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qwen/nodejs/node_modules/eslint/lib/rules/consistent-this.js

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+/**
+ * @fileoverview Rule to enforce consistent naming of "this" context variables
+ * @author Raphael Pigulla
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "Enforce consistent naming when capturing the current execution context",
+            recommended: false,
+            url: "https://eslint.org/docs/latest/rules/consistent-this"
+        },
+
+        schema: {
+            type: "array",
+            items: {
+                type: "string",
+                minLength: 1
+            },
+            uniqueItems: true
+        },
+
+        messages: {
+            aliasNotAssignedToThis: "Designated alias '{{name}}' is not assigned to 'this'.",
+            unexpectedAlias: "Unexpected alias '{{name}}' for 'this'."
+        }
+    },
+
+    create(context) {
+        let aliases = [];
+        const sourceCode = context.sourceCode;
+
+        if (context.options.length === 0) {
+            aliases.push("that");
+        } else {
+            aliases = context.options;
+        }
+
+        /**
+         * Reports that a variable declarator or assignment expression is assigning
+         * a non-'this' value to the specified alias.
+         * @param {ASTNode} node The assigning node.
+         * @param {string} name the name of the alias that was incorrectly used.
+         * @returns {void}
+         */
+        function reportBadAssignment(node, name) {
+            context.report({ node, messageId: "aliasNotAssignedToThis", data: { name } });
+        }
+
+        /**
+         * Checks that an assignment to an identifier only assigns 'this' to the
+         * appropriate alias, and the alias is only assigned to 'this'.
+         * @param {ASTNode} node The assigning node.
+         * @param {Identifier} name The name of the variable assigned to.
+         * @param {Expression} value The value of the assignment.
+         * @returns {void}
+         */
+        function checkAssignment(node, name, value) {
+            const isThis = value.type === "ThisExpression";
+
+            if (aliases.includes(name)) {
+                if (!isThis || node.operator && node.operator !== "=") {
+                    reportBadAssignment(node, name);
+                }
+            } else if (isThis) {
+                context.report({ node, messageId: "unexpectedAlias", data: { name } });
+            }
+        }
+
+        /**
+         * Ensures that a variable declaration of the alias in a program or function
+         * is assigned to the correct value.
+         * @param {string} alias alias the check the assignment of.
+         * @param {Object} scope scope of the current code we are checking.
+         * @private
+         * @returns {void}
+         */
+        function checkWasAssigned(alias, scope) {
+            const variable = scope.set.get(alias);
+
+            if (!variable) {
+                return;
+            }
+
+            if (variable.defs.some(def => def.node.type === "VariableDeclarator" &&
+                def.node.init !== null)) {
+                return;
+            }
+
+            /*
+             * The alias has been declared and not assigned: check it was
+             * assigned later in the same scope.
+             */
+            if (!variable.references.some(reference => {
+                const write = reference.writeExpr;
+
+                return (
+                    reference.from === scope &&
+                    write && write.type === "ThisExpression" &&
+                    write.parent.operator === "="
+                );
+            })) {
+                variable.defs.map(def => def.node).forEach(node => {
+                    reportBadAssignment(node, alias);
+                });
+            }
+        }
+
+        /**
+         * Check each alias to ensure that is was assigned to the correct value.
+         * @param {ASTNode} node The node that represents the scope to check.
+         * @returns {void}
+         */
+        function ensureWasAssigned(node) {
+            const scope = sourceCode.getScope(node);
+
+            aliases.forEach(alias => {
+                checkWasAssigned(alias, scope);
+            });
+        }
+
+        return {
+            "Program:exit": ensureWasAssigned,
+            "FunctionExpression:exit": ensureWasAssigned,
+            "FunctionDeclaration:exit": ensureWasAssigned,
+
+            VariableDeclarator(node) {
+                const id = node.id;
+                const isDestructuring =
+                    id.type === "ArrayPattern" || id.type === "ObjectPattern";
+
+                if (node.init !== null && !isDestructuring) {
+                    checkAssignment(node, id.name, node.init);
+                }
+            },
+
+            AssignmentExpression(node) {
+                if (node.left.type === "Identifier") {
+                    checkAssignment(node, node.left.name, node.right);
+                }
+            }
+        };
+
+    }
+};