/*
* Copyright 2013 Nicolas Morel
*
* 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.github.nmorel.gwtjackson.client.deser.array;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import com.github.nmorel.gwtjackson.client.JsonDeserializationContext;
import com.github.nmorel.gwtjackson.client.JsonDeserializer;
import com.github.nmorel.gwtjackson.client.JsonDeserializerParameters;
import com.github.nmorel.gwtjackson.client.stream.JsonReader;
import com.github.nmorel.gwtjackson.client.stream.JsonToken;
/**
* Base implementation of {@link JsonDeserializer} for array.
*
* @author Nicolas Morel
*/
public abstract class AbstractArrayJsonDeserializer<T> extends JsonDeserializer<T> {
@Override
public T doDeserialize( JsonReader reader, JsonDeserializationContext ctx, JsonDeserializerParameters params ) {
if ( JsonToken.BEGIN_ARRAY == reader.peek() ) {
return doDeserializeArray( reader, ctx, params );
} else {
return doDeserializeNonArray( reader, ctx, params );
}
}
protected abstract T doDeserializeArray( JsonReader reader, JsonDeserializationContext ctx, JsonDeserializerParameters params );
protected T doDeserializeNonArray( JsonReader reader, JsonDeserializationContext ctx, JsonDeserializerParameters params ) {
if ( ctx.isAcceptSingleValueAsArray() ) {
return doDeserializeSingleArray( reader, ctx, params );
} else {
throw ctx.traceError( "Cannot deserialize an array out of " + reader.peek() + " token", reader );
}
}
protected abstract T doDeserializeSingleArray( JsonReader reader, JsonDeserializationContext ctx, JsonDeserializerParameters params );
/**
* Deserializes the array into a {@link List}. We need the length of the array before creating it.
*
* @param reader reader
* @param ctx context of the deserialization process
* @param deserializer deserializer for element inside the array
* @param params Parameters for the deserializer
* @param <C> type of the element inside the array
*
* @return a list containing all the elements of the array
*/
protected <C> List<C> deserializeIntoList( JsonReader reader, JsonDeserializationContext ctx, JsonDeserializer<C> deserializer,
JsonDeserializerParameters params ) {
List<C> list;
reader.beginArray();
JsonToken token = reader.peek();
if ( JsonToken.END_ARRAY == token ) {
// empty array, no need to create a list
list = Collections.emptyList();
} else {
list = new ArrayList<C>();
while ( JsonToken.END_ARRAY != token ) {
list.add( deserializer.deserialize( reader, ctx, params ) );
token = reader.peek();
}
}
reader.endArray();
return list;
}
}