Generate grammar comments (#1335)

Author: msujew

packages/langium-cli/src/generator/grammar-serializer.ts

@@ -36,6 +36,7 @@ export function serializeGrammar(services: LangiumServices, grammars: Grammar[],
                 };
                 const serializedGrammar = services.serializer.JsonSerializer.serialize(grammar, {
                     space: production ? undefined : 2,
+                    comments: true,
                     uriConverter
                 });
                 // The json serializer returns strings with \n line delimiter by default

packages/langium-cli/test/generator/grammar-serializer.test.ts

@@ -0,0 +1,48 @@
+/******************************************************************************
+ * 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.
+ ******************************************************************************/
+
+import type { LangiumConfig } from '../../src/package.js';
+import { EmptyFileSystem, URI, type Grammar } from 'langium';
+import { describe, expect, test } from 'vitest';
+import { RelativePath } from '../../src/package.js';
+import { serializeGrammar } from '../../src/generator/grammar-serializer.js';
+import { createLangiumGrammarServices } from 'langium/grammar';
+import { expandToString } from 'langium/generate';
+
+const grammarServices = createLangiumGrammarServices(EmptyFileSystem);
+
+describe('Grammar serializer', () => {
+    test('should include comments of AST elements', async () => {
+        // arrange
+        const config: LangiumConfig = {
+            projectName: 'Magic',
+            languages: [],
+            [RelativePath]: '/path/to/magic',
+        };
+
+        const grammarText = expandToString`
+        grammar Test
+
+        /**
+         * This is the entry rule
+         */
+        entry Model: /** This is the name assignment */ name='test';
+        `;
+
+        const document = grammarServices.shared.workspace.LangiumDocumentFactory.fromString<Grammar>(grammarText, URI.file('test.langium'));
+        grammarServices.shared.workspace.LangiumDocuments.addDocument(document);
+        await grammarServices.shared.workspace.DocumentBuilder.build([document]);
+        const grammar = document.parseResult.value;
+
+        // act
+        const moduleString = serializeGrammar(grammarServices.grammar, [grammar], config);
+
+        // assert
+        expect(moduleString).toMatch('"$comment": "/** This is the name assignment */"');
+        expect(moduleString).toMatch('"$comment": "/**\\\\n * This is the entry rule\\\\n */"');
+    });
+
+});

packages/langium/src/grammar/langium-grammar.langium

@@ -1,8 +1,9 @@
-/******************************************************************************
- * 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.
- ******************************************************************************/
+// ******************************************************************************
+// 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.
+// *****************************************************************************
+
 grammar LangiumGrammar
 
 entry Grammar:

packages/langium/src/serializer/json-serializer.ts

@@ -187,7 +187,10 @@ export class DefaultJsonSerializer implements JsonSerializer {
             }
             if (comments) {
                 astNode ??= { ...value };
-                (astNode as AstNodeWithComment).$comment = this.commentProvider.getComment(value);
+                const comment = this.commentProvider.getComment(value);
+                if (comment) {
+                    (astNode as AstNodeWithComment).$comment = comment.replace(/\r/g, '');
+                }
             }
             return astNode ?? value;
         } else {