source: imaps-frontend/node_modules/eslint/lib/rules/no-extra-parens.js@ d565449

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

Update repo after prototype presentation
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1/**
2 * @fileoverview Disallow parenthesising higher precedence subexpressions.
3 * @author Michael Ficarra
4 * @deprecated in ESLint v8.53.0
5 */
6"use strict";
7
8//------------------------------------------------------------------------------
9// Rule Definition
10//------------------------------------------------------------------------------
11
12const { isParenthesized: isParenthesizedRaw } = require("@eslint-community/eslint-utils");
13const astUtils = require("./utils/ast-utils.js");
14
15/** @type {import('../shared/types').Rule} */
16module.exports = {
17 meta: {
18 deprecated: true,
19 replacedBy: [],
20 type: "layout",
21
22 docs: {
23 description: "Disallow unnecessary parentheses",
24 recommended: false,
25 url: "https://eslint.org/docs/latest/rules/no-extra-parens"
26 },
27
28 fixable: "code",
29
30 schema: {
31 anyOf: [
32 {
33 type: "array",
34 items: [
35 {
36 enum: ["functions"]
37 }
38 ],
39 minItems: 0,
40 maxItems: 1
41 },
42 {
43 type: "array",
44 items: [
45 {
46 enum: ["all"]
47 },
48 {
49 type: "object",
50 properties: {
51 conditionalAssign: { type: "boolean" },
52 ternaryOperandBinaryExpressions: { type: "boolean" },
53 nestedBinaryExpressions: { type: "boolean" },
54 returnAssign: { type: "boolean" },
55 ignoreJSX: { enum: ["none", "all", "single-line", "multi-line"] },
56 enforceForArrowConditionals: { type: "boolean" },
57 enforceForSequenceExpressions: { type: "boolean" },
58 enforceForNewInMemberExpressions: { type: "boolean" },
59 enforceForFunctionPrototypeMethods: { type: "boolean" },
60 allowParensAfterCommentPattern: { type: "string" }
61 },
62 additionalProperties: false
63 }
64 ],
65 minItems: 0,
66 maxItems: 2
67 }
68 ]
69 },
70
71 messages: {
72 unexpected: "Unnecessary parentheses around expression."
73 }
74 },
75
76 create(context) {
77 const sourceCode = context.sourceCode;
78
79 const tokensToIgnore = new WeakSet();
80 const precedence = astUtils.getPrecedence;
81 const ALL_NODES = context.options[0] !== "functions";
82 const EXCEPT_COND_ASSIGN = ALL_NODES && context.options[1] && context.options[1].conditionalAssign === false;
83 const EXCEPT_COND_TERNARY = ALL_NODES && context.options[1] && context.options[1].ternaryOperandBinaryExpressions === false;
84 const NESTED_BINARY = ALL_NODES && context.options[1] && context.options[1].nestedBinaryExpressions === false;
85 const EXCEPT_RETURN_ASSIGN = ALL_NODES && context.options[1] && context.options[1].returnAssign === false;
86 const IGNORE_JSX = ALL_NODES && context.options[1] && context.options[1].ignoreJSX;
87 const IGNORE_ARROW_CONDITIONALS = ALL_NODES && context.options[1] &&
88 context.options[1].enforceForArrowConditionals === false;
89 const IGNORE_SEQUENCE_EXPRESSIONS = ALL_NODES && context.options[1] &&
90 context.options[1].enforceForSequenceExpressions === false;
91 const IGNORE_NEW_IN_MEMBER_EXPR = ALL_NODES && context.options[1] &&
92 context.options[1].enforceForNewInMemberExpressions === false;
93 const IGNORE_FUNCTION_PROTOTYPE_METHODS = ALL_NODES && context.options[1] &&
94 context.options[1].enforceForFunctionPrototypeMethods === false;
95 const ALLOW_PARENS_AFTER_COMMENT_PATTERN = ALL_NODES && context.options[1] && context.options[1].allowParensAfterCommentPattern;
96
97 const PRECEDENCE_OF_ASSIGNMENT_EXPR = precedence({ type: "AssignmentExpression" });
98 const PRECEDENCE_OF_UPDATE_EXPR = precedence({ type: "UpdateExpression" });
99
100 let reportsBuffer;
101
102 /**
103 * Determines whether the given node is a `call` or `apply` method call, invoked directly on a `FunctionExpression` node.
104 * Example: function(){}.call()
105 * @param {ASTNode} node The node to be checked.
106 * @returns {boolean} True if the node is an immediate `call` or `apply` method call.
107 * @private
108 */
109 function isImmediateFunctionPrototypeMethodCall(node) {
110 const callNode = astUtils.skipChainExpression(node);
111
112 if (callNode.type !== "CallExpression") {
113 return false;
114 }
115 const callee = astUtils.skipChainExpression(callNode.callee);
116
117 return (
118 callee.type === "MemberExpression" &&
119 callee.object.type === "FunctionExpression" &&
120 ["call", "apply"].includes(astUtils.getStaticPropertyName(callee))
121 );
122 }
123
124 /**
125 * Determines if this rule should be enforced for a node given the current configuration.
126 * @param {ASTNode} node The node to be checked.
127 * @returns {boolean} True if the rule should be enforced for this node.
128 * @private
129 */
130 function ruleApplies(node) {
131 if (node.type === "JSXElement" || node.type === "JSXFragment") {
132 const isSingleLine = node.loc.start.line === node.loc.end.line;
133
134 switch (IGNORE_JSX) {
135
136 // Exclude this JSX element from linting
137 case "all":
138 return false;
139
140 // Exclude this JSX element if it is multi-line element
141 case "multi-line":
142 return isSingleLine;
143
144 // Exclude this JSX element if it is single-line element
145 case "single-line":
146 return !isSingleLine;
147
148 // Nothing special to be done for JSX elements
149 case "none":
150 break;
151
152 // no default
153 }
154 }
155
156 if (node.type === "SequenceExpression" && IGNORE_SEQUENCE_EXPRESSIONS) {
157 return false;
158 }
159
160 if (isImmediateFunctionPrototypeMethodCall(node) && IGNORE_FUNCTION_PROTOTYPE_METHODS) {
161 return false;
162 }
163
164 return ALL_NODES || node.type === "FunctionExpression" || node.type === "ArrowFunctionExpression";
165 }
166
167 /**
168 * Determines if a node is surrounded by parentheses.
169 * @param {ASTNode} node The node to be checked.
170 * @returns {boolean} True if the node is parenthesised.
171 * @private
172 */
173 function isParenthesised(node) {
174 return isParenthesizedRaw(1, node, sourceCode);
175 }
176
177 /**
178 * Determines if a node is surrounded by parentheses twice.
179 * @param {ASTNode} node The node to be checked.
180 * @returns {boolean} True if the node is doubly parenthesised.
181 * @private
182 */
183 function isParenthesisedTwice(node) {
184 return isParenthesizedRaw(2, node, sourceCode);
185 }
186
187 /**
188 * Determines if a node is surrounded by (potentially) invalid parentheses.
189 * @param {ASTNode} node The node to be checked.
190 * @returns {boolean} True if the node is incorrectly parenthesised.
191 * @private
192 */
193 function hasExcessParens(node) {
194 return ruleApplies(node) && isParenthesised(node);
195 }
196
197 /**
198 * Determines if a node that is expected to be parenthesised is surrounded by
199 * (potentially) invalid extra parentheses.
200 * @param {ASTNode} node The node to be checked.
201 * @returns {boolean} True if the node is has an unexpected extra pair of parentheses.
202 * @private
203 */
204 function hasDoubleExcessParens(node) {
205 return ruleApplies(node) && isParenthesisedTwice(node);
206 }
207
208 /**
209 * Determines if a node that is expected to be parenthesised is surrounded by
210 * (potentially) invalid extra parentheses with considering precedence level of the node.
211 * If the preference level of the node is not higher or equal to precedence lower limit, it also checks
212 * whether the node is surrounded by parentheses twice or not.
213 * @param {ASTNode} node The node to be checked.
214 * @param {number} precedenceLowerLimit The lower limit of precedence.
215 * @returns {boolean} True if the node is has an unexpected extra pair of parentheses.
216 * @private
217 */
218 function hasExcessParensWithPrecedence(node, precedenceLowerLimit) {
219 if (ruleApplies(node) && isParenthesised(node)) {
220 if (
221 precedence(node) >= precedenceLowerLimit ||
222 isParenthesisedTwice(node)
223 ) {
224 return true;
225 }
226 }
227 return false;
228 }
229
230 /**
231 * Determines if a node test expression is allowed to have a parenthesised assignment
232 * @param {ASTNode} node The node to be checked.
233 * @returns {boolean} True if the assignment can be parenthesised.
234 * @private
235 */
236 function isCondAssignException(node) {
237 return EXCEPT_COND_ASSIGN && node.test.type === "AssignmentExpression";
238 }
239
240 /**
241 * Determines if a node is in a return statement
242 * @param {ASTNode} node The node to be checked.
243 * @returns {boolean} True if the node is in a return statement.
244 * @private
245 */
246 function isInReturnStatement(node) {
247 for (let currentNode = node; currentNode; currentNode = currentNode.parent) {
248 if (
249 currentNode.type === "ReturnStatement" ||
250 (currentNode.type === "ArrowFunctionExpression" && currentNode.body.type !== "BlockStatement")
251 ) {
252 return true;
253 }
254 }
255
256 return false;
257 }
258
259 /**
260 * Determines if a constructor function is newed-up with parens
261 * @param {ASTNode} newExpression The NewExpression node to be checked.
262 * @returns {boolean} True if the constructor is called with parens.
263 * @private
264 */
265 function isNewExpressionWithParens(newExpression) {
266 const lastToken = sourceCode.getLastToken(newExpression);
267 const penultimateToken = sourceCode.getTokenBefore(lastToken);
268
269 return newExpression.arguments.length > 0 ||
270 (
271
272 // The expression should end with its own parens, e.g., new new foo() is not a new expression with parens
273 astUtils.isOpeningParenToken(penultimateToken) &&
274 astUtils.isClosingParenToken(lastToken) &&
275 newExpression.callee.range[1] < newExpression.range[1]
276 );
277 }
278
279 /**
280 * Determines if a node is or contains an assignment expression
281 * @param {ASTNode} node The node to be checked.
282 * @returns {boolean} True if the node is or contains an assignment expression.
283 * @private
284 */
285 function containsAssignment(node) {
286 if (node.type === "AssignmentExpression") {
287 return true;
288 }
289 if (node.type === "ConditionalExpression" &&
290 (node.consequent.type === "AssignmentExpression" || node.alternate.type === "AssignmentExpression")) {
291 return true;
292 }
293 if ((node.left && node.left.type === "AssignmentExpression") ||
294 (node.right && node.right.type === "AssignmentExpression")) {
295 return true;
296 }
297
298 return false;
299 }
300
301 /**
302 * Determines if a node is contained by or is itself a return statement and is allowed to have a parenthesised assignment
303 * @param {ASTNode} node The node to be checked.
304 * @returns {boolean} True if the assignment can be parenthesised.
305 * @private
306 */
307 function isReturnAssignException(node) {
308 if (!EXCEPT_RETURN_ASSIGN || !isInReturnStatement(node)) {
309 return false;
310 }
311
312 if (node.type === "ReturnStatement") {
313 return node.argument && containsAssignment(node.argument);
314 }
315 if (node.type === "ArrowFunctionExpression" && node.body.type !== "BlockStatement") {
316 return containsAssignment(node.body);
317 }
318 return containsAssignment(node);
319
320 }
321
322 /**
323 * Determines if a node following a [no LineTerminator here] restriction is
324 * surrounded by (potentially) invalid extra parentheses.
325 * @param {Token} token The token preceding the [no LineTerminator here] restriction.
326 * @param {ASTNode} node The node to be checked.
327 * @returns {boolean} True if the node is incorrectly parenthesised.
328 * @private
329 */
330 function hasExcessParensNoLineTerminator(token, node) {
331 if (token.loc.end.line === node.loc.start.line) {
332 return hasExcessParens(node);
333 }
334
335 return hasDoubleExcessParens(node);
336 }
337
338 /**
339 * Determines whether a node should be preceded by an additional space when removing parens
340 * @param {ASTNode} node node to evaluate; must be surrounded by parentheses
341 * @returns {boolean} `true` if a space should be inserted before the node
342 * @private
343 */
344 function requiresLeadingSpace(node) {
345 const leftParenToken = sourceCode.getTokenBefore(node);
346 const tokenBeforeLeftParen = sourceCode.getTokenBefore(leftParenToken, { includeComments: true });
347 const tokenAfterLeftParen = sourceCode.getTokenAfter(leftParenToken, { includeComments: true });
348
349 return tokenBeforeLeftParen &&
350 tokenBeforeLeftParen.range[1] === leftParenToken.range[0] &&
351 leftParenToken.range[1] === tokenAfterLeftParen.range[0] &&
352 !astUtils.canTokensBeAdjacent(tokenBeforeLeftParen, tokenAfterLeftParen);
353 }
354
355 /**
356 * Determines whether a node should be followed by an additional space when removing parens
357 * @param {ASTNode} node node to evaluate; must be surrounded by parentheses
358 * @returns {boolean} `true` if a space should be inserted after the node
359 * @private
360 */
361 function requiresTrailingSpace(node) {
362 const nextTwoTokens = sourceCode.getTokensAfter(node, { count: 2 });
363 const rightParenToken = nextTwoTokens[0];
364 const tokenAfterRightParen = nextTwoTokens[1];
365 const tokenBeforeRightParen = sourceCode.getLastToken(node);
366
367 return rightParenToken && tokenAfterRightParen &&
368 !sourceCode.isSpaceBetweenTokens(rightParenToken, tokenAfterRightParen) &&
369 !astUtils.canTokensBeAdjacent(tokenBeforeRightParen, tokenAfterRightParen);
370 }
371
372 /**
373 * Determines if a given expression node is an IIFE
374 * @param {ASTNode} node The node to check
375 * @returns {boolean} `true` if the given node is an IIFE
376 */
377 function isIIFE(node) {
378 const maybeCallNode = astUtils.skipChainExpression(node);
379
380 return maybeCallNode.type === "CallExpression" && maybeCallNode.callee.type === "FunctionExpression";
381 }
382
383 /**
384 * Determines if the given node can be the assignment target in destructuring or the LHS of an assignment.
385 * This is to avoid an autofix that could change behavior because parsers mistakenly allow invalid syntax,
386 * such as `(a = b) = c` and `[(a = b) = c] = []`. Ideally, this function shouldn't be necessary.
387 * @param {ASTNode} [node] The node to check
388 * @returns {boolean} `true` if the given node can be a valid assignment target
389 */
390 function canBeAssignmentTarget(node) {
391 return node && (node.type === "Identifier" || node.type === "MemberExpression");
392 }
393
394 /**
395 * Checks if a node is fixable.
396 * A node is fixable if removing a single pair of surrounding parentheses does not turn it
397 * into a directive after fixing other nodes.
398 * Almost all nodes are fixable, except if all of the following conditions are met:
399 * The node is a string Literal
400 * It has a single pair of parentheses
401 * It is the only child of an ExpressionStatement
402 * @param {ASTNode} node The node to evaluate.
403 * @returns {boolean} Whether or not the node is fixable.
404 * @private
405 */
406 function isFixable(node) {
407
408 // if it's not a string literal it can be autofixed
409 if (node.type !== "Literal" || typeof node.value !== "string") {
410 return true;
411 }
412 if (isParenthesisedTwice(node)) {
413 return true;
414 }
415 return !astUtils.isTopLevelExpressionStatement(node.parent);
416 }
417
418 /**
419 * Report the node
420 * @param {ASTNode} node node to evaluate
421 * @returns {void}
422 * @private
423 */
424 function report(node) {
425 const leftParenToken = sourceCode.getTokenBefore(node);
426 const rightParenToken = sourceCode.getTokenAfter(node);
427
428 if (!isParenthesisedTwice(node)) {
429 if (tokensToIgnore.has(sourceCode.getFirstToken(node))) {
430 return;
431 }
432
433 if (isIIFE(node) && !isParenthesised(node.callee)) {
434 return;
435 }
436
437 if (ALLOW_PARENS_AFTER_COMMENT_PATTERN) {
438 const commentsBeforeLeftParenToken = sourceCode.getCommentsBefore(leftParenToken);
439 const totalCommentsBeforeLeftParenTokenCount = commentsBeforeLeftParenToken.length;
440 const ignorePattern = new RegExp(ALLOW_PARENS_AFTER_COMMENT_PATTERN, "u");
441
442 if (
443 totalCommentsBeforeLeftParenTokenCount > 0 &&
444 ignorePattern.test(commentsBeforeLeftParenToken[totalCommentsBeforeLeftParenTokenCount - 1].value)
445 ) {
446 return;
447 }
448 }
449 }
450
451 /**
452 * Finishes reporting
453 * @returns {void}
454 * @private
455 */
456 function finishReport() {
457 context.report({
458 node,
459 loc: leftParenToken.loc,
460 messageId: "unexpected",
461 fix: isFixable(node)
462 ? fixer => {
463 const parenthesizedSource = sourceCode.text.slice(leftParenToken.range[1], rightParenToken.range[0]);
464
465 return fixer.replaceTextRange([
466 leftParenToken.range[0],
467 rightParenToken.range[1]
468 ], (requiresLeadingSpace(node) ? " " : "") + parenthesizedSource + (requiresTrailingSpace(node) ? " " : ""));
469 }
470 : null
471 });
472 }
473
474 if (reportsBuffer) {
475 reportsBuffer.reports.push({ node, finishReport });
476 return;
477 }
478
479 finishReport();
480 }
481
482 /**
483 * Evaluate a argument of the node.
484 * @param {ASTNode} node node to evaluate
485 * @returns {void}
486 * @private
487 */
488 function checkArgumentWithPrecedence(node) {
489 if (hasExcessParensWithPrecedence(node.argument, precedence(node))) {
490 report(node.argument);
491 }
492 }
493
494 /**
495 * Check if a member expression contains a call expression
496 * @param {ASTNode} node MemberExpression node to evaluate
497 * @returns {boolean} true if found, false if not
498 */
499 function doesMemberExpressionContainCallExpression(node) {
500 let currentNode = node.object;
501 let currentNodeType = node.object.type;
502
503 while (currentNodeType === "MemberExpression") {
504 currentNode = currentNode.object;
505 currentNodeType = currentNode.type;
506 }
507
508 return currentNodeType === "CallExpression";
509 }
510
511 /**
512 * Evaluate a new call
513 * @param {ASTNode} node node to evaluate
514 * @returns {void}
515 * @private
516 */
517 function checkCallNew(node) {
518 const callee = node.callee;
519
520 if (hasExcessParensWithPrecedence(callee, precedence(node))) {
521 if (
522 hasDoubleExcessParens(callee) ||
523 !(
524 isIIFE(node) ||
525
526 // (new A)(); new (new A)();
527 (
528 callee.type === "NewExpression" &&
529 !isNewExpressionWithParens(callee) &&
530 !(
531 node.type === "NewExpression" &&
532 !isNewExpressionWithParens(node)
533 )
534 ) ||
535
536 // new (a().b)(); new (a.b().c);
537 (
538 node.type === "NewExpression" &&
539 callee.type === "MemberExpression" &&
540 doesMemberExpressionContainCallExpression(callee)
541 ) ||
542
543 // (a?.b)(); (a?.())();
544 (
545 !node.optional &&
546 callee.type === "ChainExpression"
547 )
548 )
549 ) {
550 report(node.callee);
551 }
552 }
553 node.arguments
554 .filter(arg => hasExcessParensWithPrecedence(arg, PRECEDENCE_OF_ASSIGNMENT_EXPR))
555 .forEach(report);
556 }
557
558 /**
559 * Evaluate binary logicals
560 * @param {ASTNode} node node to evaluate
561 * @returns {void}
562 * @private
563 */
564 function checkBinaryLogical(node) {
565 const prec = precedence(node);
566 const leftPrecedence = precedence(node.left);
567 const rightPrecedence = precedence(node.right);
568 const isExponentiation = node.operator === "**";
569 const shouldSkipLeft = NESTED_BINARY && (node.left.type === "BinaryExpression" || node.left.type === "LogicalExpression");
570 const shouldSkipRight = NESTED_BINARY && (node.right.type === "BinaryExpression" || node.right.type === "LogicalExpression");
571
572 if (!shouldSkipLeft && hasExcessParens(node.left)) {
573 if (
574 !(["AwaitExpression", "UnaryExpression"].includes(node.left.type) && isExponentiation) &&
575 !astUtils.isMixedLogicalAndCoalesceExpressions(node.left, node) &&
576 (leftPrecedence > prec || (leftPrecedence === prec && !isExponentiation)) ||
577 isParenthesisedTwice(node.left)
578 ) {
579 report(node.left);
580 }
581 }
582
583 if (!shouldSkipRight && hasExcessParens(node.right)) {
584 if (
585 !astUtils.isMixedLogicalAndCoalesceExpressions(node.right, node) &&
586 (rightPrecedence > prec || (rightPrecedence === prec && isExponentiation)) ||
587 isParenthesisedTwice(node.right)
588 ) {
589 report(node.right);
590 }
591 }
592 }
593
594 /**
595 * Check the parentheses around the super class of the given class definition.
596 * @param {ASTNode} node The node of class declarations to check.
597 * @returns {void}
598 */
599 function checkClass(node) {
600 if (!node.superClass) {
601 return;
602 }
603
604 /*
605 * If `node.superClass` is a LeftHandSideExpression, parentheses are extra.
606 * Otherwise, parentheses are needed.
607 */
608 const hasExtraParens = precedence(node.superClass) > PRECEDENCE_OF_UPDATE_EXPR
609 ? hasExcessParens(node.superClass)
610 : hasDoubleExcessParens(node.superClass);
611
612 if (hasExtraParens) {
613 report(node.superClass);
614 }
615 }
616
617 /**
618 * Check the parentheses around the argument of the given spread operator.
619 * @param {ASTNode} node The node of spread elements/properties to check.
620 * @returns {void}
621 */
622 function checkSpreadOperator(node) {
623 if (hasExcessParensWithPrecedence(node.argument, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
624 report(node.argument);
625 }
626 }
627
628 /**
629 * Checks the parentheses for an ExpressionStatement or ExportDefaultDeclaration
630 * @param {ASTNode} node The ExpressionStatement.expression or ExportDefaultDeclaration.declaration node
631 * @returns {void}
632 */
633 function checkExpressionOrExportStatement(node) {
634 const firstToken = isParenthesised(node) ? sourceCode.getTokenBefore(node) : sourceCode.getFirstToken(node);
635 const secondToken = sourceCode.getTokenAfter(firstToken, astUtils.isNotOpeningParenToken);
636 const thirdToken = secondToken ? sourceCode.getTokenAfter(secondToken) : null;
637 const tokenAfterClosingParens = secondToken ? sourceCode.getTokenAfter(secondToken, astUtils.isNotClosingParenToken) : null;
638
639 if (
640 astUtils.isOpeningParenToken(firstToken) &&
641 (
642 astUtils.isOpeningBraceToken(secondToken) ||
643 secondToken.type === "Keyword" && (
644 secondToken.value === "function" ||
645 secondToken.value === "class" ||
646 secondToken.value === "let" &&
647 tokenAfterClosingParens &&
648 (
649 astUtils.isOpeningBracketToken(tokenAfterClosingParens) ||
650 tokenAfterClosingParens.type === "Identifier"
651 )
652 ) ||
653 secondToken && secondToken.type === "Identifier" && secondToken.value === "async" && thirdToken && thirdToken.type === "Keyword" && thirdToken.value === "function"
654 )
655 ) {
656 tokensToIgnore.add(secondToken);
657 }
658
659 const hasExtraParens = node.parent.type === "ExportDefaultDeclaration"
660 ? hasExcessParensWithPrecedence(node, PRECEDENCE_OF_ASSIGNMENT_EXPR)
661 : hasExcessParens(node);
662
663 if (hasExtraParens) {
664 report(node);
665 }
666 }
667
668 /**
669 * Finds the path from the given node to the specified ancestor.
670 * @param {ASTNode} node First node in the path.
671 * @param {ASTNode} ancestor Last node in the path.
672 * @returns {ASTNode[]} Path, including both nodes.
673 * @throws {Error} If the given node does not have the specified ancestor.
674 */
675 function pathToAncestor(node, ancestor) {
676 const path = [node];
677 let currentNode = node;
678
679 while (currentNode !== ancestor) {
680
681 currentNode = currentNode.parent;
682
683 /* c8 ignore start */
684 if (currentNode === null) {
685 throw new Error("Nodes are not in the ancestor-descendant relationship.");
686 }/* c8 ignore stop */
687
688 path.push(currentNode);
689 }
690
691 return path;
692 }
693
694 /**
695 * Finds the path from the given node to the specified descendant.
696 * @param {ASTNode} node First node in the path.
697 * @param {ASTNode} descendant Last node in the path.
698 * @returns {ASTNode[]} Path, including both nodes.
699 * @throws {Error} If the given node does not have the specified descendant.
700 */
701 function pathToDescendant(node, descendant) {
702 return pathToAncestor(descendant, node).reverse();
703 }
704
705 /**
706 * Checks whether the syntax of the given ancestor of an 'in' expression inside a for-loop initializer
707 * is preventing the 'in' keyword from being interpreted as a part of an ill-formed for-in loop.
708 * @param {ASTNode} node Ancestor of an 'in' expression.
709 * @param {ASTNode} child Child of the node, ancestor of the same 'in' expression or the 'in' expression itself.
710 * @returns {boolean} True if the keyword 'in' would be interpreted as the 'in' operator, without any parenthesis.
711 */
712 function isSafelyEnclosingInExpression(node, child) {
713 switch (node.type) {
714 case "ArrayExpression":
715 case "ArrayPattern":
716 case "BlockStatement":
717 case "ObjectExpression":
718 case "ObjectPattern":
719 case "TemplateLiteral":
720 return true;
721 case "ArrowFunctionExpression":
722 case "FunctionExpression":
723 return node.params.includes(child);
724 case "CallExpression":
725 case "NewExpression":
726 return node.arguments.includes(child);
727 case "MemberExpression":
728 return node.computed && node.property === child;
729 case "ConditionalExpression":
730 return node.consequent === child;
731 default:
732 return false;
733 }
734 }
735
736 /**
737 * Starts a new reports buffering. Warnings will be stored in a buffer instead of being reported immediately.
738 * An additional logic that requires multiple nodes (e.g. a whole subtree) may dismiss some of the stored warnings.
739 * @returns {void}
740 */
741 function startNewReportsBuffering() {
742 reportsBuffer = {
743 upper: reportsBuffer,
744 inExpressionNodes: [],
745 reports: []
746 };
747 }
748
749 /**
750 * Ends the current reports buffering.
751 * @returns {void}
752 */
753 function endCurrentReportsBuffering() {
754 const { upper, inExpressionNodes, reports } = reportsBuffer;
755
756 if (upper) {
757 upper.inExpressionNodes.push(...inExpressionNodes);
758 upper.reports.push(...reports);
759 } else {
760
761 // flush remaining reports
762 reports.forEach(({ finishReport }) => finishReport());
763 }
764
765 reportsBuffer = upper;
766 }
767
768 /**
769 * Checks whether the given node is in the current reports buffer.
770 * @param {ASTNode} node Node to check.
771 * @returns {boolean} True if the node is in the current buffer, false otherwise.
772 */
773 function isInCurrentReportsBuffer(node) {
774 return reportsBuffer.reports.some(r => r.node === node);
775 }
776
777 /**
778 * Removes the given node from the current reports buffer.
779 * @param {ASTNode} node Node to remove.
780 * @returns {void}
781 */
782 function removeFromCurrentReportsBuffer(node) {
783 reportsBuffer.reports = reportsBuffer.reports.filter(r => r.node !== node);
784 }
785
786 /**
787 * Checks whether a node is a MemberExpression at NewExpression's callee.
788 * @param {ASTNode} node node to check.
789 * @returns {boolean} True if the node is a MemberExpression at NewExpression's callee. false otherwise.
790 */
791 function isMemberExpInNewCallee(node) {
792 if (node.type === "MemberExpression") {
793 return node.parent.type === "NewExpression" && node.parent.callee === node
794 ? true
795 : node.parent.object === node && isMemberExpInNewCallee(node.parent);
796 }
797 return false;
798 }
799
800 /**
801 * Checks if the left-hand side of an assignment is an identifier, the operator is one of
802 * `=`, `&&=`, `||=` or `??=` and the right-hand side is an anonymous class or function.
803 *
804 * As per https://tc39.es/ecma262/#sec-assignment-operators-runtime-semantics-evaluation, an
805 * assignment involving one of the operators `=`, `&&=`, `||=` or `??=` where the right-hand
806 * side is an anonymous class or function and the left-hand side is an *unparenthesized*
807 * identifier has different semantics than other assignments.
808 * Specifically, when an expression like `foo = function () {}` is evaluated, `foo.name`
809 * will be set to the string "foo", i.e. the identifier name. The same thing does not happen
810 * when evaluating `(foo) = function () {}`.
811 * Since the parenthesizing of the identifier in the left-hand side is significant in this
812 * special case, the parentheses, if present, should not be flagged as unnecessary.
813 * @param {ASTNode} node an AssignmentExpression node.
814 * @returns {boolean} `true` if the left-hand side of the assignment is an identifier, the
815 * operator is one of `=`, `&&=`, `||=` or `??=` and the right-hand side is an anonymous
816 * class or function; otherwise, `false`.
817 */
818 function isAnonymousFunctionAssignmentException({ left, operator, right }) {
819 if (left.type === "Identifier" && ["=", "&&=", "||=", "??="].includes(operator)) {
820 const rhsType = right.type;
821
822 if (rhsType === "ArrowFunctionExpression") {
823 return true;
824 }
825 if ((rhsType === "FunctionExpression" || rhsType === "ClassExpression") && !right.id) {
826 return true;
827 }
828 }
829 return false;
830 }
831
832 return {
833 ArrayExpression(node) {
834 node.elements
835 .filter(e => e && hasExcessParensWithPrecedence(e, PRECEDENCE_OF_ASSIGNMENT_EXPR))
836 .forEach(report);
837 },
838
839 ArrayPattern(node) {
840 node.elements
841 .filter(e => canBeAssignmentTarget(e) && hasExcessParens(e))
842 .forEach(report);
843 },
844
845 ArrowFunctionExpression(node) {
846 if (isReturnAssignException(node)) {
847 return;
848 }
849
850 if (node.body.type === "ConditionalExpression" &&
851 IGNORE_ARROW_CONDITIONALS
852 ) {
853 return;
854 }
855
856 if (node.body.type !== "BlockStatement") {
857 const firstBodyToken = sourceCode.getFirstToken(node.body, astUtils.isNotOpeningParenToken);
858 const tokenBeforeFirst = sourceCode.getTokenBefore(firstBodyToken);
859
860 if (astUtils.isOpeningParenToken(tokenBeforeFirst) && astUtils.isOpeningBraceToken(firstBodyToken)) {
861 tokensToIgnore.add(firstBodyToken);
862 }
863 if (hasExcessParensWithPrecedence(node.body, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
864 report(node.body);
865 }
866 }
867 },
868
869 AssignmentExpression(node) {
870 if (canBeAssignmentTarget(node.left) && hasExcessParens(node.left) &&
871 (!isAnonymousFunctionAssignmentException(node) || isParenthesisedTwice(node.left))) {
872 report(node.left);
873 }
874
875 if (!isReturnAssignException(node) && hasExcessParensWithPrecedence(node.right, precedence(node))) {
876 report(node.right);
877 }
878 },
879
880 BinaryExpression(node) {
881 if (reportsBuffer && node.operator === "in") {
882 reportsBuffer.inExpressionNodes.push(node);
883 }
884
885 checkBinaryLogical(node);
886 },
887
888 CallExpression: checkCallNew,
889
890 ConditionalExpression(node) {
891 if (isReturnAssignException(node)) {
892 return;
893 }
894
895 const availableTypes = new Set(["BinaryExpression", "LogicalExpression"]);
896
897 if (
898 !(EXCEPT_COND_TERNARY && availableTypes.has(node.test.type)) &&
899 !isCondAssignException(node) &&
900 hasExcessParensWithPrecedence(node.test, precedence({ type: "LogicalExpression", operator: "||" }))
901 ) {
902 report(node.test);
903 }
904
905 if (
906 !(EXCEPT_COND_TERNARY && availableTypes.has(node.consequent.type)) &&
907 hasExcessParensWithPrecedence(node.consequent, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
908 report(node.consequent);
909 }
910
911 if (
912 !(EXCEPT_COND_TERNARY && availableTypes.has(node.alternate.type)) &&
913 hasExcessParensWithPrecedence(node.alternate, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
914 report(node.alternate);
915 }
916 },
917
918 DoWhileStatement(node) {
919 if (hasExcessParens(node.test) && !isCondAssignException(node)) {
920 report(node.test);
921 }
922 },
923
924 ExportDefaultDeclaration: node => checkExpressionOrExportStatement(node.declaration),
925 ExpressionStatement: node => checkExpressionOrExportStatement(node.expression),
926
927 ForInStatement(node) {
928 if (node.left.type !== "VariableDeclaration") {
929 const firstLeftToken = sourceCode.getFirstToken(node.left, astUtils.isNotOpeningParenToken);
930
931 if (
932 firstLeftToken.value === "let" &&
933 astUtils.isOpeningBracketToken(
934 sourceCode.getTokenAfter(firstLeftToken, astUtils.isNotClosingParenToken)
935 )
936 ) {
937
938 // ForInStatement#left expression cannot start with `let[`.
939 tokensToIgnore.add(firstLeftToken);
940 }
941 }
942
943 if (hasExcessParens(node.left)) {
944 report(node.left);
945 }
946
947 if (hasExcessParens(node.right)) {
948 report(node.right);
949 }
950 },
951
952 ForOfStatement(node) {
953 if (node.left.type !== "VariableDeclaration") {
954 const firstLeftToken = sourceCode.getFirstToken(node.left, astUtils.isNotOpeningParenToken);
955
956 if (firstLeftToken.value === "let") {
957
958 // ForOfStatement#left expression cannot start with `let`.
959 tokensToIgnore.add(firstLeftToken);
960 }
961 }
962
963 if (hasExcessParens(node.left)) {
964 report(node.left);
965 }
966
967 if (hasExcessParensWithPrecedence(node.right, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
968 report(node.right);
969 }
970 },
971
972 ForStatement(node) {
973 if (node.test && hasExcessParens(node.test) && !isCondAssignException(node)) {
974 report(node.test);
975 }
976
977 if (node.update && hasExcessParens(node.update)) {
978 report(node.update);
979 }
980
981 if (node.init) {
982
983 if (node.init.type !== "VariableDeclaration") {
984 const firstToken = sourceCode.getFirstToken(node.init, astUtils.isNotOpeningParenToken);
985
986 if (
987 firstToken.value === "let" &&
988 astUtils.isOpeningBracketToken(
989 sourceCode.getTokenAfter(firstToken, astUtils.isNotClosingParenToken)
990 )
991 ) {
992
993 // ForStatement#init expression cannot start with `let[`.
994 tokensToIgnore.add(firstToken);
995 }
996 }
997
998 startNewReportsBuffering();
999
1000 if (hasExcessParens(node.init)) {
1001 report(node.init);
1002 }
1003 }
1004 },
1005
1006 "ForStatement > *.init:exit"(node) {
1007
1008 /*
1009 * Removing parentheses around `in` expressions might change semantics and cause errors.
1010 *
1011 * For example, this valid for loop:
1012 * for (let a = (b in c); ;);
1013 * after removing parentheses would be treated as an invalid for-in loop:
1014 * for (let a = b in c; ;);
1015 */
1016
1017 if (reportsBuffer.reports.length) {
1018 reportsBuffer.inExpressionNodes.forEach(inExpressionNode => {
1019 const path = pathToDescendant(node, inExpressionNode);
1020 let nodeToExclude;
1021
1022 for (let i = 0; i < path.length; i++) {
1023 const pathNode = path[i];
1024
1025 if (i < path.length - 1) {
1026 const nextPathNode = path[i + 1];
1027
1028 if (isSafelyEnclosingInExpression(pathNode, nextPathNode)) {
1029
1030 // The 'in' expression in safely enclosed by the syntax of its ancestor nodes (e.g. by '{}' or '[]').
1031 return;
1032 }
1033 }
1034
1035 if (isParenthesised(pathNode)) {
1036 if (isInCurrentReportsBuffer(pathNode)) {
1037
1038 // This node was supposed to be reported, but parentheses might be necessary.
1039
1040 if (isParenthesisedTwice(pathNode)) {
1041
1042 /*
1043 * This node is parenthesised twice, it certainly has at least one pair of `extra` parentheses.
1044 * If the --fix option is on, the current fixing iteration will remove only one pair of parentheses.
1045 * The remaining pair is safely enclosing the 'in' expression.
1046 */
1047 return;
1048 }
1049
1050 // Exclude the outermost node only.
1051 if (!nodeToExclude) {
1052 nodeToExclude = pathNode;
1053 }
1054
1055 // Don't break the loop here, there might be some safe nodes or parentheses that will stay inside.
1056
1057 } else {
1058
1059 // This node will stay parenthesised, the 'in' expression in safely enclosed by '()'.
1060 return;
1061 }
1062 }
1063 }
1064
1065 // Exclude the node from the list (i.e. treat parentheses as necessary)
1066 removeFromCurrentReportsBuffer(nodeToExclude);
1067 });
1068 }
1069
1070 endCurrentReportsBuffering();
1071 },
1072
1073 IfStatement(node) {
1074 if (hasExcessParens(node.test) && !isCondAssignException(node)) {
1075 report(node.test);
1076 }
1077 },
1078
1079 ImportExpression(node) {
1080 const { source } = node;
1081
1082 if (source.type === "SequenceExpression") {
1083 if (hasDoubleExcessParens(source)) {
1084 report(source);
1085 }
1086 } else if (hasExcessParens(source)) {
1087 report(source);
1088 }
1089 },
1090
1091 LogicalExpression: checkBinaryLogical,
1092
1093 MemberExpression(node) {
1094 const shouldAllowWrapOnce = isMemberExpInNewCallee(node) &&
1095 doesMemberExpressionContainCallExpression(node);
1096 const nodeObjHasExcessParens = shouldAllowWrapOnce
1097 ? hasDoubleExcessParens(node.object)
1098 : hasExcessParens(node.object) &&
1099 !(
1100 isImmediateFunctionPrototypeMethodCall(node.parent) &&
1101 node.parent.callee === node &&
1102 IGNORE_FUNCTION_PROTOTYPE_METHODS
1103 );
1104
1105 if (
1106 nodeObjHasExcessParens &&
1107 precedence(node.object) >= precedence(node) &&
1108 (
1109 node.computed ||
1110 !(
1111 astUtils.isDecimalInteger(node.object) ||
1112
1113 // RegExp literal is allowed to have parens (#1589)
1114 (node.object.type === "Literal" && node.object.regex)
1115 )
1116 )
1117 ) {
1118 report(node.object);
1119 }
1120
1121 if (nodeObjHasExcessParens &&
1122 node.object.type === "CallExpression"
1123 ) {
1124 report(node.object);
1125 }
1126
1127 if (nodeObjHasExcessParens &&
1128 !IGNORE_NEW_IN_MEMBER_EXPR &&
1129 node.object.type === "NewExpression" &&
1130 isNewExpressionWithParens(node.object)) {
1131 report(node.object);
1132 }
1133
1134 if (nodeObjHasExcessParens &&
1135 node.optional &&
1136 node.object.type === "ChainExpression"
1137 ) {
1138 report(node.object);
1139 }
1140
1141 if (node.computed && hasExcessParens(node.property)) {
1142 report(node.property);
1143 }
1144 },
1145
1146 "MethodDefinition[computed=true]"(node) {
1147 if (hasExcessParensWithPrecedence(node.key, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
1148 report(node.key);
1149 }
1150 },
1151
1152 NewExpression: checkCallNew,
1153
1154 ObjectExpression(node) {
1155 node.properties
1156 .filter(property => property.value && hasExcessParensWithPrecedence(property.value, PRECEDENCE_OF_ASSIGNMENT_EXPR))
1157 .forEach(property => report(property.value));
1158 },
1159
1160 ObjectPattern(node) {
1161 node.properties
1162 .filter(property => {
1163 const value = property.value;
1164
1165 return canBeAssignmentTarget(value) && hasExcessParens(value);
1166 }).forEach(property => report(property.value));
1167 },
1168
1169 Property(node) {
1170 if (node.computed) {
1171 const { key } = node;
1172
1173 if (key && hasExcessParensWithPrecedence(key, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
1174 report(key);
1175 }
1176 }
1177 },
1178
1179 PropertyDefinition(node) {
1180 if (node.computed && hasExcessParensWithPrecedence(node.key, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
1181 report(node.key);
1182 }
1183
1184 if (node.value && hasExcessParensWithPrecedence(node.value, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
1185 report(node.value);
1186 }
1187 },
1188
1189 RestElement(node) {
1190 const argument = node.argument;
1191
1192 if (canBeAssignmentTarget(argument) && hasExcessParens(argument)) {
1193 report(argument);
1194 }
1195 },
1196
1197 ReturnStatement(node) {
1198 const returnToken = sourceCode.getFirstToken(node);
1199
1200 if (isReturnAssignException(node)) {
1201 return;
1202 }
1203
1204 if (node.argument &&
1205 hasExcessParensNoLineTerminator(returnToken, node.argument) &&
1206
1207 // RegExp literal is allowed to have parens (#1589)
1208 !(node.argument.type === "Literal" && node.argument.regex)) {
1209 report(node.argument);
1210 }
1211 },
1212
1213 SequenceExpression(node) {
1214 const precedenceOfNode = precedence(node);
1215
1216 node.expressions
1217 .filter(e => hasExcessParensWithPrecedence(e, precedenceOfNode))
1218 .forEach(report);
1219 },
1220
1221 SwitchCase(node) {
1222 if (node.test && hasExcessParens(node.test)) {
1223 report(node.test);
1224 }
1225 },
1226
1227 SwitchStatement(node) {
1228 if (hasExcessParens(node.discriminant)) {
1229 report(node.discriminant);
1230 }
1231 },
1232
1233 ThrowStatement(node) {
1234 const throwToken = sourceCode.getFirstToken(node);
1235
1236 if (hasExcessParensNoLineTerminator(throwToken, node.argument)) {
1237 report(node.argument);
1238 }
1239 },
1240
1241 UnaryExpression: checkArgumentWithPrecedence,
1242 UpdateExpression(node) {
1243 if (node.prefix) {
1244 checkArgumentWithPrecedence(node);
1245 } else {
1246 const { argument } = node;
1247 const operatorToken = sourceCode.getLastToken(node);
1248
1249 if (argument.loc.end.line === operatorToken.loc.start.line) {
1250 checkArgumentWithPrecedence(node);
1251 } else {
1252 if (hasDoubleExcessParens(argument)) {
1253 report(argument);
1254 }
1255 }
1256 }
1257 },
1258 AwaitExpression: checkArgumentWithPrecedence,
1259
1260 VariableDeclarator(node) {
1261 if (
1262 node.init && hasExcessParensWithPrecedence(node.init, PRECEDENCE_OF_ASSIGNMENT_EXPR) &&
1263
1264 // RegExp literal is allowed to have parens (#1589)
1265 !(node.init.type === "Literal" && node.init.regex)
1266 ) {
1267 report(node.init);
1268 }
1269 },
1270
1271 WhileStatement(node) {
1272 if (hasExcessParens(node.test) && !isCondAssignException(node)) {
1273 report(node.test);
1274 }
1275 },
1276
1277 WithStatement(node) {
1278 if (hasExcessParens(node.object)) {
1279 report(node.object);
1280 }
1281 },
1282
1283 YieldExpression(node) {
1284 if (node.argument) {
1285 const yieldToken = sourceCode.getFirstToken(node);
1286
1287 if ((precedence(node.argument) >= precedence(node) &&
1288 hasExcessParensNoLineTerminator(yieldToken, node.argument)) ||
1289 hasDoubleExcessParens(node.argument)) {
1290 report(node.argument);
1291 }
1292 }
1293 },
1294
1295 ClassDeclaration: checkClass,
1296 ClassExpression: checkClass,
1297
1298 SpreadElement: checkSpreadOperator,
1299 SpreadProperty: checkSpreadOperator,
1300 ExperimentalSpreadProperty: checkSpreadOperator,
1301
1302 TemplateLiteral(node) {
1303 node.expressions
1304 .filter(e => e && hasExcessParens(e))
1305 .forEach(report);
1306 },
1307
1308 AssignmentPattern(node) {
1309 const { left, right } = node;
1310
1311 if (canBeAssignmentTarget(left) && hasExcessParens(left)) {
1312 report(left);
1313 }
1314
1315 if (right && hasExcessParensWithPrecedence(right, PRECEDENCE_OF_ASSIGNMENT_EXPR)) {
1316 report(right);
1317 }
1318 }
1319 };
1320
1321 }
1322};
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