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149 lines
5.0 KiB
149 lines
5.0 KiB
/**
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* @fileoverview Rule to disallow unnecessary labels
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* @author Toru Nagashima
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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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// 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 unnecessary labels",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/no-extra-label"
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},
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schema: [],
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fixable: "code",
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messages: {
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unexpected: "This label '{{name}}' is unnecessary."
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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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let scopeInfo = null;
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/**
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* Creates a new scope with a breakable statement.
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* @param {ASTNode} node A node to create. This is a BreakableStatement.
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* @returns {void}
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*/
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function enterBreakableStatement(node) {
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scopeInfo = {
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label: node.parent.type === "LabeledStatement" ? node.parent.label : null,
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breakable: true,
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upper: scopeInfo
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};
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}
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/**
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* Removes the top scope of the stack.
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* @returns {void}
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*/
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function exitBreakableStatement() {
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scopeInfo = scopeInfo.upper;
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}
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/**
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* Creates a new scope with a labeled statement.
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*
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* This ignores it if the body is a breakable statement.
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* In this case it's handled in the `enterBreakableStatement` function.
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* @param {ASTNode} node A node to create. This is a LabeledStatement.
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* @returns {void}
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*/
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function enterLabeledStatement(node) {
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if (!astUtils.isBreakableStatement(node.body)) {
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scopeInfo = {
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label: node.label,
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breakable: false,
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upper: scopeInfo
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};
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}
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}
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/**
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* Removes the top scope of the stack.
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*
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* This ignores it if the body is a breakable statement.
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* In this case it's handled in the `exitBreakableStatement` function.
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* @param {ASTNode} node A node. This is a LabeledStatement.
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* @returns {void}
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*/
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function exitLabeledStatement(node) {
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if (!astUtils.isBreakableStatement(node.body)) {
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scopeInfo = scopeInfo.upper;
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}
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}
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/**
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* Reports a given control node if it's unnecessary.
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* @param {ASTNode} node A node. This is a BreakStatement or a
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* ContinueStatement.
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* @returns {void}
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*/
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function reportIfUnnecessary(node) {
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if (!node.label) {
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return;
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}
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const labelNode = node.label;
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for (let info = scopeInfo; info !== null; info = info.upper) {
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if (info.breakable || info.label && info.label.name === labelNode.name) {
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if (info.breakable && info.label && info.label.name === labelNode.name) {
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context.report({
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node: labelNode,
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messageId: "unexpected",
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data: labelNode,
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fix(fixer) {
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const breakOrContinueToken = sourceCode.getFirstToken(node);
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if (sourceCode.commentsExistBetween(breakOrContinueToken, labelNode)) {
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return null;
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}
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return fixer.removeRange([breakOrContinueToken.range[1], labelNode.range[1]]);
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}
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});
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}
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return;
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}
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}
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}
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return {
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WhileStatement: enterBreakableStatement,
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"WhileStatement:exit": exitBreakableStatement,
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DoWhileStatement: enterBreakableStatement,
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"DoWhileStatement:exit": exitBreakableStatement,
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ForStatement: enterBreakableStatement,
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"ForStatement:exit": exitBreakableStatement,
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ForInStatement: enterBreakableStatement,
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"ForInStatement:exit": exitBreakableStatement,
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ForOfStatement: enterBreakableStatement,
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"ForOfStatement:exit": exitBreakableStatement,
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SwitchStatement: enterBreakableStatement,
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"SwitchStatement:exit": exitBreakableStatement,
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LabeledStatement: enterLabeledStatement,
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"LabeledStatement:exit": exitLabeledStatement,
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BreakStatement: reportIfUnnecessary,
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ContinueStatement: reportIfUnnecessary
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};
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}
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};
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