Content of file Finder.java

/*
 * *********************************************************************************************************************
 *
 * TheseFoolishThings: Miscellaneous utilities
 * http://tidalwave.it/projects/thesefoolishthings
 *
 * Copyright (C) 2009 - 2024 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.OptionalInt;
import java.util.function.BiFunction;
import java.util.function.Consumer;
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 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}
     * @since   3.2-ALPHA-19
     *
     ******************************************************************************************************************/
    @Nonnull
    public default Finder<T> from (@Nonnull final Optional<Integer> firstResult)
      {
        return firstResult.map(this::from).orElse(this);
      }

    /*******************************************************************************************************************
     *
     * 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}
     * @since   3.2-ALPHA-22
     *
     ******************************************************************************************************************/
    @Nonnull
    public default Finder<T> from (@Nonnull final OptionalInt firstResult)
      {
        return firstResult.isPresent() ? from(firstResult.getAsInt()) : this;
      }

    /*******************************************************************************************************************
     *
     * 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 only a maximum number of found items will be returned.
     *
     * @param   maxResults    the max number of results to return
     * @return                the {@code Finder}
     * @since   3.2-ALPHA-19
     *
     ******************************************************************************************************************/
    @Nonnull
    public default Finder<T> max (@Nonnull final Optional<Integer> maxResults)
      {
        return maxResults.map(this::max).orElse(this);
      }

    /*******************************************************************************************************************
     *
     * 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}
     * @since   3.2-ALPHA-22
     *
     ******************************************************************************************************************/
    @Nonnull
    public default Finder<T> max (@Nonnull final OptionalInt maxResults)
      {
        return maxResults.isPresent() ? max(maxResults.getAsInt()) : this;
      }

    /*******************************************************************************************************************
     *
     * 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();
redundant cast to List
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 an iterator of results. * * @return the iterator * @since 3.2-ALPHA-1 (previously in Finder8) * ******************************************************************************************************************/ @Nonnull public default Iterator<T> iterator() { return stream().iterator(); } /******************************************************************************************************************* * * Iterates through results. * * @param consumer the consumer * @since 3.2-ALPHA-22 * ******************************************************************************************************************/ public default void forEach (@Nonnull final Consumer<? super T> consumer) { stream().forEach(consumer); } /******************************************************************************************************************* * * 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); } }