Finder.java
/*
* *********************************************************************************************************************
*
* TheseFoolishThings: Miscellaneous utilities
* http://tidalwave.it/projects/thesefoolishthings
*
* Copyright (C) 2009 - 2023 by Tidalwave s.a.s. (http://tidalwave.it)
*
* *********************************************************************************************************************
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*
* *********************************************************************************************************************
*
* git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
* git clone https://github.com/tidalwave-it/thesefoolishthings-src
*
* *********************************************************************************************************************
*/
package it.tidalwave.util;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Stream;
import java.io.Serializable;
import it.tidalwave.util.impl.finder.ArrayListFinder;
import it.tidalwave.util.impl.finder.MappingFinder;
import it.tidalwave.util.impl.finder.ProviderFinder;
import it.tidalwave.util.impl.finder.SupplierFinder;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.EqualsAndHashCode;
import lombok.RequiredArgsConstructor;
import lombok.ToString;
/***********************************************************************************************************************
*
* A factory for providing results of a search. {@code Finder} implementations must be <em>immutable</em>.
*
* @author Fabrizio Giudici
* @it.tidalwave.javadoc.draft
*
**********************************************************************************************************************/
public interface Finder<T> extends Cloneable, Serializable
{
/*******************************************************************************************************************
*
* A tag interface to mark objects which are meaningful sort criteria that can be passed to
* {@link Finder#sort(it.tidalwave.util.Finder.SortCriterion)}. In general, a {@code SortCriterion} is just a
* behaviourless and methodless object, that should be specifically handled by concrete implementations of
* {@link Finder}. The only exceptions are {@link InMemorySortCriterion} objects.
*
******************************************************************************************************************/
public static interface SortCriterion
{
public static final Class<SortCriterion> _SortCriterion_ = SortCriterion.class;
/** A special {@link SortCriterion} which indicates that no sort has been performed. */
public static final SortCriterion UNSORTED = (InMemorySortCriterion<Object>)(results, sortDirection) -> {};
public static final SortCriterion DEFAULT = UNSORTED;
}
/*******************************************************************************************************************
*
* An interface that should be implemented by specific {@link SortCriterion} objects which are capable to implement
* by themselves the sorting of objects, by post-processing an existing collection of objects. While this is often
* convenient, it is possible for it to be inefficient in cases in which the original source of objects is capable
* to perform the sort in an optimized way (e.g. an SQL database by means of {@code ORDER BY}). The facility class
* {@link it.tidalwave.util.spi.HierarchicFinderSupport} supports {@code FilterSortCriterion} objects out of the box.
*
******************************************************************************************************************/
public static interface InMemorySortCriterion<U> extends SortCriterion
{
/***************************************************************************************************************
*
* Performs the sort of results.
*
* @param results the list of objects to be sorted in place
*
**************************************************************************************************************/
public default void sort (@Nonnull final List<? extends U> results)
{
sort(results, SortDirection.ASCENDING);
}
/***************************************************************************************************************
*
* Performs the sort of results.
*
* @param results the list of objects to be sorted in place
* @param sortDirection the sort direction
*
**************************************************************************************************************/
// START SNIPPET: sort
public void sort (@Nonnull List<? extends U> results, @Nonnull SortDirection sortDirection);
// END SNIPPET: sort
/***************************************************************************************************************
*
* Creates a new in-memory {@code SortCriterion} based on a {@link Comparator}.
*
* @param <U> the type of the objects to compare
* @param comparator the {@code Comparator}
* @return the new {@code SortCriterion}
*
**************************************************************************************************************/
@Nonnull
public static <U> InMemorySortCriterion<U> of (@Nonnull final Comparator<? super U> comparator)
{
return of(comparator, comparator.getClass().getSimpleName());
}
/***************************************************************************************************************
*
* Creates a new in-memory {@code SortCriterion} based on a {@link Comparator}.
*
* @param <U> the type of the objects to compare
* @param comparator the {@code Comparator}
* @param name a name
* @return the new {@code SortCriterion}
*
**************************************************************************************************************/
@Nonnull
public static <U> InMemorySortCriterion<U> of (@Nonnull final Comparator<? super U> comparator,
@Nonnull final String name)
{
return new DefaultInMemorySortCriterion<>(comparator, name);
}
/***************************************************************************************************************
*
**************************************************************************************************************/
@AllArgsConstructor @ToString @EqualsAndHashCode
static class DefaultInMemorySortCriterion<U> implements Finder.InMemorySortCriterion<U>, Serializable
{
private static final long serialVersionUID = 76093596048395982L;
@Nonnull
private final Comparator<? super U> comparator;
@Nonnull
private final String name;
@Override
public void sort (@Nonnull final List<? extends U> results, @Nonnull final SortDirection sortDirection)
{
results.sort((Comparator<U>)(o1, o2) -> comparator.compare(o1, o2) * sortDirection.intValue());
}
}
}
/*******************************************************************************************************************
*
* An enumeration to define the direction of a sort (ascending or descending).
*
* @it.tidalwave.javadoc.stable
*
******************************************************************************************************************/
@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
public static enum SortDirection
{
ASCENDING(+1), DESCENDING(-1);
private final int intValue;
/** @return +1 for ascending direction, -1 for descending */
public int intValue()
{
return intValue;
}
}
/*******************************************************************************************************************
*
* Tells the {@code Finder} that only a subset of found items will be returned, starting from the given position.
*
* @param firstResult the index of the first result to return
* @return the {@code Finder}
*
******************************************************************************************************************/
// START SNIPPET: from
@Nonnull
public Finder<T> from (@Nonnegative int firstResult);
// END SNIPPET: from
/*******************************************************************************************************************
*
* Tells the {@code Finder} that only a maximum number of found items will be returned.
*
* @param maxResults the max number of results to return
* @return the {@code Finder}
*
******************************************************************************************************************/
// START SNIPPET: max
@Nonnull
public Finder<T> max (@Nonnegative int maxResults);
// END SNIPPET: max
/*******************************************************************************************************************
*
* Tells the {@code Finder} that results should be created with the given context. This method can be called
* multiple times; contexts are accumulated.
*
* @param context the context
* @return the {@code Finder}
*
******************************************************************************************************************/
@Nonnull
public default Finder<T> withContext (@Nonnull final Object context)
{
throw new UnsupportedOperationException("Not implemented yet.");
}
/*******************************************************************************************************************
*
* Tells the {@code Finder} that the specified type of results is expected.
*
* @param <U> the static type
* @param type the dynamic type
* @return the {@code Finder}
*
******************************************************************************************************************/
@Nonnull
public default <U> Finder<U> ofType (@Nonnull final Class<U> type)
{
throw new UnsupportedOperationException("Not implemented yet.");
}
/*******************************************************************************************************************
*
* Tells the {@code Finder} that results will be sorted according to the given criterion, in ascending direction.
*
* @param criterion the sort criterion
* @return the {@code Finder}
*
******************************************************************************************************************/
@Nonnull
public default Finder<T> sort (@Nonnull final SortCriterion criterion)
{
return sort(criterion, SortDirection.ASCENDING);
}
/*******************************************************************************************************************
*
* Tells the {@code Finder} that results will be sorted according to the given criterion and direction.
*
* @param criterion the sort criterion
* @param direction the sort direction
* @return the {@code Finder}
*
******************************************************************************************************************/
@Nonnull
public Finder<T> sort (@Nonnull SortCriterion criterion, @Nonnull SortDirection direction);
/*******************************************************************************************************************
*
* Performs the search and returns the found items.
*
* @return the searched items
*
******************************************************************************************************************/
// START SNIPPET: results
@Nonnull
public List<T> results();
// END SNIPPET: results
/*******************************************************************************************************************
*
* Performs the search and returns the count of found items.
*
* @return the count of found items
*
******************************************************************************************************************/
// START SNIPPET: count
@Nonnegative
public int count();
// END SNIPPET: count
/*******************************************************************************************************************
*
* Performs the search assuming that it will return a single item and returns it. This method fails if the search
* returns more than one single item.
*
* @return the optional result
* @throws RuntimeException if the search returned more than one single item
*
* @since 3.2-ALPHA-1 (previously in Finder8)
*
******************************************************************************************************************/
// START SNIPPET: optionalResult
@Nonnull
public default Optional<T> optionalResult()
// END SNIPPET: optionalResult
{
final var results = (List<T>)results();
if (results.size() > 1)
{
throw new RuntimeException("" + results.size() + " results, expected only one");
}
return results.stream().findFirst();
}
/*******************************************************************************************************************
*
* Performs the search and returns only the first found item.
*
* @return the first result
* @since 3.2-ALPHA-1 (previously in Finder8)
*
******************************************************************************************************************/
// START SNIPPET: optionalFirstResult
@Nonnull
public default Optional<T> optionalFirstResult()
// END SNIPPET: optionalFirstResult
{
return stream().findFirst();
}
/*******************************************************************************************************************
*
* Returns a stream of results.
*
* @return the stream
* @since 3.2-ALPHA-1 (previously in Finder8)
*
******************************************************************************************************************/
@Nonnull
public default Stream<T> stream()
{
return results().stream();
}
/*******************************************************************************************************************
*
* Returns am iterator of results.
*
* @return the iterator
* @since 3.2-ALPHA-1 (previously in Finder8)
*
******************************************************************************************************************/
@Nonnull
public default Iterator<T> iterator()
{
return results().iterator();
}
/*******************************************************************************************************************
*
* Performs the search assuming that it will return a single item and returns it. This method fails if the search
* returns more than one single item.
*
* @return the found item
* @throws NotFoundException if the search didn't find anything
* @throws RuntimeException if the search returned more than one single item
* @deprecated Use {@link #optionalResult()} instead
*
******************************************************************************************************************/
@Nonnull @Deprecated
public default T result()
throws NotFoundException, RuntimeException
{
return optionalResult().orElseThrow(NotFoundException::new);
}
/*******************************************************************************************************************
*
* Performs the search and returns only the first found item.
*
* @return the first found item
* @throws NotFoundException if the search didn't find anything
* @deprecated Use {@link #optionalFirstResult()} instead
*
******************************************************************************************************************/
@Nonnull @Deprecated
public default T firstResult()
throws NotFoundException
{
return optionalFirstResult().orElseThrow(NotFoundException::new);
}
/*******************************************************************************************************************
*
* Returns an empty {@code Finder}.
*
* @param <U> the type of the {@code Finder}
* @return the empty {@code Finder}
* @since 3.2-ALPHA-1 (previously in HierarchicFinderSupport.emptyFinder())
*
******************************************************************************************************************/
@Nonnull
public static <U> Finder<U> empty()
{
return ofCloned(Collections.emptyList());
}
/*******************************************************************************************************************
*
* Returns a wrapped {@code Finder} on a given collection of elements. The collection is cloned and will be
* immutable.
* If you need to compute the collection on demand, use {@link #ofSupplier(Supplier)}.
* This method retrieves the full range of results that will be later segmented in compliance with the values
* specified by {@link #from(int)} and {@link #max(int)}; this is ok if the whole list of results is already
* available of if it is not expensive to compute. The alternate method {@link #ofProvider(BiFunction)} allows
* to access the 'from' and 'max' parameter, so only the required items need to be provided.
*
* @param <U> the type of the {@code Finder}
* @param items the objects to wrap
* @return the wrapped {@code Finder}
* @see #ofSupplier(Supplier)
* @see #ofProvider(BiFunction)
* @since 3.2-ALPHA-1
*
******************************************************************************************************************/
// START SNIPPET: ofCloned
@Nonnull
public static <U> Finder<U> ofCloned (@Nonnull final Collection<? extends U> items)
// END SNIPPET: ofCloned
{
return new ArrayListFinder<>(items);
}
/*******************************************************************************************************************
*
* Returns a wrapped {@code Finder} on a given supplier. The collection will be cloned after being supplied.
* This method retrieves the full range of results that will be later segmented in compliance with the values
* specified by {@link #from(int)} and {@link #max(int)}; this is ok if the whole list of results is already
* available of if it is not expensive to compute. The alternate method {@link #ofProvider(BiFunction)} allows
* to access the 'from' and 'max' parameter, so only the required items need to be provided.
*
* @param <U> the type of the {@code Finder}
* @param supplier the supplier
* @return the wrapped {@code Finder}
* @see #ofCloned(Collection)
* @see #ofProvider(BiFunction)
* @since 3.2-ALPHA-15
*
******************************************************************************************************************/
// START SNIPPET: ofsupplier
@Nonnull
public static <U> Finder<U> ofSupplier (@Nonnull final Supplier<? extends Collection<? extends U>> supplier)
// END SNIPPET: ofsupplier
{
return new SupplierFinder<>(supplier);
}
/*******************************************************************************************************************
*
* Returns a wrapped {@code Finder} on a given function to provide results. The function receives the 'from' and
* 'max' arguments to select a subrange of the results. The collection will be cloned after being supplied.
*
* @param <U> the type of the {@code Finder}
* @param provider the function providing results
* @return the wrapped {@code Finder}
* @see #ofCloned(Collection)
* @see #ofSupplier(Supplier)
* @since 3.2-ALPHA-15
*
******************************************************************************************************************/
// START SNIPPET: ofProvider
@Nonnull
public static <U> Finder<U> ofProvider (
@Nonnull final BiFunction<Integer, Integer, ? extends Collection<? extends U>> provider)
// END SNIPPET: ofProvider
{
return new ProviderFinder<>(provider);
}
/*******************************************************************************************************************
*
* Returns a mapping {@code Finder} on a given delegate {@code Finder}. The mapper finder provides the same
* results as the delegate, transformed by a mapper function.
*
* @param <U> the type of the {@code Finder}
* @param <V> the type of the delegate {@code Finder}
* @param delegate the delegate finder
* @param mapper the mapper function
* @return the wrapped {@code Finder}
* @since 3.2-ALPHA-15
*
******************************************************************************************************************/
// START SNIPPET: mapping
@Nonnull
public static <U, V> Finder<U> mapping (@Nonnull final Finder<V> delegate,
@Nonnull final Function<? super V, ? extends U> mapper)
// END SNIPPET: mapping
{
return new MappingFinder<>(delegate, mapper);
}
}