feat(parser): create info parser with exporting parser internals

packages/parser/src/index.ts

@@ -0,0 +1,3 @@
+export type { Info } from './language/index.js';
+export type { DiagramAST } from './parse.js';
+export { parse, MermaidParseError } from './parse.js';

packages/parser/src/language/index.ts

@@ -3,3 +3,4 @@ export * from './generated/grammar.js';
 export * from './generated/module.js';
 
 export * from './common/index.js';
+export * from './info/index.js';

packages/parser/src/language/info/index.ts

@@ -0,0 +1 @@
+export * from './infoModule.js';

packages/parser/src/language/info/info.langium

@@ -0,0 +1,9 @@
+grammar Info
+import "../common/common";
+
+entry Info:
+  NEWLINE*
+  "info" NEWLINE*
+  ("showInfo" NEWLINE*)?
+  TitleAndAccessibilities?
+;

packages/parser/src/language/info/infoModule.ts

@@ -0,0 +1,72 @@
+import type {
+  DefaultSharedModuleContext,
+  LangiumServices,
+  LangiumSharedServices,
+  Module,
+  PartialLangiumServices,
+} from 'langium';
+import { EmptyFileSystem, createDefaultModule, createDefaultSharedModule, inject } from 'langium';
+
+import { MermaidGeneratedSharedModule, InfoGeneratedModule } from '../generated/module.js';
+import { CommonLexer } from '../common/commonLexer.js';
+import { CommonValueConverter } from '../common/commonValueConverters.js';
+import { InfoTokenBuilder } from './infoTokenBuilder.js';
+
+/**
+ * Declaration of `Info` services.
+ */
+type InfoAddedServices = {
+  parser: {
+    Lexer: CommonLexer;
+    TokenBuilder: InfoTokenBuilder;
+    ValueConverter: CommonValueConverter;
+  };
+};
+
+/**
+ * Union of Langium default services and `Info` services.
+ */
+export type InfoServices = LangiumServices & InfoAddedServices;
+
+/**
+ * Dependency injection module that overrides Langium default services and
+ * contributes the declared `Info` services.
+ */
+const InfoModule: Module<InfoServices, PartialLangiumServices & InfoAddedServices> = {
+  parser: {
+    Lexer: (services) => new CommonLexer(services),
+    TokenBuilder: () => new InfoTokenBuilder(),
+    ValueConverter: () => new CommonValueConverter(),
+  },
+};
+
+/**
+ * Create the full set of services required by Langium.
+ *
+ * First inject the shared services by merging two modules:
+ *  - Langium default shared services
+ *  - Services generated by langium-cli
+ *
+ * Then inject the language-specific services by merging three modules:
+ *  - Langium default language-specific services
+ *  - Services generated by langium-cli
+ *  - Services specified in this file
+ * @param context - Optional module context with the LSP connection
+ * @returns An object wrapping the shared services and the language-specific services
+ */
+export function createInfoServices(context: DefaultSharedModuleContext = EmptyFileSystem): {
+  shared: LangiumSharedServices;
+  Info: InfoServices;
+} {
+  const shared: LangiumSharedServices = inject(
+    createDefaultSharedModule(context),
+    MermaidGeneratedSharedModule
+  );
+  const Info: InfoServices = inject(
+    createDefaultModule({ shared }),
+    InfoGeneratedModule,
+    InfoModule
+  );
+  shared.ServiceRegistry.register(Info);
+  return { shared, Info };
+}

packages/parser/src/language/info/infoTokenBuilder.ts

@@ -0,0 +1,24 @@
+import type { GrammarAST, Stream, TokenBuilderOptions } from 'langium';
+import { DefaultTokenBuilder } from 'langium';
+
+import type { TokenType } from '../chevrotainWrapper.js';
+
+export class InfoTokenBuilder extends DefaultTokenBuilder {
+  protected override buildKeywordTokens(
+    rules: Stream<GrammarAST.AbstractRule>,
+    terminalTokens: TokenType[],
+    options?: TokenBuilderOptions
+  ): TokenType[] {
+    const tokenTypes: TokenType[] = super.buildKeywordTokens(rules, terminalTokens, options);
+    // to restrict users, they mustn't have any non-whitespace characters after the keyword.
+    tokenTypes.forEach((tokenType: TokenType): void => {
+      if (
+        (tokenType.name === 'info' || tokenType.name === 'showInfo') &&
+        tokenType.PATTERN !== undefined
+      ) {
+        tokenType.PATTERN = new RegExp(tokenType.PATTERN.toString() + '(?!\\S)');
+      }
+    });
+    return tokenTypes;
+  }
+}

packages/parser/src/parse.ts

@@ -0,0 +1,43 @@
+import type { LangiumParser, ParseResult } from 'langium';
+import type { Info } from './index.js';
+import { createInfoServices } from './language/index.js';
+
+export type DiagramAST = Info;
+
+const parsers: Record<string, LangiumParser> = {};
+
+const initializers = {
+  info: () => {
+    // Will have to make parse async to use this. Can try later...
+    // const { createInfoServices } = await import('./language/info/index.js');
+    const parser = createInfoServices().Info.parser.LangiumParser;
+    parsers['info'] = parser;
+  },
+} as const;
+export function parse(diagramType: 'info', text: string): Info;
+export function parse<T extends DiagramAST>(
+  diagramType: keyof typeof initializers,
+  text: string
+): T {
+  const initializer = initializers[diagramType];
+  if (!initializer) {
+    throw new Error(`Unknown diagram type: ${diagramType}`);
+  }
+  if (!parsers[diagramType]) {
+    initializer();
+  }
+  const parser: LangiumParser = parsers[diagramType];
+  const result: ParseResult<T> = parser.parse<T>(text);
+  if (result.lexerErrors.length > 0 || result.parserErrors.length > 0) {
+    throw new MermaidParseError(result);
+  }
+  return result.value;
+}
+
+export class MermaidParseError extends Error {
+  constructor(public result: ParseResult<DiagramAST>) {
+    const lexerErrors: string = result.lexerErrors.map((err) => err.message).join('\n');
+    const parserErrors: string = result.parserErrors.map((err) => err.message).join('\n');
+    super(`Parsing failed: ${lexerErrors} ${parserErrors}`);
+  }
+}

packages/parser/tests/info.test.ts

@@ -0,0 +1,58 @@
+import { describe, expect, it } from 'vitest';
+import type { LangiumParser, ParseResult } from 'langium';
+
+import type { InfoServices } from '../src/language/index.js';
+import { Info, createInfoServices } from '../src/language/index.js';
+
+const services: InfoServices = createInfoServices().Info;
+const parser: LangiumParser = services.parser.LangiumParser;
+export function createInfoTestServices(): {
+  services: InfoServices;
+  parse: (input: string) => ParseResult<Info>;
+} {
+  const parse = (input: string) => {
+    return parser.parse<Info>(input);
+  };
+
+  return { services, parse };
+}
+
+describe('info', () => {
+  const { parse } = createInfoTestServices();
+
+  it.each([
+    `info`,
+    `
+    info`,
+    `info
+    `,
+    `
+    info
+    `,
+  ])('should handle empty info', (context: string) => {
+    const { parserErrors, lexerErrors, value } = parse(context);
+    expect(parserErrors).toHaveLength(0);
+    expect(lexerErrors).toHaveLength(0);
+
+    expect(value.$type).toBe(Info);
+  });
+
+  it.each([
+    `info showInfo`,
+    `
+    info showInfo`,
+    `info
+    showInfo
+    `,
+    `
+    info
+    showInfo
+    `,
+  ])('should handle showInfo', (context: string) => {
+    const { parserErrors, lexerErrors, value } = parse(context);
+    expect(parserErrors).toHaveLength(0);
+    expect(lexerErrors).toHaveLength(0);
+
+    expect(value.$type).toBe(Info);
+  });
+});