Add type narrowing to parse.

mermaid-js · Aug 17, 2023 · efad6b3 · efad6b3
1 parent 6fa8294
commit efad6b3
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 5 deletions.
diff --git a/packages/mermaid/src/diagrams/info/infoParser.ts b/packages/mermaid/src/diagrams/info/infoParser.ts
@@ -14,7 +14,7 @@ function populateDb(ast: Info, db: InfoDB) {
 
 export const parser: ParserDefinition = {
   parse: (input: string): void => {
-    const result = parse<Info>('info', input);
+    const result = parse('info', input);
     log.debug(result);
     populateDb(result, db);
   },

diff --git a/packages/parser/src/parse.ts b/packages/parser/src/parse.ts
@@ -1,5 +1,4 @@
 import type { LangiumParser, ParseResult } from 'langium';
-
 import type { Info } from './index.js';
 import { createInfoServices } from './language/index.js';
 
@@ -16,10 +15,11 @@ const initializers = {
   },
 } as const;
 
-export const parse = <T extends DiagramAST>(
+export function parse<Info>(diagramType: 'info', text: string): Info;
+export function parse<T extends DiagramAST>(
   diagramType: keyof typeof initializers,
   text: string
-): T => {
+): T {
   const initializer = initializers[diagramType];
   if (!initializer) {
     throw new Error(`Unknown diagram type: ${diagramType}`);
@@ -33,7 +33,7 @@ export const parse = <T extends DiagramAST>(
     throw new MermaidParseError(result);
   }
   return result.value;
-};
+}
 
 export class MermaidParseError extends Error {
   constructor(public result: ParseResult<DiagramAST>) {