feat: scoping for inherited members (#706)

Closes #540

### Summary of Changes

Implement reference resolution to inherited class members.

Author: lars-reimann

packages/safe-ds-lang/src/language/scoping/safe-ds-scope-provider.ts

@@ -63,14 +63,16 @@ import {
     getTypeParameters,
     isStatic,
 } from '../helpers/nodeProperties.js';
+import { SafeDsNodeMapper } from '../helpers/safe-ds-node-mapper.js';
 import { SafeDsServices } from '../safe-ds-module.js';
+import { ClassType, EnumVariantType } from '../typing/model.js';
+import type { SafeDsClassHierarchy } from '../typing/safe-ds-class-hierarchy.js';
 import { SafeDsTypeComputer } from '../typing/safe-ds-type-computer.js';
 import { SafeDsPackageManager } from '../workspace/safe-ds-package-manager.js';
-import { SafeDsNodeMapper } from '../helpers/safe-ds-node-mapper.js';
-import { ClassType, EnumVariantType } from '../typing/model.js';
 
 export class SafeDsScopeProvider extends DefaultScopeProvider {
     private readonly astReflection: AstReflection;
+    private readonly classHierarchy: SafeDsClassHierarchy;
     private readonly nodeMapper: SafeDsNodeMapper;
     private readonly packageManager: SafeDsPackageManager;
     private readonly typeComputer: SafeDsTypeComputer;
@@ -79,6 +81,7 @@ export class SafeDsScopeProvider extends DefaultScopeProvider {
         super(services);
 
         this.astReflection = services.shared.AstReflection;
+        this.classHierarchy = services.types.ClassHierarchy;
         this.nodeMapper = services.helpers.NodeMapper;
         this.packageManager = services.workspace.PackageManager;
         this.typeComputer = services.types.TypeComputer;
@@ -178,12 +181,9 @@ export class SafeDsScopeProvider extends DefaultScopeProvider {
         const declaration = this.getUniqueReferencedDeclarationForExpression(node.receiver);
         if (isSdsClass(declaration)) {
             const ownStaticMembers = getMatchingClassMembers(declaration, isStatic);
-            // val superTypeMembers = receiverDeclaration.superClassMembers()
-            //     .filter { it.isStatic() }
-            //     .toList()
-            //
-            // return Scopes.scopeFor(ownStaticMembers, Scopes.scopeFor(superTypeMembers))
-            return this.createScopeForNodes(ownStaticMembers);
+            const superclassStaticMembers = this.classHierarchy.streamSuperclassMembers(declaration).filter(isStatic);
+
+            return this.createScopeForNodes(ownStaticMembers, this.createScopeForNodes(superclassStaticMembers));
         } else if (isSdsEnum(declaration)) {
             return this.createScopeForNodes(getEnumVariants(declaration));
         }
@@ -208,12 +208,14 @@ export class SafeDsScopeProvider extends DefaultScopeProvider {
 
         if (receiverType instanceof ClassType) {
             const ownInstanceMembers = getMatchingClassMembers(receiverType.declaration, (it) => !isStatic(it));
-            // val superTypeMembers = type.sdsClass.superClassMembers()
-            //     .filter { !it.isStatic() }
-            //     .toList()
-            //
-            // Scopes.scopeFor(members, Scopes.scopeFor(superTypeMembers, resultScope))
-            return this.createScopeForNodes(ownInstanceMembers, resultScope);
+            const superclassInstanceMembers = this.classHierarchy
+                .streamSuperclassMembers(receiverType.declaration)
+                .filter((it) => !isStatic(it));
+
+            return this.createScopeForNodes(
+                ownInstanceMembers,
+                this.createScopeForNodes(superclassInstanceMembers, resultScope),
+            );
         } else if (receiverType instanceof EnumVariantType) {
             const parameters = getParameters(receiverType.declaration);
             return this.createScopeForNodes(parameters, resultScope);

packages/safe-ds-lang/src/language/typing/model.ts

@@ -137,17 +137,6 @@ export class NamedTupleType<T extends SdsDeclaration> extends Type {
         return this.entries[index]?.type ?? UnknownType;
     }
 
-    /**
-     * If this only has one entry, returns its type. Otherwise, returns this.
-     */
-    override unwrap(): Type {
-        if (this.entries.length === 1) {
-            return this.entries[0].type;
-        }
-
-        return this;
-    }
-
     override equals(other: Type): boolean {
         if (other === this) {
             return true;
@@ -164,6 +153,17 @@ export class NamedTupleType<T extends SdsDeclaration> extends Type {
     override toString(): string {
         return `(${this.entries.join(', ')})`;
     }
+
+    /**
+     * If this only has one entry, returns its type. Otherwise, returns this.
+     */
+    override unwrap(): Type {
+        if (this.entries.length === 1) {
+            return this.entries[0].type;
+        }
+
+        return this;
+    }
 }
 
 export class NamedTupleEntry<T extends SdsDeclaration> {

packages/safe-ds-lang/src/language/typing/safe-ds-class-hierarchy.ts

@@ -1,10 +1,10 @@
-import { SafeDsServices } from '../safe-ds-module.js';
-import { SafeDsClasses } from '../builtins/safe-ds-classes.js';
-import { SdsClass } from '../generated/ast.js';
 import { EMPTY_STREAM, stream, Stream } from 'langium';
-import { getParentTypes } from '../helpers/nodeProperties.js';
-import { SafeDsTypeComputer } from './safe-ds-type-computer.js';
+import { SafeDsClasses } from '../builtins/safe-ds-classes.js';
+import { SdsClass, type SdsClassMember } from '../generated/ast.js';
+import { getMatchingClassMembers, getParentTypes } from '../helpers/nodeProperties.js';
+import { SafeDsServices } from '../safe-ds-module.js';
 import { ClassType } from './model.js';
+import { SafeDsTypeComputer } from './safe-ds-type-computer.js';
 
 export class SafeDsClassHierarchy {
     private readonly builtinClasses: SafeDsClasses;
@@ -60,6 +60,14 @@ export class SafeDsClassHierarchy {
         }
     }
 
+    streamSuperclassMembers(node: SdsClass | undefined): Stream<SdsClassMember> {
+        if (!node) {
+            return EMPTY_STREAM;
+        }
+
+        return this.streamSuperclasses(node).flatMap(getMatchingClassMembers);
+    }
+
     /**
      * Returns the parent class of the given class, or undefined if there is no parent class. Only the first parent
      * type is considered, i.e. multiple inheritance is not supported.
@@ -74,22 +82,3 @@ export class SafeDsClassHierarchy {
         return undefined;
     }
 }
-
-// fun SdsClass.superClassMembers() =
-//     this.superClasses().flatMap { it.classMembersOrEmpty().asSequence() }
-//
-// // TODO only static methods can be hidden
-// fun SdsFunction.hiddenFunction(): SdsFunction? {
-//     val containingClassOrInterface = closestAncestorOrNull<SdsClass>() ?: return null
-//     return containingClassOrInterface.superClassMembers()
-//         .filterIsInstance<SdsFunction>()
-//         .firstOrNull { it.name == name }
-// }
-//
-// fun SdsClass?.inheritedNonStaticMembersOrEmpty(): Set<SdsAbstractDeclaration> {
-//     return this?.parentClassesOrEmpty()
-//         ?.flatMap { it.classMembersOrEmpty() }
-// ?.filter { it is SdsAttribute && !it.isStatic || it is SdsFunction && !it.isStatic }
-// ?.toSet()
-//     .orEmpty()
-// }

packages/safe-ds-lang/tests/language/typing/safe-ds-class-hierarchy.test.ts

@@ -1,8 +1,8 @@
-import { afterEach, beforeEach, describe, expect, it } from 'vitest';
-import { createSafeDsServices } from '../../../src/language/safe-ds-module.js';
 import { NodeFileSystem } from 'langium/node';
 import { clearDocuments } from 'langium/test';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 import { isSdsClass, SdsClass } from '../../../src/language/generated/ast.js';
+import { createSafeDsServices } from '../../../src/language/index.js';
 import { getNodeOfType } from '../../helpers/nodeFinder.js';
 
 const services = createSafeDsServices(NodeFileSystem).SafeDs;
@@ -131,4 +131,73 @@ describe('SafeDsClassHierarchy', async () => {
             expect(superclassNames(firstClass)).toStrictEqual(expected);
         });
     });
+
+    describe('streamSuperclassMembers', () => {
+        const superclassMemberNames = (node: SdsClass | undefined) =>
+            classHierarchy
+                .streamSuperclassMembers(node)
+                .map((member) => member.name)
+                .toArray();
+
+        it('should return an empty stream if passed undefined', () => {
+            expect(superclassMemberNames(undefined)).toStrictEqual([]);
+        });
+
+        const testCases = [
+            {
+                testName: 'should return the members of the parent type',
+                code: `
+                    class A {
+                        attr a: Int
+                        fun f()
+                    }
+
+                    class B sub A
+                `,
+                index: 1,
+                expected: ['a', 'f'],
+            },
+            {
+                testName: 'should only consider members of the first parent type',
+                code: `
+                    class A {
+                        attr a: Int
+                        fun f()
+                    }
+
+                    class B {
+                        attr b: Int
+                        fun g()
+                    }
+
+                    class C sub A, B
+                `,
+                index: 2,
+                expected: ['a', 'f'],
+            },
+            {
+                testName: 'should return members of all superclasses',
+                code: `
+                    class A {
+                        attr a: Int
+                        fun f()
+                    }
+
+                    class B sub A {
+                        attr b: Int
+                        fun g()
+                    }
+
+                    class C sub B
+                `,
+                index: 2,
+                expected: ['b', 'g', 'a', 'f'],
+            },
+        ];
+
+        it.each(testCases)('$testName', async ({ code, index, expected }) => {
+            const firstClass = await getNodeOfType(services, code, isSdsClass, index);
+            expect(superclassMemberNames(firstClass)).toStrictEqual(expected);
+        });
+    });
 });