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- /**
- * @fileoverview Disallow parenthesising higher precedence subexpressions.
- * @author Michael Ficarra
- * @deprecated in ESLint v8.53.0
- */
- "use strict";
- //------------------------------------------------------------------------------
- // Rule Definition
- //------------------------------------------------------------------------------
- const {
- isParenthesized: isParenthesizedRaw,
- } = require("@eslint-community/eslint-utils");
- const astUtils = require("./utils/ast-utils.js");
- /** @type {import('../types').Rule.RuleModule} */
- module.exports = {
- meta: {
- deprecated: {
- message: "Formatting rules are being moved out of ESLint core.",
- url: "https://eslint.org/blog/2023/10/deprecating-formatting-rules/",
- deprecatedSince: "8.53.0",
- availableUntil: "11.0.0",
- replacedBy: [
- {
- message:
- "ESLint Stylistic now maintains deprecated stylistic core rules.",
- url: "https://eslint.style/guide/migration",
- plugin: {
- name: "@stylistic/eslint-plugin",
- url: "https://eslint.style",
- },
- rule: {
- name: "no-extra-parens",
- url: "https://eslint.style/rules/no-extra-parens",
- },
- },
- ],
- },
- type: "layout",
- docs: {
- description: "Disallow unnecessary parentheses",
- recommended: false,
- url: "https://eslint.org/docs/latest/rules/no-extra-parens",
- },
- fixable: "code",
- schema: {
- anyOf: [
- {
- type: "array",
- items: [
- {
- enum: ["functions"],
- },
- ],
- minItems: 0,
- maxItems: 1,
- },
- {
- type: "array",
- items: [
- {
- enum: ["all"],
- },
- {
- type: "object",
- properties: {
- conditionalAssign: { type: "boolean" },
- ternaryOperandBinaryExpressions: {
- type: "boolean",
- },
- nestedBinaryExpressions: { type: "boolean" },
- returnAssign: { type: "boolean" },
- ignoreJSX: {
- enum: [
- "none",
- "all",
- "single-line",
- "multi-line",
- ],
- },
- enforceForArrowConditionals: {
- type: "boolean",
- },
- enforceForSequenceExpressions: {
- type: "boolean",
- },
- enforceForNewInMemberExpressions: {
- type: "boolean",
- },
- enforceForFunctionPrototypeMethods: {
- type: "boolean",
- },
- allowParensAfterCommentPattern: {
- type: "string",
- },
- },
- additionalProperties: false,
- },
- ],
- minItems: 0,
- maxItems: 2,
- },
- ],
- },
- messages: {
- unexpected: "Unnecessary parentheses around expression.",
- },
- },
- create(context) {
- const sourceCode = context.sourceCode;
- const tokensToIgnore = new WeakSet();
- const precedence = astUtils.getPrecedence;
- const ALL_NODES = context.options[0] !== "functions";
- const EXCEPT_COND_ASSIGN =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].conditionalAssign === false;
- const EXCEPT_COND_TERNARY =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].ternaryOperandBinaryExpressions === false;
- const NESTED_BINARY =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].nestedBinaryExpressions === false;
- const EXCEPT_RETURN_ASSIGN =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].returnAssign === false;
- const IGNORE_JSX =
- ALL_NODES && context.options[1] && context.options[1].ignoreJSX;
- const IGNORE_ARROW_CONDITIONALS =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].enforceForArrowConditionals === false;
- const IGNORE_SEQUENCE_EXPRESSIONS =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].enforceForSequenceExpressions === false;
- const IGNORE_NEW_IN_MEMBER_EXPR =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].enforceForNewInMemberExpressions === false;
- const IGNORE_FUNCTION_PROTOTYPE_METHODS =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].enforceForFunctionPrototypeMethods === false;
- const ALLOW_PARENS_AFTER_COMMENT_PATTERN =
- ALL_NODES &&
- context.options[1] &&
- context.options[1].allowParensAfterCommentPattern;
- const PRECEDENCE_OF_ASSIGNMENT_EXPR = precedence({
- type: "AssignmentExpression",
- });
- const PRECEDENCE_OF_UPDATE_EXPR = precedence({
- type: "UpdateExpression",
- });
- let reportsBuffer;
- /**
- * Determines whether the given node is a `call` or `apply` method call, invoked directly on a `FunctionExpression` node.
- * Example: function(){}.call()
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is an immediate `call` or `apply` method call.
- * @private
- */
- function isImmediateFunctionPrototypeMethodCall(node) {
- const callNode = astUtils.skipChainExpression(node);
- if (callNode.type !== "CallExpression") {
- return false;
- }
- const callee = astUtils.skipChainExpression(callNode.callee);
- return (
- callee.type === "MemberExpression" &&
- callee.object.type === "FunctionExpression" &&
- ["call", "apply"].includes(
- astUtils.getStaticPropertyName(callee),
- )
- );
- }
- /**
- * Determines if this rule should be enforced for a node given the current configuration.
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the rule should be enforced for this node.
- * @private
- */
- function ruleApplies(node) {
- if (node.type === "JSXElement" || node.type === "JSXFragment") {
- const isSingleLine = node.loc.start.line === node.loc.end.line;
- switch (IGNORE_JSX) {
- // Exclude this JSX element from linting
- case "all":
- return false;
- // Exclude this JSX element if it is multi-line element
- case "multi-line":
- return isSingleLine;
- // Exclude this JSX element if it is single-line element
- case "single-line":
- return !isSingleLine;
- // Nothing special to be done for JSX elements
- case "none":
- break;
- // no default
- }
- }
- if (
- node.type === "SequenceExpression" &&
- IGNORE_SEQUENCE_EXPRESSIONS
- ) {
- return false;
- }
- if (
- isImmediateFunctionPrototypeMethodCall(node) &&
- IGNORE_FUNCTION_PROTOTYPE_METHODS
- ) {
- return false;
- }
- return (
- ALL_NODES ||
- node.type === "FunctionExpression" ||
- node.type === "ArrowFunctionExpression"
- );
- }
- /**
- * Determines if a node is surrounded by parentheses.
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is parenthesised.
- * @private
- */
- function isParenthesised(node) {
- return isParenthesizedRaw(1, node, sourceCode);
- }
- /**
- * Determines if a node is surrounded by parentheses twice.
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is doubly parenthesised.
- * @private
- */
- function isParenthesisedTwice(node) {
- return isParenthesizedRaw(2, node, sourceCode);
- }
- /**
- * Determines if a node is surrounded by (potentially) invalid parentheses.
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is incorrectly parenthesised.
- * @private
- */
- function hasExcessParens(node) {
- return ruleApplies(node) && isParenthesised(node);
- }
- /**
- * Determines if a node that is expected to be parenthesised is surrounded by
- * (potentially) invalid extra parentheses.
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is has an unexpected extra pair of parentheses.
- * @private
- */
- function hasDoubleExcessParens(node) {
- return ruleApplies(node) && isParenthesisedTwice(node);
- }
- /**
- * Determines if a node that is expected to be parenthesised is surrounded by
- * (potentially) invalid extra parentheses with considering precedence level of the node.
- * If the preference level of the node is not higher or equal to precedence lower limit, it also checks
- * whether the node is surrounded by parentheses twice or not.
- * @param {ASTNode} node The node to be checked.
- * @param {number} precedenceLowerLimit The lower limit of precedence.
- * @returns {boolean} True if the node is has an unexpected extra pair of parentheses.
- * @private
- */
- function hasExcessParensWithPrecedence(node, precedenceLowerLimit) {
- if (ruleApplies(node) && isParenthesised(node)) {
- if (
- precedence(node) >= precedenceLowerLimit ||
- isParenthesisedTwice(node)
- ) {
- return true;
- }
- }
- return false;
- }
- /**
- * Determines if a node test expression is allowed to have a parenthesised assignment
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the assignment can be parenthesised.
- * @private
- */
- function isCondAssignException(node) {
- return (
- EXCEPT_COND_ASSIGN && node.test.type === "AssignmentExpression"
- );
- }
- /**
- * Determines if a node is in a return statement
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is in a return statement.
- * @private
- */
- function isInReturnStatement(node) {
- for (
- let currentNode = node;
- currentNode;
- currentNode = currentNode.parent
- ) {
- if (
- currentNode.type === "ReturnStatement" ||
- (currentNode.type === "ArrowFunctionExpression" &&
- currentNode.body.type !== "BlockStatement")
- ) {
- return true;
- }
- }
- return false;
- }
- /**
- * Determines if a constructor function is newed-up with parens
- * @param {ASTNode} newExpression The NewExpression node to be checked.
- * @returns {boolean} True if the constructor is called with parens.
- * @private
- */
- function isNewExpressionWithParens(newExpression) {
- const lastToken = sourceCode.getLastToken(newExpression);
- const penultimateToken = sourceCode.getTokenBefore(lastToken);
- return (
- newExpression.arguments.length > 0 ||
- // The expression should end with its own parens, e.g., new new foo() is not a new expression with parens
- (astUtils.isOpeningParenToken(penultimateToken) &&
- astUtils.isClosingParenToken(lastToken) &&
- newExpression.callee.range[1] < newExpression.range[1])
- );
- }
- /**
- * Determines if a node is or contains an assignment expression
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is or contains an assignment expression.
- * @private
- */
- function containsAssignment(node) {
- if (node.type === "AssignmentExpression") {
- return true;
- }
- if (
- node.type === "ConditionalExpression" &&
- (node.consequent.type === "AssignmentExpression" ||
- node.alternate.type === "AssignmentExpression")
- ) {
- return true;
- }
- if (
- (node.left && node.left.type === "AssignmentExpression") ||
- (node.right && node.right.type === "AssignmentExpression")
- ) {
- return true;
- }
- return false;
- }
- /**
- * Determines if a node is contained by or is itself a return statement and is allowed to have a parenthesised assignment
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the assignment can be parenthesised.
- * @private
- */
- function isReturnAssignException(node) {
- if (!EXCEPT_RETURN_ASSIGN || !isInReturnStatement(node)) {
- return false;
- }
- if (node.type === "ReturnStatement") {
- return node.argument && containsAssignment(node.argument);
- }
- if (
- node.type === "ArrowFunctionExpression" &&
- node.body.type !== "BlockStatement"
- ) {
- return containsAssignment(node.body);
- }
- return containsAssignment(node);
- }
- /**
- * Determines if a node following a [no LineTerminator here] restriction is
- * surrounded by (potentially) invalid extra parentheses.
- * @param {Token} token The token preceding the [no LineTerminator here] restriction.
- * @param {ASTNode} node The node to be checked.
- * @returns {boolean} True if the node is incorrectly parenthesised.
- * @private
- */
- function hasExcessParensNoLineTerminator(token, node) {
- if (token.loc.end.line === node.loc.start.line) {
- return hasExcessParens(node);
- }
- return hasDoubleExcessParens(node);
- }
- /**
- * Determines whether a node should be preceded by an additional space when removing parens
- * @param {ASTNode} node node to evaluate; must be surrounded by parentheses
- * @returns {boolean} `true` if a space should be inserted before the node
- * @private
- */
- function requiresLeadingSpace(node) {
- const leftParenToken = sourceCode.getTokenBefore(node);
- const tokenBeforeLeftParen = sourceCode.getTokenBefore(
- leftParenToken,
- { includeComments: true },
- );
- const tokenAfterLeftParen = sourceCode.getTokenAfter(
- leftParenToken,
- { includeComments: true },
- );
- return (
- tokenBeforeLeftParen &&
- tokenBeforeLeftParen.range[1] === leftParenToken.range[0] &&
- leftParenToken.range[1] === tokenAfterLeftParen.range[0] &&
- !astUtils.canTokensBeAdjacent(
- tokenBeforeLeftParen,
- tokenAfterLeftParen,
- )
- );
- }
- /**
- * Determines whether a node should be followed by an additional space when removing parens
- * @param {ASTNode} node node to evaluate; must be surrounded by parentheses
- * @returns {boolean} `true` if a space should be inserted after the node
- * @private
- */
- function requiresTrailingSpace(node) {
- const nextTwoTokens = sourceCode.getTokensAfter(node, { count: 2 });
- const rightParenToken = nextTwoTokens[0];
- const tokenAfterRightParen = nextTwoTokens[1];
- const tokenBeforeRightParen = sourceCode.getLastToken(node);
- return (
- rightParenToken &&
- tokenAfterRightParen &&
- !sourceCode.isSpaceBetweenTokens(
- rightParenToken,
- tokenAfterRightParen,
- ) &&
- !astUtils.canTokensBeAdjacent(
- tokenBeforeRightParen,
- tokenAfterRightParen,
- )
- );
- }
- /**
- * Determines if a given expression node is an IIFE
- * @param {ASTNode} node The node to check
- * @returns {boolean} `true` if the given node is an IIFE
- */
- function isIIFE(node) {
- const maybeCallNode = astUtils.skipChainExpression(node);
- return (
- maybeCallNode.type === "CallExpression" &&
- maybeCallNode.callee.type === "FunctionExpression"
- );
- }
- /**
- * Determines if the given node can be the assignment target in destructuring or the LHS of an assignment.
- * This is to avoid an autofix that could change behavior because parsers mistakenly allow invalid syntax,
- * such as `(a = b) = c` and `[(a = b) = c] = []`. Ideally, this function shouldn't be necessary.
- * @param {ASTNode} [node] The node to check
- * @returns {boolean} `true` if the given node can be a valid assignment target
- */
- function canBeAssignmentTarget(node) {
- return (
- node &&
- (node.type === "Identifier" || node.type === "MemberExpression")
- );
- }
- /**
- * Checks if a node is fixable.
- * A node is fixable if removing a single pair of surrounding parentheses does not turn it
- * into a directive after fixing other nodes.
- * Almost all nodes are fixable, except if all of the following conditions are met:
- * The node is a string Literal
- * It has a single pair of parentheses
- * It is the only child of an ExpressionStatement
- * @param {ASTNode} node The node to evaluate.
- * @returns {boolean} Whether or not the node is fixable.
- * @private
- */
- function isFixable(node) {
- // if it's not a string literal it can be autofixed
- if (node.type !== "Literal" || typeof node.value !== "string") {
- return true;
- }
- if (isParenthesisedTwice(node)) {
- return true;
- }
- return !astUtils.isTopLevelExpressionStatement(node.parent);
- }
- /**
- * Report the node
- * @param {ASTNode} node node to evaluate
- * @returns {void}
- * @private
- */
- function report(node) {
- const leftParenToken = sourceCode.getTokenBefore(node);
- const rightParenToken = sourceCode.getTokenAfter(node);
- if (!isParenthesisedTwice(node)) {
- if (tokensToIgnore.has(sourceCode.getFirstToken(node))) {
- return;
- }
- if (isIIFE(node) && !isParenthesised(node.callee)) {
- return;
- }
- if (ALLOW_PARENS_AFTER_COMMENT_PATTERN) {
- const commentsBeforeLeftParenToken =
- sourceCode.getCommentsBefore(leftParenToken);
- const totalCommentsBeforeLeftParenTokenCount =
- commentsBeforeLeftParenToken.length;
- const ignorePattern = new RegExp(
- ALLOW_PARENS_AFTER_COMMENT_PATTERN,
- "u",
- );
- if (
- totalCommentsBeforeLeftParenTokenCount > 0 &&
- ignorePattern.test(
- commentsBeforeLeftParenToken[
- totalCommentsBeforeLeftParenTokenCount - 1
- ].value,
- )
- ) {
- return;
- }
- }
- }
- /**
- * Finishes reporting
- * @returns {void}
- * @private
- */
- function finishReport() {
- context.report({
- node,
- loc: leftParenToken.loc,
- messageId: "unexpected",
- fix: isFixable(node)
- ? fixer => {
- const parenthesizedSource =
- sourceCode.text.slice(
- leftParenToken.range[1],
- rightParenToken.range[0],
- );
- return fixer.replaceTextRange(
- [
- leftParenToken.range[0],
- rightParenToken.range[1],
- ],
- (requiresLeadingSpace(node) ? " " : "") +
- parenthesizedSource +
- (requiresTrailingSpace(node)
- ? " "
- : ""),
- );
- }
- : null,
- });
- }
- if (reportsBuffer) {
- reportsBuffer.reports.push({ node, finishReport });
- return;
- }
- finishReport();
- }
- /**
- * Evaluate a argument of the node.
- * @param {ASTNode} node node to evaluate
- * @returns {void}
- * @private
- */
- function checkArgumentWithPrecedence(node) {
- if (
- hasExcessParensWithPrecedence(node.argument, precedence(node))
- ) {
- report(node.argument);
- }
- }
- /**
- * Check if a member expression contains a call expression
- * @param {ASTNode} node MemberExpression node to evaluate
- * @returns {boolean} true if found, false if not
- */
- function doesMemberExpressionContainCallExpression(node) {
- let currentNode = node.object;
- let currentNodeType = node.object.type;
- while (currentNodeType === "MemberExpression") {
- currentNode = currentNode.object;
- currentNodeType = currentNode.type;
- }
- return currentNodeType === "CallExpression";
- }
- /**
- * Evaluate a new call
- * @param {ASTNode} node node to evaluate
- * @returns {void}
- * @private
- */
- function checkCallNew(node) {
- const callee = node.callee;
- if (hasExcessParensWithPrecedence(callee, precedence(node))) {
- if (
- hasDoubleExcessParens(callee) ||
- !(
- isIIFE(node) ||
- // (new A)(); new (new A)();
- (callee.type === "NewExpression" &&
- !isNewExpressionWithParens(callee) &&
- !(
- node.type === "NewExpression" &&
- !isNewExpressionWithParens(node)
- )) ||
- // new (a().b)(); new (a.b().c);
- (node.type === "NewExpression" &&
- callee.type === "MemberExpression" &&
- doesMemberExpressionContainCallExpression(
- callee,
- )) ||
- // (a?.b)(); (a?.())();
- (!node.optional && callee.type === "ChainExpression")
- )
- ) {
- report(node.callee);
- }
- }
- node.arguments
- .filter(arg =>
- hasExcessParensWithPrecedence(
- arg,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- ),
- )
- .forEach(report);
- }
- /**
- * Evaluate binary logicals
- * @param {ASTNode} node node to evaluate
- * @returns {void}
- * @private
- */
- function checkBinaryLogical(node) {
- const prec = precedence(node);
- const leftPrecedence = precedence(node.left);
- const rightPrecedence = precedence(node.right);
- const isExponentiation = node.operator === "**";
- const shouldSkipLeft =
- NESTED_BINARY &&
- (node.left.type === "BinaryExpression" ||
- node.left.type === "LogicalExpression");
- const shouldSkipRight =
- NESTED_BINARY &&
- (node.right.type === "BinaryExpression" ||
- node.right.type === "LogicalExpression");
- if (!shouldSkipLeft && hasExcessParens(node.left)) {
- if (
- (!(
- ["AwaitExpression", "UnaryExpression"].includes(
- node.left.type,
- ) && isExponentiation
- ) &&
- !astUtils.isMixedLogicalAndCoalesceExpressions(
- node.left,
- node,
- ) &&
- (leftPrecedence > prec ||
- (leftPrecedence === prec && !isExponentiation))) ||
- isParenthesisedTwice(node.left)
- ) {
- report(node.left);
- }
- }
- if (!shouldSkipRight && hasExcessParens(node.right)) {
- if (
- (!astUtils.isMixedLogicalAndCoalesceExpressions(
- node.right,
- node,
- ) &&
- (rightPrecedence > prec ||
- (rightPrecedence === prec && isExponentiation))) ||
- isParenthesisedTwice(node.right)
- ) {
- report(node.right);
- }
- }
- }
- /**
- * Check the parentheses around the super class of the given class definition.
- * @param {ASTNode} node The node of class declarations to check.
- * @returns {void}
- */
- function checkClass(node) {
- if (!node.superClass) {
- return;
- }
- /*
- * If `node.superClass` is a LeftHandSideExpression, parentheses are extra.
- * Otherwise, parentheses are needed.
- */
- const hasExtraParens =
- precedence(node.superClass) > PRECEDENCE_OF_UPDATE_EXPR
- ? hasExcessParens(node.superClass)
- : hasDoubleExcessParens(node.superClass);
- if (hasExtraParens) {
- report(node.superClass);
- }
- }
- /**
- * Check the parentheses around the argument of the given spread operator.
- * @param {ASTNode} node The node of spread elements/properties to check.
- * @returns {void}
- */
- function checkSpreadOperator(node) {
- if (
- hasExcessParensWithPrecedence(
- node.argument,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.argument);
- }
- }
- /**
- * Checks the parentheses for an ExpressionStatement or ExportDefaultDeclaration
- * @param {ASTNode} node The ExpressionStatement.expression or ExportDefaultDeclaration.declaration node
- * @returns {void}
- */
- function checkExpressionOrExportStatement(node) {
- const firstToken = isParenthesised(node)
- ? sourceCode.getTokenBefore(node)
- : sourceCode.getFirstToken(node);
- const secondToken = sourceCode.getTokenAfter(
- firstToken,
- astUtils.isNotOpeningParenToken,
- );
- const thirdToken = secondToken
- ? sourceCode.getTokenAfter(secondToken)
- : null;
- const tokenAfterClosingParens = secondToken
- ? sourceCode.getTokenAfter(
- secondToken,
- astUtils.isNotClosingParenToken,
- )
- : null;
- if (
- astUtils.isOpeningParenToken(firstToken) &&
- (astUtils.isOpeningBraceToken(secondToken) ||
- (secondToken.type === "Keyword" &&
- (secondToken.value === "function" ||
- secondToken.value === "class" ||
- (secondToken.value === "let" &&
- tokenAfterClosingParens &&
- (astUtils.isOpeningBracketToken(
- tokenAfterClosingParens,
- ) ||
- tokenAfterClosingParens.type ===
- "Identifier")))) ||
- (secondToken &&
- secondToken.type === "Identifier" &&
- secondToken.value === "async" &&
- thirdToken &&
- thirdToken.type === "Keyword" &&
- thirdToken.value === "function"))
- ) {
- tokensToIgnore.add(secondToken);
- }
- const hasExtraParens =
- node.parent.type === "ExportDefaultDeclaration"
- ? hasExcessParensWithPrecedence(
- node,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- : hasExcessParens(node);
- if (hasExtraParens) {
- report(node);
- }
- }
- /**
- * Finds the path from the given node to the specified ancestor.
- * @param {ASTNode} node First node in the path.
- * @param {ASTNode} ancestor Last node in the path.
- * @returns {ASTNode[]} Path, including both nodes.
- * @throws {Error} If the given node does not have the specified ancestor.
- */
- function pathToAncestor(node, ancestor) {
- const path = [node];
- let currentNode = node;
- while (currentNode !== ancestor) {
- currentNode = currentNode.parent;
- /* c8 ignore start */
- if (currentNode === null) {
- throw new Error(
- "Nodes are not in the ancestor-descendant relationship.",
- );
- } /* c8 ignore stop */
- path.push(currentNode);
- }
- return path;
- }
- /**
- * Finds the path from the given node to the specified descendant.
- * @param {ASTNode} node First node in the path.
- * @param {ASTNode} descendant Last node in the path.
- * @returns {ASTNode[]} Path, including both nodes.
- * @throws {Error} If the given node does not have the specified descendant.
- */
- function pathToDescendant(node, descendant) {
- return pathToAncestor(descendant, node).reverse();
- }
- /**
- * Checks whether the syntax of the given ancestor of an 'in' expression inside a for-loop initializer
- * is preventing the 'in' keyword from being interpreted as a part of an ill-formed for-in loop.
- * @param {ASTNode} node Ancestor of an 'in' expression.
- * @param {ASTNode} child Child of the node, ancestor of the same 'in' expression or the 'in' expression itself.
- * @returns {boolean} True if the keyword 'in' would be interpreted as the 'in' operator, without any parenthesis.
- */
- function isSafelyEnclosingInExpression(node, child) {
- switch (node.type) {
- case "ArrayExpression":
- case "ArrayPattern":
- case "BlockStatement":
- case "ObjectExpression":
- case "ObjectPattern":
- case "TemplateLiteral":
- return true;
- case "ArrowFunctionExpression":
- case "FunctionExpression":
- return node.params.includes(child);
- case "CallExpression":
- case "NewExpression":
- return node.arguments.includes(child);
- case "MemberExpression":
- return node.computed && node.property === child;
- case "ConditionalExpression":
- return node.consequent === child;
- default:
- return false;
- }
- }
- /**
- * Starts a new reports buffering. Warnings will be stored in a buffer instead of being reported immediately.
- * An additional logic that requires multiple nodes (e.g. a whole subtree) may dismiss some of the stored warnings.
- * @returns {void}
- */
- function startNewReportsBuffering() {
- reportsBuffer = {
- upper: reportsBuffer,
- inExpressionNodes: [],
- reports: [],
- };
- }
- /**
- * Ends the current reports buffering.
- * @returns {void}
- */
- function endCurrentReportsBuffering() {
- const { upper, inExpressionNodes, reports } = reportsBuffer;
- if (upper) {
- upper.inExpressionNodes.push(...inExpressionNodes);
- upper.reports.push(...reports);
- } else {
- // flush remaining reports
- reports.forEach(({ finishReport }) => finishReport());
- }
- reportsBuffer = upper;
- }
- /**
- * Checks whether the given node is in the current reports buffer.
- * @param {ASTNode} node Node to check.
- * @returns {boolean} True if the node is in the current buffer, false otherwise.
- */
- function isInCurrentReportsBuffer(node) {
- return reportsBuffer.reports.some(r => r.node === node);
- }
- /**
- * Removes the given node from the current reports buffer.
- * @param {ASTNode} node Node to remove.
- * @returns {void}
- */
- function removeFromCurrentReportsBuffer(node) {
- reportsBuffer.reports = reportsBuffer.reports.filter(
- r => r.node !== node,
- );
- }
- /**
- * Checks whether a node is a MemberExpression at NewExpression's callee.
- * @param {ASTNode} node node to check.
- * @returns {boolean} True if the node is a MemberExpression at NewExpression's callee. false otherwise.
- */
- function isMemberExpInNewCallee(node) {
- if (node.type === "MemberExpression") {
- return node.parent.type === "NewExpression" &&
- node.parent.callee === node
- ? true
- : node.parent.object === node &&
- isMemberExpInNewCallee(node.parent);
- }
- return false;
- }
- /**
- * Checks if the left-hand side of an assignment is an identifier, the operator is one of
- * `=`, `&&=`, `||=` or `??=` and the right-hand side is an anonymous class or function.
- *
- * As per https://tc39.es/ecma262/#sec-assignment-operators-runtime-semantics-evaluation, an
- * assignment involving one of the operators `=`, `&&=`, `||=` or `??=` where the right-hand
- * side is an anonymous class or function and the left-hand side is an *unparenthesized*
- * identifier has different semantics than other assignments.
- * Specifically, when an expression like `foo = function () {}` is evaluated, `foo.name`
- * will be set to the string "foo", i.e. the identifier name. The same thing does not happen
- * when evaluating `(foo) = function () {}`.
- * Since the parenthesizing of the identifier in the left-hand side is significant in this
- * special case, the parentheses, if present, should not be flagged as unnecessary.
- * @param {ASTNode} node an AssignmentExpression node.
- * @returns {boolean} `true` if the left-hand side of the assignment is an identifier, the
- * operator is one of `=`, `&&=`, `||=` or `??=` and the right-hand side is an anonymous
- * class or function; otherwise, `false`.
- */
- function isAnonymousFunctionAssignmentException({
- left,
- operator,
- right,
- }) {
- if (
- left.type === "Identifier" &&
- ["=", "&&=", "||=", "??="].includes(operator)
- ) {
- const rhsType = right.type;
- if (rhsType === "ArrowFunctionExpression") {
- return true;
- }
- if (
- (rhsType === "FunctionExpression" ||
- rhsType === "ClassExpression") &&
- !right.id
- ) {
- return true;
- }
- }
- return false;
- }
- return {
- ArrayExpression(node) {
- node.elements
- .filter(
- e =>
- e &&
- hasExcessParensWithPrecedence(
- e,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- ),
- )
- .forEach(report);
- },
- ArrayPattern(node) {
- node.elements
- .filter(e => canBeAssignmentTarget(e) && hasExcessParens(e))
- .forEach(report);
- },
- ArrowFunctionExpression(node) {
- if (isReturnAssignException(node)) {
- return;
- }
- if (
- node.body.type === "ConditionalExpression" &&
- IGNORE_ARROW_CONDITIONALS
- ) {
- return;
- }
- if (node.body.type !== "BlockStatement") {
- const firstBodyToken = sourceCode.getFirstToken(
- node.body,
- astUtils.isNotOpeningParenToken,
- );
- const tokenBeforeFirst =
- sourceCode.getTokenBefore(firstBodyToken);
- if (
- astUtils.isOpeningParenToken(tokenBeforeFirst) &&
- astUtils.isOpeningBraceToken(firstBodyToken)
- ) {
- tokensToIgnore.add(firstBodyToken);
- }
- if (
- hasExcessParensWithPrecedence(
- node.body,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.body);
- }
- }
- },
- AssignmentExpression(node) {
- if (
- canBeAssignmentTarget(node.left) &&
- hasExcessParens(node.left) &&
- (!isAnonymousFunctionAssignmentException(node) ||
- isParenthesisedTwice(node.left))
- ) {
- report(node.left);
- }
- if (
- !isReturnAssignException(node) &&
- hasExcessParensWithPrecedence(node.right, precedence(node))
- ) {
- report(node.right);
- }
- },
- BinaryExpression(node) {
- if (reportsBuffer && node.operator === "in") {
- reportsBuffer.inExpressionNodes.push(node);
- }
- checkBinaryLogical(node);
- },
- CallExpression: checkCallNew,
- ConditionalExpression(node) {
- if (isReturnAssignException(node)) {
- return;
- }
- const availableTypes = new Set([
- "BinaryExpression",
- "LogicalExpression",
- ]);
- if (
- !(
- EXCEPT_COND_TERNARY &&
- availableTypes.has(node.test.type)
- ) &&
- !isCondAssignException(node) &&
- hasExcessParensWithPrecedence(
- node.test,
- precedence({
- type: "LogicalExpression",
- operator: "||",
- }),
- )
- ) {
- report(node.test);
- }
- if (
- !(
- EXCEPT_COND_TERNARY &&
- availableTypes.has(node.consequent.type)
- ) &&
- hasExcessParensWithPrecedence(
- node.consequent,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.consequent);
- }
- if (
- !(
- EXCEPT_COND_TERNARY &&
- availableTypes.has(node.alternate.type)
- ) &&
- hasExcessParensWithPrecedence(
- node.alternate,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.alternate);
- }
- },
- DoWhileStatement(node) {
- if (
- hasExcessParens(node.test) &&
- !isCondAssignException(node)
- ) {
- report(node.test);
- }
- },
- ExportDefaultDeclaration: node =>
- checkExpressionOrExportStatement(node.declaration),
- ExpressionStatement: node =>
- checkExpressionOrExportStatement(node.expression),
- ForInStatement(node) {
- if (node.left.type !== "VariableDeclaration") {
- const firstLeftToken = sourceCode.getFirstToken(
- node.left,
- astUtils.isNotOpeningParenToken,
- );
- if (
- firstLeftToken.value === "let" &&
- astUtils.isOpeningBracketToken(
- sourceCode.getTokenAfter(
- firstLeftToken,
- astUtils.isNotClosingParenToken,
- ),
- )
- ) {
- // ForInStatement#left expression cannot start with `let[`.
- tokensToIgnore.add(firstLeftToken);
- }
- }
- if (hasExcessParens(node.left)) {
- report(node.left);
- }
- if (hasExcessParens(node.right)) {
- report(node.right);
- }
- },
- ForOfStatement(node) {
- if (node.left.type !== "VariableDeclaration") {
- const firstLeftToken = sourceCode.getFirstToken(
- node.left,
- astUtils.isNotOpeningParenToken,
- );
- if (firstLeftToken.value === "let") {
- // ForOfStatement#left expression cannot start with `let`.
- tokensToIgnore.add(firstLeftToken);
- }
- }
- if (hasExcessParens(node.left)) {
- report(node.left);
- }
- if (
- hasExcessParensWithPrecedence(
- node.right,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.right);
- }
- },
- ForStatement(node) {
- if (
- node.test &&
- hasExcessParens(node.test) &&
- !isCondAssignException(node)
- ) {
- report(node.test);
- }
- if (node.update && hasExcessParens(node.update)) {
- report(node.update);
- }
- if (node.init) {
- if (node.init.type !== "VariableDeclaration") {
- const firstToken = sourceCode.getFirstToken(
- node.init,
- astUtils.isNotOpeningParenToken,
- );
- if (
- firstToken.value === "let" &&
- astUtils.isOpeningBracketToken(
- sourceCode.getTokenAfter(
- firstToken,
- astUtils.isNotClosingParenToken,
- ),
- )
- ) {
- // ForStatement#init expression cannot start with `let[`.
- tokensToIgnore.add(firstToken);
- }
- }
- startNewReportsBuffering();
- if (hasExcessParens(node.init)) {
- report(node.init);
- }
- }
- },
- "ForStatement > *.init:exit"(node) {
- /*
- * Removing parentheses around `in` expressions might change semantics and cause errors.
- *
- * For example, this valid for loop:
- * for (let a = (b in c); ;);
- * after removing parentheses would be treated as an invalid for-in loop:
- * for (let a = b in c; ;);
- */
- if (reportsBuffer.reports.length) {
- reportsBuffer.inExpressionNodes.forEach(
- inExpressionNode => {
- const path = pathToDescendant(
- node,
- inExpressionNode,
- );
- let nodeToExclude;
- for (let i = 0; i < path.length; i++) {
- const pathNode = path[i];
- if (i < path.length - 1) {
- const nextPathNode = path[i + 1];
- if (
- isSafelyEnclosingInExpression(
- pathNode,
- nextPathNode,
- )
- ) {
- // The 'in' expression in safely enclosed by the syntax of its ancestor nodes (e.g. by '{}' or '[]').
- return;
- }
- }
- if (isParenthesised(pathNode)) {
- if (isInCurrentReportsBuffer(pathNode)) {
- // This node was supposed to be reported, but parentheses might be necessary.
- if (isParenthesisedTwice(pathNode)) {
- /*
- * This node is parenthesised twice, it certainly has at least one pair of `extra` parentheses.
- * If the --fix option is on, the current fixing iteration will remove only one pair of parentheses.
- * The remaining pair is safely enclosing the 'in' expression.
- */
- return;
- }
- // Exclude the outermost node only.
- if (!nodeToExclude) {
- nodeToExclude = pathNode;
- }
- // Don't break the loop here, there might be some safe nodes or parentheses that will stay inside.
- } else {
- // This node will stay parenthesised, the 'in' expression in safely enclosed by '()'.
- return;
- }
- }
- }
- // Exclude the node from the list (i.e. treat parentheses as necessary)
- removeFromCurrentReportsBuffer(nodeToExclude);
- },
- );
- }
- endCurrentReportsBuffering();
- },
- IfStatement(node) {
- if (
- hasExcessParens(node.test) &&
- !isCondAssignException(node)
- ) {
- report(node.test);
- }
- },
- ImportExpression(node) {
- const { source } = node;
- if (source.type === "SequenceExpression") {
- if (hasDoubleExcessParens(source)) {
- report(source);
- }
- } else if (hasExcessParens(source)) {
- report(source);
- }
- },
- LogicalExpression: checkBinaryLogical,
- MemberExpression(node) {
- const shouldAllowWrapOnce =
- isMemberExpInNewCallee(node) &&
- doesMemberExpressionContainCallExpression(node);
- const nodeObjHasExcessParens = shouldAllowWrapOnce
- ? hasDoubleExcessParens(node.object)
- : hasExcessParens(node.object) &&
- !(
- isImmediateFunctionPrototypeMethodCall(
- node.parent,
- ) &&
- node.parent.callee === node &&
- IGNORE_FUNCTION_PROTOTYPE_METHODS
- );
- if (
- nodeObjHasExcessParens &&
- precedence(node.object) >= precedence(node) &&
- (node.computed ||
- !(
- astUtils.isDecimalInteger(node.object) ||
- // RegExp literal is allowed to have parens (#1589)
- (node.object.type === "Literal" &&
- node.object.regex)
- ))
- ) {
- report(node.object);
- }
- if (
- nodeObjHasExcessParens &&
- node.object.type === "CallExpression"
- ) {
- report(node.object);
- }
- if (
- nodeObjHasExcessParens &&
- !IGNORE_NEW_IN_MEMBER_EXPR &&
- node.object.type === "NewExpression" &&
- isNewExpressionWithParens(node.object)
- ) {
- report(node.object);
- }
- if (
- nodeObjHasExcessParens &&
- node.optional &&
- node.object.type === "ChainExpression"
- ) {
- report(node.object);
- }
- if (node.computed && hasExcessParens(node.property)) {
- report(node.property);
- }
- },
- "MethodDefinition[computed=true]"(node) {
- if (
- hasExcessParensWithPrecedence(
- node.key,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.key);
- }
- },
- NewExpression: checkCallNew,
- ObjectExpression(node) {
- node.properties
- .filter(
- property =>
- property.value &&
- hasExcessParensWithPrecedence(
- property.value,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- ),
- )
- .forEach(property => report(property.value));
- },
- ObjectPattern(node) {
- node.properties
- .filter(property => {
- const value = property.value;
- return (
- canBeAssignmentTarget(value) &&
- hasExcessParens(value)
- );
- })
- .forEach(property => report(property.value));
- },
- Property(node) {
- if (node.computed) {
- const { key } = node;
- if (
- key &&
- hasExcessParensWithPrecedence(
- key,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(key);
- }
- }
- },
- PropertyDefinition(node) {
- if (
- node.computed &&
- hasExcessParensWithPrecedence(
- node.key,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.key);
- }
- if (
- node.value &&
- hasExcessParensWithPrecedence(
- node.value,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(node.value);
- }
- },
- RestElement(node) {
- const argument = node.argument;
- if (
- canBeAssignmentTarget(argument) &&
- hasExcessParens(argument)
- ) {
- report(argument);
- }
- },
- ReturnStatement(node) {
- const returnToken = sourceCode.getFirstToken(node);
- if (isReturnAssignException(node)) {
- return;
- }
- if (
- node.argument &&
- hasExcessParensNoLineTerminator(
- returnToken,
- node.argument,
- ) &&
- // RegExp literal is allowed to have parens (#1589)
- !(node.argument.type === "Literal" && node.argument.regex)
- ) {
- report(node.argument);
- }
- },
- SequenceExpression(node) {
- const precedenceOfNode = precedence(node);
- node.expressions
- .filter(e =>
- hasExcessParensWithPrecedence(e, precedenceOfNode),
- )
- .forEach(report);
- },
- SwitchCase(node) {
- if (node.test && hasExcessParens(node.test)) {
- report(node.test);
- }
- },
- SwitchStatement(node) {
- if (hasExcessParens(node.discriminant)) {
- report(node.discriminant);
- }
- },
- ThrowStatement(node) {
- const throwToken = sourceCode.getFirstToken(node);
- if (
- hasExcessParensNoLineTerminator(throwToken, node.argument)
- ) {
- report(node.argument);
- }
- },
- UnaryExpression: checkArgumentWithPrecedence,
- UpdateExpression(node) {
- if (node.prefix) {
- checkArgumentWithPrecedence(node);
- } else {
- const { argument } = node;
- const operatorToken = sourceCode.getLastToken(node);
- if (
- argument.loc.end.line === operatorToken.loc.start.line
- ) {
- checkArgumentWithPrecedence(node);
- } else {
- if (hasDoubleExcessParens(argument)) {
- report(argument);
- }
- }
- }
- },
- AwaitExpression: checkArgumentWithPrecedence,
- VariableDeclarator(node) {
- if (
- node.init &&
- hasExcessParensWithPrecedence(
- node.init,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- ) &&
- // RegExp literal is allowed to have parens (#1589)
- !(node.init.type === "Literal" && node.init.regex)
- ) {
- report(node.init);
- }
- },
- WhileStatement(node) {
- if (
- hasExcessParens(node.test) &&
- !isCondAssignException(node)
- ) {
- report(node.test);
- }
- },
- WithStatement(node) {
- if (hasExcessParens(node.object)) {
- report(node.object);
- }
- },
- YieldExpression(node) {
- if (node.argument) {
- const yieldToken = sourceCode.getFirstToken(node);
- if (
- (precedence(node.argument) >= precedence(node) &&
- hasExcessParensNoLineTerminator(
- yieldToken,
- node.argument,
- )) ||
- hasDoubleExcessParens(node.argument)
- ) {
- report(node.argument);
- }
- }
- },
- ClassDeclaration: checkClass,
- ClassExpression: checkClass,
- SpreadElement: checkSpreadOperator,
- SpreadProperty: checkSpreadOperator,
- ExperimentalSpreadProperty: checkSpreadOperator,
- TemplateLiteral(node) {
- node.expressions
- .filter(e => e && hasExcessParens(e))
- .forEach(report);
- },
- AssignmentPattern(node) {
- const { left, right } = node;
- if (canBeAssignmentTarget(left) && hasExcessParens(left)) {
- report(left);
- }
- if (
- right &&
- hasExcessParensWithPrecedence(
- right,
- PRECEDENCE_OF_ASSIGNMENT_EXPR,
- )
- ) {
- report(right);
- }
- },
- };
- },
- };
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