Move dart2js from sdk/lib/_internal/compiler to pkg/compiler

sdk/lib/_internal/compiler/implementation/js_backend/type_variable_handler.dart

-// Copyright (c) 2013, 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.
-
-part of js_backend;
-
-/**
- * Handles construction of TypeVariable constants needed at runtime.
- */
-class TypeVariableHandler {
-  JavaScriptBackend backend;
-  FunctionElement typeVariableConstructor;
-  CompileTimeConstantEvaluator evaluator;
-
-  /**
-   * Contains all instantiated classes that have type variables and are needed
-   * for reflection.
-   */
-  List<ClassElement> typeVariableClasses = new List<ClassElement>();
-
-  /**
-   *  Maps a class element to a list with indices that point to type variables
-   *  constants for each of the class' type variables.
-   */
-  Map<ClassElement, List<int>> typeVariables =
-      new Map<ClassElement, List<int>>();
-
-  /**
-   *  Maps a TypeVariableType to the index pointing to the constant representing
-   *  the corresponding type variable at runtime.
-   */
-  Map<TypeVariableElement, int> typeVariableConstants =
-      new Map<TypeVariableElement, int>();
-
-  TypeVariableHandler(this.backend);
-
-  ClassElement get typeVariableClass => backend.typeVariableClass;
-  CodeEmitterTask get task => backend.emitter;
-  MetadataEmitter get emitter => task.oldEmitter.metadataEmitter;
-  Compiler get compiler => backend.compiler;
-
-  void registerClassWithTypeVariables(ClassElement cls) {
-    if (typeVariableClasses != null) {
-      typeVariableClasses.add(cls);
-    }
-  }
-
-  void processTypeVariablesOf(ClassElement cls) {
-    //TODO(zarah): Running through all the members is suboptimal. Change this
-    // as part of marking elements for reflection.
-    bool hasMemberNeededForReflection(ClassElement cls) {
-      bool result = false;
-      cls.implementation.forEachMember((ClassElement cls, Element member) {
-        result = result || backend.referencedFromMirrorSystem(member);
-      });
-      return result;
-    }
-
-    if (!backend.referencedFromMirrorSystem(cls) &&
-        !hasMemberNeededForReflection(cls)) {
-      return;
-    }
-
-    InterfaceType typeVariableType = typeVariableClass.thisType;
-    List<int> constants = <int>[];
-
-    for (TypeVariableType currentTypeVariable in cls.typeVariables) {
-      TypeVariableElement typeVariableElement = currentTypeVariable.element;
-
-      AstConstant wrapConstant(ConstantExpression constant) {
-        return new AstConstant(typeVariableElement,
-                                     typeVariableElement.node,
-                                     constant);
-      }
-
-      ConstantExpression name = new PrimitiveConstantExpression(
-          backend.constantSystem.createString(
-              new DartString.literal(currentTypeVariable.name)));
-      ConstantExpression bound = new PrimitiveConstantExpression(
-          backend.constantSystem.createInt(
-              emitter.reifyType(typeVariableElement.bound)));
-      ConstantExpression type = backend.constants.createTypeConstant(cls);
-      List<AstConstant> arguments =
-          [wrapConstant(type), wrapConstant(name), wrapConstant(bound)];
-
-      // TODO(johnniwinther): Support a less front-end specific creation of
-      // constructed constants.
-      AstConstant constant =
-          CompileTimeConstantEvaluator.makeConstructedConstant(
-              compiler,
-              backend.constants,
-              typeVariableElement,
-              typeVariableElement.node,
-              typeVariableType,
-              typeVariableConstructor,
-              new Selector.callConstructor('', null, 3),
-              arguments,
-              arguments);
-      ConstantValue value = constant.value;
-      backend.registerCompileTimeConstant(value, compiler.globalDependencies);
-      backend.constants.addCompileTimeConstantForEmission(value);
-      constants.add(
-          reifyTypeVariableConstant(value, currentTypeVariable.element));
-    }
-    typeVariables[cls] = constants;
-  }
-
-  void onTreeShakingDisabled(Enqueuer enqueuer) {
-    if (enqueuer.isResolutionQueue) {
-      backend.enqueueClass(
-            enqueuer, typeVariableClass, compiler.globalDependencies);
-      typeVariableClass.ensureResolved(compiler);
-      Link constructors = typeVariableClass.constructors;
-      if (constructors.isEmpty && constructors.tail.isEmpty) {
-        compiler.internalError(typeVariableClass,
-            "Class '$typeVariableClass' should only have one constructor");
-      }
-      typeVariableConstructor = typeVariableClass.constructors.head;
-      backend.enqueueInResolution(typeVariableConstructor,
-          compiler.globalDependencies);
-      enqueuer.registerInstantiatedType(typeVariableClass.rawType,
-          compiler.globalDependencies);
-      enqueuer.registerStaticUse(backend.getCreateRuntimeType());
-    } else if (typeVariableClasses != null) {
-      List<ClassElement> worklist = typeVariableClasses;
-      typeVariableClasses = null;
-      worklist.forEach((cls) => processTypeVariablesOf(cls));
-    }
-  }
-
-  /**
-   * Adds [c] to [emitter.globalMetadata] and returns the index pointing to
-   * the entry.
-   *
-   * If the corresponding type variable has already been encountered an
-   * entry in the list has already been reserved and the constant is added
-   * there, otherwise a new entry for [c] is created.
-   */
-  int reifyTypeVariableConstant(ConstantValue c, TypeVariableElement variable) {
-    String name = jsAst.prettyPrint(task.constantReference(c),
-                                    compiler).getText();
-    int index;
-    if (typeVariableConstants.containsKey(variable)) {
-      index = typeVariableConstants[variable];
-      emitter.globalMetadata[index] = name;
-    } else {
-      index = emitter.addGlobalMetadata(name);
-      typeVariableConstants[variable] = index;
-    }
-    return index;
-  }
-
-  /**
-   * Returns the index pointing to the constant in [emitter.globalMetadata]
-   * representing this type variable.
-   *
-   * If the constant has not yet been constructed, an entry is  allocated in
-   * the global metadata list and the index pointing to this entry is returned.
-   * When the corresponding constant is constructed later,
-   * [reifyTypeVariableConstant] will be called and the constant will be added
-   * on the allocated entry.
-   */
-  int reifyTypeVariable(TypeVariableElement variable) {
-    if (typeVariableConstants.containsKey(variable)) {
-      return typeVariableConstants[variable];
-    }
-
-    // TODO(15613): Remove quotes.
-    emitter.globalMetadata.add('"Placeholder for ${variable}"');
-    return typeVariableConstants[variable] = emitter.globalMetadata.length - 1;
-  }
-
-  List<int> typeVariablesOf(ClassElement classElement) {
-    List<int> result = typeVariables[classElement];
-    if (result == null) {
-      result = const <int>[];
-    }
-    return result;
-  }
-}