107 lines
3.1 KiB
JavaScript
107 lines
3.1 KiB
JavaScript
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/**
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* @fileoverview Rule to disallow unused 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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// 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: "disallow unused labels",
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category: "Best Practices",
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recommended: true
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},
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schema: [],
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fixable: "code"
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},
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create(context) {
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const sourceCode = context.getSourceCode();
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let scopeInfo = null;
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/**
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* Adds a scope info to the stack.
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*
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* @param {ASTNode} node - A node to add. This is a LabeledStatement.
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* @returns {void}
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*/
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function enterLabeledScope(node) {
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scopeInfo = {
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label: node.label.name,
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used: false,
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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 of the stack.
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* At the same time, this reports the label if it's never used.
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*
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* @param {ASTNode} node - A node to report. This is a LabeledStatement.
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* @returns {void}
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*/
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function exitLabeledScope(node) {
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if (!scopeInfo.used) {
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context.report({
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node: node.label,
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message: "'{{name}}:' is defined but never used.",
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data: node.label,
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fix(fixer) {
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/*
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* Only perform a fix if there are no comments between the label and the body. This will be the case
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* when there is exactly one token/comment (the ":") between the label and the body.
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*/
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if (sourceCode.getTokenAfter(node.label, { includeComments: true }) ===
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sourceCode.getTokenBefore(node.body, { includeComments: true })) {
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return fixer.removeRange([node.range[0], node.body.range[0]]);
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}
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return null;
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}
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});
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}
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scopeInfo = scopeInfo.upper;
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}
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/**
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* Marks the label of a given node as used.
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*
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* @param {ASTNode} node - A node to mark. This is a BreakStatement or
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* ContinueStatement.
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* @returns {void}
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*/
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function markAsUsed(node) {
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if (!node.label) {
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return;
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}
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const label = node.label.name;
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let info = scopeInfo;
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while (info) {
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if (info.label === label) {
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info.used = true;
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break;
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}
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info = info.upper;
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}
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}
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return {
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LabeledStatement: enterLabeledScope,
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"LabeledStatement:exit": exitLabeledScope,
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BreakStatement: markAsUsed,
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ContinueStatement: markAsUsed
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};
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}
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};
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