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package com.fasterxml.jackson.databind.deser;
import com.fasterxml.jackson.databind.*;
/**
* Interface for providers of {@link ValueInstantiator} instances.
* Implemented when an object wants to provide custom value instantiators,
* usually to support custom value types with alternate constructors, or
* which need specified post-processing after construction but before
* binding data.
*/
public interface ValueInstantiators
{
/**
* Method called to find the {@link ValueInstantiator} to use for creating
* instances of specified type during deserialization.
* Note that a default value instantiator is always created first and passed;
* if an implementation does not want to modify or replace it, it has to return
* passed instance as is (returning null is an error)
*
* @param config Deserialization configuration in use
* @param beanDesc Additional information about POJO type to be instantiated
* @param defaultInstantiator Instantiator that will be used if no changes are made;
* passed to allow custom instances to use annotation-provided information
* (note, however, that earlier {@link ValueInstantiators} may have changed it to
* a custom instantiator already)
*
* @return Instantiator to use; either defaultInstantiator that was passed,
* or a custom variant; cannot be null.
*/
public ValueInstantiator findValueInstantiator(DeserializationConfig config,
BeanDescription beanDesc, ValueInstantiator defaultInstantiator);
/**
* Basic "NOP" implementation that can be used as the base class for custom implementations.
* Safer to extend (instead of implementing {@link ValueInstantiators}) in case later
* Jackson versions add new methods in base interface.
*/
public static class Base implements ValueInstantiators
{
@Override
public ValueInstantiator findValueInstantiator(DeserializationConfig config,
BeanDescription beanDesc, ValueInstantiator defaultInstantiator) {
return defaultInstantiator;
}
}
}