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191 lines
6.3 KiB
191 lines
6.3 KiB
/**
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* @fileoverview Rule to warn when a function expression does not have a name.
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* @author Kyle T. Nunery
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("./utils/ast-utils");
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/**
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* Checks whether or not a given variable is a function name.
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* @param {eslint-scope.Variable} variable A variable to check.
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* @returns {boolean} `true` if the variable is a function name.
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*/
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function isFunctionName(variable) {
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return variable && variable.defs[0].type === "FunctionName";
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}
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../shared/types').Rule} */
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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 or disallow named `function` expressions",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/func-names"
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},
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schema: {
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definitions: {
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value: {
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enum: [
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"always",
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"as-needed",
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"never"
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]
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}
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},
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items: [
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{
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$ref: "#/definitions/value"
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},
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{
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type: "object",
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properties: {
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generators: {
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$ref: "#/definitions/value"
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}
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},
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additionalProperties: false
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}
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]
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},
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messages: {
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unnamed: "Unexpected unnamed {{name}}.",
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named: "Unexpected named {{name}}."
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}
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},
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create(context) {
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const sourceCode = context.sourceCode;
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/**
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* Returns the config option for the given node.
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* @param {ASTNode} node A node to get the config for.
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* @returns {string} The config option.
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*/
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function getConfigForNode(node) {
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if (
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node.generator &&
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context.options.length > 1 &&
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context.options[1].generators
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) {
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return context.options[1].generators;
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}
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return context.options[0] || "always";
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}
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/**
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* Determines whether the current FunctionExpression node is a get, set, or
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* shorthand method in an object literal or a class.
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* @param {ASTNode} node A node to check.
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* @returns {boolean} True if the node is a get, set, or shorthand method.
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*/
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function isObjectOrClassMethod(node) {
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const parent = node.parent;
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return (parent.type === "MethodDefinition" || (
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parent.type === "Property" && (
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parent.method ||
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parent.kind === "get" ||
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parent.kind === "set"
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)
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));
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}
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/**
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* Determines whether the current FunctionExpression node has a name that would be
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* inferred from context in a conforming ES6 environment.
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* @param {ASTNode} node A node to check.
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* @returns {boolean} True if the node would have a name assigned automatically.
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*/
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function hasInferredName(node) {
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const parent = node.parent;
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return isObjectOrClassMethod(node) ||
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(parent.type === "VariableDeclarator" && parent.id.type === "Identifier" && parent.init === node) ||
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(parent.type === "Property" && parent.value === node) ||
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(parent.type === "PropertyDefinition" && parent.value === node) ||
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(parent.type === "AssignmentExpression" && parent.left.type === "Identifier" && parent.right === node) ||
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(parent.type === "AssignmentPattern" && parent.left.type === "Identifier" && parent.right === node);
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}
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/**
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* Reports that an unnamed function should be named
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* @param {ASTNode} node The node to report in the event of an error.
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* @returns {void}
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*/
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function reportUnexpectedUnnamedFunction(node) {
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context.report({
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node,
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messageId: "unnamed",
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loc: astUtils.getFunctionHeadLoc(node, sourceCode),
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data: { name: astUtils.getFunctionNameWithKind(node) }
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});
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}
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/**
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* Reports that a named function should be unnamed
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* @param {ASTNode} node The node to report in the event of an error.
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* @returns {void}
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*/
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function reportUnexpectedNamedFunction(node) {
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context.report({
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node,
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messageId: "named",
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loc: astUtils.getFunctionHeadLoc(node, sourceCode),
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data: { name: astUtils.getFunctionNameWithKind(node) }
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});
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}
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/**
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* The listener for function nodes.
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* @param {ASTNode} node function node
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* @returns {void}
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*/
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function handleFunction(node) {
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// Skip recursive functions.
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const nameVar = sourceCode.getDeclaredVariables(node)[0];
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if (isFunctionName(nameVar) && nameVar.references.length > 0) {
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return;
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}
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const hasName = Boolean(node.id && node.id.name);
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const config = getConfigForNode(node);
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if (config === "never") {
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if (hasName && node.type !== "FunctionDeclaration") {
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reportUnexpectedNamedFunction(node);
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}
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} else if (config === "as-needed") {
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if (!hasName && !hasInferredName(node)) {
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reportUnexpectedUnnamedFunction(node);
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}
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} else {
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if (!hasName && !isObjectOrClassMethod(node)) {
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reportUnexpectedUnnamedFunction(node);
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}
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}
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}
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return {
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"FunctionExpression:exit": handleFunction,
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"ExportDefaultDeclaration > FunctionDeclaration": handleFunction
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};
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}
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};
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