97 lines
3.3 KiB
JavaScript
97 lines
3.3 KiB
JavaScript
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/**
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* @fileoverview A rule to suggest using of the spread operator instead of `.apply()`.
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* @author Toru Nagashima
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*/
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"use strict";
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const astUtils = require("../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 or not a node is a `.apply()` for variadic.
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* @param {ASTNode} node - A CallExpression node to check.
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* @returns {boolean} Whether or not the node is a `.apply()` for variadic.
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*/
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function isVariadicApplyCalling(node) {
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return (
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node.callee.type === "MemberExpression" &&
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node.callee.property.type === "Identifier" &&
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node.callee.property.name === "apply" &&
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node.callee.computed === false &&
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node.arguments.length === 2 &&
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node.arguments[1].type !== "ArrayExpression" &&
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node.arguments[1].type !== "SpreadElement"
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);
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}
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/**
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* Checks whether or not `thisArg` is not changed by `.apply()`.
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* @param {ASTNode|null} expectedThis - The node that is the owner of the applied function.
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* @param {ASTNode} thisArg - The node that is given to the first argument of the `.apply()`.
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* @param {RuleContext} context - The ESLint rule context object.
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* @returns {boolean} Whether or not `thisArg` is not changed by `.apply()`.
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*/
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function isValidThisArg(expectedThis, thisArg, context) {
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if (!expectedThis) {
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return astUtils.isNullOrUndefined(thisArg);
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}
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return astUtils.equalTokens(expectedThis, thisArg, context);
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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module.exports = {
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meta: {
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docs: {
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description: "require spread operators instead of `.apply()`",
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category: "ECMAScript 6",
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recommended: false
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},
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schema: [],
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fixable: "code"
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},
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create(context) {
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const sourceCode = context.getSourceCode();
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return {
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CallExpression(node) {
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if (!isVariadicApplyCalling(node)) {
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return;
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}
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const applied = node.callee.object;
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const expectedThis = (applied.type === "MemberExpression") ? applied.object : null;
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const thisArg = node.arguments[0];
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if (isValidThisArg(expectedThis, thisArg, sourceCode)) {
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context.report({
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node,
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message: "Use the spread operator instead of '.apply()'.",
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fix(fixer) {
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if (expectedThis && expectedThis.type !== "Identifier") {
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// Don't fix cases where the `this` value could be a computed expression.
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return null;
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}
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const propertyDot = sourceCode.getFirstTokenBetween(applied, node.callee.property, token => token.value === ".");
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return fixer.replaceTextRange([propertyDot.range[0], node.range[1]], `(...${sourceCode.getText(node.arguments[1])})`);
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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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