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Diffstat (limited to 'tools/node_modules/eslint/lib/rules/no-unreachable.js')
| -rw-r--r-- | tools/node_modules/eslint/lib/rules/no-unreachable.js | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/no-unreachable.js b/tools/node_modules/eslint/lib/rules/no-unreachable.js new file mode 100644 index 0000000000..217a6a4299 --- /dev/null +++ b/tools/node_modules/eslint/lib/rules/no-unreachable.js @@ -0,0 +1,212 @@ +/** + * @fileoverview Checks for unreachable code due to return, throws, break, and continue. + * @author Joel Feenstra + */ +"use strict"; + +//------------------------------------------------------------------------------ +// Helpers +//------------------------------------------------------------------------------ + +/** + * Checks whether or not a given variable declarator has the initializer. + * @param {ASTNode} node - A VariableDeclarator node to check. + * @returns {boolean} `true` if the node has the initializer. + */ +function isInitialized(node) { + return Boolean(node.init); +} + +/** + * Checks whether or not a given code path segment is unreachable. + * @param {CodePathSegment} segment - A CodePathSegment to check. + * @returns {boolean} `true` if the segment is unreachable. + */ +function isUnreachable(segment) { + return !segment.reachable; +} + +/** + * The class to distinguish consecutive unreachable statements. + */ +class ConsecutiveRange { + constructor(sourceCode) { + this.sourceCode = sourceCode; + this.startNode = null; + this.endNode = null; + } + + /** + * The location object of this range. + * @type {Object} + */ + get location() { + return { + start: this.startNode.loc.start, + end: this.endNode.loc.end + }; + } + + /** + * `true` if this range is empty. + * @type {boolean} + */ + get isEmpty() { + return !(this.startNode && this.endNode); + } + + /** + * Checks whether the given node is inside of this range. + * @param {ASTNode|Token} node - The node to check. + * @returns {boolean} `true` if the node is inside of this range. + */ + contains(node) { + return ( + node.range[0] >= this.startNode.range[0] && + node.range[1] <= this.endNode.range[1] + ); + } + + /** + * Checks whether the given node is consecutive to this range. + * @param {ASTNode} node - The node to check. + * @returns {boolean} `true` if the node is consecutive to this range. + */ + isConsecutive(node) { + return this.contains(this.sourceCode.getTokenBefore(node)); + } + + /** + * Merges the given node to this range. + * @param {ASTNode} node - The node to merge. + * @returns {void} + */ + merge(node) { + this.endNode = node; + } + + /** + * Resets this range by the given node or null. + * @param {ASTNode|null} node - The node to reset, or null. + * @returns {void} + */ + reset(node) { + this.startNode = this.endNode = node; + } +} + +//------------------------------------------------------------------------------ +// Rule Definition +//------------------------------------------------------------------------------ + +module.exports = { + meta: { + docs: { + description: "disallow unreachable code after `return`, `throw`, `continue`, and `break` statements", + category: "Possible Errors", + recommended: true + }, + + schema: [] + }, + + create(context) { + let currentCodePath = null; + + const range = new ConsecutiveRange(context.getSourceCode()); + + /** + * Reports a given node if it's unreachable. + * @param {ASTNode} node - A statement node to report. + * @returns {void} + */ + function reportIfUnreachable(node) { + let nextNode = null; + + if (node && currentCodePath.currentSegments.every(isUnreachable)) { + + // Store this statement to distinguish consecutive statements. + if (range.isEmpty) { + range.reset(node); + return; + } + + // Skip if this statement is inside of the current range. + if (range.contains(node)) { + return; + } + + // Merge if this statement is consecutive to the current range. + if (range.isConsecutive(node)) { + range.merge(node); + return; + } + + nextNode = node; + } + + /* + * Report the current range since this statement is reachable or is + * not consecutive to the current range. + */ + if (!range.isEmpty) { + context.report({ + message: "Unreachable code.", + loc: range.location, + node: range.startNode + }); + } + + // Update the current range. + range.reset(nextNode); + } + + return { + + // Manages the current code path. + onCodePathStart(codePath) { + currentCodePath = codePath; + }, + + onCodePathEnd() { + currentCodePath = currentCodePath.upper; + }, + + // Registers for all statement nodes (excludes FunctionDeclaration). + BlockStatement: reportIfUnreachable, + BreakStatement: reportIfUnreachable, + ClassDeclaration: reportIfUnreachable, + ContinueStatement: reportIfUnreachable, + DebuggerStatement: reportIfUnreachable, + DoWhileStatement: reportIfUnreachable, + EmptyStatement: reportIfUnreachable, + ExpressionStatement: reportIfUnreachable, + ForInStatement: reportIfUnreachable, + ForOfStatement: reportIfUnreachable, + ForStatement: reportIfUnreachable, + IfStatement: reportIfUnreachable, + ImportDeclaration: reportIfUnreachable, + LabeledStatement: reportIfUnreachable, + ReturnStatement: reportIfUnreachable, + SwitchStatement: reportIfUnreachable, + ThrowStatement: reportIfUnreachable, + TryStatement: reportIfUnreachable, + + VariableDeclaration(node) { + if (node.kind !== "var" || node.declarations.some(isInitialized)) { + reportIfUnreachable(node); + } + }, + + WhileStatement: reportIfUnreachable, + WithStatement: reportIfUnreachable, + ExportNamedDeclaration: reportIfUnreachable, + ExportDefaultDeclaration: reportIfUnreachable, + ExportAllDeclaration: reportIfUnreachable, + + "Program:exit"() { + reportIfUnreachable(); + } + }; + } +}; |