chore(parser)!: upgrade parser to Langium v4

aloisklink · aloisklink · commit 72433401a8c9 · 2026-02-13T20:40:20.000+09:00
Updates the `@mermaid-js/parser` to Langium v4.

There were a couple of breaking changes we had to fix to do this
upgrade:

- Rename all the grammers from Abc to AbcGrammar, as rules
  within grammars cannot have the same name as the grammar.
- Update the tests, since the generated type names from `ast.ts` have
  been moved from `&lt;typeName&gt;` to `&lt;typeName&gt;.$type`.
- Turn the EOL fragment into a rule, as in Langium v4, it's no longer
  allowed and throws an error.

As this is a **BREAKING CHANGE** for users, I've made a new major
release in the changeset (and it means we can finally get a v1.0.0 of
`@mermaid-js/parser`).
diff --git a/.changeset/shiny-coats-stay.md b/.changeset/shiny-coats-stay.md
@@ -0,0 +1,22 @@
+---
+'@mermaid-js/parser': major
+---
+
+chore: upgrade to Langium v4
+
+Upgrade `@mermaid-js/parser` to use Langium v4,
+see https://github.com/eclipse-langium/langium/releases/tag/v4.0.0
+for more details.
+
+The major breaking changes that impact consumers of this package are:
+
+- Due to various type-related changes, `langium` now requires version `>= 5.8.0`
+  of TypeScript.
+- The generated type names from `ast.ts` have been moved from `<typeName>` to
+  `<typeName>.$type`
+  ([langium#1942](https://github.com/eclipse-langium/langium/pull/1942)).
+
+This also removes a transitive dependency on lodash versions that are vulnerable
+to CVE-2025-13465, although
+[chevrotain doesn't use the affected functions](https://github.com/Chevrotain/chevrotain/blob/21f20cd9754f8d5e85243fd9286d1fff397363ab/packages/website/docs/changes/CHANGELOG.md?plain=1#L5-L8),
+so this is only to silence security scanners.
diff --git a/package.json b/package.json
@@ -113,7 +113,7 @@
     "jison": "^0.4.18",
     "js-yaml": "^4.1.0",
     "jsdom": "^26.1.0",
-    "langium-cli": "^3.5.0",
+    "langium-cli": "^4.0.0",
     "lint-staged": "^16.1.6",
     "markdown-table": "^3.0.4",
     "nyc": "^17.1.0",
diff --git a/packages/mermaid/src/diagrams/git/gitGraphParser.ts b/packages/mermaid/src/diagrams/git/gitGraphParser.ts
@@ -181,6 +181,9 @@ if (import.meta.vitest) {
       const dummy: GitGraph = {
         $type: 'GitGraph',
         statements: [],
+        accDescr: '',
+        accTitle: '',
+        title: '',
       };
       const gitGraphAst: GitGraph = {
         $type: 'GitGraph',
@@ -220,6 +223,9 @@ if (import.meta.vitest) {
             parent: '2',
           },
         ],
+        accDescr: '',
+        accTitle: '',
+        title: '',
       };
 
       populate(gitGraphAst, mockDB);
diff --git a/packages/parser/package.json b/packages/parser/package.json
@@ -33,10 +33,10 @@
     "ast"
   ],
   "dependencies": {
-    "langium": "^3.5.0"
+    "langium": "^4.0.0"
   },
   "devDependencies": {
-    "chevrotain": "^11.0.3"
+    "chevrotain": "~11.1.1"
   },
   "files": [
     "dist/"
diff --git a/packages/parser/src/language/architecture/architecture.langium b/packages/parser/src/language/architecture/architecture.langium
@@ -1,4 +1,4 @@
-grammar Architecture
+grammar ArchitectureGrammar
 import "../common/common";
 import "arch";
 
diff --git a/packages/parser/src/language/architecture/module.ts b/packages/parser/src/language/architecture/module.ts
@@ -12,7 +12,10 @@ import {
   inject,
 } from 'langium';
 
-import { MermaidGeneratedSharedModule, ArchitectureGeneratedModule } from '../generated/module.js';
+import {
+  MermaidGeneratedSharedModule,
+  ArchitectureGrammarGeneratedModule as ArchitectureGeneratedModule,
+} from '../generated/module.js';
 import { ArchitectureTokenBuilder } from './tokenBuilder.js';
 import { ArchitectureValueConverter } from './valueConverter.js';
 
diff --git a/packages/parser/src/language/common/common.langium b/packages/parser/src/language/common/common.langium
@@ -3,9 +3,7 @@
 // When imported, the terminals are considered after the terminals in the importing grammar
 // Note: Hence, to add a terminal greedier than the common terminals, import it separately after the common import
 
-fragment EOL returns string:
-  NEWLINE+ | EOF
-;
+EOL returns string: NEWLINE+ | EOF;
 
 fragment TitleAndAccessibilities:
   ((accDescr=ACC_DESCR | accTitle=ACC_TITLE | title=TITLE) EOL)+
diff --git a/packages/parser/src/language/gitGraph/gitGraph.langium b/packages/parser/src/language/gitGraph/gitGraph.langium
@@ -1,4 +1,4 @@
-grammar GitGraph
+grammar GitGraphGrammar
 import "../common/common";
 import "reference";
 
diff --git a/packages/parser/src/language/gitGraph/module.ts b/packages/parser/src/language/gitGraph/module.ts
@@ -12,7 +12,10 @@ import {
   EmptyFileSystem,
 } from 'langium';
 import { CommonValueConverter } from '../common/valueConverter.js';
-import { MermaidGeneratedSharedModule, GitGraphGeneratedModule } from '../generated/module.js';
+import {
+  MermaidGeneratedSharedModule,
+  GitGraphGrammarGeneratedModule as GitGraphGeneratedModule,
+} from '../generated/module.js';
 import { GitGraphTokenBuilder } from './tokenBuilder.js';
 
 interface GitGraphAddedServices {
diff --git a/packages/parser/src/language/index.ts b/packages/parser/src/language/index.ts
@@ -27,14 +27,14 @@ export {
 } from './generated/ast.js';
 
 export {
-  InfoGeneratedModule,
+  InfoGrammarGeneratedModule as InfoGeneratedModule,
   MermaidGeneratedSharedModule,
-  PacketGeneratedModule,
-  PieGeneratedModule,
-  ArchitectureGeneratedModule,
-  GitGraphGeneratedModule,
-  RadarGeneratedModule,
-  TreemapGeneratedModule,
+  PacketGrammarGeneratedModule as PacketGeneratedModule,
+  PieGrammarGeneratedModule as PieGeneratedModule,
+  ArchitectureGrammarGeneratedModule as ArchitectureGeneratedModule,
+  GitGraphGrammarGeneratedModule as GitGraphGeneratedModule,
+  RadarGrammarGeneratedModule as RadarGeneratedModule,
+  TreemapGrammarGeneratedModule as TreemapGeneratedModule,
 } from './generated/module.js';
 
 export * from './gitGraph/index.js';
diff --git a/packages/parser/src/language/info/info.langium b/packages/parser/src/language/info/info.langium
@@ -1,4 +1,4 @@
-grammar Info
+grammar InfoGrammar
 import "../common/common";
 
 entry Info:
diff --git a/packages/parser/src/language/info/module.ts b/packages/parser/src/language/info/module.ts
@@ -13,7 +13,10 @@ import {
 } from 'langium';
 
 import { CommonValueConverter } from '../common/index.js';
-import { InfoGeneratedModule, MermaidGeneratedSharedModule } from '../generated/module.js';
+import {
+  InfoGrammarGeneratedModule as InfoGeneratedModule,
+  MermaidGeneratedSharedModule,
+} from '../generated/module.js';
 import { InfoTokenBuilder } from './tokenBuilder.js';
 
 /**
diff --git a/packages/parser/src/language/packet/module.ts b/packages/parser/src/language/packet/module.ts
@@ -13,7 +13,10 @@ import {
 } from 'langium';
 
 import { CommonValueConverter } from '../common/valueConverter.js';
-import { MermaidGeneratedSharedModule, PacketGeneratedModule } from '../generated/module.js';
+import {
+  MermaidGeneratedSharedModule,
+  PacketGrammarGeneratedModule as PacketGeneratedModule,
+} from '../generated/module.js';
 import { PacketTokenBuilder } from './tokenBuilder.js';
 
 /**
diff --git a/packages/parser/src/language/packet/packet.langium b/packages/parser/src/language/packet/packet.langium
@@ -1,4 +1,4 @@
-grammar Packet
+grammar PacketGrammar
 import "../common/common";
 
 entry Packet:
diff --git a/packages/parser/src/language/pie/module.ts b/packages/parser/src/language/pie/module.ts
@@ -12,7 +12,10 @@ import {
   inject,
 } from 'langium';
 
-import { MermaidGeneratedSharedModule, PieGeneratedModule } from '../generated/module.js';
+import {
+  MermaidGeneratedSharedModule,
+  PieGrammarGeneratedModule as PieGeneratedModule,
+} from '../generated/module.js';
 import { PieTokenBuilder } from './tokenBuilder.js';
 import { PieValueConverter } from './valueConverter.js';
 
diff --git a/packages/parser/src/language/pie/pie.langium b/packages/parser/src/language/pie/pie.langium
@@ -1,4 +1,4 @@
-grammar Pie
+grammar PieGrammar
 import "../common/common";
 
 entry Pie:
@@ -17,4 +17,4 @@ PieSection:
 
 terminal FLOAT_PIE returns number: /-?[0-9]+\.[0-9]+(?!\.)/;
 terminal INT_PIE returns number: /-?(0|[1-9][0-9]*)(?!\.)/;
-terminal NUMBER_PIE returns number: FLOAT_PIE |  INT_PIE;
+terminal NUMBER_PIE returns number: FLOAT_PIE |  INT_PIE;
diff --git a/packages/parser/src/language/radar/module.ts b/packages/parser/src/language/radar/module.ts
@@ -12,7 +12,10 @@ import {
   inject,
 } from 'langium';
 import { CommonValueConverter } from '../common/valueConverter.js';
-import { MermaidGeneratedSharedModule, RadarGeneratedModule } from '../generated/module.js';
+import {
+  MermaidGeneratedSharedModule,
+  RadarGrammarGeneratedModule as RadarGeneratedModule,
+} from '../generated/module.js';
 import { RadarTokenBuilder } from './tokenBuilder.js';
 
 /**
diff --git a/packages/parser/src/language/radar/radar.langium b/packages/parser/src/language/radar/radar.langium
@@ -1,4 +1,4 @@
-grammar Radar
+grammar RadarGrammar
 import "../common/common";
 
 entry Radar:
@@ -52,4 +52,4 @@ Option:
     )
 ;   
 
-terminal GRATICULE returns string: 'circle' | 'polygon';
+terminal GRATICULE returns string: 'circle' | 'polygon';
diff --git a/packages/parser/src/language/treemap/module.ts b/packages/parser/src/language/treemap/module.ts
@@ -12,7 +12,10 @@ import {
   inject,
 } from 'langium';
 
-import { MermaidGeneratedSharedModule, TreemapGeneratedModule } from '../generated/module.js';
+import {
+  MermaidGeneratedSharedModule,
+  TreemapGrammarGeneratedModule as TreemapGeneratedModule,
+} from '../generated/module.js';
 import { TreemapTokenBuilder } from './tokenBuilder.js';
 import { TreemapValueConverter } from './valueConverter.js';
 import { TreemapValidator, registerValidationChecks } from './treemap-validator.js';
diff --git a/packages/parser/src/language/treemap/treemap.langium b/packages/parser/src/language/treemap/treemap.langium
@@ -6,7 +6,7 @@
  * before the treemap keyword, allowing for empty lines and comments before the
  * treemap declaration.
  */
-grammar Treemap
+grammar TreemapGrammar
 
 
 
diff --git a/packages/parser/tests/architecture.test.ts b/packages/parser/tests/architecture.test.ts
@@ -15,7 +15,7 @@ describe('architecture', () => {
     ])('should handle regular architecture', (context: string) => {
       const result = parse(context);
       expectNoErrorsOrAlternatives(result);
-      expect(result.value.$type).toBe(Architecture);
+      expect(result.value.$type).toBe(Architecture.$type);
     });
   });
 
@@ -30,7 +30,7 @@ describe('architecture', () => {
     ])('should handle regular architecture + title in same line', (context: string) => {
       const result = parse(context);
       expectNoErrorsOrAlternatives(result);
-      expect(result.value.$type).toBe(Architecture);
+      expect(result.value.$type).toBe(Architecture.$type);
 
       const { title } = result.value;
       expect(title).toBe('sample title');
@@ -45,7 +45,7 @@ describe('architecture', () => {
     ])('should handle regular architecture + title in next line', (context: string) => {
       const result = parse(context);
       expectNoErrorsOrAlternatives(result);
-      expect(result.value.$type).toBe(Architecture);
+      expect(result.value.$type).toBe(Architecture.$type);
 
       const { title } = result.value;
       expect(title).toBe('sample title');
@@ -59,7 +59,7 @@ describe('architecture', () => {
             `;
       const result = parse(context);
       expectNoErrorsOrAlternatives(result);
-      expect(result.value.$type).toBe(Architecture);
+      expect(result.value.$type).toBe(Architecture.$type);
 
       const { title, accTitle, accDescr } = result.value;
       expect(title).toBe('sample title');
@@ -77,7 +77,7 @@ describe('architecture', () => {
             `;
       const result = parse(context);
       expectNoErrorsOrAlternatives(result);
-      expect(result.value.$type).toBe(Architecture);
+      expect(result.value.$type).toBe(Architecture.$type);
 
       const { title, accTitle, accDescr } = result.value;
       expect(title).toBe('sample title');
diff --git a/packages/parser/tests/info.test.ts b/packages/parser/tests/info.test.ts
@@ -16,7 +16,7 @@ describe('info', () => {
   ])('should handle empty info', (context: string) => {
     const result = parse(context);
     expectNoErrorsOrAlternatives(result);
-    expect(result.value.$type).toBe(Info);
+    expect(result.value.$type).toBe(Info.$type);
   });
 
   it.each([
@@ -43,6 +43,6 @@ describe('info', () => {
   ])('should handle showInfo', (context: string) => {
     const result = parse(context);
     expectNoErrorsOrAlternatives(result);
-    expect(result.value.$type).toBe(Info);
+    expect(result.value.$type).toBe(Info.$type);
   });
 });
diff --git a/packages/parser/tests/packet.test.ts b/packages/parser/tests/packet.test.ts
@@ -20,6 +20,6 @@ describe('packet', () => {
   ])('should handle regular packet', (context: string) => {
     const result = parse(context);
     expectNoErrorsOrAlternatives(result);
-    expect(result.value.$type).toBe(Packet);
+    expect(result.value.$type).toBe(Packet.$type);
   });
 });
diff --git a/packages/parser/tests/pie.test.ts b/packages/parser/tests/pie.test.ts
diff --git a/packages/parser/tests/radar.test.ts b/packages/parser/tests/radar.test.ts
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-grammar Architecture`
	`1`	`+grammar ArchitectureGrammar`
`2`	`2`	`import "../common/common";`
`3`	`3`	`import "arch";`
`4`	`4`
Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-grammar GitGraph`
	`1`	`+grammar GitGraphGrammar`
`2`	`2`	`import "../common/common";`
`3`	`3`	`import "reference";`
`4`	`4`