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qwen/nodejs/node_modules/eslint/lib/rules/no-invalid-this.js

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+/**
+ * @fileoverview A rule to disallow `this` keywords in contexts where the value of `this` is `undefined`.
+ * @author Toru Nagashima
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const astUtils = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * Determines if the given code path is a code path with lexical `this` binding.
+ * That is, if `this` within the code path refers to `this` of surrounding code path.
+ * @param {CodePath} codePath Code path.
+ * @param {ASTNode} node Node that started the code path.
+ * @returns {boolean} `true` if it is a code path with lexical `this` binding.
+ */
+function isCodePathWithLexicalThis(codePath, node) {
+    return codePath.origin === "function" && node.type === "ArrowFunctionExpression";
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "Disallow use of `this` in contexts where the value of `this` is `undefined`",
+            recommended: false,
+            url: "https://eslint.org/docs/latest/rules/no-invalid-this"
+        },
+
+        schema: [
+            {
+                type: "object",
+                properties: {
+                    capIsConstructor: {
+                        type: "boolean",
+                        default: true
+                    }
+                },
+                additionalProperties: false
+            }
+        ],
+
+        messages: {
+            unexpectedThis: "Unexpected 'this'."
+        }
+    },
+
+    create(context) {
+        const options = context.options[0] || {};
+        const capIsConstructor = options.capIsConstructor !== false;
+        const stack = [],
+            sourceCode = context.sourceCode;
+
+        /**
+         * Gets the current checking context.
+         *
+         * The return value has a flag that whether or not `this` keyword is valid.
+         * The flag is initialized when got at the first time.
+         * @returns {{valid: boolean}}
+         *   an object which has a flag that whether or not `this` keyword is valid.
+         */
+        stack.getCurrent = function() {
+            const current = this[this.length - 1];
+
+            if (!current.init) {
+                current.init = true;
+                current.valid = !astUtils.isDefaultThisBinding(
+                    current.node,
+                    sourceCode,
+                    { capIsConstructor }
+                );
+            }
+            return current;
+        };
+
+        return {
+
+            onCodePathStart(codePath, node) {
+                if (isCodePathWithLexicalThis(codePath, node)) {
+                    return;
+                }
+
+                if (codePath.origin === "program") {
+                    const scope = sourceCode.getScope(node);
+                    const features = context.languageOptions.parserOptions.ecmaFeatures || {};
+
+                    // `this` at the top level of scripts always refers to the global object
+                    stack.push({
+                        init: true,
+                        node,
+                        valid: !(
+                            node.sourceType === "module" ||
+                            (features.globalReturn && scope.childScopes[0].isStrict)
+                        )
+                    });
+
+                    return;
+                }
+
+                /*
+                 * `init: false` means that `valid` isn't determined yet.
+                 * Most functions don't use `this`, and the calculation for `valid`
+                 * is relatively costly, so we'll calculate it lazily when the first
+                 * `this` within the function is traversed. A special case are non-strict
+                 * functions, because `this` refers to the global object and therefore is
+                 * always valid, so we can set `init: true` right away.
+                 */
+                stack.push({
+                    init: !sourceCode.getScope(node).isStrict,
+                    node,
+                    valid: true
+                });
+            },
+
+            onCodePathEnd(codePath, node) {
+                if (isCodePathWithLexicalThis(codePath, node)) {
+                    return;
+                }
+
+                stack.pop();
+            },
+
+            // Reports if `this` of the current context is invalid.
+            ThisExpression(node) {
+                const current = stack.getCurrent();
+
+                if (current && !current.valid) {
+                    context.report({
+                        node,
+                        messageId: "unexpectedThis"
+                    });
+                }
+            }
+        };
+    }
+};