Add util method to get a child translator

Author: christopherswenson

packages/malloy/src/lang/parse-malloy.ts

@@ -918,6 +918,14 @@ export abstract class MalloyTranslation {
     return attempt;
   }
 
+  translatorForDependency(url: string): MalloyTranslation {
+    const child = this.childTranslators.get(url);
+    if (child === undefined) {
+      throw new Error(`No child translator for ${url}`);
+    }
+    return child;
+  }
+
   importAt(position: DocumentPosition): ImportLocation | undefined {
     // Here we assume that imports DO NOT overlap. And then we do a linear
     // search to find the one we're looking for.

packages/malloy/src/lang/test/imports.spec.ts

@@ -147,6 +147,12 @@ source: botProjQSrc is botProjQ
         'internal://test/langtests/grandChild': {},
       },
     });
+    const child = docParse.translatorForDependency(
+      'internal://test/langtests/child'
+    );
+    expect(child.translate().modelDef?.dependencies).toMatchObject({
+      'internal://test/langtests/grandChild': {},
+    });
   });
   test('relative imports', () => {
     const docParse = new TestTranslator('import "../parent.malloy"');

packages/malloy/src/lang/test/pretranslate.spec.ts

@@ -40,5 +40,9 @@ describe('pretranslated models', () => {
     expect(docParse.translate().modelDef?.dependencies).toMatchObject({
       'internal://test/langtests/child': {},
     });
+    const child = docParse.translatorForDependency(
+      'internal://test/langtests/child'
+    );
+    expect(child.translate().modelDef?.dependencies).toMatchObject({});
   });
 });