Extend type checker to support tuples (#4863)

piotrswigon · web-flow · commit 29adb3920aef · 2020-03-09T10:12:40.000-07:00
diff --git a/src/runtime/recipe/type-checker.ts b/src/runtime/recipe/type-checker.ts
@@ -8,7 +8,7 @@
  * http://polymer.github.io/PATENTS.txt
  */
 
-import {BigCollectionType, CollectionType, EntityType, InterfaceType, ReferenceType, SlotType, Type, TypeVariable} from '../type.js';
+import {BigCollectionType, CollectionType, EntityType, InterfaceType, ReferenceType, SlotType, Type, TypeVariable, TupleType} from '../type.js';
 import {Direction} from '../manifest-ast-nodes.js';
 
 export interface TypeListInfo {
@@ -24,7 +24,24 @@ export class TypeChecker {
 
   // NOTE: you almost definitely don't want to call this function, if you think
   // you do, talk to shans@.
-  private static getResolution(candidate: Type, options: TypeCheckOptions) {
+  private static getResolution(candidate: Type, options: TypeCheckOptions): Type | null {
+    if (candidate.isCollectionType()) {
+      const resolution = TypeChecker.getResolution(candidate.collectionType, options);
+      return (resolution !== null) ? resolution.collectionOf() : null;
+    }
+    if (candidate.isBigCollectionType()) {
+      const resolution = TypeChecker.getResolution(candidate.bigCollectionType, options);
+      return (resolution !== null) ? resolution.bigCollectionOf() : null;
+    }
+    if (candidate.isReferenceType()) {
+      const resolution = TypeChecker.getResolution(candidate.referredType, options);
+      return (resolution !== null) ? resolution.referenceTo() : null;
+    }
+    if (candidate.isTupleType()) {
+      const resolutions = candidate.innerTypes.map(t => TypeChecker.getResolution(t, options));
+      return resolutions.every(r => r !== null) ? new TupleType(resolutions) : null;
+    }
+
     if (!(candidate instanceof TypeVariable)) {
       return candidate;
     }
@@ -95,18 +112,7 @@ export class TypeChecker {
       }
     }
 
-    const candidate = baseType.resolvedType();
-
-    if (candidate.isCollectionType()) {
-      const resolution = TypeChecker.getResolution(candidate.collectionType, options);
-      return (resolution !== null) ? resolution.collectionOf() : null;
-    }
-    if (candidate.isBigCollectionType()) {
-      const resolution = TypeChecker.getResolution(candidate.bigCollectionType, options);
-      return (resolution !== null) ? resolution.bigCollectionOf() : null;
-    }
-
-    return TypeChecker.getResolution(candidate, options);
+    return TypeChecker.getResolution(baseType.resolvedType(), options);
   }
 
   static _tryMergeTypeVariable(base: Type, onto: Type, options: {typeErrors?: string[]} = {}): Type {
@@ -150,9 +156,23 @@ export class TypeChecker {
   }
 
   static _tryMergeConstraints(handleType: Type, {type, relaxed, direction}: TypeListInfo, options: {typeErrors?: string[]} = {}): boolean {
-    let [primitiveHandleType, primitiveConnectionType] = Type.unwrapPair(handleType.resolvedType(), type.resolvedType());
+    const [handleInnerTypes, connectionInnerTypes] = Type.tryUnwrapMulti(handleType.resolvedType(), type.resolvedType());
+    // If both handle and connection are matching type containers with multiple arguments,
+    // merge constraints pairwaise for all inner types.
+    if (handleInnerTypes != null) {
+      if (handleInnerTypes.length !== connectionInnerTypes.length) return false;
+      for (let i = 0; i < handleInnerTypes.length; i++) {
+        if (!this._tryMergeConstraints(handleInnerTypes[i], {type: connectionInnerTypes[i], relaxed, direction}, options)) {
+          return false;
+        }
+      }
+      return true;
+    }
+
+    const [primitiveHandleType, primitiveConnectionType] = Type.unwrapPair(handleType.resolvedType(), type.resolvedType());
+
     if (primitiveHandleType instanceof TypeVariable) {
-      while (primitiveConnectionType.isTypeContainer()) {
+      if (primitiveConnectionType.isTypeContainer()) {
         if (primitiveHandleType.variable.resolution != null
             || primitiveHandleType.variable.canReadSubset != null
             || primitiveHandleType.variable.canWriteSuperset != null) {
@@ -162,21 +182,21 @@ export class TypeChecker {
         // If this is an undifferentiated variable then we need to create structure to match against. That's
         // allowed because this variable could represent anything, and it needs to represent this structure
         // in order for type resolution to succeed.
-        const newVar = TypeVariable.make('a');
         if (primitiveConnectionType instanceof CollectionType) {
-          primitiveHandleType.variable.resolution = new CollectionType(newVar);
+          primitiveHandleType.variable.resolution = new CollectionType(TypeVariable.make('a'));
         } else if (primitiveConnectionType instanceof BigCollectionType) {
-          primitiveHandleType.variable.resolution = new BigCollectionType(newVar);
+          primitiveHandleType.variable.resolution = new BigCollectionType(TypeVariable.make('a'));
+        } else if (primitiveConnectionType instanceof ReferenceType) {
+          primitiveHandleType.variable.resolution = new ReferenceType(TypeVariable.make('a'));
+        } else if (primitiveConnectionType instanceof TupleType) {
+          primitiveHandleType.variable.resolution = new TupleType(
+            primitiveConnectionType.innerTypes.map((_, idx) => TypeVariable.make(`a${idx}`)));
         } else {
-          primitiveHandleType.variable.resolution = new ReferenceType(newVar);
+          throw new TypeError(`Unrecognized type container: ${primitiveConnectionType.tag}`);
         }
 
-        const unwrap = Type.unwrapPair(primitiveHandleType.resolvedType(), primitiveConnectionType);
-        [primitiveHandleType, primitiveConnectionType] = unwrap;
-        if (!(primitiveHandleType instanceof TypeVariable)) {
-          // This should never happen, and the guard above is just here so we type-check.
-          throw new TypeError('unwrapping a wrapped TypeVariable somehow didn\'t become a TypeVariable');
-        }
+        // Call recursively to unwrap and merge constraints of potentially multiple type variables (e.g. for tuples).
+        return this._tryMergeConstraints(primitiveHandleType.resolvedType(), {type: primitiveConnectionType, relaxed, direction}, options);
       }
 
       if (direction === 'writes' || direction === 'reads writes' || direction === '`provides') {
diff --git a/src/runtime/tests/manifest-test.ts b/src/runtime/tests/manifest-test.ts
@@ -2630,9 +2630,9 @@ resource SomeName
     const collection = connection.type as CollectionType<TupleType>;
     assert.strictEqual(collection.collectionType.tag, 'Tuple');
     const tuple = collection.collectionType as TupleType;
-    assert.lengthOf(tuple.tupleTypes, 2);
-    assert.strictEqual(tuple.tupleTypes[0].tag, 'Reference');
-    assert.strictEqual(tuple.tupleTypes[1].tag, 'Reference');
+    assert.lengthOf(tuple.innerTypes, 2);
+    assert.strictEqual(tuple.innerTypes[0].tag, 'Reference');
+    assert.strictEqual(tuple.innerTypes[1].tag, 'Reference');
   });
 
   it('parsing a particle with tuple of non reference fails', async () => {
diff --git a/src/runtime/tests/type-checker-test.ts b/src/runtime/tests/type-checker-test.ts
@@ -12,7 +12,7 @@ import {assert} from '../../platform/chai-web.js';
 import {Manifest} from '../manifest.js';
 import {Handle} from '../recipe/handle.js';
 import {TypeChecker, TypeListInfo} from '../recipe/type-checker.js';
-import {EntityType, SlotType, TypeVariable, CollectionType, BigCollectionType} from '../type.js';
+import {EntityType, SlotType, TypeVariable, CollectionType, BigCollectionType, TupleType, Type} from '../type.js';
 
 describe('TypeChecker', () => {
   it('resolves a trio of in [~a], out [~b], in [Product]', async () => {
@@ -358,7 +358,7 @@ describe('TypeChecker', () => {
     const baseType = TypeVariable.make('a');
     const newType = Handle.effectiveType(baseType, [
       {type: EntityType.make(['Thing'], {}), direction: 'reads writes'}]);
-    assert.notStrictEqual(baseType, newType);
+    assert.notStrictEqual(baseType as Type, newType);
     assert.isNull(baseType.variable.resolution);
     assert.isNotNull(newType instanceof TypeVariable && newType.variable.resolution);
   });
@@ -408,4 +408,100 @@ describe('TypeChecker', () => {
     assert(result.isResolved());
     assert(result.resolvedType() instanceof SlotType);
   });
+
+  describe('Tuples', () => {
+    it('does not resolve tuple reads of different arities', () => {
+      assert.isNull(TypeChecker.processTypeList(null, [
+        {
+          direction: 'reads',
+          type: new TupleType([
+            EntityType.make([], {}),
+            EntityType.make([], {}),
+          ]),
+        },
+        {
+          direction: 'reads',
+          type: new TupleType([
+            EntityType.make([], {}),
+          ]),
+        },
+      ]));
+    });
+
+    it('does not resolve conflicting entities in tuple read and write', () => {
+      assert.isNull(TypeChecker.processTypeList(null, [
+        {
+          direction: 'reads',
+          type: new TupleType([EntityType.make(['Product'], {})]),
+        },
+        {
+          direction: 'writes',
+          type: new TupleType([EntityType.make(['Thing'], {})]),
+        },
+      ]));
+    });
+
+    it('does not resolve conflicting types in tuple read and write', () => {
+      assert.isNull(TypeChecker.processTypeList(null, [
+        {
+          direction: 'reads',
+          type: new TupleType([EntityType.make(['Product'], {})]),
+        },
+        {
+          direction: 'writes',
+          type: new TupleType([EntityType.make(['Product'], {}).referenceTo()]),
+        },
+      ]));
+    });
+
+    it('can resolve multiple tuple reads', () => {
+      const result = TypeChecker.processTypeList(null, [
+        {
+          direction: 'reads',
+          type: new TupleType([
+            EntityType.make(['Product'], {}),
+            EntityType.make(['Place'], {}),
+          ]),
+        },
+        {
+          direction: 'reads',
+          type: new TupleType([
+            EntityType.make(['Object'], {}),
+            EntityType.make(['Location'], {}),
+          ]),
+        },
+      ]);
+      // We only have read constraints, so we need to force the type variable to resolve.
+      assert(result.maybeEnsureResolved());
+      assert.deepEqual(result.resolvedType(), new TupleType([
+        EntityType.make(['Product', 'Object'], {}),
+        EntityType.make(['Place', 'Location'], {})
+      ]));
+    });
+
+    const ENTITY_TUPLE_CONNECTION_LIST: TypeListInfo[] = [
+      {direction: 'reads', type: new TupleType([EntityType.make(['Product'], {}), EntityType.make([], {})])},
+      {direction: 'reads', type: new TupleType([EntityType.make([], {}), EntityType.make(['Location'], {})])},
+      {direction: 'writes', type: new TupleType([EntityType.make(['Product'], {}), EntityType.make(['Place', 'Location'], {})])},
+      {direction: 'writes', type: new TupleType([EntityType.make(['Product', 'Object'], {}), EntityType.make(['Location'], {})])},
+    ];
+    const ENTITY_TUPLE_CONNECTION_LIST_RESULT = new TupleType([EntityType.make(['Product'], {}), EntityType.make(['Location'], {})]);
+
+    it('can resolve tuple of entities with read and write', () => {
+      assert.deepEqual(
+        TypeChecker.processTypeList(null, ENTITY_TUPLE_CONNECTION_LIST).resolvedType(),
+        ENTITY_TUPLE_CONNECTION_LIST_RESULT
+      );
+    });
+
+    it('can resolve collections of tuple of entities with read and write', () => {
+      assert.deepEqual(
+        TypeChecker.processTypeList(null, ENTITY_TUPLE_CONNECTION_LIST.map(({type, direction}) => ({
+          type: type.collectionOf(),
+          direction
+        }))).resolvedType(),
+        ENTITY_TUPLE_CONNECTION_LIST_RESULT.collectionOf()
+      );
+    });
+  });
 });
diff --git a/src/runtime/type.ts b/src/runtime/type.ts
@@ -52,6 +52,17 @@ export abstract class Type {
     return [type1, type2];
   }
 
+  static tryUnwrapMulti(type1: Type, type2: Type): [Type[], Type[]] {
+    [type1, type2] = this.unwrapPair(type1, type2);
+    if (type1.tag === type2.tag) {
+      const contained1 = type1.getContainedTypes();
+      if (contained1 !== null) {
+        return [contained1, type2.getContainedTypes()];
+      }
+    }
+    return [null, null];
+  }
+
   /** Tests whether two types' constraints are compatible with each other. */
   static canMergeConstraints(type1: Type, type2: Type): boolean {
     return Type._canMergeCanReadSubset(type1, type2) && Type._canMergeCanWriteSuperset(type1, type2);
@@ -111,6 +122,14 @@ export abstract class Type {
     return this instanceof BigCollectionType;
   }
 
+  isReferenceType(): this is ReferenceType {
+    return this instanceof ReferenceType;
+  }
+
+  isTupleType(): this is TupleType {
+    return this instanceof TupleType;
+  }
+
   isResolved(): boolean {
     // TODO: one of these should not exist.
     return !this.hasUnresolvedVariable;
@@ -136,6 +155,10 @@ export abstract class Type {
     return null;
   }
 
+  getContainedTypes(): Type[]|null {
+    return null;
+  }
+
   isTypeContainer(): boolean {
     return false;
   }
@@ -160,6 +183,10 @@ export abstract class Type {
     return false;
   }
 
+  get isTuple(): boolean {
+    return false;
+  }
+
   collectionOf() {
     return new CollectionType(this);
   }
@@ -172,6 +199,10 @@ export abstract class Type {
     return new BigCollectionType(this);
   }
 
+  referenceTo() {
+    return new ReferenceType(this);
+  }
+
   resolvedType(): Type {
     return this;
   }
@@ -682,23 +713,72 @@ export class BigCollectionType<T extends Type> extends Type {
 }
 
 export class TupleType extends Type {
-  readonly tupleTypes: Type[];
+  readonly innerTypes: Type[];
 
   constructor(tuple: Type[]) {
     super('Tuple');
-    this.tupleTypes = tuple;
+    this.innerTypes = tuple;
   }
 
-  get isTuple() {
+  get isTuple(): boolean {
     return true;
   }
 
+  isTypeContainer(): boolean {
+    return true;
+  }
+
+  getContainedTypes(): Type[]|null {
+    return this.innerTypes;
+  }
+
+  get canWriteSuperset() {
+    return new TupleType(this.innerTypes.map(t => t.canWriteSuperset));
+  }
+
+  get canReadSubset() {
+    return new TupleType(this.innerTypes.map(t => t.canReadSubset));
+  }
+
+  resolvedType() {
+    let returnSelf = true;
+    const resolvedinnerTypes = [];
+    for (const t of this.innerTypes) {
+      const resolved = t.resolvedType();
+      if (resolved !== t) returnSelf = false;
+      resolvedinnerTypes.push(resolved);
+    }
+    if (returnSelf) return this;
+    return new TupleType(resolvedinnerTypes);
+  }
+
+  _canEnsureResolved(): boolean {
+    return this.innerTypesSatisfy((type) => type.canEnsureResolved());
+  }
+
+  maybeEnsureResolved(): boolean {
+    return this.innerTypesSatisfy((type) => type.maybeEnsureResolved());
+  }
+
+  _isAtleastAsSpecificAs(other: TupleType): boolean {
+    if (this.innerTypes.length !== other.innerTypes.length) return false;
+    return this.innerTypesSatisfy((type, idx) => type.isAtleastAsSpecificAs(other.innerTypes[idx]));
+  }
+
+  private innerTypesSatisfy(predicate: ((type: Type, idx: number) => boolean)): boolean {
+    return this.innerTypes.reduce((result: boolean, type: Type, idx: number) => result && predicate(type, idx), true);
+  }
+
   toLiteral(): TypeLiteral {
-    return {tag: this.tag, data: this.tupleTypes.map(t => t.toLiteral())};
+    return {tag: this.tag, data: this.innerTypes.map(t => t.toLiteral())};
+  }
+
+  toString(options = undefined ): string {
+    return `(${this.innerTypes.map(t => t.toString(options)).join(', ')})`;
   }
 
   toPrettyString(): string {
-    return JSON.stringify(this.tupleTypes);
+    return 'Tuple of ' + this.innerTypes.map(t => t.toPrettyString()).join(', ');
   }
 }
 
