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Mini Shell
Mini Shell
/**
* @fileoverview Rule to disallow negating the left operand of relational operators
* @author Toru Nagashima
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------
/**
* Checks whether the given operator is `in` or `instanceof`
* @param {string} op The operator type to check.
* @returns {boolean} `true` if the operator is `in` or `instanceof`
*/
function isInOrInstanceOfOperator(op) {
return op === "in" || op === "instanceof";
}
/**
* Checks whether the given operator is an ordering relational operator or not.
* @param {string} op The operator type to check.
* @returns {boolean} `true` if the operator is an ordering relational operator.
*/
function isOrderingRelationalOperator(op) {
return op === "<" || op === ">" || op === ">=" || op === "<=";
}
/**
* Checks whether the given node is a logical negation expression or not.
* @param {ASTNode} node The node to check.
* @returns {boolean} `true` if the node is a logical negation expression.
*/
function isNegation(node) {
return node.type === "UnaryExpression" && node.operator === "!";
}
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../types').Rule.RuleModule} */
module.exports = {
meta: {
type: "problem",
defaultOptions: [
{
enforceForOrderingRelations: false,
},
],
docs: {
description:
"Disallow negating the left operand of relational operators",
recommended: true,
url: "https://eslint.org/docs/latest/rules/no-unsafe-negation",
},
hasSuggestions: true,
schema: [
{
type: "object",
properties: {
enforceForOrderingRelations: {
type: "boolean",
},
},
additionalProperties: false,
},
],
fixable: null,
messages: {
unexpected:
"Unexpected negating the left operand of '{{operator}}' operator.",
suggestNegatedExpression:
"Negate '{{operator}}' expression instead of its left operand. This changes the current behavior.",
suggestParenthesisedNegation:
"Wrap negation in '()' to make the intention explicit. This preserves the current behavior.",
},
},
create(context) {
const sourceCode = context.sourceCode;
const [{ enforceForOrderingRelations }] = context.options;
return {
BinaryExpression(node) {
const operator = node.operator;
const orderingRelationRuleApplies =
enforceForOrderingRelations &&
isOrderingRelationalOperator(operator);
if (
(isInOrInstanceOfOperator(operator) ||
orderingRelationRuleApplies) &&
isNegation(node.left) &&
!astUtils.isParenthesised(sourceCode, node.left)
) {
context.report({
node,
loc: node.left.loc,
messageId: "unexpected",
data: { operator },
suggest: [
{
messageId: "suggestNegatedExpression",
data: { operator },
fix(fixer) {
const negationToken =
sourceCode.getFirstToken(node.left);
const fixRange = [
negationToken.range[1],
node.range[1],
];
const text = sourceCode.text.slice(
fixRange[0],
fixRange[1],
);
return fixer.replaceTextRange(
fixRange,
`(${text})`,
);
},
},
{
messageId: "suggestParenthesisedNegation",
fix(fixer) {
return fixer.replaceText(
node.left,
`(${sourceCode.getText(node.left)})`,
);
},
},
],
});
}
},
};
},
};
Zerion Mini Shell 1.0