1.9.10/src/mapper/java/org/codehaus/jackson/map/ContextualDeserializer.java

package org.codehaus.jackson.map;

/**
 * Add-on interface that {@link JsonDeserializer}s can implement to get a callback
 * that can be used to create contextual instances of deserializer to use for
 * handling properties of supported type. This can be useful
 * for deserializers that can be configured by annotations, or should otherwise
 * have differing behavior depending on what kind of property is being deserialized.
 *
 * @param <T> Type of deserializer to contextualize
 * 
 * @since 1.7
 */
public interface ContextualDeserializer<T>
{
    /**
     * Method called to see if a different (or differently configured) deserializer
     * is needed to deserialize values of specified property.
     * Note that instance that this method is called on is typically shared one and
     * as a result method should <b>NOT</b> modify this instance but rather construct
     * and return a new instance. This instance should only be returned as-is, in case
     * it is already suitable for use.
     * 
     * @param config Current deserialization configuration
     * @param property Method, field or constructor parameter that represents the property
     *   (and is used to assign deserialized value).
     *   Should be available; but there may be cases where caller can not provide it and
     *   null is passed instead (in which case impls usually pass 'this' deserializer as is)
     * 
     * @return Deserializer to use for deserializing values of specified property;
     *   may be this instance or a new instance.
     * 
     * @throws JsonMappingException
     */
    public JsonDeserializer<T> createContextual(DeserializationConfig config,
            BeanProperty property)
        throws JsonMappingException;
}