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					184 lines
				
				6.1 KiB
			
		
		
			
		
	
	
					184 lines
				
				6.1 KiB
			| 
								 
											4 years ago
										 
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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("./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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								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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								            category: "Stylistic Issues",
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								            recommended: false,
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								            url: "https://eslint.org/docs/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.getSourceCode();
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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 === "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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								        /**
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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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								        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 config = getConfigForNode(node);
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								                if (config === "never") {
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								                    if (hasName) {
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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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								        };
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								    }
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								};
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