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102 lines
3.4 KiB
102 lines
3.4 KiB
/**
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* @fileoverview Checks for unreachable code due to return, throws, break, and continue.
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* @author Joel Feenstra
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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/**
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* Checks whether or not a given variable declarator has the initializer.
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* @param {ASTNode} node - A VariableDeclarator node to check.
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* @returns {boolean} `true` if the node has the initializer.
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*/
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function isInitialized(node) {
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return Boolean(node.init);
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}
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/**
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* Checks whether or not a given code path segment is unreachable.
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* @param {CodePathSegment} segment - A CodePathSegment to check.
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* @returns {boolean} `true` if the segment is unreachable.
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*/
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function isUnreachable(segment) {
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return !segment.reachable;
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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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docs: {
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description: "disallow unreachable code after `return`, `throw`, `continue`, and `break` statements",
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category: "Possible Errors",
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recommended: true
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},
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schema: []
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},
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create: function(context) {
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var currentCodePath = null;
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/**
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* Reports a given node if it's unreachable.
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* @param {ASTNode} node - A statement node to report.
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* @returns {void}
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*/
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function reportIfUnreachable(node) {
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if (currentCodePath.currentSegments.every(isUnreachable)) {
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context.report({message: "Unreachable code.", node: node});
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}
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}
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return {
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// Manages the current code path.
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onCodePathStart: function(codePath) {
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currentCodePath = codePath;
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},
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onCodePathEnd: function() {
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currentCodePath = currentCodePath.upper;
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},
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// Registers for all statement nodes (excludes FunctionDeclaration).
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BlockStatement: reportIfUnreachable,
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BreakStatement: reportIfUnreachable,
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ClassDeclaration: reportIfUnreachable,
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ContinueStatement: reportIfUnreachable,
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DebuggerStatement: reportIfUnreachable,
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DoWhileStatement: reportIfUnreachable,
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EmptyStatement: reportIfUnreachable,
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ExpressionStatement: reportIfUnreachable,
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ForInStatement: reportIfUnreachable,
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ForOfStatement: reportIfUnreachable,
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ForStatement: reportIfUnreachable,
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IfStatement: reportIfUnreachable,
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ImportDeclaration: reportIfUnreachable,
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LabeledStatement: reportIfUnreachable,
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ReturnStatement: reportIfUnreachable,
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SwitchStatement: reportIfUnreachable,
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ThrowStatement: reportIfUnreachable,
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TryStatement: reportIfUnreachable,
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VariableDeclaration: function(node) {
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if (node.kind !== "var" || node.declarations.some(isInitialized)) {
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reportIfUnreachable(node);
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}
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},
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WhileStatement: reportIfUnreachable,
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WithStatement: reportIfUnreachable,
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ExportNamedDeclaration: reportIfUnreachable,
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ExportDefaultDeclaration: reportIfUnreachable,
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ExportAllDeclaration: reportIfUnreachable
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};
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}
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};
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