org.refcodes.mixin.PayloadAccessor Maven / Gradle / Ivy
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// /////////////////////////////////////////////////////////////////////////////
// REFCODES.ORG
// =============================================================================
// This code is copyright (c) by Siegfried Steiner, Munich, Germany, distributed
// on an "AS IS" BASIS WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, and licen-
// sed under the following (see "http://en.wikipedia.org/wiki/Multi-licensing")
// licenses:
// =============================================================================
// GNU General Public License, v3.0 ("http://www.gnu.org/licenses/gpl-3.0.html")
// together with the GPL linking exception applied; as being applied by the GNU
// Classpath ("http://www.gnu.org/software/classpath/license.html")
// =============================================================================
// Apache License, v2.0 ("http://www.apache.org/licenses/TEXT-2.0")
// =============================================================================
// Please contact the copyright holding author(s) of the software artifacts in
// question for licensing issues not being covered by the above listed licenses,
// also regarding commercial licensing models or regarding the compatibility
// with other open source licenses.
// /////////////////////////////////////////////////////////////////////////////
package org.refcodes.mixin;
/**
* Provides an accessor for a payload property.
*
* @param The type of the payload to be carried.
*/
public interface PayloadAccessor
{
/**
* Retrieves the payload from the payload property.
*
* @return The payload stored by the payload property.
*/
P getPayload();
/**
* Retrieves the value from the payload property. If there is no value for
* the property, then the provided value is returned. Depending on the
* implementation, not present might mean null or empty as well
* (being "" for a {@link String}).
*
* @param aValue In case the value to be retrieved is null, then the given
* value is returned.
*
* @return The value stored by the payload property or the given value if
* the stored value is null.
*/
default P getPayloadOr( P aValue ) {
final P theValue = getPayload();
if ( theValue == null || ( theValue instanceof String && ( (String) theValue ).isEmpty() ) ) {
return aValue;
}
return theValue;
}
/**
* Provides a mutator for a payload property.
*
* @param
The type of the payload to be carried.
*/
public interface PayloadMutator
{
/**
* Sets the payload for the payload property.
*
* @param aPayload The payload to be stored by the payload property.
*/
void setPayload( P aPayload );
}
/**
* Provides a builder method for a payload property returning the builder
* for applying multiple build operations.
*
* @param
The type of the payload to be carried.
* @param The builder to return in order to be able to apply multiple
* build operations.
*/
public interface PayloadBuilder> {
/**
* Sets the payload for the payload property.
*
* @param aPayload The payload to be stored by the payload property.
*
* @return The builder for applying multiple build operations.
*/
B withPayload( P aPayload );
}
/**
* Provides a payload property.
*
* @param The type of the payload to be carried.
*/
public interface PayloadProperty
extends PayloadAccessor
, PayloadMutator
{
/**
* This method stores and passes through the given argument, which is
* very useful for builder APIs: Sets the given value (setter) as of
* {@link #setPayload(Object)} and returns the very same value (getter).
*
* @param aPayload The value to set (via {@link #setPayload(Object)}).
*
* @return Returns the value passed for it to be used in conclusive
* processing steps.
*/
default P letPayload( P aPayload ) {
setPayload( aPayload );
return aPayload;
}
}
}