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150 lines
4.8 KiB
150 lines
4.8 KiB
/**
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* @fileoverview Rule to flag use constant conditions
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* @author Christian Schulz <http://rndm.de>
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*/
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"use strict";
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const { isConstant } = require("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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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: "problem",
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docs: {
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description: "Disallow constant expressions in conditions",
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recommended: true,
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url: "https://eslint.org/docs/latest/rules/no-constant-condition"
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},
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schema: [
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{
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type: "object",
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properties: {
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checkLoops: {
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type: "boolean",
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default: true
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}
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},
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additionalProperties: false
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}
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],
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messages: {
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unexpected: "Unexpected constant condition."
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}
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},
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create(context) {
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const options = context.options[0] || {},
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checkLoops = options.checkLoops !== false,
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loopSetStack = [];
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const sourceCode = context.sourceCode;
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let loopsInCurrentScope = new Set();
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//--------------------------------------------------------------------------
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// Helpers
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//--------------------------------------------------------------------------
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/**
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* Tracks when the given node contains a constant condition.
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* @param {ASTNode} node The AST node to check.
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* @returns {void}
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* @private
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*/
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function trackConstantConditionLoop(node) {
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if (node.test && isConstant(sourceCode.getScope(node), node.test, true)) {
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loopsInCurrentScope.add(node);
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}
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}
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/**
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* Reports when the set contains the given constant condition node
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* @param {ASTNode} node The AST node to check.
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* @returns {void}
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* @private
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*/
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function checkConstantConditionLoopInSet(node) {
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if (loopsInCurrentScope.has(node)) {
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loopsInCurrentScope.delete(node);
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context.report({ node: node.test, messageId: "unexpected" });
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}
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}
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/**
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* Reports when the given node contains a constant condition.
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* @param {ASTNode} node The AST node to check.
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* @returns {void}
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* @private
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*/
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function reportIfConstant(node) {
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if (node.test && isConstant(sourceCode.getScope(node), node.test, true)) {
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context.report({ node: node.test, messageId: "unexpected" });
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}
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}
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/**
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* Stores current set of constant loops in loopSetStack temporarily
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* and uses a new set to track constant loops
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* @returns {void}
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* @private
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*/
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function enterFunction() {
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loopSetStack.push(loopsInCurrentScope);
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loopsInCurrentScope = new Set();
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}
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/**
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* Reports when the set still contains stored constant conditions
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* @returns {void}
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* @private
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*/
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function exitFunction() {
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loopsInCurrentScope = loopSetStack.pop();
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}
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/**
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* Checks node when checkLoops option is enabled
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* @param {ASTNode} node The AST node to check.
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* @returns {void}
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* @private
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*/
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function checkLoop(node) {
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if (checkLoops) {
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trackConstantConditionLoop(node);
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}
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}
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//--------------------------------------------------------------------------
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// Public
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//--------------------------------------------------------------------------
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return {
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ConditionalExpression: reportIfConstant,
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IfStatement: reportIfConstant,
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WhileStatement: checkLoop,
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"WhileStatement:exit": checkConstantConditionLoopInSet,
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DoWhileStatement: checkLoop,
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"DoWhileStatement:exit": checkConstantConditionLoopInSet,
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ForStatement: checkLoop,
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"ForStatement > .test": node => checkLoop(node.parent),
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"ForStatement:exit": checkConstantConditionLoopInSet,
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FunctionDeclaration: enterFunction,
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"FunctionDeclaration:exit": exitFunction,
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FunctionExpression: enterFunction,
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"FunctionExpression:exit": exitFunction,
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YieldExpression: () => loopsInCurrentScope.clear()
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};
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}
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};
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