diff options
Diffstat (limited to 'gson/src/main/java/com/google/gson/TreeTypeAdapter.java')
-rw-r--r-- | gson/src/main/java/com/google/gson/TreeTypeAdapter.java | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/gson/src/main/java/com/google/gson/TreeTypeAdapter.java b/gson/src/main/java/com/google/gson/TreeTypeAdapter.java new file mode 100644 index 00000000..a05c1fe0 --- /dev/null +++ b/gson/src/main/java/com/google/gson/TreeTypeAdapter.java @@ -0,0 +1,140 @@ +/* + * Copyright (C) 2011 Google Inc. + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package com.google.gson; + +import com.google.gson.internal.$Gson$Preconditions; +import com.google.gson.internal.Streams; +import com.google.gson.reflect.TypeToken; +import com.google.gson.stream.JsonReader; +import com.google.gson.stream.JsonWriter; +import java.io.IOException; + +/** + * Adapts a Gson 1.x tree-style adapter as a streaming TypeAdapter. Since the + * tree adapter may be serialization-only or deserialization-only, this class + * has a facility to lookup a delegate type adapter on demand. + */ +final class TreeTypeAdapter<T> extends TypeAdapter<T> { + private final JsonSerializer<T> serializer; + private final JsonDeserializer<T> deserializer; + private final Gson gson; + private final TypeToken<T> typeToken; + private final TypeAdapterFactory skipPast; + + /** The delegate is lazily created because it may not be needed, and creating it may fail. */ + private TypeAdapter<T> delegate; + + private TreeTypeAdapter(JsonSerializer<T> serializer, JsonDeserializer<T> deserializer, + Gson gson, TypeToken<T> typeToken, TypeAdapterFactory skipPast) { + this.serializer = serializer; + this.deserializer = deserializer; + this.gson = gson; + this.typeToken = typeToken; + this.skipPast = skipPast; + } + + @Override public T read(JsonReader in) throws IOException { + if (deserializer == null) { + return delegate().read(in); + } + JsonElement value = Streams.parse(in); + if (value.isJsonNull()) { + return null; + } + return deserializer.deserialize(value, typeToken.getType(), gson.deserializationContext); + } + + @Override public void write(JsonWriter out, T value) throws IOException { + if (serializer == null) { + delegate().write(out, value); + return; + } + if (value == null) { + out.nullValue(); + return; + } + JsonElement tree = serializer.serialize(value, typeToken.getType(), gson.serializationContext); + Streams.write(tree, out); + } + + private TypeAdapter<T> delegate() { + TypeAdapter<T> d = delegate; + return d != null + ? d + : (delegate = gson.getDelegateAdapter(skipPast, typeToken)); + } + + /** + * Returns a new factory that will match each type against {@code exactType}. + */ + public static TypeAdapterFactory newFactory(TypeToken<?> exactType, Object typeAdapter) { + return new SingleTypeFactory(typeAdapter, exactType, false, null); + } + + /** + * Returns a new factory that will match each type and its raw type against + * {@code exactType}. + */ + public static TypeAdapterFactory newFactoryWithMatchRawType( + TypeToken<?> exactType, Object typeAdapter) { + // only bother matching raw types if exact type is a raw type + boolean matchRawType = exactType.getType() == exactType.getRawType(); + return new SingleTypeFactory(typeAdapter, exactType, matchRawType, null); + } + + /** + * Returns a new factory that will match each type's raw type for assignability + * to {@code hierarchyType}. + */ + public static TypeAdapterFactory newTypeHierarchyFactory( + Class<?> hierarchyType, Object typeAdapter) { + return new SingleTypeFactory(typeAdapter, null, false, hierarchyType); + } + + private static class SingleTypeFactory implements TypeAdapterFactory { + private final TypeToken<?> exactType; + private final boolean matchRawType; + private final Class<?> hierarchyType; + private final JsonSerializer<?> serializer; + private final JsonDeserializer<?> deserializer; + + private SingleTypeFactory(Object typeAdapter, TypeToken<?> exactType, boolean matchRawType, + Class<?> hierarchyType) { + serializer = typeAdapter instanceof JsonSerializer + ? (JsonSerializer<?>) typeAdapter + : null; + deserializer = typeAdapter instanceof JsonDeserializer + ? (JsonDeserializer<?>) typeAdapter + : null; + $Gson$Preconditions.checkArgument(serializer != null || deserializer != null); + this.exactType = exactType; + this.matchRawType = matchRawType; + this.hierarchyType = hierarchyType; + } + + @SuppressWarnings("unchecked") // guarded by typeToken.equals() call + public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) { + boolean matches = exactType != null + ? exactType.equals(type) || matchRawType && exactType.getType() == type.getRawType() + : hierarchyType.isAssignableFrom(type.getRawType()); + return matches + ? new TreeTypeAdapter<T>((JsonSerializer<T>) serializer, + (JsonDeserializer<T>) deserializer, gson, type, this) + : null; + } + } +} |