[d565449] | 1 | /**
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| 2 | * @fileoverview Rule to disallow negating the left operand of relational operators
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| 3 | * @author Toru Nagashima
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| 4 | */
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| 5 |
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| 6 | "use strict";
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| 7 |
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| 8 | //------------------------------------------------------------------------------
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| 9 | // Requirements
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| 10 | //------------------------------------------------------------------------------
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| 11 |
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| 12 | const astUtils = require("./utils/ast-utils");
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| 13 |
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| 14 | //------------------------------------------------------------------------------
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| 15 | // Helpers
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| 16 | //------------------------------------------------------------------------------
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| 17 |
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| 18 | /**
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| 19 | * Checks whether the given operator is `in` or `instanceof`
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| 20 | * @param {string} op The operator type to check.
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| 21 | * @returns {boolean} `true` if the operator is `in` or `instanceof`
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| 22 | */
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| 23 | function isInOrInstanceOfOperator(op) {
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| 24 | return op === "in" || op === "instanceof";
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| 25 | }
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| 26 |
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| 27 | /**
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| 28 | * Checks whether the given operator is an ordering relational operator or not.
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| 29 | * @param {string} op The operator type to check.
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| 30 | * @returns {boolean} `true` if the operator is an ordering relational operator.
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| 31 | */
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| 32 | function isOrderingRelationalOperator(op) {
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| 33 | return op === "<" || op === ">" || op === ">=" || op === "<=";
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| 34 | }
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| 35 |
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| 36 | /**
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| 37 | * Checks whether the given node is a logical negation expression or not.
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| 38 | * @param {ASTNode} node The node to check.
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| 39 | * @returns {boolean} `true` if the node is a logical negation expression.
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| 40 | */
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| 41 | function isNegation(node) {
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| 42 | return node.type === "UnaryExpression" && node.operator === "!";
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| 43 | }
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| 44 |
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| 45 | //------------------------------------------------------------------------------
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| 46 | // Rule Definition
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| 47 | //------------------------------------------------------------------------------
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| 48 |
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| 49 | /** @type {import('../shared/types').Rule} */
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| 50 | module.exports = {
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| 51 | meta: {
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| 52 | type: "problem",
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| 53 |
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| 54 | docs: {
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| 55 | description: "Disallow negating the left operand of relational operators",
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| 56 | recommended: true,
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| 57 | url: "https://eslint.org/docs/latest/rules/no-unsafe-negation"
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| 58 | },
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| 59 |
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| 60 | hasSuggestions: true,
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| 61 |
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| 62 | schema: [
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| 63 | {
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| 64 | type: "object",
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| 65 | properties: {
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| 66 | enforceForOrderingRelations: {
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| 67 | type: "boolean",
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| 68 | default: false
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| 69 | }
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| 70 | },
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| 71 | additionalProperties: false
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| 72 | }
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| 73 | ],
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| 74 |
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| 75 | fixable: null,
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| 76 |
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| 77 | messages: {
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| 78 | unexpected: "Unexpected negating the left operand of '{{operator}}' operator.",
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| 79 | suggestNegatedExpression: "Negate '{{operator}}' expression instead of its left operand. This changes the current behavior.",
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| 80 | suggestParenthesisedNegation: "Wrap negation in '()' to make the intention explicit. This preserves the current behavior."
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| 81 | }
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| 82 | },
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| 83 |
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| 84 | create(context) {
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| 85 | const sourceCode = context.sourceCode;
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| 86 | const options = context.options[0] || {};
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| 87 | const enforceForOrderingRelations = options.enforceForOrderingRelations === true;
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| 88 |
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| 89 | return {
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| 90 | BinaryExpression(node) {
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| 91 | const operator = node.operator;
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| 92 | const orderingRelationRuleApplies = enforceForOrderingRelations && isOrderingRelationalOperator(operator);
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| 93 |
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| 94 | if (
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| 95 | (isInOrInstanceOfOperator(operator) || orderingRelationRuleApplies) &&
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| 96 | isNegation(node.left) &&
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| 97 | !astUtils.isParenthesised(sourceCode, node.left)
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| 98 | ) {
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| 99 | context.report({
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| 100 | node,
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| 101 | loc: node.left.loc,
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| 102 | messageId: "unexpected",
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| 103 | data: { operator },
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| 104 | suggest: [
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| 105 | {
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| 106 | messageId: "suggestNegatedExpression",
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| 107 | data: { operator },
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| 108 | fix(fixer) {
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| 109 | const negationToken = sourceCode.getFirstToken(node.left);
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| 110 | const fixRange = [negationToken.range[1], node.range[1]];
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| 111 | const text = sourceCode.text.slice(fixRange[0], fixRange[1]);
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| 112 |
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| 113 | return fixer.replaceTextRange(fixRange, `(${text})`);
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| 114 | }
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| 115 | },
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| 116 | {
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| 117 | messageId: "suggestParenthesisedNegation",
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| 118 | fix(fixer) {
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| 119 | return fixer.replaceText(node.left, `(${sourceCode.getText(node.left)})`);
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| 120 | }
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| 121 | }
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| 122 | ]
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| 123 | });
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| 124 | }
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| 125 | }
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| 126 | };
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| 127 | }
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| 128 | };
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