package com.fasterxml.jackson.databind.ser.std;

import java.lang.reflect.Type;
import java.io.IOException;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatVisitorWrapper;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;

This is a simple dummy serializer that will just output literal
JSON null value whenever serialization is requested.
Used as the default "null serializer" (which is used for serializing
null object references unless overridden), as well as for some
more exotic types (java.lang.Void).
/**
 * This is a simple dummy serializer that will just output literal
 * JSON null value whenever serialization is requested.
 * Used as the default "null serializer" (which is used for serializing
 * null object references unless overridden), as well as for some
 * more exotic types (java.lang.Void).
 */
@JacksonStdImpl
@SuppressWarnings("serial")
public class NullSerializer
    extends StdSerializer<Object>
{
    public final static NullSerializer instance = new NullSerializer();
    
    private NullSerializer() { super(Object.class); }
    
    @Override
    public void serialize(Object value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeNull();
    }

    
Although this method should rarely get called, for convenience we should override
it, and handle it same way as "natural" types: by serializing exactly as is,
without type decorations. The most common possible use case is that of delegation
by JSON filter; caller cannot know what kind of serializer it gets handed.
/**
     * Although this method should rarely get called, for convenience we should override
     * it, and handle it same way as "natural" types: by serializing exactly as is,
     * without type decorations. The most common possible use case is that of delegation
     * by JSON filter; caller cannot know what kind of serializer it gets handed.
     */
    @Override
    public void serializeWithType(Object value, JsonGenerator gen, SerializerProvider serializers,
            TypeSerializer typeSer)
        throws IOException
    {
        gen.writeNull();
    }
    
    @Override
    public JsonNode getSchema(SerializerProvider provider, Type typeHint) throws JsonMappingException {
        return createSchemaNode("null");
    }
    
    @Override
    public void acceptJsonFormatVisitor(JsonFormatVisitorWrapper visitor, JavaType typeHint) throws JsonMappingException {
        visitor.expectNullFormat(typeHint);
    }
}