Support serialization of the compiler backbone.

pkg/compiler/lib/src/serialization/serialization.dart

Index: pkg/compiler/lib/src/serialization/serialization.dart
diff --git a/pkg/compiler/lib/src/serialization/serialization.dart b/pkg/compiler/lib/src/serialization/serialization.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5dd1ce8fc81a51061ffc5fcf34f27887fc7d5420
--- /dev/null
+++ b/pkg/compiler/lib/src/serialization/serialization.dart
@@ -0,0 +1,730 @@
+// Copyright (c) 2015, 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 dart2js.serialization;
+
+import '../elements/elements.dart';
+import '../constants/expressions.dart';
+import '../dart_types.dart';
+
+import 'element_serialization.dart';
+import 'constant_serialization.dart';
+import 'type_serialization.dart';
+import 'keys.dart';
+import 'json_serializer.dart';
+import 'values.dart';
+
+/// Abstract base interface for [ObjectSerializer] and [MapSerializer].

[floitsch, 2015/06/26 20:54:05]

Misses documentation.

[Johnni Winther, 2015/07/03 12:13:45]

Done.

+abstract class AbstractSerializer<K> {
+  /// Maps the [key] entry to the enum [value] in this serializer.
+  void setEnum(K key, var value);
+
+  /// Maps the [key] entry to the [element] in this serializer.
+  void setElement(K key, Element element);
+
+  /// Maps the [key] entry to the [elements] in this serializer.
+  ///
+  /// If [elements] is empty, it is skipped.
+  void setElements(K key, Iterable<Element> elements);
+
+  /// Maps the [key] entry to the [constant] in this serializer.
+  void setConstant(K key, ConstantExpression constant);
+
+  /// Maps the [key] entry to the [constants] in this serializer.
+  ///
+  /// If [constants] is empty, it is skipped.
+  void setConstants(K key, Iterable<ConstantExpression> constants);
+
+  /// Maps the [key] entry to the [type] in this serializer.
+  void setType(K key, DartType type);
+
+  /// Maps the [key] entry to the [types] in this serializer.
+  ///
+  /// If [types] is empty, it is skipped.
+  void setTypes(K key, Iterable<DartType> types);
+
+  /// Maps the [key] entry to the [uri] in this serializer using [baseUri] to
+  /// relatives the encoding.
+  ///
+  /// For instance, a source file like `sdk/lib/core/string.dart` should be
+  /// serialized relative to the library root.
+  void setUri(K key, Uri baseUri, Uri uri);
+
+  /// Maps the [key] entry to the string [value] in this serializer.
+  void setString(K key, String value);
+
+  /// Maps the [key] entry to the string [values] in this serializer.
+  ///
+  /// If [values] is empty, it is skipped.
+  void setStrings(K key, Iterable<String> values);
+
+  /// Maps the [key] entry to the bool [value] in this serializer.
+  void setBool(K key, bool value);
+
+  /// Maps the [key] entry to the int [value] in this serializer.
+  void setInt(K key, int value);
+
+  /// Maps the [key] entry to the int [values] in this serializer.
+  ///
+  /// If [values] is empty, it is skipped.
+  void setInts(K key, Iterable<int> values);
+
+  /// Maps the [key] entry to the double [value] in this serializer.
+  void setDouble(K key, double value);
+
+  /// Creates and returns an [ObjectSerializer] that is mapped to the [key]
+  /// entry in this serializer.
+  ObjectSerializer createObject(K key);
+
+  /// Creates and returns a [MapSerializer] that is mapped to the [key] entry in
+  /// this serializer.
+  MapSerializer createMap(K key);
+
+  /// Creates and returns a [ListSerializer] that is mapped to the [key] entry
+  /// in this serializer.
+  ListSerializer createList(K key);
+}
+
+/// A serializer that associates values with [Key]s.

[floitsch, 2015/06/26 20:54:05]

Documentation.

[Johnni Winther, 2015/07/03 12:13:45]

Done.

+abstract class ObjectSerializer implements AbstractSerializer<Key> {
+
+}
+
+/// A serializer that associates values with [String]s.
+abstract class MapSerializer implements AbstractSerializer<String> {
+
+}
+
+/// A serializer that contains a list of [ObjectSerializer]s or
+/// [MapSerializer]s.

[floitsch, 2015/06/26 20:54:05]

this doesn't help.
Why would I have a list of ObjectSerializers and MapSerializers?
The API doesn't even reflect this.

[Johnni Winther, 2015/07/03 12:13:45]

Done.

+abstract class ListSerializer {
+  /// Creates an [ObjectSerializer] and adds it to this serializer.
+  ObjectSerializer createObject();
+
+  /// Creates an [ObjectSerializer] and adds it to this serializer.
+  MapSerializer createMap();
+}
+
+/// Abstract base interface for [ObjectDeserializer] and [MapDeserializer].
+abstract class AbstractDeserializer<K> {
+  /// Returns `true` if [key] has an associated value in this deserializer.
+  bool containsKey(K key);
+
+  /// Returns the enum value from the [enumValues] associated with [key] in this
+  /// deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// [defaultValue] is returned, otherwise an exception is thrown.
+  getEnum(K key, Iterable enumValues, {bool isOptional: false, defaultValue});
+
+  /// Returns the [Element] value associated with [key] in this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// `null` is returned, otherwise an exception is thrown.
+  Element getElement(K key, {bool isOptional: false});
+
+  /// Returns the list of [Element] values associated with [key] in this
+  /// deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// and empty [List] is returned, otherwise an exception is thrown.
+  List<Element> getElements(K key, {bool isOptional: false});
+
+  /// Returns the [ConstantExpression] value associated with [key] in this
+  /// deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// `null` is returned, otherwise an exception is thrown.
+  ConstantExpression getConstant(K key, {bool isOptional: false});
+
+  /// Returns the list of [ConstantExpression] values associated with [key] in
+  /// this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// and empty [List] is returned, otherwise an exception is thrown.
+  List<ConstantExpression> getConstants(K key, {bool isOptional: false});
+
+  /// Returns the [DartType] value associated with [key] in this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// `null` is returned, otherwise an exception is thrown.
+  DartType getType(K key, {bool isOptional: false});
+
+  /// Returns the list of [DartType] values associated with [key] in this
+  /// deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// and empty [List] is returned, otherwise an exception is thrown.
+  List<DartType> getTypes(K key, {bool isOptional: false});
+
+  /// Returns the [Uri] value associated with [key] in this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// [defaultValue] is returned, otherwise an exception is thrown.
+  Uri getUri(K key, {bool isOptional: false, Uri defaultValue});
+
+  /// Returns the [String] value associated with [key] in this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// [defaultValue] is returned, otherwise an exception is thrown.
+  String getString(K key, {bool isOptional: false, String defaultValue});
+
+  /// Returns the list of [String] values associated with [key] in this
+  /// deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// and empty [List] is returned, otherwise an exception is thrown.
+  List<String> getStrings(K key, {bool isOptional: false});
+
+  /// Returns the [bool] value associated with [key] in this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// [defaultValue] is returned, otherwise an exception is thrown.
+  bool getBool(K key, {bool isOptional: false, bool defaultValue});
+
+  /// Returns the [int] value associated with [key] in this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// [defaultValue] is returned, otherwise an exception is thrown.
+  int getInt(K key, {bool isOptional: false, int defaultValue});
+
+  /// Returns the list of [int] values associated with [key] in this
+  /// deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// and empty [List] is returned, otherwise an exception is thrown.
+  List<int> getInts(K key, {bool isOptional: false});
+
+  /// Returns the [double] value associated with [key] in this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// [defaultValue] is returned, otherwise an exception is thrown.
+  double getDouble(K key, {bool isOptional: false, double defaultValue});
+
+  /// Returns an [ObjectDeserializer] for the map value associated with [key] in
+  /// this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// `null` is returned, otherwise an exception is thrown.
+  ObjectDeserializer getObject(K key, {bool isOptional: false});
+
+  /// Returns an [MapDeserializer] for the map value associated with [key] in
+  /// this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// `null` is returned, otherwise an exception is thrown.
+  MapDeserializer getMap(K key, {bool isOptional: false});
+
+  /// Returns an [ListDeserializer] for the list value associated with [key] in
+  /// this deserializer.
+  ///
+  /// If no value is associated with [key], then if [isOptional] is `true`,
+  /// `null` is returned, otherwise an exception is thrown.
+  ListDeserializer getList(K key, {bool isOptional: false});
+}
+
+/// A deserializer where values are associated with [Key]s.
+abstract class ObjectDeserializer implements AbstractDeserializer<Key> {
+
+}
+
+/// A deserializer where values are associated with [String]s.
+abstract class MapDeserializer implements AbstractDeserializer<String> {
+  /// Applies [f] to every key in the deserializer.
+  void forEachKey(f(String key));
+}
+
+/// A deserializer of a list of map values.

[floitsch, 2015/06/26 20:54:05]

what "map" values?

[Johnni Winther, 2015/07/03 12:13:45]

Done.

+abstract class ListDeserializer {
+  /// The number of values in this deserializer.
+  int get length;
+
+  /// Returns an [ObjectDeserializer] for the [index]th map value in
+  /// this deserializer.
+  ObjectDeserializer getObject(int index);
+
+  /// Returns an [MapDeserializer] for the [index]th map value in
+  /// this deserializer.
+  MapDeserializer getMap(int index);
+}
+
+/// A nominal object containing its serialized value.
+abstract class DataObject {
+  /// The id for the object.
+  get id;
+
+  /// The serialized value of the object.
+  ObjectValue get objectValue;
+}
+
+/// Serializer for the transitive closure of a collection of libraries.
+// TODO(johnniwinther): Support per-library serialization and dependencies
+// between serialized subcomponent.
+class Serializer {
+  final SerializationEncoder _encoder;
+
+  Map<Element, DataObject> _elementMap = <Element, DataObject>{};
+  Map<ConstantExpression, DataObject> _constantMap =
+      <ConstantExpression, DataObject>{};
+  Map<DartType, DataObject> _typeMap = <DartType, DataObject>{};
+  List _pendingList = [];
+
+  Serializer(this._encoder);
+
+  /// Add the transitive closure of [library] to this serializer.
+  void serialize(LibraryElement library) {
+    _getElementValue(library);

[floitsch, 2015/06/26 20:54:05]

Add comment, why we don't care for the ElementValue.

[Johnni Winther, 2015/07/03 12:13:45]

Done.

+    _emptyWorklist();
+  }
+
+  void _emptyWorklist() {
+    while (_pendingList.isNotEmpty) {
+      _pendingList.removeLast()();
+    }
+  }
+
+  DataObject _createDataObject(IntValue id, EnumValue kind) {
+    return _encoder.createDataObject(id,  kind);
+  }
+
+  ObjectSerializer _createObjectSerializer(Serializer serializer,
+                                           DataObject dataObject) {
+    return _encoder.createObjectSerializer(serializer, dataObject);
+  }
+
+  DataObject _getElementData(Element element) {
+    if (element == null) {
+      throw new ArgumentError('Serializer._getElementData(null)');
+    }
+    return _elementMap.putIfAbsent(element, () {
+      for (ElementSerializer serializer in ELEMENT_SERIALIZERS) {
+        SerializedElementKind kind = serializer.getSerializedKind(element);
+        if (kind != null) {
+          DataObject dataObject = _createDataObject(
+              new IntValue(_elementMap.length), new EnumValue(kind));
+          _pendingList.add(() {
+            serializer.serialize(

[floitsch, 2015/06/26 20:54:05]

Ideally (especially if we decide not to use the encoder for the memory layout),
this could become:

// Delay the serialization of the object itself to avoid loops, and to keep the
// call stack small.
_pendingList.add(() {
  dataObject.setValue(serializer.serialize(element, kind));
});

[Johnni Winther, 2015/07/03 12:13:45]

You would need to pass the [Serializer] around then.

+                element, _createObjectSerializer(this, dataObject), kind);
+          });
+          return dataObject;
+        }
+      }
+      throw new UnsupportedError(
+          'Unsupported element: $element (${element.kind})');
+    });
+  }
+
+  ElementValue _getElementValue(Element element) {
+    return new ElementValue(element, _getElementData(element).id);
+  }
+
+  void setElement(Map<dynamic, Value> map, key, Element element) {
+    map[key] = _getElementValue(element);
+  }
+
+  void setElements(Map<dynamic, Value> map, key, List<Element> elements) {
+    if (elements.isNotEmpty) {
+      map[key] = new ListValue(elements.map(_getElementValue).toList());
+    }
+  }
+
+  DataObject _getConstantData(ConstantExpression constant) {
+    return _constantMap.putIfAbsent(constant, () {
+      DataObject dataObject = _createDataObject(
+          new IntValue(_constantMap.length), new EnumValue(constant.kind));
+      _pendingList.add(() => _serializeConstant(constant, dataObject));
+      return dataObject;
+    });
+  }
+
+  void _serializeConstant(ConstantExpression constant, DataObject dataObject) {
+    const ConstantSerializer().apply(constant,
+        _createObjectSerializer(this, dataObject));
+  }
+
+  ConstantValue _getConstantValue(ConstantExpression constant) {
+    return new ConstantValue(constant, _getConstantData(constant).id);
+  }
+
+  void setConstant(Map<dynamic, Value> map, key, ConstantExpression constant) {
+    map[key] = _getConstantValue(constant);
+  }
+
+  void setConstants(Map<dynamic, Value> map,

[floitsch, 2015/06/26 20:54:05]

There is no reason to be imperative here. Return the ListValue directly (or null
if empty).

Don't call this "setConstants" which is the same name as in the
AbstractSerializer.
Maybe really just "serializeConstants".

Same for setConstant, setType, ...

[Johnni Winther, 2015/07/03 12:13:45]

Done.

+                    key,
+                    List<ConstantExpression> constants) {
+    if (constants.isNotEmpty) {
+      map[key] = new ListValue(constants.map(_getConstantValue).toList());
+    }
+  }
+
+  DataObject _getTypeData(DartType type) {
+    return _typeMap.putIfAbsent(type, () {
+      DataObject dataObject = _createDataObject(
+          new IntValue(_typeMap.length), new EnumValue(type.kind));
+      _pendingList.add(() => _serializeType(type, dataObject));
+      return dataObject;
+    });
+  }
+
+  void _serializeType(DartType type, DataObject dataObject) {
+    const TypeSerializer().apply(type,
+        _createObjectSerializer(this, dataObject));
+  }
+
+  TypeValue _getTypeValue(DartType type) {
+    return new TypeValue(type, _getTypeData(type).id);
+  }
+
+  void setType(Map<dynamic, Value> map, key, DartType type) {
+    map[key] = _getTypeValue(type);
+  }
+
+  void setTypes(Map<dynamic, Value> map, key, List<DartType> types) {
+    if (types.isNotEmpty) {
+      map[key] = new ListValue(types.map(_getTypeValue).toList());
+    }
+  }
+
+  void setBool(Map<dynamic, Value> map, key, bool value) {
+    map[key] = new BoolValue(value);
+  }
+
+  void setInt(Map<dynamic, Value> map, key, int value) {
+    map[key] = new IntValue(value);
+  }
+
+  void setInts(Map<dynamic, Value> map, key, List<int> values) {
+    if (values.isNotEmpty) {
+      map[key] = new ListValue(
+          values.map((v) => new IntValue(v)).toList());
+    }
+  }
+
+  void setDouble(Map<dynamic, Value> map, key, double value) {
+    map[key] = new DoubleValue(value);
+  }
+
+  void setString(Map<dynamic, Value> map, key, String value) {
+    map[key] = new StringValue(value);
+  }
+
+  void setStrings(Map<dynamic, Value> map, key, List<String> values) {
+    if (values.isNotEmpty) {
+      map[key] = new ListValue(
+          values.map((v) => new StringValue(v)).toList());
+    }
+  }
+
+  void setEnum(Map<dynamic, Value> map, key, value) {
+    map[key] = new EnumValue(value);
+  }
+
+  void setUri(Map<dynamic, Value> map, key, Uri baseUri, Uri value) {
+    map[key] = new UriValue(baseUri, value);
+  }
+
+  ObjectValue get objectValue {
+    Map<Key, Value> map = <Key, Value>{};
+    map[Key.ELEMENTS] =
+        new ListValue(_elementMap.values.map((l) => l.objectValue).toList());
+    if (_typeMap.isNotEmpty) {
+      map[Key.TYPES] =
+          new ListValue(_typeMap.values.map((l) => l.objectValue).toList());
+    }
+    if (_constantMap.isNotEmpty) {
+      map[Key.CONSTANTS] =
+          new ListValue(_constantMap.values.map((l) => l.objectValue).toList());
+    }
+    return new ObjectValue(map);
+  }
+
+  String toText() {
+    return _encoder.encode(objectValue);
+  }
+
+  String prettyPrint() {
+    PrettyPrintEncoder encoder = new PrettyPrintEncoder();
+    return encoder.toText(objectValue);
+  }
+}
+
+/// Deserializer for a closed collection of libraries.
+// TODO(johnniwinther): Support per-library deserialization and dependencies
+// between deserialized subcomponent.
+class Deserializer {
+  final SerializationDecoder _decoder;
+  final _mainData;

[floitsch, 2015/06/26 20:54:05]

mainData is not a good name.

[Johnni Winther, 2015/07/03 12:13:45]

'mainData' -> 'headerObject'.

+  Map<int, Element> _elementMap = {};
+  Map<int, DartType> _typeMap = {};
+  Map<int, ConstantExpression> _constantMap = {};
+
+  Deserializer.fromText(String text, SerializationDecoder decoder)
+      : this._mainData = decoder.decode(text),
+        this._decoder = decoder;
+
+  List _readMainData(Key key) {
+    return _decoder.readMainData(_mainData, key);
+  }
+
+  _readEntry(data, key) {
+    return _decoder.readEntry(data, key);
+  }
+
+  /// Returns the [LibraryElement] for [uri] if part of the deserializer.
+  LibraryElement lookupLibrary(Uri uri) {
+    for (var data in _readMainData(Key.ELEMENTS)) {
+      SerializedElementKind kind =
+          getEnum(data, Key.KIND, SerializedElementKind.values);
+      if (kind == SerializedElementKind.LIBRARY) {
+        Uri libraryUri = getUri(data, Key.CANONICAL_URI);
+        if (libraryUri == uri) {
+          return getElement(data, Key.ID);
+        }
+      }
+    }
+    return null;
+  }
+
+  Element getElement(data, key, {bool isOptional: false}) {
+    int id = _readEntry(data, key);
+    if (id == null) {
+      if (isOptional) {
+        return null;
+      }
+      throw new StateError("Element value '$key' not found in $data.");
+    }
+    return _getElementById(id);
+  }
+
+  Element _getElementById(int id) {
+    if (id == null) throw new ArgumentError('Deserializer.getElement(null)');
+    return _elementMap.putIfAbsent(id, () {
+      return ElementDeserializer.deserialize(
+          new JsonObjectDeserializer(this, _readMainData(Key.ELEMENTS)[id]));
+    });
+  }
+
+  List<Element> getElements(data, key, {bool isOptional: false}) {
+    List list = _readEntry(data, key);
+    if (list == null) {
+      if (isOptional) {
+        return const [];
+      }
+      throw new StateError("Elements value '$key' not found in $data.");
+    }
+    return list.map(_getElementById).toList();
+  }
+
+  DartType getType(data, key, {bool isOptional: false}) {
+    int id = _readEntry(data, key);
+    if (id == null) {
+      if (isOptional) {
+        return null;
+      }
+      throw new StateError("Type value '$key' not found in $data.");
+    }
+    return _getTypeById(id);
+  }
+
+  DartType _getTypeById(int id) {
+    if (id == null) throw new ArgumentError('Deserializer.getType(null)');
+    return _typeMap.putIfAbsent(id, () {
+      return TypeDeserializer.deserialize(
+          new JsonObjectDeserializer(this, _readMainData(Key.TYPES)[id]));
+    });
+  }
+
+  List<DartType> getTypes(data, key, {bool isOptional: false}) {
+    List list = _readEntry(data, key);
+    if (list == null) {
+      if (isOptional) {
+        return const [];
+      }
+      throw new StateError("Types value '$key' not found in $data.");
+    }
+    return list.map(_getTypeById).toList();
+  }
+
+  ConstantExpression getConstant(data, key, {bool isOptional: false}) {
+    int id = _readEntry(data, key);
+    if (id == null) {
+      if (isOptional) {
+        return null;
+      }
+      throw new StateError("Constant value '$key' not found in $data.");
+    }
+    return _getConstantById(id);
+  }
+
+  ConstantExpression _getConstantById(int id) {
+    if (id == null) throw new ArgumentError('Deserializer.getConstant(null)');
+    return _constantMap.putIfAbsent(id, () {
+      return ConstantDeserializer.deserialize(
+          new JsonObjectDeserializer(this, _readMainData(Key.CONSTANTS)[id]));
+    });
+  }
+
+  List<ConstantExpression> getConstants(data, key, {bool isOptional: false}) {
+    List list = _readEntry(data, key);
+    if (list == null) {
+      if (isOptional) {
+        return const [];
+      }
+      throw new StateError("Constants value '$key' not found in $data.");
+    }
+    return list.map(_getConstantById).toList();
+  }
+
+  bool getBool(data, key, {bool isOptional: false, bool defaultValue}) {
+    bool value = _readEntry(data, key);
+    if (value == null) {
+      if (isOptional || defaultValue != null) {
+        return defaultValue;
+      }
+      throw new StateError("bool value '$key' not found in $data.");
+    }
+    return value;
+  }
+
+  int getInt(data, key, {bool isOptional: false, int defaultValue}) {
+    int value = _readEntry(data, key);
+    if (value == null) {
+      if (isOptional || defaultValue != null) {
+        return defaultValue;
+      }
+      throw new StateError("int value '$key' not found in $data.");
+    }
+    return value;
+  }
+
+  List<int> getInts(data, key, {bool isOptional: false}) {
+    List list = _readEntry(data, key);
+    if (list == null) {
+      if (isOptional) {
+        return const [];
+      }
+      throw new StateError("Ints value '$key' not found in $data.");
+    }
+    return list;
+  }
+
+  double getDouble(data, key, {bool isOptional: false, double defaultValue}) {
+    double value = _readEntry(data, key);
+    if (value == null) {
+      if (isOptional || defaultValue != null) {
+        return defaultValue;
+      }
+      throw new StateError("double value '$key' not found in $data.");
+    }
+    return value;
+  }
+
+  String getString(data, key, {bool isOptional: false, String defaultValue}) {
+    String value = _readEntry(data, key);
+    if (value == null) {
+      if (isOptional || defaultValue != null) {
+        return defaultValue;
+      }
+      throw new StateError("String value '$key' not found in $data.");
+    }
+    return value;
+  }
+
+  List<String> getStrings(data, key, {bool isOptional: false}) {
+    List list = _readEntry(data, key);
+    if (list == null) {
+      if (isOptional) {
+        return const [];
+      }
+      throw new StateError("Strings value '$key' not found in $data.");
+    }
+    return list;
+  }
+
+  getEnum(data, key, List values,
+          {bool isOptional: false, defaultValue}) {
+    int value = _readEntry(data, key);
+    if (value == null) {
+      if (isOptional || defaultValue != null) {
+        return defaultValue;
+      }
+      throw new StateError("enum value '$key' not found in $data.");
+    }
+    return values[value];
+  }
+
+  ObjectDeserializer getObject(data, key, {bool isOptional: false}) {
+    Map map = _readEntry(data, key);
+    if (map == null) {
+      if (isOptional) {
+        return null;
+      }
+      throw new StateError("Object value '$key' not found in $data.");
+    }
+    return new JsonObjectDeserializer(this, map);
+  }
+
+  MapDeserializer getMap(data, key, {bool isOptional: false}) {
+    Map map = _readEntry(data, key);
+    if (map == null) {
+      if (isOptional) {
+        return null;
+      }
+      throw new StateError("Map value '$key' not found in $data.");
+    }
+    return new JsonMapDeserializer(this, map);
+  }
+
+  ListDeserializer getList(data, key, {bool isOptional: false}) {
+    List list = _readEntry(data, key);
+    if (list == null) {
+      if (isOptional) {
+        return null;
+      }
+      throw new StateError("List value '$key' not found in $data.");
+    }
+    return new JsonListDeserializer(this, list);
+  }
+
+  Uri getUri(data, key, {bool isOptional: false, Uri defaultValue}) {
+    // TODO(johnniwinther): Support scheme specific encoding.
+    String value = _readEntry(data, key);
+    if (value == null) {
+      if (isOptional || defaultValue != null) {
+        return defaultValue;
+      }
+      throw new StateError("Uri value '$key' not found in $data.");
+    }
+    return Uri.parse(value);
+  }
+}
+
+/// Strategy used by [Serializer] to define the memory and output encoding.
+// TODO(johnniwinther): Split output encoding from memory object encoding.

[floitsch, 2015/06/26 20:54:05]

Yes. But by removing the memory strategy. Just go for one simply IR that has
nothing to do with the encoder.
That could potentially change a lot of the other things (and definitely remove
some interfaces).

[Johnni Winther, 2015/07/03 12:13:45]

Done.

+abstract class SerializationEncoder {
+  /// Encode [objectValue] into text.
+  String encode(ObjectValue objectValue);
+
+  /// Create a [DataObject] for an entity with the given [id] and [kind].
+  DataObject createDataObject(IntValue id, EnumValue kind);
+
+  /// Create an [ObjectSerializer] for [dataObject].
+  ObjectSerializer createObjectSerializer(
+      Serializer serializer, DataObject dataObject);
+}
+
+/// Strategy used by [Deserializer] for decoding and reading data from a
+/// serialized output.
+// TODO(johnniwinther): Split input encoding from memory object encoding.
+abstract class SerializationDecoder {
+  /// Decode [text] into an internal data model.
+  decode(String text);
+
+  /// Read the main data entry for [key] from [mainData].
+  List readMainData(mainData, Key key);
+
+  /// Read the entry [key] from the [data] object.
+  readEntry(data, key);
+}