140 lines
4.1 KiB
JavaScript
140 lines
4.1 KiB
JavaScript
/**
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* @fileoverview Rule to disallow negating the left operand of relational operators
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* @author Toru Nagashima
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*/
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'use strict';
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require('./utils/ast-utils');
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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/**
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* Checks whether the given operator is `in` or `instanceof`
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* @param {string} op The operator type to check.
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* @returns {boolean} `true` if the operator is `in` or `instanceof`
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*/
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function isInOrInstanceOfOperator(op) {
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return op === 'in' || op === 'instanceof';
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}
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/**
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* Checks whether the given operator is an ordering relational operator or not.
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* @param {string} op The operator type to check.
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* @returns {boolean} `true` if the operator is an ordering relational operator.
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*/
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function isOrderingRelationalOperator(op) {
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return op === '<' || op === '>' || op === '>=' || op === '<=';
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}
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/**
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* Checks whether the given node is a logical negation expression or not.
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* @param {ASTNode} node The node to check.
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* @returns {boolean} `true` if the node is a logical negation expression.
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*/
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function isNegation(node) {
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return node.type === 'UnaryExpression' && node.operator === '!';
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: 'problem',
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defaultOptions: [
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{
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enforceForOrderingRelations: false,
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},
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],
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docs: {
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description: 'Disallow negating the left operand of relational operators',
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recommended: true,
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url: 'https://eslint.org/docs/latest/rules/no-unsafe-negation',
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},
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hasSuggestions: true,
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schema: [
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{
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type: 'object',
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properties: {
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enforceForOrderingRelations: {
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type: 'boolean',
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},
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},
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additionalProperties: false,
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},
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],
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fixable: null,
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messages: {
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unexpected:
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"Unexpected negating the left operand of '{{operator}}' operator.",
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suggestNegatedExpression:
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"Negate '{{operator}}' expression instead of its left operand. This changes the current behavior.",
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suggestParenthesisedNegation:
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"Wrap negation in '()' to make the intention explicit. This preserves the current behavior.",
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},
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},
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create(context) {
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const sourceCode = context.sourceCode;
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const [{ enforceForOrderingRelations }] = context.options;
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return {
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BinaryExpression(node) {
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const operator = node.operator;
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const orderingRelationRuleApplies =
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enforceForOrderingRelations && isOrderingRelationalOperator(operator);
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if (
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(isInOrInstanceOfOperator(operator) || orderingRelationRuleApplies) &&
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isNegation(node.left) &&
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!astUtils.isParenthesised(sourceCode, node.left)
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) {
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context.report({
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node,
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loc: node.left.loc,
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messageId: 'unexpected',
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data: { operator },
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suggest: [
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{
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messageId: 'suggestNegatedExpression',
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data: { operator },
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fix(fixer) {
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const negationToken = sourceCode.getFirstToken(node.left);
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const fixRange = [negationToken.range[1], node.range[1]];
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const text = sourceCode.text.slice(fixRange[0], fixRange[1]);
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return fixer.replaceTextRange(fixRange, `(${text})`);
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},
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},
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{
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messageId: 'suggestParenthesisedNegation',
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fix(fixer) {
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return fixer.replaceText(
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node.left,
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`(${sourceCode.getText(node.left)})`
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);
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},
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},
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],
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});
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}
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},
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};
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},
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};
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