| 1 | /* |
| 2 | * Copyright (C) 2011 Google Inc. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package com.google.gson; |
| 18 | |
| 19 | import com.google.gson.internal.$Gson$Preconditions; |
| 20 | import com.google.gson.internal.Streams; |
| 21 | import com.google.gson.reflect.TypeToken; |
| 22 | import com.google.gson.stream.JsonReader; |
| 23 | import com.google.gson.stream.JsonWriter; |
| 24 | import java.io.IOException; |
| 25 | |
| 26 | /** |
| 27 | * Adapts a Gson 1.x tree-style adapter as a streaming TypeAdapter. Since the |
| 28 | * tree adapter may be serialization-only or deserialization-only, this class |
| 29 | * has a facility to lookup a delegate type adapter on demand. |
| 30 | */ |
| 31 | final class TreeTypeAdapter<T> extends TypeAdapter<T> { |
| 32 | private final JsonSerializer<T> serializer; |
| 33 | private final JsonDeserializer<T> deserializer; |
| 34 | private final Gson gson; |
| 35 | private final TypeToken<T> typeToken; |
| 36 | private final TypeAdapterFactory skipPast; |
| 37 | |
| 38 | /** The delegate is lazily created because it may not be needed, and creating it may fail. */ |
| 39 | private TypeAdapter<T> delegate; |
| 40 | |
| 41 | private TreeTypeAdapter(JsonSerializer<T> serializer, JsonDeserializer<T> deserializer, |
| 42 | Gson gson, TypeToken<T> typeToken, TypeAdapterFactory skipPast) { |
| 43 | this.serializer = serializer; |
| 44 | this.deserializer = deserializer; |
| 45 | this.gson = gson; |
| 46 | this.typeToken = typeToken; |
| 47 | this.skipPast = skipPast; |
| 48 | } |
| 49 | |
| 50 | @Override public T read(JsonReader in) throws IOException { |
| 51 | if (deserializer == null) { |
| 52 | return delegate().read(in); |
| 53 | } |
| 54 | JsonElement value = Streams.parse(in); |
| 55 | if (value.isJsonNull()) { |
| 56 | return null; |
| 57 | } |
| 58 | return deserializer.deserialize(value, typeToken.getType(), gson.deserializationContext); |
| 59 | } |
| 60 | |
| 61 | @Override public void write(JsonWriter out, T value) throws IOException { |
| 62 | if (serializer == null) { |
| 63 | delegate().write(out, value); |
| 64 | return; |
| 65 | } |
| 66 | if (value == null) { |
| 67 | out.nullValue(); |
| 68 | return; |
| 69 | } |
| 70 | JsonElement tree = serializer.serialize(value, typeToken.getType(), gson.serializationContext); |
| 71 | Streams.write(tree, out); |
| 72 | } |
| 73 | |
| 74 | private TypeAdapter<T> delegate() { |
| 75 | TypeAdapter<T> d = delegate; |
| 76 | return d != null |
| 77 | ? d |
| 78 | : (delegate = gson.getDelegateAdapter(skipPast, typeToken)); |
| 79 | } |
| 80 | |
| 81 | /** |
| 82 | * Returns a new factory that will match each type against {@code exactType}. |
| 83 | */ |
| 84 | public static TypeAdapterFactory newFactory(TypeToken<?> exactType, Object typeAdapter) { |
| 85 | return new SingleTypeFactory(typeAdapter, exactType, false, null); |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * Returns a new factory that will match each type and its raw type against |
| 90 | * {@code exactType}. |
| 91 | */ |
| 92 | public static TypeAdapterFactory newFactoryWithMatchRawType( |
| 93 | TypeToken<?> exactType, Object typeAdapter) { |
| 94 | // only bother matching raw types if exact type is a raw type |
| 95 | boolean matchRawType = exactType.getType() == exactType.getRawType(); |
| 96 | return new SingleTypeFactory(typeAdapter, exactType, matchRawType, null); |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * Returns a new factory that will match each type's raw type for assignability |
| 101 | * to {@code hierarchyType}. |
| 102 | */ |
| 103 | public static TypeAdapterFactory newTypeHierarchyFactory( |
| 104 | Class<?> hierarchyType, Object typeAdapter) { |
| 105 | return new SingleTypeFactory(typeAdapter, null, false, hierarchyType); |
| 106 | } |
| 107 | |
| 108 | private static class SingleTypeFactory implements TypeAdapterFactory { |
| 109 | private final TypeToken<?> exactType; |
| 110 | private final boolean matchRawType; |
| 111 | private final Class<?> hierarchyType; |
| 112 | private final JsonSerializer<?> serializer; |
| 113 | private final JsonDeserializer<?> deserializer; |
| 114 | |
| 115 | private SingleTypeFactory(Object typeAdapter, TypeToken<?> exactType, boolean matchRawType, |
| 116 | Class<?> hierarchyType) { |
| 117 | serializer = typeAdapter instanceof JsonSerializer |
| 118 | ? (JsonSerializer<?>) typeAdapter |
| 119 | : null; |
| 120 | deserializer = typeAdapter instanceof JsonDeserializer |
| 121 | ? (JsonDeserializer<?>) typeAdapter |
| 122 | : null; |
| 123 | $Gson$Preconditions.checkArgument(serializer != null || deserializer != null); |
| 124 | this.exactType = exactType; |
| 125 | this.matchRawType = matchRawType; |
| 126 | this.hierarchyType = hierarchyType; |
| 127 | } |
| 128 | |
| 129 | @SuppressWarnings("unchecked") // guarded by typeToken.equals() call |
| 130 | public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) { |
| 131 | boolean matches = exactType != null |
| 132 | ? exactType.equals(type) || matchRawType && exactType.getType() == type.getRawType() |
| 133 | : hierarchyType.isAssignableFrom(type.getRawType()); |
| 134 | return matches |
| 135 | ? new TreeTypeAdapter<T>((JsonSerializer<T>) serializer, |
| 136 | (JsonDeserializer<T>) deserializer, gson, type, this) |
| 137 | : null; |
| 138 | } |
| 139 | } |
| 140 | } |