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Core of the Object/Lucene mapper, query engine and index management
/*
* Hibernate Search, full-text search for your domain model
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later
* See the lgpl.txt file in the root directory or .
*/
package org.hibernate.search.util.impl;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
/**
* Provides some methods for simplified collection instantiation.
*
* @author Gunnar Morling
* @author Hardy Ferentschik
*/
public final class CollectionHelper {
private CollectionHelper() {
// not allowed
}
public static HashMap newHashMap() {
return new HashMap();
}
public static HashMap newHashMap(int size) {
return new HashMap( size );
}
public static SortedMap newSortedMap() {
return new TreeMap();
}
public static HashSet newHashSet() {
return new HashSet();
}
public static ArrayList newArrayList() {
return new ArrayList();
}
public static ArrayList newArrayList(final int size) {
return new ArrayList( size );
}
public static Set asSet(T... ts) {
HashSet set = new HashSet( ts.length );
Collections.addAll( set, ts );
return set;
}
public static List toImmutableList(final Collection c) {
if ( c.isEmpty() ) {
return Collections.emptyList();
}
else {
return Collections.unmodifiableList( new ArrayList( c ) );
}
}
public static Set asImmutableSet(String[] names) {
//The intention here is to save some memory by picking the simplest safe representation,
// as we usually require immutable sets for long living metadata:
if ( names == null || names.length == 0 ) {
return Collections.emptySet();
}
else if ( names.length == 1 ) {
return Collections.singleton( names[0] );
}
else {
HashSet hashSet = new HashSet<>( Arrays.asList( names ) );
return Collections.unmodifiableSet( hashSet );
}
}
/**
* Builds an {@link Iterator} for a given array. It is (un)necessarily ugly because we have to deal with array of primitives.
*
* @param object a given array
* @return an {@code Iterator} iterating over the array
*/
@SuppressWarnings({ "unchecked", "rawtypes" }) // Reflection is used to ensure the correct types are used
public static Iterator iteratorFromArray(Object object) {
return new ArrayIterator( accessorFromArray( object ), object );
}
/**
* Builds an {@link Iterable} for a given array. It is (un)necessarily ugly because we have to deal with array of primitives.
*
* @param object a given array
* @return an {@code Iterable} providing iterators over the array
*/
@SuppressWarnings({ "unchecked", "rawtypes" }) // Reflection is used to ensure the correct types are used
public static Iterable iterableFromArray(Object object) {
return new ArrayIterable( accessorFromArray( object ), object );
}
public static Iterable flatten(Iterable> nonFlat) {
return new Iterable() {
@Override
public Iterator iterator() {
return flatten( nonFlat.iterator() );
}
};
}
public static Iterator flatten(Iterator> nonFlat) {
return new FlatteningIterator<>( nonFlat );
}
private static ArrayAccessor accessorFromArray(Object object) {
ArrayAccessor accessor;
if ( Object.class.isAssignableFrom( object.getClass().getComponentType() ) ) {
accessor = ArrayAccessor.OBJECT;
}
else if ( object.getClass() == boolean[].class ) {
accessor = ArrayAccessor.BOOLEAN;
}
else if ( object.getClass() == int[].class ) {
accessor = ArrayAccessor.INT;
}
else if ( object.getClass() == long[].class ) {
accessor = ArrayAccessor.LONG;
}
else if ( object.getClass() == double[].class ) {
accessor = ArrayAccessor.DOUBLE;
}
else if ( object.getClass() == float[].class ) {
accessor = ArrayAccessor.FLOAT;
}
else if ( object.getClass() == byte[].class ) {
accessor = ArrayAccessor.BYTE;
}
else if ( object.getClass() == short[].class ) {
accessor = ArrayAccessor.SHORT;
}
else if ( object.getClass() == char[].class ) {
accessor = ArrayAccessor.CHAR;
}
else {
throw new IllegalArgumentException( "Provided object " + object + " is not a supported array type" );
}
return accessor;
}
private static class ArrayIterable implements Iterable {
private final ArrayAccessor accessor;
private final A values;
public ArrayIterable(ArrayAccessor accessor, A values) {
this.accessor = accessor;
this.values = values;
}
@Override
public final Iterator iterator() {
return new ArrayIterator<>( accessor, values );
}
}
private static class ArrayIterator implements Iterator {
private final ArrayAccessor accessor;
private final A values;
private int current = 0;
public ArrayIterator(ArrayAccessor accessor, A values) {
this.accessor = accessor;
this.values = values;
}
@Override
public boolean hasNext() {
return current < accessor.size( values );
}
@Override
public T next() {
T result = accessor.get( values, current );
current++;
return result;
}
}
private interface ArrayAccessor {
int size(A array);
T get(A array, int index);
ArrayAccessor OBJECT = new ArrayAccessor() {
@Override
public int size(Object[] array) {
return array.length;
}
@Override
public Object get(Object[] array, int index) {
return array[index];
}
};
ArrayAccessor BOOLEAN = new ArrayAccessor() {
@Override
public int size(boolean[] array) {
return array.length;
}
@Override
public Boolean get(boolean[] array, int index) {
return array[index];
}
};
ArrayAccessor INT = new ArrayAccessor() {
@Override
public int size(int[] array) {
return array.length;
}
@Override
public Integer get(int[] array, int index) {
return array[index];
}
};
ArrayAccessor LONG = new ArrayAccessor() {
@Override
public int size(long[] array) {
return array.length;
}
@Override
public Long get(long[] array, int index) {
return array[index];
}
};
ArrayAccessor DOUBLE = new ArrayAccessor() {
@Override
public int size(double[] array) {
return array.length;
}
@Override
public Double get(double[] array, int index) {
return array[index];
}
};
ArrayAccessor FLOAT = new ArrayAccessor() {
@Override
public int size(float[] array) {
return array.length;
}
@Override
public Float get(float[] array, int index) {
return array[index];
}
};
ArrayAccessor BYTE = new ArrayAccessor() {
@Override
public int size(byte[] array) {
return array.length;
}
@Override
public Byte get(byte[] array, int index) {
return array[index];
}
};
ArrayAccessor SHORT = new ArrayAccessor() {
@Override
public int size(short[] array) {
return array.length;
}
@Override
public Short get(short[] array, int index) {
return array[index];
}
};
ArrayAccessor CHAR = new ArrayAccessor() {
@Override
public int size(char[] array) {
return array.length;
}
@Override
public Character get(char[] array, int index) {
return array[index];
}
};
}
private static class FlatteningIterator implements Iterator {
private Iterator> nonFlatIterator;
private Iterator current = Collections.emptyIterator();
public FlatteningIterator(Iterator> nonFlatIterator) {
this.nonFlatIterator = nonFlatIterator;
}
@Override
public boolean hasNext() {
// Get the next iterable if we iterated through all elements of the current one
while ( ! current.hasNext() && nonFlatIterator.hasNext() ) {
current = nonFlatIterator.next().iterator();
}
return current.hasNext() || nonFlatIterator.hasNext();
}
@Override
public T next() {
// force the position to an non empty current or the end of the flow
if ( ! hasNext() ) {
throw new NoSuchElementException();
}
return current.next();
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
}
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