115 lines
4 KiB
JavaScript
115 lines
4 KiB
JavaScript
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/**
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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("../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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module.exports = {
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meta: {
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docs: {
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description: "require or disallow named `function` expressions",
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category: "Stylistic Issues",
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recommended: false
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},
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schema: [
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{
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enum: ["always", "as-needed", "never"]
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}
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]
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},
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create(context) {
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const never = context.options[0] === "never";
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const asNeeded = context.options[0] === "as-needed";
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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 === "AssignmentExpression" && parent.left.type === "Identifier" && parent.right === node) ||
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(parent.type === "ExportDefaultDeclaration" && parent.declaration === node) ||
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(parent.type === "AssignmentPattern" && parent.right === node);
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}
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return {
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"FunctionExpression:exit"(node) {
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// Skip recursive functions.
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const nameVar = context.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 name = astUtils.getFunctionNameWithKind(node);
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if (never) {
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if (hasName) {
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context.report({
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node,
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message: "Unexpected named {{name}}.",
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data: { name }
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});
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}
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} else {
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if (!hasName && (asNeeded ? !hasInferredName(node) : !isObjectOrClassMethod(node))) {
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context.report({
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node,
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message: "Unexpected unnamed {{name}}.",
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data: { 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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}
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};
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