add hw2

node_modules/langium/lib/workspace/ast-node-locator.js

@@ -0,0 +1,46 @@
+/******************************************************************************
+ * Copyright 2021 TypeFox GmbH
+ * This program and the accompanying materials are made available under the
+ * terms of the MIT License, which is available in the project root.
+ ******************************************************************************/
+export class DefaultAstNodeLocator {
+    constructor() {
+        this.segmentSeparator = '/';
+        this.indexSeparator = '@';
+    }
+    getAstNodePath(node) {
+        if (node.$container) {
+            const containerPath = this.getAstNodePath(node.$container);
+            const newSegment = this.getPathSegment(node);
+            const nodePath = containerPath + this.segmentSeparator + newSegment;
+            return nodePath;
+        }
+        return '';
+    }
+    getPathSegment({ $containerProperty, $containerIndex }) {
+        if (!$containerProperty) {
+            throw new Error("Missing '$containerProperty' in AST node.");
+        }
+        if ($containerIndex !== undefined) {
+            return $containerProperty + this.indexSeparator + $containerIndex;
+        }
+        return $containerProperty;
+    }
+    getAstNode(node, path) {
+        const segments = path.split(this.segmentSeparator);
+        return segments.reduce((previousValue, currentValue) => {
+            if (!previousValue || currentValue.length === 0) {
+                return previousValue;
+            }
+            const propertyIndex = currentValue.indexOf(this.indexSeparator);
+            if (propertyIndex > 0) {
+                const property = currentValue.substring(0, propertyIndex);
+                const arrayIndex = parseInt(currentValue.substring(propertyIndex + 1));
+                const array = previousValue[property];
+                return array === null || array === void 0 ? void 0 : array[arrayIndex];
+            }
+            return previousValue[currentValue];
+        }, node);
+    }
+}
+//# sourceMappingURL=ast-node-locator.js.map