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/** * @fileoverview Disallow parenthesising higher precedence subexpressions. * @author Michael Ficarra */ "use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
const { isParenthesized: isParenthesizedRaw } = require("eslint-utils"); const astUtils = require("./utils/ast-utils.js");
module.exports = { meta: { type: "layout",
docs: { description: "disallow unnecessary parentheses", category: "Possible Errors", recommended: false, url: "https://eslint.org/docs/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" }, 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" } }, additionalProperties: false } ], minItems: 0, maxItems: 2 } ] },
messages: { unexpected: "Unnecessary parentheses around expression." } },
create(context) { const sourceCode = context.getSourceCode();
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 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 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"); }
/** * 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; } }
/** * Finishes reporting * @returns {void} * @private */ function finishReport() { context.report({ node, loc: leftParenToken.loc, messageId: "unexpected", fix(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) ? " " : "")); } }); }
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))) { const hasNewParensException = callee.type === "NewExpression" && !isNewExpressionWithParens(callee);
if ( hasDoubleExcessParens(callee) || !isIIFE(node) && !hasNewParensException && !(
// Allow extra parens around a new expression if they are intervening parentheses.
node.type === "NewExpression" && callee.type === "MemberExpression" && doesMemberExpressionContainCallExpression(callee) ) && !(!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 ( !(node.left.type === "UnaryExpression" && 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;
/* istanbul ignore if */ if (currentNode === null) { throw new Error("Nodes are not in the ancestor-descendant relationship."); }
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; }
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)) { 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,
ClassBody(node) { node.body .filter(member => member.type === "MethodDefinition" && member.computed && member.key) .filter(member => hasExcessParensWithPrecedence(member.key, PRECEDENCE_OF_ASSIGNMENT_EXPR)) .forEach(member => report(member.key)); },
ConditionalExpression(node) { if (isReturnAssignException(node)) { return; } if ( !isCondAssignException(node) && hasExcessParensWithPrecedence(node.test, precedence({ type: "LogicalExpression", operator: "||" })) ) { report(node.test); }
if (hasExcessParensWithPrecedence(node.consequent, PRECEDENCE_OF_ASSIGNMENT_EXPR)) { report(node.consequent); }
if (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, ForOfStatement"(node) { if (node.left.type !== "VariableDeclarator") { const firstLeftToken = sourceCode.getFirstToken(node.left, astUtils.isNotOpeningParenToken);
if ( firstLeftToken.value === "let" && (
/* * If `let` is the only thing on the left side of the loop, it's the loop variable: `for ((let) of foo);` * Removing it will cause a syntax error, because it will be parsed as the start of a VariableDeclarator. */ (firstLeftToken.range[1] === node.left.range[1] || /* * If `let` is followed by a `[` token, it's a property access on the `let` value: `for ((let[foo]) of bar);` * Removing it will cause the property access to be parsed as a destructuring declaration of `foo` instead. */ astUtils.isOpeningBracketToken( sourceCode.getTokenAfter(firstLeftToken, astUtils.isNotClosingParenToken) )) ) ) { tokensToIgnore.add(firstLeftToken); } }
if (node.type === "ForOfStatement") { const hasExtraParens = node.right.type === "SequenceExpression" ? hasDoubleExcessParens(node.right) : hasExcessParens(node.right);
if (hasExtraParens) { report(node.right); } } else if (hasExcessParens(node.right)) { report(node.right); }
if (hasExcessParens(node.left)) { report(node.left); } },
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) { 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); } },
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); } } },
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: checkArgumentWithPrecedence, 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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