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no-array-push-push and prefer-ternary: Improve same reference det…
…ection (#1123)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,152 @@ | ||
| 'use strict'; | ||
| const {getStaticValue} = require('eslint-utils'); | ||
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| // Copied from https://github.com/eslint/eslint/blob/c3e9accce2f61b04ab699fd37c90703305281aa3/lib/rules/utils/ast-utils.js#L379 | ||
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| /** | ||
| Gets the property name of a given node. | ||
| The node can be a MemberExpression, a Property, or a MethodDefinition. | ||
| If the name is dynamic, this returns `null`. | ||
| For examples: | ||
| a.b // => "b" | ||
| a["b"] // => "b" | ||
| a['b'] // => "b" | ||
| a[`b`] // => "b" | ||
| a[100] // => "100" | ||
| a[b] // => null | ||
| a["a" + "b"] // => null | ||
| a[tag`b`] // => null | ||
| a[`${b}`] // => null | ||
| let a = {b: 1} // => "b" | ||
| let a = {["b"]: 1} // => "b" | ||
| let a = {['b']: 1} // => "b" | ||
| let a = {[`b`]: 1} // => "b" | ||
| let a = {[100]: 1} // => "100" | ||
| let a = {[b]: 1} // => null | ||
| let a = {["a" + "b"]: 1} // => null | ||
| let a = {[tag`b`]: 1} // => null | ||
| let a = {[`${b}`]: 1} // => null | ||
| @param {ASTNode} node The node to get. | ||
| @returns {string|undefined} The property name if static. Otherwise, undefined. | ||
| */ | ||
| function getStaticPropertyName(node) { | ||
| let property; | ||
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| switch (node && node.type) { | ||
| case 'MemberExpression': | ||
| property = node.property; | ||
| break; | ||
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| /* istanbul ignore next: Hard to test */ | ||
| case 'ChainExpression': | ||
| return getStaticPropertyName(node.expression); | ||
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| /* istanbul ignore next: Only reachable when use this to get class/object member key */ | ||
| case 'Property': | ||
| case 'MethodDefinition': | ||
| /* istanbul ignore next */ | ||
| property = node.key; | ||
| /* istanbul ignore next */ | ||
| break; | ||
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| // No default | ||
| } | ||
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| if (property) { | ||
| if (property.type === 'Identifier' && !node.computed) { | ||
| return property.name; | ||
| } | ||
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| const staticResult = getStaticValue(property); | ||
| if (!staticResult) { | ||
| return; | ||
| } | ||
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| return String(staticResult.value); | ||
| } | ||
| } | ||
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| /** | ||
| Check if two literal nodes are the same value. | ||
| @param {ASTNode} left The Literal node to compare. | ||
| @param {ASTNode} right The other Literal node to compare. | ||
| @returns {boolean} `true` if the two literal nodes are the same value. | ||
| */ | ||
| function equalLiteralValue(left, right) { | ||
| // RegExp literal. | ||
| if (left.regex || right.regex) { | ||
| return Boolean( | ||
| left.regex && | ||
| right.regex && | ||
| left.regex.pattern === right.regex.pattern && | ||
| left.regex.flags === right.regex.flags | ||
| ); | ||
| } | ||
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| // BigInt literal. | ||
| if (left.bigint || right.bigint) { | ||
| return left.bigint === right.bigint; | ||
| } | ||
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| return left.value === right.value; | ||
| } | ||
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| /** | ||
| Check if two expressions reference the same value. For example: | ||
| a = a | ||
| a.b = a.b | ||
| a[0] = a[0] | ||
| a['b'] = a['b'] | ||
| @param {ASTNode} left The left side of the comparison. | ||
| @param {ASTNode} right The right side of the comparison. | ||
| @returns {boolean} `true` if both sides match and reference the same value. | ||
| */ | ||
| function isSameReference(left, right) { | ||
| if (left.type !== right.type) { | ||
| // Handle `a.b` and `a?.b` are samely. | ||
| if (left.type === 'ChainExpression') { | ||
| return isSameReference(left.expression, right); | ||
| } | ||
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| if (right.type === 'ChainExpression') { | ||
| return isSameReference(left, right.expression); | ||
| } | ||
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| return false; | ||
| } | ||
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| switch (left.type) { | ||
| case 'Super': | ||
| case 'ThisExpression': | ||
| return true; | ||
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| case 'Identifier': | ||
| return left.name === right.name; | ||
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| case 'Literal': | ||
| return equalLiteralValue(left, right); | ||
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| case 'ChainExpression': | ||
| return isSameReference(left.expression, right.expression); | ||
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| case 'MemberExpression': { | ||
| const nameA = getStaticPropertyName(left); | ||
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| // X.y = x["y"] | ||
| return ( | ||
| typeof nameA !== 'undefined' && | ||
| isSameReference(left.object, right.object) && | ||
| nameA === getStaticPropertyName(right) | ||
| ); | ||
| } | ||
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| default: | ||
| return false; | ||
| } | ||
| } | ||
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| module.exports = isSameReference; |
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