TypeAdapters.java

/*
 * 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.smartandroid.sa.json.internal.bind;

import java.io.IOException;

import com.smartandroid.sa.json.reflect.TypeToken;
import com.smartandroid.sa.json.stream.JsonReader;
import com.smartandroid.sa.json.stream.JsonWriter;

/**
 * Type adapters for basic types.
 */
public final class TypeAdapters {
	private TypeAdapters() {
	}

	public static final TypeAdapter<Boolean> BOOLEAN = new TypeAdapter<Boolean>() {
		public Boolean read(JsonReader reader) throws IOException {
			return reader.nextBoolean();
		}

		public void write(JsonWriter writer, Boolean value) throws IOException {
			writer.value(value);
		}
	};

	public static final TypeAdapter.Factory BOOLEAN_FACTORY = newFactory(
			boolean.class, Boolean.class, BOOLEAN);

	public static final TypeAdapter<Integer> INTEGER = new TypeAdapter<Integer>() {
		public Integer read(JsonReader reader) throws IOException {
			return reader.nextInt();
		}

		public void write(JsonWriter writer, Integer value) throws IOException {
			writer.value(value);
		}
	};

	public static final TypeAdapter.Factory INTEGER_FACTORY = newFactory(
			int.class, Integer.class, INTEGER);

	public static final TypeAdapter<Long> LONG = new TypeAdapter<Long>() {
		public Long read(JsonReader reader) throws IOException {
			return reader.nextLong();
		}

		public void write(JsonWriter writer, Long value) throws IOException {
			writer.value(value);
		}
	};

	public static final TypeAdapter.Factory LONG_FACTORY = newFactory(
			long.class, Long.class, LONG);

	public static final TypeAdapter<Double> DOUBLE = new TypeAdapter<Double>() {
		public Double read(JsonReader reader) throws IOException {
			return reader.nextDouble();
		}

		public void write(JsonWriter writer, Double value) throws IOException {
			writer.value(value);
		}
	};

	public static final TypeAdapter.Factory DOUBLE_FACTORY = newFactory(
			double.class, Double.class, DOUBLE);

	public static final TypeAdapter<Float> FLOAT = new TypeAdapter<Float>() {
		public Float read(JsonReader reader) throws IOException {
			return (float) reader.nextDouble();
		}

		public void write(JsonWriter writer, Float value) throws IOException {
			writer.value(value);
		}
	};

	public static final TypeAdapter.Factory FLOAT_FACTORY = newFactory(
			float.class, Float.class, FLOAT);

	public static final TypeAdapter<String> STRING = new TypeAdapter<String>() {
		public String read(JsonReader reader) throws IOException {
			return reader.nextString();
		}

		public void write(JsonWriter writer, String value) throws IOException {
			writer.value(value);
		}
	};

	public static final TypeAdapter.Factory STRING_FACTORY = newFactory(
			String.class, STRING);

	public static final TypeAdapter EXCLUDED_TYPE_ADAPTER = new TypeAdapter<Object>() {
		@Override
		public Object read(JsonReader reader) throws IOException {
			reader.skipValue();
			return null;
		}

		@Override
		public void write(JsonWriter writer, Object value) throws IOException {
			writer.nullValue();
		}
	};

	public static <T> TypeAdapter.Factory newFactory(final TypeToken<T> type,
			final TypeAdapter<T> typeAdapter) {
		return new TypeAdapter.Factory() {
			@SuppressWarnings("unchecked")
			// we use a runtime check to make sure the 'T's equal
			public <T> TypeAdapter<T> create(MiniGson context,
					TypeToken<T> typeToken) {
				return typeToken.equals(type) ? (TypeAdapter<T>) typeAdapter
						: null;
			}
		};
	}

	public static <T> TypeAdapter.Factory newFactory(final Class<T> type,
			final TypeAdapter<T> typeAdapter) {
		return new TypeAdapter.Factory() {
			@SuppressWarnings("unchecked")
			// we use a runtime check to make sure the 'T's equal
			public <T> TypeAdapter<T> create(MiniGson context,
					TypeToken<T> typeToken) {
				return typeToken.getRawType() == type ? (TypeAdapter<T>) typeAdapter
						: null;
			}
		};
	}

	public static <T> TypeAdapter.Factory newFactory(final Class<T> unboxed,
			final Class<T> boxed, final TypeAdapter<T> typeAdapter) {
		return new TypeAdapter.Factory() {
			@SuppressWarnings("unchecked")
			// we use a runtime check to make sure the 'T's equal
			public <T> TypeAdapter<T> create(MiniGson context,
					TypeToken<T> typeToken) {
				Class<? super T> rawType = typeToken.getRawType();
				return (rawType == unboxed || rawType == boxed) ? (TypeAdapter<T>) typeAdapter
						: null;
			}
		};
	}

	public static <T> TypeAdapter.Factory newTypeHierarchyFactory(
			TypeToken<T> type, TypeAdapter<T> typeAdapter) {
		return new TypeAdapter.Factory() {
			public <T> TypeAdapter<T> create(MiniGson context,
					TypeToken<T> typeToken) {
				// TODO: use Inder's TypeHierarchyAdapter here
				throw new UnsupportedOperationException();
			}
		};
	}
}