rune-langium / core/src / parse

Function: parse()

function parse(input, uri?): Promise<ParseResult>;

Defined in: packages/core/src/api/parse.ts:111

Parse a Rosetta DSL source string into a typed AST.

Parameters

Parameter	Type	Description
input	string	The Rosetta DSL source text.
uri?	string	Optional URI for the document (defaults to inmemory:///model.rosetta).

Returns

Promise<ParseResult>

A ParseResult with the root RosettaModel node and any errors.

Remarks

Services are lazily initialized on first call and reused across subsequent calls. The services singleton is module-level — concurrent calls to parse() in tests that re-import the module may share state unexpectedly. Use createRuneDslServices() directly in long-running servers.

Use When

• Validating a single .rosetta file or snippet in memory
• Building a parse pipeline in a Node.js script
• Unit-testing grammar rules in isolation

Avoid When

• Parsing files that have cross-references to other documents — unresolved references will have ref === undefined. Use parseWorkspace() instead.
• Running inside a Langium LSP server — the DocumentBuilder is already managed by the server lifecycle; calling parse() creates a second services instance and wastes memory.

Pitfalls

• Do NOT call parse() on a file whose type references live in other .rosetta files — cross-file references will be unresolved (undefined). Provide all documents to parseWorkspace() for resolved cross-references.
• Do NOT mutate nodes in the returned value — Langium's index tracks AST node identity; mutations bypass incremental reparse and corrupt the scope graph.

Example

import { parse } from '@rune-langium/core';

const result = await parse(`
  namespace com.example
  version "1.0.0"

  type Trade:
    quantity number (1..1)
`);

if (result.hasErrors) {
  console.error(result.lexerErrors, result.parserErrors);
} else {
  console.log(result.value.elements.length, 'elements');
}