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

sdk/lib/_internal/compiler/implementation/js_backend/custom_elements_analysis.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;
-
-/**
- * Support for Custom Elements.
- *
- * The support for custom elements the compiler builds a table that maps the
- * custom element class's [Type] to the interceptor for the class and the
- * constructor(s) for the class.
- *
- * We want the table to contain only the custom element classes used, and we
- * want to avoid resolving and compiling constructors that are not used since
- * that may bring in unused code.  This class controls the resolution and code
- * generation to restrict the impact.
- *
- * The following line of code requires the generation of the generative
- * constructor factory function(s) for FancyButton, and their insertion into the
- * table:
- *
- *     document.register(FancyButton, 'x-fancy-button');
- *
- * We detect this by 'joining' the classes that are referenced as type literals
- * with the classes that are custom elements, enabled by detecting the presence
- * of the table access code used by document.register.
- *
- * We have to be more conservative when the type is unknown, e.g.
- *
- *     document.register(classMirror.reflectedType, tagFromMetadata);
- *
- * and
- *
- *     class Component<T> {
- *       final tag;
- *       Component(this.tag);
- *       void register() => document.register(T, tag);
- *     }
- *     const Component<FancyButton>('x-fancy-button').register();
- *
- * In these cases we conservatively generate all viable entries in the table.
- */
-class CustomElementsAnalysis {
-  final JavaScriptBackend backend;
-  final Compiler compiler;
-  final CustomElementsAnalysisJoin resolutionJoin;
-  final CustomElementsAnalysisJoin codegenJoin;
-  bool fetchedTableAccessorMethod = false;
-  Element tableAccessorMethod;
-
-  CustomElementsAnalysis(JavaScriptBackend backend)
-      : this.backend = backend,
-        this.compiler = backend.compiler,
-        resolutionJoin = new CustomElementsAnalysisJoin(backend),
-        codegenJoin = new CustomElementsAnalysisJoin(backend) {
-    // TODO(sra): Remove this work-around.  We should mark allClassesSelected in
-    // both joins only when we see a construct generating an unknown [Type] but
-    // we can't currently recognize all cases.  In particular, the work-around
-    // for the unimplemented `ClassMirror.reflectedType` is not recognizable.
-    // TODO(12607): Match on [ClassMirror.reflectedType]
-    resolutionJoin.allClassesSelected = true;
-    codegenJoin.allClassesSelected = true;
-  }
-
-  CustomElementsAnalysisJoin joinFor(Enqueuer enqueuer) =>
-      enqueuer.isResolutionQueue ? resolutionJoin : codegenJoin;
-
-  void registerInstantiatedClass(ClassElement classElement, Enqueuer enqueuer) {
-    classElement.ensureResolved(compiler);
-    if (!Elements.isNativeOrExtendsNative(classElement)) return;
-    if (classElement.isMixinApplication) return;
-    if (classElement.isAbstract) return;
-    joinFor(enqueuer).instantiatedClasses.add(classElement);
-  }
-
-  void registerTypeLiteral(DartType type, Registry registry) {
-    assert(registry.isForResolution);
-    // In codegen we see the TypeConstants instead.
-    if (!registry.isForResolution) return;
-
-    if (type.isInterfaceType) {
-      // TODO(sra): If we had a flow query from the type literal expression to
-      // the Type argument of the metadata lookup, we could tell if this type
-      // literal is really a demand for the metadata.
-      resolutionJoin.selectedClasses.add(type.element);
-    } else if (type.isTypeVariable) {
-      // This is a type parameter of a parameterized class.
-      // TODO(sra): Is there a way to determine which types are bound to the
-      // parameter?
-      resolutionJoin.allClassesSelected = true;
-    }
-  }
-
-  void registerTypeConstant(Element element, Enqueuer enqueuer) {
-    assert(element.isClass);
-    assert(!enqueuer.isResolutionQueue);
-    codegenJoin.selectedClasses.add(element);
-  }
-
-  void registerStaticUse(Element element, Enqueuer enqueuer) {
-    assert(element != null);
-    if (!fetchedTableAccessorMethod) {
-      fetchedTableAccessorMethod = true;
-      tableAccessorMethod = backend.findInterceptor(
-          'findIndexForNativeSubclassType');
-    }
-    if (element == tableAccessorMethod) {
-      joinFor(enqueuer).demanded = true;
-    }
-  }
-
-  void onQueueEmpty(Enqueuer enqueuer) {
-    joinFor(enqueuer).flush(enqueuer);
-  }
-
-  bool get needsTable => codegenJoin.demanded;
-
-  bool needsClass(ClassElement classElement) =>
-      codegenJoin.activeClasses.contains(classElement);
-
-  List<Element> constructors(ClassElement classElement) =>
-      codegenJoin.computeEscapingConstructors(classElement);
-}
-
-
-class CustomElementsAnalysisJoin {
-  final JavaScriptBackend backend;
-  Compiler get compiler => backend.compiler;
-
-  // Classes that are candidates for needing constructors.  Classes are moved to
-  // [activeClasses] when we know they need constructors.
-  final instantiatedClasses = new Set<ClassElement>();
-
-  // Classes explicitly named.
-  final selectedClasses = new Set<ClassElement>();
-
-  // True if we must conservatively include all extension classes.
-  bool allClassesSelected = false;
-
-  // Did we see a demand for the data?
-  bool demanded = false;
-
-  // ClassesOutput: classes requiring metadata.
-  final activeClasses = new Set<ClassElement>();
-
-  CustomElementsAnalysisJoin(this.backend);
-
-  void flush(Enqueuer enqueuer) {
-    if (!demanded) return;
-    var newActiveClasses = new Set<ClassElement>();
-    for (ClassElement classElement in instantiatedClasses) {
-      bool isNative = classElement.isNative;
-      bool isExtension =
-          !isNative && Elements.isNativeOrExtendsNative(classElement);
-      // Generate table entries for native classes that are explicitly named and
-      // extensions that fix our criteria.
-      if ((isNative && selectedClasses.contains(classElement)) ||
-          (isExtension &&
-              (allClassesSelected || selectedClasses.contains(classElement)))) {
-        newActiveClasses.add(classElement);
-        Iterable<Element> escapingConstructors =
-            computeEscapingConstructors(classElement);
-        escapingConstructors.forEach(enqueuer.registerStaticUse);
-        escapingConstructors
-            .forEach(compiler.globalDependencies.registerDependency);
-        // Force the generaton of the type constant that is the key to an entry
-        // in the generated table.
-        ConstantValue constant = makeTypeConstant(classElement);
-        backend.registerCompileTimeConstant(
-            constant, compiler.globalDependencies);
-        backend.constants.addCompileTimeConstantForEmission(constant);
-      }
-    }
-    activeClasses.addAll(newActiveClasses);
-    instantiatedClasses.removeAll(newActiveClasses);
-  }
-
-  TypeConstantValue makeTypeConstant(ClassElement element) {
-    DartType elementType = element.rawType;
-    DartType constantType = backend.typeImplementation.rawType;
-    return new TypeConstantValue(elementType, constantType);
-  }
-
-  List<Element> computeEscapingConstructors(ClassElement classElement) {
-    List<Element> result = <Element>[];
-    // Only classes that extend native classes have constructors in the table.
-    // We could refine this to classes that extend Element, but that would break
-    // the tests and there is no sane reason to subclass other native classes.
-    if (classElement.isNative) return result;
-
-    selectGenerativeConstructors(ClassElement enclosing, Element member) {
-      if (member.isGenerativeConstructor) {
-        // Ignore constructors that cannot be called with zero arguments.
-        FunctionElement constructor = member;
-        FunctionSignature parameters = constructor.functionSignature;
-        if (parameters.requiredParameterCount == 0) {
-          result.add(member);
-        }
-      }
-    }
-    classElement.forEachMember(selectGenerativeConstructors,
-        includeBackendMembers: false,
-        includeSuperAndInjectedMembers: false);
-    return result;
-  }
-}