscape = match.input[match.index + 2] !== "{";
140 } else if (escapedChar === "{") {
141
142 /*
143 * Warn if `\{` is not preceded by `$`. If preceded by `$`, escaping
144 * is necessary and the rule should not warn. If preceded by `/$`, the rule
145 * will warn for the `/$` instead, as it is the first unnecessarily escaped character.
146 */
147 isUnnecessaryEscape = match.input[match.index - 1] !== "$";
148 }
149 } else {
150 isQuoteEscape = escapedChar === node.raw[0];
151 }
152
153 if (isUnnecessaryEscape && !isQuoteEscape) {
154 report(node, match.index, match[0].slice(1));
155 }
156 }
157
158 /**
159 * Checks if the escape character in given regexp is unnecessary.
160 * @private
161 * @param {ASTNode} node node to validate.
162 * @returns {void}
163 */
164 function validateRegExp(node) {
165 const { pattern, flags } = node.regex;
166 let patternNode;
167 const unicode = flags.includes("u");
168 const unicodeSets = flags.includes("v");
169
170 try {
171 patternNode = parser.parsePattern(pattern, 0, pattern.length, { unicode, unicodeSets });
172 } catch {
173
174 // Ignore regular expressions with syntax errors
175 return;
176 }
177
178 /** @type {(CharacterClass | ExpressionCharacterClass)[]} */
179 const characterClassStack = [];
180
181 visitRegExpAST(patternNode, {
182 onCharacterClassEnter: characterClassNode => characterClassStack.unshift(characterClassNode),
183 onCharacterClassLeave: () => characterClassStack.shift(),
184 onExpressionCharacterClassEnter: characterClassNode => characterClassStack.unshift(characterClassNode),
185 onExpressionCharacterClassLeave: () => characterClassStack.shift(),
186 onCharacterEnter(characterNode) {
187 if (!characterNode.raw.startsWith("\\")) {
188
189 // It's not an escaped character.
190 return;
191 }
192
193 const escapedChar = characterNode.raw.slice(1);
194
195 if (escapedChar !== String.fromCodePoint(characterNode.value)) {
196
197 // It's a valid escape.
198 return;
199 }
200 let allowedEscapes;
201
202 if (characterClassStack.length) {
203 allowedEscapes = unicodeSets ? REGEX_CLASSSET_CHARACTER_ESCAPES : REGEX_GENERAL_ESCAPES;
204 } else {
205 allowedEscapes = REGEX_NON_CHARCLASS_ESCAPES;
206 }
207 if (allowedEscapes.has(escapedChar)) {
208 return;
209 }
210
211 const reportedIndex = characterNode.start + 1;
212 let disableEscapeBackslashSuggest = false;
213
214 if (characterClassStack.length) {
215 const characterClassNode = characterClassStack[0];
216
217 if (escapedChar === "^") {
218
219 /*
220 * The '^' character is also a special case; it must always be escaped outside of character classes, but
221 * it only needs to be escaped in character classes if it's at the beginning of the character class. To
222 * account for this, consider it to be a valid escape character outside of character classes, and filter
223 * out '^' characters that appear at the start of a character class.
224 */
225 if (characterClassNode.start + 1 === characterNode.start) {
226
227 return;
228 }
229 }
230 if (!unicodeSets) {
231 if (escapedChar === "-") {
232
233 /*
234 * The '-' character is a special case, because it's only valid to escape it if it's in a character
235 * class, and is not at either edge of the character class. To account for this, don't consider '-'
236 * characters to be valid in general, and filter out '-' characters that appear in the middle of a
237 * character class.
238 */
239 if (characterClassNode.start + 1 !== characterNode.start && characterNode.end !== characterClassNode.end - 1) {
240
241 return;
242 }
243 }
244 } else { // unicodeSets mode
245 if (REGEX_CLASS_SET_RESERVED_DOUBLE_PUNCTUATOR.has(escapedChar)) {
246
247 // Escaping is valid if it is a ClassSetReservedDoublePunctuator.
248 if (pattern[characterNode.end] === escapedChar) {
249 return;
250 }
251 if (pattern[characterNode.start - 1] === escapedChar) {
252 if (escapedChar !== "^") {
253 return;
254 }
255
256 // If the previous character is a `negate` caret(`^`), escape to caret is unnecessary.
257
258 if (!characterClassNode.negate) {
259 return;
260 }
261 const negateCaretIndex = characterClassNode.start + 1;
262
263 if (negateCaretIndex < characterNode.start - 1) {
264 return;
265 }
266 }
267 }
268
269 if (characterNode.parent.type === "ClassIntersection" || characterNode.parent.type === "ClassSubtraction") {
270 disableEscapeBackslashSuggest = true;
271 }
272 }
273 }
274
275 report(
276 node,
277 reportedIndex,
278 escapedChar,
279 disableEscapeBackslashSuggest
280 );
281 }
282 });
283 }
284
285 /**
286 * Checks if a node has an escape.
287 * @param {ASTNode} node node to check.
288 * @returns {void}
289 */
290 function check(node) {
291 const isTemplateElement = node.type === "TemplateElement";
292
293 if (
294 isTemplateElement &&
295 node.parent &&
296 node.parent.parent &&
297 node.parent.parent.type === "TaggedTemplateExpression" &&
298 node.parent === node.parent.parent.quasi
299 ) {
300
301 // Don't report tagged template literals, because the backslash character is accessible to the tag function.
302 return;
303 }
304
305 if (typeof node.value === "string" || isTemplateElement) {
306
307 /*
308 * JSXAttribute doesn't have any escape sequence: https://facebook.github.io/jsx/.
309 * In addition, backticks are not supported by JSX yet: https://github.com/facebook/jsx/issues/25.
310 */
311 if (node.parent.type === "JSXAttribute" || node.parent.type === "JSXElement" || node.parent.type === "JSXFragment") {
312 return;
313 }
314
315 const value = isTemplateElement ? sourceCode.getText(node) : node.raw;
316 const pattern = /\\[^\d]/gu;
317 let match;
318
319 while ((match = pattern.exec(value))) {
320 validateString(node, match);
321 }
322 } else if (node.regex) {
323 validateRegExp(node);
324 }
325
326 }
327
328 return {
329 Literal: check,
330 TemplateElement: check
331 };
332 }
333};
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