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