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Oracle Coherence Community Edition
/*
* Copyright (c) 2020 Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.net;
import com.tangosol.net.cache.ContinuousQueryCache;
import com.tangosol.util.Base;
import com.tangosol.util.Filter;
import com.tangosol.util.MapListener;
import com.tangosol.util.ValueExtractor;
import com.tangosol.util.filter.AlwaysFilter;
import java.util.function.Supplier;
/**
* The {@link ViewBuilder} provides a means to {@link #build()} a {@code map view}
* using a fluent pattern / style.
*
* @param the type of the map entry keys
* @param the type of the entry values in the backing map that is used
* as the source for this {@code view}
* @param the type of the entry values in this {@code view}, which
* will be the same as {@code V_BACK}, unless a {@code transformer} is specified
* when creating this {@code view}
*
* @author Aleks Seovic 2020.06.06
*
* @since 20.06
*/
public class MapViewBuilder
{
// ---- constructors ----------------------------------------------------
/**
* Construct a new {@link MapViewBuilder} for the provided {@link NamedMap}.
*
* @param map the {@link NamedMap} from which the view will be created
*/
MapViewBuilder(NamedMap map)
{
this(() -> (NamedCache) map);
}
/**
* Construct a new {@link ViewBuilder} for the provided {@link Supplier}.
*
* @param supplierNamedCache the {@link Supplier} returning a {@link NamedCache}
* from which the view will be created
*/
protected MapViewBuilder(Supplier> supplierNamedCache)
{
f_supplierNamedCache = supplierNamedCache;
}
// ----- builder interface ----------------------------------------------
/**
* The {@link Filter} that will be used to define the entries maintained in this view.
* If no {@link Filter} is specified, {@link AlwaysFilter#INSTANCE} will be used.
*
* @param filter the {@link Filter} that will be used to query the
* underlying {@link NamedMap}
*
* @return this {@link MapViewBuilder}
*/
public MapViewBuilder filter(Filter filter)
{
m_filter = filter;
return this;
}
/**
* The {@link MapListener} that will receive all events, including those that
* result from the initial population of the {@code view}.
*
* @param listener the {@link MapListener} that will receive all the events from
* the {@code view}, including those corresponding to its initial
* population.
*
* @return this {@link MapViewBuilder}
*/
public MapViewBuilder listener(MapListener listener)
{
m_listener = listener;
return this;
}
/**
* The {@link ValueExtractor} that this {@code view} will use to transform the results from
* the underlying map prior to storing them locally.
*
* @param mapper the {@link ValueExtractor} that will be used to
* transform values retrieved from the underlying map
* before storing them locally; if specified, this
* {@code view} will become {@code read-only}
*
* @return this {@link MapViewBuilder}
*/
public MapViewBuilder map(ValueExtractor mapper)
{
m_mapper = mapper;
return this;
}
/**
* The resulting {@code view} will only map keys.
*
* NOTE: this is mutually exclusive with {@link #values()}.
*
* @return this {@link MapViewBuilder}
*/
public MapViewBuilder keys()
{
m_fCacheValues = false;
return this;
}
/**
* The resulting {@code view} with both map keys and values.
*
* NOTE: this is mutually exclusive with {@link #keys()}, and the default.
*
* @return this {@link MapViewBuilder}
*/
public MapViewBuilder values()
{
m_fCacheValues = true;
return this;
}
/**
* The optional {@link ClassLoader} to use when performing serialization/de-serialization operations.
*
* @param loader the {@link ClassLoader}
*
* @return this {@link MapViewBuilder}
*/
public MapViewBuilder withClassLoader(ClassLoader loader)
{
m_loader = loader;
return this;
}
/**
* Construct a {@code view} of the {@link NamedMap} provided to this builder.
*
* @return the {@code view} of the {@link NamedMap} provided to this builder
*/
public NamedMap build()
{
Filter filter = m_filter;
ClassLoader loader = m_loader;
return new ContinuousQueryCache<>(f_supplierNamedCache,
filter == null ? AlwaysFilter.INSTANCE : filter,
m_fCacheValues,
m_listener,
m_mapper,
loader == null ? Base.getContextClassLoader(this) : loader);
}
// ----- data members ---------------------------------------------------
/**
* The {@link Supplier} returning a {@link NamedCache} from which the
* view will be created.
*/
protected final Supplier> f_supplierNamedCache;
/**
* The {@link Filter} that will be used to define the entries maintained
* in this view.
*/
protected Filter m_filter;
/**
* The {@link MapListener} that will receive all the events from
* the {@code view}, including those corresponding to its initial
* population.
*/
protected MapListener m_listener;
/**
* The {@link ValueExtractor} that will be used to transform values
* retrieved from the underlying map before storing them locally; if
* specified, this {@code view} will become {@code read-only}.
*/
protected ValueExtractor m_mapper;
/**
* Flag controlling if the {@code view} will store both keys and values
* or only keys. {@code true} by default.
*/
protected boolean m_fCacheValues = true;
/**
* The View's {@link ClassLoader}.
*/
protected ClassLoader m_loader;
}