Add importExtension to LangiumConfig (#1072)

When downstream projects are using `nodenext` module resolution, file extensions are mandatory. Developers can use `importExtension` to specify the extension used in generated import statements. --------- Co-authored-by: Mark Sujew <mark.sujew@typefox.io>
eclipse-langium · Aug 15, 2023 · 45e8c5d · 45e8c5d
1 parent df21799
commit 45e8c5d
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Showing 4 changed files with 53 additions and 3 deletions.
diff --git a/packages/langium-cli/langium-config-schema.json b/packages/langium-cli/langium-config-schema.json
@@ -130,6 +130,10 @@
             "description": "The relative directory to the code generated by the langium-cli",
             "type": "string"
         },
+        "importExtension": {
+            "description": "File extension used for TypeScript import statements. Empty by default",
+            "type": "string"
+        },
         "chevrotainParserConfig": {
             "$ref": "#/$defs/chevrotainParserConfig"
         },

diff --git a/packages/langium-cli/src/generator/module-generator.ts b/packages/langium-cli/src/generator/module-generator.ts
@@ -13,6 +13,7 @@ export function generateModule(grammars: Grammar[], config: LangiumConfig, gramm
     const parserConfig = config.chevrotainParserConfig;
     const hasIParserConfigImport = Boolean(parserConfig) || grammars.some(grammar => grammarConfigMap.get(grammar)?.chevrotainParserConfig !== undefined);
     const node = new CompositeGeneratorNode();
+    const importExtension = config.importExtension ?? '';
 
     node.append(generatedHeader);
     if (config.langiumInternal) {
@@ -25,9 +26,11 @@ export function generateModule(grammars: Grammar[], config: LangiumConfig, gramm
     } else {
         node.append(`import type { LangiumGeneratedServices, LangiumGeneratedSharedServices, LangiumSharedServices, LangiumServices, LanguageMetaData, Module${hasIParserConfigImport ? ', IParserConfig' : ''} } from 'langium';`, NL);
     }
-
     node.append(
-        'import { ', config.projectName, "AstReflection } from './ast';", NL,
+        'import { ',
+        config.projectName,
+        `AstReflection } from './ast${importExtension}';`,
+        NL,
         'import { '
     );
     for (let i = 0; i < grammars.length; i++) {
@@ -39,7 +42,7 @@ export function generateModule(grammars: Grammar[], config: LangiumConfig, gramm
             }
         }
     }
-    node.append(" } from './grammar';", NL, NL);
+    node.append(` } from './grammar${importExtension}';`, NL, NL);
 
     for (const grammar of grammars) {
         if (grammar.name) {

diff --git a/packages/langium-cli/src/package.ts b/packages/langium-cli/src/package.ts
@@ -29,6 +29,8 @@ export interface LangiumConfig {
     languages: LangiumLanguageConfig[]
     /** Main output directory for TypeScript code */
     out?: string
+    /** File extension for import statements of generated files */
+    importExtension?: string
     /** Configure the chevrotain parser for all languages */
     chevrotainParserConfig?: IParserConfig,
     /** The following option is meant to be used only by Langium itself */

diff --git a/packages/langium-cli/test/generator/module-generator.test.ts b/packages/langium-cli/test/generator/module-generator.test.ts
@@ -49,4 +49,45 @@ describe('Module generator', () => {
             expect(moduleString).toMatch(/^import .* IParserConfig/gm);
         });
     });
+
+    describe('File extension inclusion', () => {
+        test('should not include .js extension in imports', () => {
+            // arrange
+            const config = {
+                projectName: 'Magic',
+                languages: [],
+                [RelativePath]: '/path/to/magic',
+            };
+
+            // act
+            const moduleString = generateModule([], config, new Map());
+
+            // assert
+            expect(moduleString.includes("from './grammar';")).toBeTruthy();
+            expect(moduleString.includes("from './ast';")).toBeTruthy();
+
+            expect(moduleString.includes("from './grammar.js';")).toBeFalsy();
+            expect(moduleString.includes("from './ast.js';")).toBeFalsy();
+        });
+
+        test('should include .js extension in imports', () => {
+            // arrange
+            const config: LangiumConfig = {
+                projectName: 'Magic',
+                languages: [],
+                [RelativePath]: '/path/to/magic',
+                importExtension: '.js'
+            };
+
+            // act
+            const moduleString = generateModule([], config, new Map());
+
+            // assert
+            expect(moduleString.includes("from './grammar.js';")).toBeTruthy();
+            expect(moduleString.includes("from './ast.js';")).toBeTruthy();
+
+            expect(moduleString.includes("from './grammar';")).toBeFalsy();
+            expect(moduleString.includes("from './ast';")).toBeFalsy();
+        });
+    });
 });