Merge the work on Generic Types Reification from 'dart-lang/reify' repo

pkg/kernel/lib/transformations/reify/transformation/builder.dart

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library kernel.transformations.reify.transformation.builder;
+
+import '../asts.dart';
+import 'package:kernel/ast.dart';
+import 'dart:collection' show LinkedHashMap;
+import 'binding.dart' show RuntimeLibrary;
+import 'package:kernel/core_types.dart' show CoreTypes;
+
+class Scope {
+  final Map<String, TreeNode> names = <String, TreeNode>{};
+
+  bool nameAlreadyTaken(String name, TreeNode node) {
+    TreeNode existing = names[name];
+    return existing != null && existing == node;
+  }
+
+  void add(String name, TreeNode node) {
+    assert(!nameAlreadyTaken(name, node));
+    names[name] = node;
+  }
+}
+
+class Namer {
+  final Scope scope;
+  Namer([Scope scope]) : this.scope = scope ?? new Scope();
+
+  String _getProposal(TreeNode node) {
+    if (node is Class) {
+      return node.name;
+    }
+    throw 'unsupported node: $node';
+  }
+
+  String getNameFor(TreeNode node) {
+    String base = _getProposal(node);
+    int id = 0;
+    String proposal = base;
+    while (scope.nameAlreadyTaken(proposal, node)) {
+      proposal = "$base${++id}";
+    }
+    scope.add(proposal, node);
+    return proposal;
+  }
+}
+
+class RuntimeTypeSupportBuilder {
+  // TODO(karlklose): group this together with other information about what
+  // needs to be built.
+  final LinkedHashMap<Class, int> reifiedClassIds =
+      new LinkedHashMap<Class, int>();
+
+  int currentDeclarationId = 0;
+
+  final Field declarations;
+
+  final RuntimeLibrary rtiLibrary;
+
+  final CoreTypes coreTypes;
+
+  final DartType declarationType;
+
+  RuntimeTypeSupportBuilder(
+      RuntimeLibrary rtiLibrary, CoreTypes coreTypes, Library mainLibrary)
+      : declarations = new Field(new Name(r"$declarations"),
+            isFinal: true, isStatic: true, fileUri: mainLibrary.fileUri),
+        declarationType = new InterfaceType(coreTypes.listClass,
+            <DartType>[rtiLibrary.declarationClass.rawType]),
+        rtiLibrary = rtiLibrary,
+        coreTypes = coreTypes {
+    mainLibrary.addMember(declarations);
+  }
+
+  int addDeclaration(Class cls) {
+    return reifiedClassIds.putIfAbsent(cls, () {
+      return currentDeclarationId++;
+    });
+  }
+
+  final Name indexOperatorName = new Name("[]");
+
+  MethodInvocation createArrayAccess(Expression target, int index) {
+    return new MethodInvocation(target, indexOperatorName,
+        new Arguments(<Expression>[new IntLiteral(index)]));
+  }
+
+  Expression createAccessDeclaration(Class cls) {
+    return createArrayAccess(new StaticGet(declarations), addDeclaration(cls));
+  }
+
+  Name getTypeTestTagName(Class cls) {
+    return new Name('\$is\$${cls.name}');
+  }
+
+  Name typeVariableGetterName(TypeParameter parameter) {
+    Class cls = getEnclosingClass(parameter);
+    return new Name("\$${cls.name}\$${parameter.name}");
+  }
+
+  // A call to a constructor or factory of a class that we have not transformed
+  // is wrapped in a call to `attachType`.
+  Expression attachTypeToConstructorInvocation(
+      InvocationExpression invocation, Member member) {
+    assert(member is Procedure && member.kind == ProcedureKind.Factory ||
+        member is Constructor);
+    Class targetClass = member.parent;
+    assert(targetClass != null);
+    DartType type = new InterfaceType(targetClass, invocation.arguments.types);
+    return callAttachType(invocation, type);
+  }
+
+  Expression callAttachType(Expression expression, DartType type) {
+    return new StaticInvocation(rtiLibrary.attachTypeFunction,
+        new Arguments(<Expression>[expression, createRuntimeType(type)]));
+  }
+
+  Expression createGetType(Expression receiver, {needsInterceptor: true}) {
+    if (receiver is ThisExpression || !needsInterceptor) {
+      return new PropertyGet(receiver, rtiLibrary.runtimeTypeName);
+    }
+    return new StaticInvocation(
+        rtiLibrary.interceptorFunction, new Arguments(<Expression>[receiver]));
+  }
+
+  Expression createGetTypeArguments(Expression typeObject) {
+    return new StaticInvocation(rtiLibrary.typeArgumentsFunction,
+        new Arguments(<Expression>[typeObject]));
+  }
+
+  // TODO(karlklose): consider adding a unique identifier for each test site.
+  /// `receiver.[subtypeTestName]([type])`
+  StaticInvocation createIsSubtypeOf(
+      Expression receiver, Expression typeExpression,
+      {targetHasTypeProperty: false}) {
+    Expression receiverType =
+        createGetType(receiver, needsInterceptor: !targetHasTypeProperty);
+    return new StaticInvocation(rtiLibrary.isSubtypeOfFunction,
+        new Arguments(<Expression>[receiverType, typeExpression]));
+  }
+
+  int getTypeVariableIndex(TypeParameter variable) {
+    Class c = getEnclosingClass(variable);
+    List<TypeParameter> variables = c.typeParameters;
+    for (int i = 0; i < variables.length; ++i) {
+      if (variables[i].name == variable.name) {
+        return i;
+      }
+    }
+    throw new Exception(
+        "Type variable $variable not found in enclosing class $c");
+  }
+
+  Expression createNewInterface(
+      Expression declaration, Expression typeArgumentList) {
+    List<Expression> arguments = <Expression>[declaration];
+    if (typeArgumentList != null) {
+      arguments.add(typeArgumentList);
+    }
+    return new ConstructorInvocation(
+        rtiLibrary.interfaceTypeConstructor, new Arguments(arguments));
+  }
+
+  /// Returns `true` if [types] is a list of [TypeParameterType]s that exactly
+  /// match the [TypeParameters] of the class they are defined in, i.e.,
+  ///   for all 0 <= i < cls.typeParameters.length.
+  ///     types[i].parameter == cls.typeParameters[i].
+  bool matchesTypeParameters(List<DartType> types) {
+    List<TypeParameter> parameters;
+    for (int i = 0; i < types.length; ++i) {
+      var type = types[i];
+      if (type is TypeParameterType) {
+        if (parameters == null) {
+          Class cls = getEnclosingClass(type.parameter);
+          parameters = cls.typeParameters;
+          if (parameters.length != types.length) return false;
+        }
+        if (type.parameter != parameters[i]) {
+          return false;
+        }
+      } else {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  // TODO(karlklose): Refactor into visitor.
+  // TODO(karlklose): split this method in different strategies.
+  /// Creates an expression to represent a runtime type instance of type [type].
+  Expression createRuntimeType(DartType type,
+      {reifyTypeVariable: false,
+      Expression createReference(Class cls),
+      VariableDeclaration typeContext}) {
+    Expression buildReifiedTypeVariable(TypeParameterType type) {
+      Expression typeVariables = new PropertyGet(
+          createReference(type.parameter.parent),
+          rtiLibrary.variablesFieldName);
+      return createArrayAccess(
+          typeVariables, getTypeVariableIndex(type.parameter));
+    }
+
+    Expression buildDirectTypeVariableAccess(TypeParameterType variable) {
+      Class cls = getEnclosingClass(variable.parameter);
+      return extractTypeVariable(
+          cls,
+          variable.parameter,
+          getTypeVariableIndex(variable.parameter),
+          new VariableGet(typeContext));
+    }
+
+    Expression buildGetterTypeVariableAccess(TypeParameterType type) {
+      return new PropertyGet(
+          new ThisExpression(), typeVariableGetterName(type.parameter));
+    }
+
+    Expression buildTypeVariable(TypeParameterType type) {
+      if (reifyTypeVariable) {
+        assert(typeContext == null);
+        return buildReifiedTypeVariable(type);
+      } else if (typeContext != null) {
+        return buildDirectTypeVariableAccess(type);
+      } else {
+        return buildGetterTypeVariableAccess(type);
+      }
+    }
+
+    createReference ??= createAccessDeclaration;
+
+    /// Helper to make recursive invocation more readable.
+    Expression createPart(DartType type) {
+      return createRuntimeType(type,
+          reifyTypeVariable: reifyTypeVariable,
+          createReference: createReference,
+          typeContext: typeContext);
+    }
+
+    if (type is InterfaceType || type is Supertype) {
+      InterfaceType interfaceType = null;
+      if (type is InterfaceType) {
+        interfaceType = type;
+      } else {
+        interfaceType = (type as Supertype).asInterfaceType;
+      }
+      Class cls = interfaceType.classNode;
+      Expression declaration = createReference(cls);
+      List<DartType> typeArguments = interfaceType.typeArguments;
+      Expression typeArgumentList;
+      if (typeArguments.isNotEmpty) {
+        if (!reifyTypeVariable && matchesTypeParameters(typeArguments)) {
+          // The type argument list corresponds to the list of type parameters
+          // and we are not in "declaration emitter" mode, we can reuse the
+          // type argument vector.
+          TypeParameterType parameterType = typeArguments[0];
+          Class cls = parameterType.parameter.parent;
+          Expression typeObject = typeContext != null
+              ? new VariableGet(typeContext)
+              : createGetType(new ThisExpression());
+          typeArgumentList =
+              createGetTypeArguments(createCallAsInstanceOf(typeObject, cls));
+        } else {
+          typeArgumentList =
+              new ListLiteral(typeArguments.map(createPart).toList());
+        }
+      }
+      return createNewInterface(declaration, typeArgumentList);
+    } else if (type is DynamicType) {
+      return new ConstructorInvocation(
+          rtiLibrary.dynamicTypeConstructor, new Arguments([]),
+          isConst: true);
+    } else if (type is TypeParameterType) {
+      return buildTypeVariable(type);
+    } else if (type is FunctionType) {
+      FunctionType functionType = type;
+      Expression returnType = createPart(functionType.returnType);
+      List<Expression> encodedParameterTypes =
+          functionType.positionalParameters.map(createPart).toList();
+      List<NamedType> namedParameters = functionType.namedParameters;
+      int data;
+      if (namedParameters.isNotEmpty) {
+        for (NamedType param in namedParameters) {
+          encodedParameterTypes.add(new StringLiteral(param.name));
+          encodedParameterTypes.add(createPart(param.type));
+        }
+        data = functionType.namedParameters.length << 1 | 1;
+      } else {
+        data = (functionType.positionalParameters.length -
+                functionType.requiredParameterCount) <<
+            1;
+      }
+      Expression functionTypeExpression = new ConstructorInvocation(
+          rtiLibrary.interfaceTypeConstructor,
+          new Arguments(
+              <Expression>[createReference(coreTypes.functionClass)]));
+      Arguments arguments = new Arguments(<Expression>[
+        functionTypeExpression,
+        returnType,
+        new IntLiteral(data),
+        new ListLiteral(encodedParameterTypes)
+      ]);
+      return new ConstructorInvocation(
+          rtiLibrary.functionTypeConstructor, arguments);
+    } else if (type is VoidType) {
+      return new ConstructorInvocation(
+          rtiLibrary.voidTypeConstructor, new Arguments(<Expression>[]));
+    }
+    return new InvalidExpression();
+  }
+
+  Expression createCallAsInstanceOf(Expression receiver, Class cls) {
+    return new StaticInvocation(rtiLibrary.asInstanceOfFunction,
+        new Arguments(<Expression>[receiver, createAccessDeclaration(cls)]));
+  }
+
+  /// `get get$<variable-name> => <get-type>.arguments[<variable-index>]`
+  Member createTypeVariableGetter(
+      Class cls, TypeParameter variable, int index) {
+    Expression type = createGetType(new ThisExpression());
+    Expression argument = extractTypeVariable(cls, variable, index, type);
+    return new Procedure(
+        typeVariableGetterName(variable),
+        ProcedureKind.Getter,
+        new FunctionNode(new ReturnStatement(argument),
+            returnType: rtiLibrary.typeType),
+        fileUri: cls.fileUri);
+  }
+
+  Expression extractTypeVariable(
+      Class cls, TypeParameter variable, int index, Expression typeObject) {
+    Expression type = createCallAsInstanceOf(typeObject, cls);
+    Expression arguments = new StaticInvocation(
+        rtiLibrary.typeArgumentsFunction, new Arguments(<Expression>[type]));
+    // TODO(karlklose): use the global index instead of the local one.
+    return createArrayAccess(arguments, index);
+  }
+
+  void insertAsFirstArgument(Arguments arguments, Expression expression) {
+    expression.parent = arguments;
+    arguments.positional.insert(0, expression);
+  }
+
+  /// Creates a call to the `init` function that completes the definition of a
+  /// class by setting its (direct) supertypes.
+  Expression createCallInit(
+      VariableDeclaration declarations,
+      int index,
+      InterfaceType supertype,
+      List<InterfaceType> interfaces,
+      FunctionType callableType) {
+    /// Helper to create a reference to the declaration in the declaration
+    /// list instead of the field to avoid cycles if that field's
+    /// initialization depends on the class we are currently initializing.
+    Expression createReference(Class declaration) {
+      int id = reifiedClassIds[declaration];
+      return createArrayAccess(new VariableGet(declarations), id);
+    }
+
+    bool isNotMarkerInterface(InterfaceType interface) {
+      return interface.classNode != rtiLibrary.markerClass;
+    }
+
+    Expression createLocalType(DartType type) {
+      if (type == null) return null;
+      return createRuntimeType(type,
+          reifyTypeVariable: true, createReference: createReference);
+    }
+
+    Expression supertypeExpression =
+        supertype == null ? new NullLiteral() : createLocalType(supertype);
+
+    List<Expression> interfaceTypes = interfaces
+        .where(isNotMarkerInterface)
+        .map(createLocalType)
+        .toList(growable: false);
+
+    Expression callableTypeExpression = createLocalType(callableType);
+
+    List<Expression> arguments = <Expression>[
+      new VariableGet(declarations),
+      new IntLiteral(index),
+      supertypeExpression,
+    ];
+
+    if (interfaceTypes.isNotEmpty || callableTypeExpression != null) {
+      arguments.add(new ListLiteral(interfaceTypes));
+      if (callableTypeExpression != null) {
+        arguments.add(callableTypeExpression);
+      }
+    }
+
+    return new StaticInvocation(
+        rtiLibrary.initFunction, new Arguments(arguments));
+  }
+
+  Expression createDeclarationsInitializer() {
+    List<Statement> statements = <Statement>[];
+    // Call function to allocate the class declarations given the names and
+    // number of type variables of the classes.
+    Namer classNamer = new Namer();
+    List<Expression> names = <Expression>[];
+    List<Expression> parameterCount = <Expression>[];
+    reifiedClassIds.keys.forEach((Class c) {
+      names.add(new StringLiteral(classNamer.getNameFor(c)));
+      parameterCount.add(new IntLiteral(c.typeParameters.length));
+    });
+    Expression namesList = new ListLiteral(names);
+    Expression parameterCountList = new ListLiteral(parameterCount);
+    StaticInvocation callAllocate = new StaticInvocation(
+        rtiLibrary.allocateDeclarationsFunction,
+        new Arguments(<Expression>[namesList, parameterCountList]));
+
+    VariableDeclaration parameter =
+        new VariableDeclaration("d", type: declarationType);
+
+    reifiedClassIds.forEach((Class cls, int id) {
+      if (cls == rtiLibrary.markerClass) return;
+
+      // If the class declares a `call` method, translate the signature to a
+      // reified type.
+      FunctionType callableType;
+      Procedure call = cls.procedures.firstWhere(
+          (Procedure p) => p.name.name == "call",
+          orElse: () => null);
+      if (call != null) {
+        FunctionNode function = call.function;
+
+        final namedParameters = new List<NamedType>();
+        for (VariableDeclaration v in function.namedParameters) {
+          namedParameters.add(new NamedType(v.name, v.type));
+        }
+
+        List<DartType> positionalArguments = function.positionalParameters
+            .map((VariableDeclaration v) => v.type)
+            .toList();
+        callableType = new FunctionType(
+            positionalArguments, function.returnType,
+            namedParameters: namedParameters,
+            requiredParameterCount: function.requiredParameterCount);
+      }
+      statements.add(new ExpressionStatement(createCallInit(
+          parameter,
+          id,
+          cls.supertype?.asInterfaceType,
+          cls.implementedTypes.map((Supertype type) => type?.asInterfaceType),
+          callableType)));
+    });
+
+    statements.add(new ReturnStatement(new VariableGet(parameter)));
+
+    Expression function = new FunctionExpression(new FunctionNode(
+        new Block(statements),
+        positionalParameters: <VariableDeclaration>[parameter],
+        returnType: declarationType));
+
+    return new MethodInvocation(
+        function, new Name("call"), new Arguments(<Expression>[callAllocate]));
+  }
+
+  void createDeclarations() {
+    /// Recursively find all referenced classes in [type].
+    void collectNewReferencedClasses(DartType type, Set<Class> newClasses) {
+      if (type is InterfaceType || type is Supertype) {
+        InterfaceType interfaceType = null;
+        if (type is InterfaceType) {
+          interfaceType = type;
+        } else {
+          interfaceType = (type as Supertype).asInterfaceType;
+        }
+        Class cls = interfaceType.classNode;
+        if (!reifiedClassIds.containsKey(cls) && !newClasses.contains(cls)) {
+          newClasses.add(cls);
+        }
+
+        interfaceType.typeArguments.forEach((DartType argument) {
+          collectNewReferencedClasses(argument, newClasses);
+        });
+      }
+      // TODO(karlklose): function types
+    }
+
+    Iterable<Class> classes = reifiedClassIds.keys;
+    while (classes.isNotEmpty) {
+      Set<Class> newClasses = new Set<Class>();
+      for (Class c in classes) {
+        collectNewReferencedClasses(c.supertype?.asInterfaceType, newClasses);
+        c.implementedTypes.forEach((Supertype supertype) {
+          collectNewReferencedClasses(supertype?.asInterfaceType, newClasses);
+        });
+      }
+      for (Class newClass in newClasses) {
+        // Make sure that there is a declaration field for the class and its
+        // library's declaration list is setup.
+        addDeclaration(newClass);
+      }
+      classes = newClasses;
+    }
+    Expression initializer = createDeclarationsInitializer();
+    initializer.parent = declarations;
+    declarations.initializer = initializer;
+    declarations.type = declarationType;
+  }
+
+  Procedure createGetter(
+      Name name, Expression expression, Class cls, DartType type) {
+    return new Procedure(name, ProcedureKind.Getter,
+        new FunctionNode(new ReturnStatement(expression), returnType: type),
+        fileUri: cls.fileUri);
+  }
+}