dd5a4e1d75We have been stalled on ESLint 3.8.0 for some time. Current ESLint is 3.13.0. We have been unable to upgrade because of more aggressive reporting on some rules, including indentation. ESLint configuration options and bugfixes are now such that we can reasonably upgrade. PR-URL: https://github.com/nodejs/node/pull/10561 Reviewed-By: Teddy Katz <teddy.katz@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
104 lines
3.4 KiB
JavaScript
104 lines
3.4 KiB
JavaScript
/**
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* @fileoverview A rule to disallow unnecessary `.call()` and `.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 `.call()`/`.apply()`.
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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 `.call()`/`.apply()`.
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*/
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function isCallOrNonVariadicApply(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.computed === false &&
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(
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(node.callee.property.name === "call" && node.arguments.length >= 1) ||
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(node.callee.property.name === "apply" && node.arguments.length === 2 && node.arguments[1].type === "ArrayExpression")
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)
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);
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}
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/**
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* Checks whether or not the tokens of two given nodes are same.
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* @param {ASTNode} left - A node 1 to compare.
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* @param {ASTNode} right - A node 2 to compare.
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* @param {SourceCode} sourceCode - The ESLint source code object.
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* @returns {boolean} the source code for the given node.
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*/
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function equalTokens(left, right, sourceCode) {
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const tokensL = sourceCode.getTokens(left);
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const tokensR = sourceCode.getTokens(right);
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if (tokensL.length !== tokensR.length) {
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return false;
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}
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for (let i = 0; i < tokensL.length; ++i) {
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if (tokensL[i].type !== tokensR[i].type ||
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tokensL[i].value !== tokensR[i].value
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) {
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return false;
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}
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}
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return true;
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}
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/**
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* Checks whether or not `thisArg` is not changed by `.call()`/`.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 `.call()`/`.apply()`.
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* @param {SourceCode} sourceCode - The ESLint source code object.
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* @returns {boolean} Whether or not `thisArg` is not changed by `.call()`/`.apply()`.
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*/
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function isValidThisArg(expectedThis, thisArg, sourceCode) {
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if (!expectedThis) {
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return astUtils.isNullOrUndefined(thisArg);
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}
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return equalTokens(expectedThis, thisArg, sourceCode);
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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: "disallow unnecessary calls to `.call()` and `.apply()`",
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category: "Best Practices",
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recommended: false
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},
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schema: []
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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 (!isCallOrNonVariadicApply(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({ node, message: "unnecessary '.{{name}}()'.", data: { name: node.callee.property.name } });
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}
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}
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};
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}
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};
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