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335 lines
13 KiB
335 lines
13 KiB
/**
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* @fileoverview Rule to flag dangling underscores in variable declarations.
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* @author Matt DuVall <http://www.mattduvall.com>
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*/
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"use strict";
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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: "Disallow dangling underscores in identifiers",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/no-underscore-dangle"
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},
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schema: [
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{
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type: "object",
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properties: {
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allow: {
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type: "array",
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items: {
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type: "string"
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}
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},
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allowAfterThis: {
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type: "boolean",
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default: false
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},
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allowAfterSuper: {
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type: "boolean",
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default: false
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},
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allowAfterThisConstructor: {
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type: "boolean",
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default: false
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},
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enforceInMethodNames: {
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type: "boolean",
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default: false
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},
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allowFunctionParams: {
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type: "boolean",
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default: true
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},
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enforceInClassFields: {
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type: "boolean",
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default: false
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},
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allowInArrayDestructuring: {
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type: "boolean",
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default: true
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},
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allowInObjectDestructuring: {
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type: "boolean",
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default: true
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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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messages: {
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unexpectedUnderscore: "Unexpected dangling '_' in '{{identifier}}'."
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}
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},
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create(context) {
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const options = context.options[0] || {};
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const ALLOWED_VARIABLES = options.allow ? options.allow : [];
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const allowAfterThis = typeof options.allowAfterThis !== "undefined" ? options.allowAfterThis : false;
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const allowAfterSuper = typeof options.allowAfterSuper !== "undefined" ? options.allowAfterSuper : false;
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const allowAfterThisConstructor = typeof options.allowAfterThisConstructor !== "undefined" ? options.allowAfterThisConstructor : false;
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const enforceInMethodNames = typeof options.enforceInMethodNames !== "undefined" ? options.enforceInMethodNames : false;
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const enforceInClassFields = typeof options.enforceInClassFields !== "undefined" ? options.enforceInClassFields : false;
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const allowFunctionParams = typeof options.allowFunctionParams !== "undefined" ? options.allowFunctionParams : true;
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const allowInArrayDestructuring = typeof options.allowInArrayDestructuring !== "undefined" ? options.allowInArrayDestructuring : true;
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const allowInObjectDestructuring = typeof options.allowInObjectDestructuring !== "undefined" ? options.allowInObjectDestructuring : true;
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const sourceCode = context.sourceCode;
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//-------------------------------------------------------------------------
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// Helpers
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//-------------------------------------------------------------------------
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/**
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* Check if identifier is present inside the allowed option
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* @param {string} identifier name of the node
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* @returns {boolean} true if its is present
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* @private
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*/
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function isAllowed(identifier) {
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return ALLOWED_VARIABLES.includes(identifier);
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}
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/**
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* Check if identifier has a dangling underscore
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* @param {string} identifier name of the node
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* @returns {boolean} true if its is present
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* @private
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*/
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function hasDanglingUnderscore(identifier) {
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const len = identifier.length;
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return identifier !== "_" && (identifier[0] === "_" || identifier[len - 1] === "_");
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}
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/**
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* Check if identifier is a special case member expression
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* @param {string} identifier name of the node
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* @returns {boolean} true if its is a special case
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* @private
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*/
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function isSpecialCaseIdentifierForMemberExpression(identifier) {
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return identifier === "__proto__";
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}
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/**
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* Check if identifier is a special case variable expression
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* @param {string} identifier name of the node
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* @returns {boolean} true if its is a special case
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* @private
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*/
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function isSpecialCaseIdentifierInVariableExpression(identifier) {
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// Checks for the underscore library usage here
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return identifier === "_";
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}
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/**
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* Check if a node is a member reference of this.constructor
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* @param {ASTNode} node node to evaluate
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* @returns {boolean} true if it is a reference on this.constructor
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* @private
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*/
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function isThisConstructorReference(node) {
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return node.object.type === "MemberExpression" &&
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node.object.property.name === "constructor" &&
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node.object.object.type === "ThisExpression";
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}
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/**
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* Check if function parameter has a dangling underscore.
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* @param {ASTNode} node function node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForDanglingUnderscoreInFunctionParameters(node) {
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if (!allowFunctionParams) {
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node.params.forEach(param => {
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const { type } = param;
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let nodeToCheck;
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if (type === "RestElement") {
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nodeToCheck = param.argument;
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} else if (type === "AssignmentPattern") {
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nodeToCheck = param.left;
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} else {
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nodeToCheck = param;
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}
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if (nodeToCheck.type === "Identifier") {
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const identifier = nodeToCheck.name;
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if (hasDanglingUnderscore(identifier) && !isAllowed(identifier)) {
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context.report({
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node: param,
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messageId: "unexpectedUnderscore",
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data: {
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identifier
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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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/**
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* Check if function has a dangling underscore
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForDanglingUnderscoreInFunction(node) {
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if (node.type === "FunctionDeclaration" && node.id) {
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const identifier = node.id.name;
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if (typeof identifier !== "undefined" && hasDanglingUnderscore(identifier) && !isAllowed(identifier)) {
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context.report({
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node,
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messageId: "unexpectedUnderscore",
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data: {
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identifier
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}
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});
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}
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}
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checkForDanglingUnderscoreInFunctionParameters(node);
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}
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/**
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* Check if variable expression has a dangling underscore
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForDanglingUnderscoreInVariableExpression(node) {
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sourceCode.getDeclaredVariables(node).forEach(variable => {
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const definition = variable.defs.find(def => def.node === node);
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const identifierNode = definition.name;
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const identifier = identifierNode.name;
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let parent = identifierNode.parent;
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while (!["VariableDeclarator", "ArrayPattern", "ObjectPattern"].includes(parent.type)) {
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parent = parent.parent;
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}
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if (
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hasDanglingUnderscore(identifier) &&
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!isSpecialCaseIdentifierInVariableExpression(identifier) &&
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!isAllowed(identifier) &&
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!(allowInArrayDestructuring && parent.type === "ArrayPattern") &&
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!(allowInObjectDestructuring && parent.type === "ObjectPattern")
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) {
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context.report({
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node,
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messageId: "unexpectedUnderscore",
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data: {
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identifier
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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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* Check if member expression has a dangling underscore
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForDanglingUnderscoreInMemberExpression(node) {
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const identifier = node.property.name,
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isMemberOfThis = node.object.type === "ThisExpression",
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isMemberOfSuper = node.object.type === "Super",
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isMemberOfThisConstructor = isThisConstructorReference(node);
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if (typeof identifier !== "undefined" && hasDanglingUnderscore(identifier) &&
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!(isMemberOfThis && allowAfterThis) &&
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!(isMemberOfSuper && allowAfterSuper) &&
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!(isMemberOfThisConstructor && allowAfterThisConstructor) &&
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!isSpecialCaseIdentifierForMemberExpression(identifier) && !isAllowed(identifier)) {
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context.report({
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node,
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messageId: "unexpectedUnderscore",
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data: {
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identifier
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}
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});
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}
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}
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/**
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* Check if method declaration or method property has a dangling underscore
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForDanglingUnderscoreInMethod(node) {
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const identifier = node.key.name;
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const isMethod = node.type === "MethodDefinition" || node.type === "Property" && node.method;
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if (typeof identifier !== "undefined" && enforceInMethodNames && isMethod && hasDanglingUnderscore(identifier) && !isAllowed(identifier)) {
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context.report({
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node,
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messageId: "unexpectedUnderscore",
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data: {
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identifier: node.key.type === "PrivateIdentifier"
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? `#${identifier}`
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: identifier
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}
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});
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}
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}
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/**
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* Check if a class field has a dangling underscore
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* @param {ASTNode} node node to evaluate
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* @returns {void}
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* @private
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*/
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function checkForDanglingUnderscoreInClassField(node) {
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const identifier = node.key.name;
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if (typeof identifier !== "undefined" && hasDanglingUnderscore(identifier) &&
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enforceInClassFields &&
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!isAllowed(identifier)) {
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context.report({
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node,
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messageId: "unexpectedUnderscore",
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data: {
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identifier: node.key.type === "PrivateIdentifier"
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? `#${identifier}`
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: identifier
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}
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});
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}
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}
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//--------------------------------------------------------------------------
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// Public API
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//--------------------------------------------------------------------------
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return {
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FunctionDeclaration: checkForDanglingUnderscoreInFunction,
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VariableDeclarator: checkForDanglingUnderscoreInVariableExpression,
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MemberExpression: checkForDanglingUnderscoreInMemberExpression,
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MethodDefinition: checkForDanglingUnderscoreInMethod,
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PropertyDefinition: checkForDanglingUnderscoreInClassField,
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Property: checkForDanglingUnderscoreInMethod,
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FunctionExpression: checkForDanglingUnderscoreInFunction,
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ArrowFunctionExpression: checkForDanglingUnderscoreInFunction
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};
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}
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};
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