Infer optional properties for guarded groups (#1116)

eclipse-langium · Jul 19, 2023 · c28b8c5 · c28b8c5
1 parent 922d377
commit c28b8c5
Show file tree

Hide file tree

Showing 4 changed files with 19 additions and 6 deletions.
diff --git a/packages/langium/src/grammar/internal-grammar-util.ts b/packages/langium/src/grammar/internal-grammar-util.ts
@@ -15,8 +15,8 @@ import { escapeRegExp } from '../utils/regex-util';
 export type Cardinality = '?' | '*' | '+' | undefined;
 export type Operator = '=' | '+=' | '?=' | undefined;
 
-export function isOptionalCardinality(cardinality?: Cardinality): boolean {
-    return cardinality === '?' || cardinality === '*';
+export function isOptionalCardinality(cardinality?: Cardinality, element?: ast.AbstractElement): boolean {
+    return cardinality === '?' || cardinality === '*' || (ast.isGroup(element) && Boolean(element.guardCondition));
 }
 
 export function isArrayCardinality(cardinality?: Cardinality): boolean {

diff --git a/packages/langium/src/grammar/type-system/type-collector/inferred-types.ts b/packages/langium/src/grammar/type-system/type-collector/inferred-types.ts
@@ -329,7 +329,7 @@ function newTypePart(element?: ParserRule | Action | string): TypePart {
  * @param element The given AST element, from which it's necessary to extract the type.
  */
 function collectElement(graph: TypeGraph, current: TypePart, element: AbstractElement): TypePart {
-    const optional = isOptionalCardinality(element.cardinality);
+    const optional = isOptionalCardinality(element.cardinality, element);
     if (isAlternatives(element)) {
         const children: TypePart[] = [];
         if (optional) {

diff --git a/packages/langium/src/lsp/completion/follow-element-computation.ts b/packages/langium/src/lsp/completion/follow-element-computation.ts
@@ -101,7 +101,7 @@ function findNextFeaturesInternal(options: { next: NextFeature, cardinalities: M
         }
         // Try to find the next elements of the parent
         // Only do this if every following element is either optional or has been parsed as +
-        if (features.every(e => isOptionalCardinality(e.feature.cardinality) || isOptionalCardinality(cardinalities.get(e.feature)) || plus.has(e.feature))) {
+        if (features.every(e => isOptionalCardinality(e.feature.cardinality, e.feature) || isOptionalCardinality(cardinalities.get(e.feature)) || plus.has(e.feature))) {
             features.push(...findNextFeaturesInternal({
                 next: {
                     feature: parent,
@@ -211,7 +211,7 @@ function findNextFeaturesInGroup(next: NextFeature<ast.Group>, index: number, ca
             visited,
             plus
         }));
-        if (!isOptionalCardinality(firstFeature.feature.cardinality ?? cardinalities.get(firstFeature.feature))) {
+        if (!isOptionalCardinality(firstFeature.feature.cardinality ?? cardinalities.get(firstFeature.feature), firstFeature.feature)) {
             break;
         }
     }
@@ -253,7 +253,7 @@ function interpretStackToken(stack: NextFeature[], token?: IToken): NextFeature[
         for (const nextFeature of allNextFeatures) {
             newStacks.push([...stack, nextFeature]);
         }
-        if (!allNextFeatures.every(e => isOptionalCardinality(e.feature.cardinality) || isOptionalCardinality(cardinalities.get(e.feature)))) {
+        if (!allNextFeatures.every(e => isOptionalCardinality(e.feature.cardinality, e.feature) || isOptionalCardinality(cardinalities.get(e.feature)))) {
             break;
         }
     }

diff --git a/packages/langium/test/grammar/type-system/inferred-types.test.ts b/packages/langium/test/grammar/type-system/inferred-types.test.ts
@@ -74,6 +74,19 @@ describe('Inferred types', () => {
         `);
     });
 
+    test('Should infer optional property for guarded group', async () => {
+        await expectTypes(`
+            A<G>: a=ID (<G> b=ID);
+            terminal ID returns string: /string/;
+        `, expandToString`
+            export interface A extends AstNode {
+                readonly $type: 'A';
+                a: string
+                b?: string
+            }
+        `);
+    });
+
     test('Should correctly infer types using chained actions', async () => {
         await expectTypes(`
             A: a=ID ({infer B} b=ID ({infer C} c=ID)?)? d=ID;