88 lines
2.8 KiB
JavaScript
88 lines
2.8 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("./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 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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astUtils.isSpecificMemberAccess(node.callee, null, "apply") &&
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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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type: "suggestion",
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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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url: "https://eslint.org/docs/rules/prefer-spread"
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},
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schema: [],
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fixable: null,
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messages: {
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preferSpread: "Use the spread operator instead of '.apply()'."
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}
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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 = astUtils.skipChainExpression(astUtils.skipChainExpression(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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messageId: "preferSpread"
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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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