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

pkg/kernel/runtime/reify/declarations.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.runtime.declarations;
+
+import 'types.dart' show FunctionType, Interface, ReifiedType, TypeVariable;
+
+typedef String Id2String(Object id);
+
+/// Represents a class.
+///
+/// There's one instance of this class for each class in the program.
+///
+/// Note: not all classes can be represented as a compile-time constants. For
+/// example, most core classes, such as, `String`, `int`, and `double`
+/// implement `Comparable` in a way that cannot be expressed as a constant.
+class Class {
+  final id;
+
+  Interface supertype;
+
+  FunctionType callableType;
+
+  final List<TypeVariable> variables;
+
+  List<Interface> interfaces;
+
+  static Id2String debugId2String;
+
+  Class(this.id, this.supertype,
+      {this.callableType,
+      this.variables: const <TypeVariable>[],
+      this.interfaces /* set in init */});
+
+  Interface get thisType {
+    return new Interface(this, variables);
+  }
+
+  String get name => debugId2String == null ? "$id" : debugId2String(id);
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.write("class $name");
+    if (variables.isNotEmpty) {
+      sb.write("<");
+      bool first = true;
+      for (TypeVariable tv in variables) {
+        if (!first) {
+          sb.write(", ");
+        }
+        sb.write(tv);
+        sb.write(" extends ");
+        sb.write(tv.bound);
+      }
+      sb.write(">");
+    }
+    if (supertype != null) {
+      sb.write(" extends $supertype");
+    }
+    if (interfaces.isNotEmpty) {
+      sb.write(" implements ");
+      sb.writeAll(interfaces, ", ");
+    }
+    return "$sb";
+  }
+}
+
+/// Allocates a (non-growable) list of [amount] class declarations with ids `0`
+/// to `amount - 1`. This function is called from the generated code that
+/// initializes the type information.
+List<Class> allocateDeclarations(List<String> names, List<int> typeParameters) {
+  List<TypeVariable> allocateVariables(int amount) {
+    if (amount == 0) return const <TypeVariable>[];
+    return new List<TypeVariable>.generate(
+        amount, (int i) => new TypeVariable(i),
+        growable: false);
+  }
+
+  return new List<Class>.generate(
+      names.length,
+      (int i) => new Class(names[i], null,
+          variables: allocateVariables(typeParameters[i])),
+      growable: false);
+}
+
+/// Initializes the supertype and interfaces of `classes[index]`.
+/// This function is called from generated code.
+void init(List<Class> classes, int index, ReifiedType supertype,
+    [List<Interface> interfaces = const <Interface>[],
+    FunctionType callableType]) {
+  Class declaration = classes[index];
+  assert(supertype == null);
+  declaration.supertype = supertype;
+  assert(interfaces == null);
+  declaration.interfaces = interfaces;
+  declaration.callableType = callableType;
+}