diff options
Diffstat (limited to 'tools/node_modules/eslint/lib/rules/no-extra-parens.js')
-rw-r--r-- | tools/node_modules/eslint/lib/rules/no-extra-parens.js | 745 |
1 files changed, 745 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-extra-parens.js b/tools/node_modules/eslint/lib/rules/no-extra-parens.js new file mode 100644 index 0000000000..d8e0df64a7 --- /dev/null +++ b/tools/node_modules/eslint/lib/rules/no-extra-parens.js @@ -0,0 +1,745 @@ +/** + * @fileoverview Disallow parenthesising higher precedence subexpressions. + * @author Michael Ficarra + */ +"use strict"; + +//------------------------------------------------------------------------------ +// Rule Definition +//------------------------------------------------------------------------------ + +const astUtils = require("../ast-utils.js"); + +module.exports = { + meta: { + docs: { + description: "disallow unnecessary parentheses", + category: "Possible Errors", + recommended: false + }, + + 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" } + }, + additionalProperties: false + } + ], + minItems: 0, + maxItems: 2 + } + ] + } + }, + + create(context) { + const sourceCode = context.getSourceCode(); + + const tokensToIgnore = new WeakSet(); + const isParenthesised = astUtils.isParenthesised.bind(astUtils, sourceCode); + 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 PRECEDENCE_OF_ASSIGNMENT_EXPR = precedence({ type: "AssignmentExpression" }); + const PRECEDENCE_OF_UPDATE_EXPR = precedence({ type: "UpdateExpression" }); + + /** + * 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") { + 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 + } + } + + return ALL_NODES || node.type === "FunctionExpression" || node.type === "ArrowFunctionExpression"; + } + + /** + * 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) { + const previousToken = sourceCode.getTokenBefore(node, 1), + nextToken = sourceCode.getTokenAfter(node, 1); + + return isParenthesised(node) && previousToken && nextToken && + astUtils.isOpeningParenToken(previousToken) && previousToken.range[1] <= node.range[0] && + astUtils.isClosingParenToken(nextToken) && nextToken.range[0] >= node.range[1]; + } + + /** + * 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 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) { + while (node) { + if (node.type === "ReturnStatement" || + (node.type === "ArrowFunctionExpression" && node.body.type !== "BlockStatement")) { + return true; + } + node = node.parent; + } + + 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 || astUtils.isOpeningParenToken(penultimateToken) && astUtils.isClosingParenToken(lastToken); + } + + /** + * 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(node, 1); + const firstToken = sourceCode.getFirstToken(node); + + return tokenBeforeLeftParen && + tokenBeforeLeftParen.range[1] === leftParenToken.range[0] && + leftParenToken.range[1] === firstToken.range[0] && + !astUtils.canTokensBeAdjacent(tokenBeforeLeftParen, firstToken); + } + + /** + * 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) { + return node.type === "CallExpression" && node.callee.type === "FunctionExpression"; + } + + /** + * 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; + } + } + + context.report({ + node, + loc: leftParenToken.loc.start, + message: "Gratuitous parentheses around expression.", + 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) ? " " : "")); + } + }); + } + + /** + * Evaluate Unary update + * @param {ASTNode} node node to evaluate + * @returns {void} + * @private + */ + function checkUnaryUpdate(node) { + if (node.type === "UnaryExpression" && node.argument.type === "BinaryExpression" && node.argument.operator === "**") { + return; + } + + if (hasExcessParens(node.argument) && precedence(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 (hasExcessParens(callee) && precedence(callee) >= precedence(node)) { + const hasNewParensException = callee.type === "NewExpression" && !isNewExpressionWithParens(callee); + + if ( + hasDoubleExcessParens(callee) || + !isIIFE(node) && !hasNewParensException && !( + + /* + * Allow extra parens around a new expression if + * there are intervening parentheses. + */ + callee.type === "MemberExpression" && + doesMemberExpressionContainCallExpression(callee) + ) + ) { + report(node.callee); + } + } + if (node.arguments.length === 1) { + if (hasDoubleExcessParens(node.arguments[0]) && precedence(node.arguments[0]) >= PRECEDENCE_OF_ASSIGNMENT_EXPR) { + report(node.arguments[0]); + } + } else { + node.arguments + .filter(arg => hasExcessParens(arg) && precedence(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")) || + node.left.type === "UnaryExpression" && isExponentiation; + const shouldSkipRight = NESTED_BINARY && (node.right.type === "BinaryExpression" || node.right.type === "LogicalExpression"); + + if (!shouldSkipLeft && hasExcessParens(node.left) && (leftPrecedence > prec || (leftPrecedence === prec && !isExponentiation))) { + report(node.left); + } + if (!shouldSkipRight && hasExcessParens(node.right) && (rightPrecedence > prec || (rightPrecedence === prec && isExponentiation))) { + 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) { + const hasExtraParens = precedence(node.argument) >= PRECEDENCE_OF_ASSIGNMENT_EXPR + ? hasExcessParens(node.argument) + : hasDoubleExcessParens(node.argument); + + if (hasExtraParens) { + 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; + + if ( + astUtils.isOpeningParenToken(firstToken) && + ( + astUtils.isOpeningBraceToken(secondToken) || + secondToken.type === "Keyword" && ( + secondToken.value === "function" || + secondToken.value === "class" || + secondToken.value === "let" && astUtils.isOpeningBracketToken(sourceCode.getTokenAfter(secondToken, astUtils.isNotClosingParenToken)) + ) || + secondToken && secondToken.type === "Identifier" && secondToken.value === "async" && thirdToken && thirdToken.type === "Keyword" && thirdToken.value === "function" + ) + ) { + tokensToIgnore.add(secondToken); + } + + if (hasExcessParens(node)) { + report(node); + } + } + + return { + ArrayExpression(node) { + node.elements + .filter(e => e && hasExcessParens(e) && precedence(e) >= PRECEDENCE_OF_ASSIGNMENT_EXPR) + .forEach(report); + }, + + ArrowFunctionExpression(node) { + if (isReturnAssignException(node)) { + return; + } + + if (node.body.type === "ConditionalExpression" && + IGNORE_ARROW_CONDITIONALS && + !isParenthesisedTwice(node.body) + ) { + 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 (hasExcessParens(node.body) && precedence(node.body) >= PRECEDENCE_OF_ASSIGNMENT_EXPR) { + report(node.body); + } + } + }, + + AssignmentExpression(node) { + if (isReturnAssignException(node)) { + return; + } + + if (hasExcessParens(node.right) && precedence(node.right) >= precedence(node)) { + report(node.right); + } + }, + + BinaryExpression: checkBinaryLogical, + CallExpression: checkCallNew, + + ConditionalExpression(node) { + if (isReturnAssignException(node)) { + return; + } + + if (hasExcessParens(node.test) && precedence(node.test) >= precedence({ type: "LogicalExpression", operator: "||" })) { + report(node.test); + } + + if (hasExcessParens(node.consequent) && precedence(node.consequent) >= PRECEDENCE_OF_ASSIGNMENT_EXPR) { + report(node.consequent); + } + + if (hasExcessParens(node.alternate) && precedence(node.alternate) >= PRECEDENCE_OF_ASSIGNMENT_EXPR) { + report(node.alternate); + } + }, + + DoWhileStatement(node) { + if (hasDoubleExcessParens(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 (hasExcessParens(node.right)) { + report(node.right); + } + if (hasExcessParens(node.left)) { + report(node.left); + } + }, + + ForStatement(node) { + if (node.init && hasExcessParens(node.init)) { + report(node.init); + } + + if (node.test && hasExcessParens(node.test) && !isCondAssignException(node)) { + report(node.test); + } + + if (node.update && hasExcessParens(node.update)) { + report(node.update); + } + }, + + IfStatement(node) { + if (hasDoubleExcessParens(node.test) && !isCondAssignException(node)) { + report(node.test); + } + }, + + LogicalExpression: checkBinaryLogical, + + MemberExpression(node) { + const nodeObjHasExcessParens = hasExcessParens(node.object); + + 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" && + node.parent.type !== "NewExpression") { + report(node.object); + } + + if (node.computed && hasExcessParens(node.property)) { + report(node.property); + } + }, + + NewExpression: checkCallNew, + + ObjectExpression(node) { + node.properties + .filter(property => { + const value = property.value; + + return value && hasExcessParens(value) && precedence(value) >= PRECEDENCE_OF_ASSIGNMENT_EXPR; + }).forEach(property => report(property.value)); + }, + + 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) { + node.expressions + .filter(e => hasExcessParens(e) && precedence(e) >= precedence(node)) + .forEach(report); + }, + + SwitchCase(node) { + if (node.test && hasExcessParens(node.test)) { + report(node.test); + } + }, + + SwitchStatement(node) { + if (hasDoubleExcessParens(node.discriminant)) { + report(node.discriminant); + } + }, + + ThrowStatement(node) { + const throwToken = sourceCode.getFirstToken(node); + + if (hasExcessParensNoLineTerminator(throwToken, node.argument)) { + report(node.argument); + } + }, + + UnaryExpression: checkUnaryUpdate, + UpdateExpression: checkUnaryUpdate, + AwaitExpression: checkUnaryUpdate, + + VariableDeclarator(node) { + if (node.init && hasExcessParens(node.init) && + precedence(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 (hasDoubleExcessParens(node.test) && !isCondAssignException(node)) { + report(node.test); + } + }, + + WithStatement(node) { + if (hasDoubleExcessParens(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 + }; + + } +}; |