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71 lines
2.7 KiB
71 lines
2.7 KiB
/**
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* @fileoverview Rule to flag unnecessary double negation in Boolean contexts
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* @author Brandon Mills
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = function(context) {
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return {
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"UnaryExpression": function (node) {
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var ancestors = context.getAncestors(),
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parent = ancestors.pop(),
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grandparent = ancestors.pop();
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// Exit early if it's guaranteed not to match
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if (node.operator !== "!" ||
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parent.type !== "UnaryExpression" ||
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parent.operator !== "!") {
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return;
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}
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// if (<bool>) ...
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if (grandparent.type === "IfStatement") {
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context.report(node, "Redundant double negation in an if statement condition.");
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// do ... while (<bool>)
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} else if (grandparent.type === "DoWhileStatement") {
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context.report(node, "Redundant double negation in a do while loop condition.");
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// while (<bool>) ...
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} else if (grandparent.type === "WhileStatement") {
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context.report(node, "Redundant double negation in a while loop condition.");
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// <bool> ? ... : ...
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} else if ((grandparent.type === "ConditionalExpression" &&
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parent === grandparent.test)) {
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context.report(node, "Redundant double negation in a ternary condition.");
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// for (...; <bool>; ...) ...
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} else if ((grandparent.type === "ForStatement" &&
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parent === grandparent.test)) {
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context.report(node, "Redundant double negation in a for loop condition.");
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// !<bool>
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} else if ((grandparent.type === "UnaryExpression" &&
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grandparent.operator === "!")) {
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context.report(node, "Redundant multiple negation.");
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// Boolean(<bool>)
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} else if ((grandparent.type === "CallExpression" &&
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grandparent.callee.type === "Identifier" &&
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grandparent.callee.name === "Boolean")) {
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context.report(node, "Redundant double negation in call to Boolean().");
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// new Boolean(<bool>)
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} else if ((grandparent.type === "NewExpression" &&
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grandparent.callee.type === "Identifier" &&
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grandparent.callee.name === "Boolean")) {
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context.report(node, "Redundant double negation in Boolean constructor call.");
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}
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}
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};
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};
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module.exports.schema = [];
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