Move gson to its own folder

[unical.git] / gson / com / google / gson / TreeTypeAdapter.java

diff --git a/gson/com/google/gson/TreeTypeAdapter.java b/gson/com/google/gson/TreeTypeAdapter.java
new file mode 100644 (file)
index 0000000..a05c1fe
--- /dev/null
+++ b/gson/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;
+    }
+  }
+}