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qwen/nodejs/node_modules/eslint/lib/rules/no-constant-condition.js

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