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/* Generic definitions */
/* Assertions (useful to generate conditional code) */
/* Current type and class (and size, if applicable) */
/* Value methods */
/* Interfaces (keys) */
/* Interfaces (values) */
/* Abstract implementations (keys) */
/* Abstract implementations (values) */
/* Static containers (keys) */
/* Static containers (values) */
/* Implementations */
/* Synchronized wrappers */
/* Unmodifiable wrappers */
/* Other wrappers */
/* Methods (keys) */
/* Methods (values) */
/* Methods (keys/values) */
/* Methods that have special names depending on keys (but the special names depend on values) */
/* Equality */
/* Object/Reference-only definitions (keys) */
/* Primitive-type-only definitions (keys) */
/* Object/Reference-only definitions (values) */
/*
* Copyright (C) 2002-2015 Sebastiano Vigna
*
* 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.
*/
package it.unimi.dsi.fastutil.ints;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.NoSuchElementException;
/** A class providing static methods and objects that do useful things with type-specific iterators.
*
* @see Iterator */
public class IntIterators {
private IntIterators() {}
/** A class returning no elements and a type-specific iterator interface.
*
* This class may be useful to implement your own in case you subclass a type-specific iterator. */
public static class EmptyIterator extends AbstractIntListIterator implements java.io.Serializable, Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
protected EmptyIterator() {}
public boolean hasNext() {
return false;
}
public boolean hasPrevious() {
return false;
}
public int nextInt() {
throw new NoSuchElementException();
}
public int previousInt() {
throw new NoSuchElementException();
}
public int nextIndex() {
return 0;
}
public int previousIndex() {
return -1;
}
public int skip( int n ) {
return 0;
};
public int back( int n ) {
return 0;
};
public Object clone() {
return EMPTY_ITERATOR;
}
private Object readResolve() {
return EMPTY_ITERATOR;
}
}
/** An empty iterator (immutable). It is serializable and cloneable.
*
*
The class of this objects represent an abstract empty iterator that can iterate as a type-specific (list) iterator. */
public final static EmptyIterator EMPTY_ITERATOR = new EmptyIterator();
/** An iterator returning a single element. */
private static class SingletonIterator extends AbstractIntListIterator {
private final int element;
private int curr;
public SingletonIterator( final int element ) {
this.element = element;
}
public boolean hasNext() {
return curr == 0;
}
public boolean hasPrevious() {
return curr == 1;
}
public int nextInt() {
if ( !hasNext() ) throw new NoSuchElementException();
curr = 1;
return element;
}
public int previousInt() {
if ( !hasPrevious() ) throw new NoSuchElementException();
curr = 0;
return element;
}
public int nextIndex() {
return curr;
}
public int previousIndex() {
return curr - 1;
}
}
/** Returns an iterator that iterates just over the given element.
*
* @param element the only element to be returned by a type-specific list iterator.
* @return an iterator that iterates just over element. */
public static IntListIterator singleton( final int element ) {
return new SingletonIterator( element );
}
/** A class to wrap arrays in iterators. */
private static class ArrayIterator extends AbstractIntListIterator {
private final int[] array;
private final int offset, length;
private int curr;
public ArrayIterator( final int[] array, final int offset, final int length ) {
this.array = array;
this.offset = offset;
this.length = length;
}
public boolean hasNext() {
return curr < length;
}
public boolean hasPrevious() {
return curr > 0;
}
public int nextInt() {
if ( !hasNext() ) throw new NoSuchElementException();
return array[ offset + curr++ ];
}
public int previousInt() {
if ( !hasPrevious() ) throw new NoSuchElementException();
return array[ offset + --curr ];
}
public int skip( int n ) {
if ( n <= length - curr ) {
curr += n;
return n;
}
n = length - curr;
curr = length;
return n;
}
public int back( int n ) {
if ( n <= curr ) {
curr -= n;
return n;
}
n = curr;
curr = 0;
return n;
}
public int nextIndex() {
return curr;
}
public int previousIndex() {
return curr - 1;
}
}
/** Wraps the given part of an array into a type-specific list iterator.
*
*
The type-specific list iterator returned by this method will iterate length times, returning consecutive elements of the given array starting from the one with index
* offset.
*
* @param array an array to wrap into a type-specific list iterator.
* @param offset the first element of the array to be returned.
* @param length the number of elements to return.
* @return an iterator that will return length elements of array starting at position offset. */
public static IntListIterator wrap( final int[] array, final int offset, final int length ) {
IntArrays.ensureOffsetLength( array, offset, length );
return new ArrayIterator( array, offset, length );
}
/** Wraps the given array into a type-specific list iterator.
*
*
The type-specific list iterator returned by this method will return all elements of the given array.
*
* @param array an array to wrap into a type-specific list iterator.
* @return an iterator that will the elements of array. */
public static IntListIterator wrap( final int[] array ) {
return new ArrayIterator( array, 0, array.length );
}
/** Unwraps an iterator into an array starting at a given offset for a given number of elements.
*
*
This method iterates over the given type-specific iterator and stores the elements returned, up to a maximum of length, in the given array starting at offset. The
* number of actually unwrapped elements is returned (it may be less than max if the iterator emits less than max elements).
*
* @param i a type-specific iterator.
* @param array an array to contain the output of the iterator.
* @param offset the first element of the array to be returned.
* @param max the maximum number of elements to unwrap.
* @return the number of elements unwrapped. */
public static int unwrap( final IntIterator i, final int array[], int offset, final int max ) {
if ( max < 0 ) throw new IllegalArgumentException( "The maximum number of elements (" + max + ") is negative" );
if ( offset < 0 || offset + max > array.length ) throw new IllegalArgumentException();
int j = max;
while ( j-- != 0 && i.hasNext() )
array[ offset++ ] = i.nextInt();
return max - j - 1;
}
/** Unwraps an iterator into an array.
*
*
This method iterates over the given type-specific iterator and stores the elements returned in the given array. The iteration will stop when the iterator has no more elements or when the end
* of the array has been reached.
*
* @param i a type-specific iterator.
* @param array an array to contain the output of the iterator.
* @return the number of elements unwrapped. */
public static int unwrap( final IntIterator i, final int array[] ) {
return unwrap( i, array, 0, array.length );
}
/** Unwraps an iterator, returning an array, with a limit on the number of elements.
*
*
This method iterates over the given type-specific iterator and returns an array containing the elements returned by the iterator. At most max elements will be returned.
*
* @param i a type-specific iterator.
* @param max the maximum number of elements to be unwrapped.
* @return an array containing the elements returned by the iterator (at most max). */
public static int[] unwrap( final IntIterator i, int max ) {
if ( max < 0 ) throw new IllegalArgumentException( "The maximum number of elements (" + max + ") is negative" );
int array[] = new int[ 16 ];
int j = 0;
while ( max-- != 0 && i.hasNext() ) {
if ( j == array.length ) array = IntArrays.grow( array, j + 1 );
array[ j++ ] = i.nextInt();
}
return IntArrays.trim( array, j );
}
/** Unwraps an iterator, returning an array.
*
*
This method iterates over the given type-specific iterator and returns an array containing the elements returned by the iterator.
*
* @param i a type-specific iterator.
* @return an array containing the elements returned by the iterator. */
public static int[] unwrap( final IntIterator i ) {
return unwrap( i, Integer.MAX_VALUE );
}
/** Unwraps an iterator into a type-specific collection, with a limit on the number of elements.
*
*
This method iterates over the given type-specific iterator and stores the elements returned, up to a maximum of max, in the given type-specific collection. The number of
* actually unwrapped elements is returned (it may be less than max if the iterator emits less than max elements).
*
* @param i a type-specific iterator.
* @param c a type-specific collection array to contain the output of the iterator.
* @param max the maximum number of elements to unwrap.
* @return the number of elements unwrapped. Note that this is the number of elements returned by the iterator, which is not necessarily the number of elements that have been added to the
* collection (because of duplicates). */
public static int unwrap( final IntIterator i, final IntCollection c, final int max ) {
if ( max < 0 ) throw new IllegalArgumentException( "The maximum number of elements (" + max + ") is negative" );
int j = max;
while ( j-- != 0 && i.hasNext() )
c.add( i.nextInt() );
return max - j - 1;
}
/** Unwraps an iterator into a type-specific collection.
*
*
This method iterates over the given type-specific iterator and stores the elements returned in the given type-specific collection. The returned count on the number unwrapped elements is a
* long, so that it will work also with very large collections.
*
* @param i a type-specific iterator.
* @param c a type-specific collection to contain the output of the iterator.
* @return the number of elements unwrapped. Note that this is the number of elements returned by the iterator, which is not necessarily the number of elements that have been added to the
* collection (because of duplicates). */
public static long unwrap( final IntIterator i, final IntCollection c ) {
long n = 0;
while ( i.hasNext() ) {
c.add( i.nextInt() );
n++;
}
return n;
}
/** Pours an iterator into a type-specific collection, with a limit on the number of elements.
*
*
This method iterates over the given type-specific iterator and adds the returned elements to the given collection (up to max).
*
* @param i a type-specific iterator.
* @param s a type-specific collection.
* @param max the maximum number of elements to be poured.
* @return the number of elements poured. Note that this is the number of elements returned by the iterator, which is not necessarily the number of elements that have been added to the collection
* (because of duplicates). */
public static int pour( final IntIterator i, final IntCollection s, final int max ) {
if ( max < 0 ) throw new IllegalArgumentException( "The maximum number of elements (" + max + ") is negative" );
int j = max;
while ( j-- != 0 && i.hasNext() )
s.add( i.nextInt() );
return max - j - 1;
}
/** Pours an iterator into a type-specific collection.
*
*
This method iterates over the given type-specific iterator and adds the returned elements to the given collection.
*
* @param i a type-specific iterator.
* @param s a type-specific collection.
* @return the number of elements poured. Note that this is the number of elements returned by the iterator, which is not necessarily the number of elements that have been added to the collection
* (because of duplicates). */
public static int pour( final IntIterator i, final IntCollection s ) {
return pour( i, s, Integer.MAX_VALUE );
}
/** Pours an iterator, returning a type-specific list, with a limit on the number of elements.
*
*
This method iterates over the given type-specific iterator and returns a type-specific list containing the returned elements (up to max). Iteration on the returned list is
* guaranteed to produce the elements in the same order in which they appeared in the iterator.
*
*
* @param i a type-specific iterator.
* @param max the maximum number of elements to be poured.
* @return a type-specific list containing the returned elements, up to max. */
public static IntList pour( final IntIterator i, int max ) {
final IntArrayList l = new IntArrayList();
pour( i, l, max );
l.trim();
return l;
}
/** Pours an iterator, returning a type-specific list.
*
*
This method iterates over the given type-specific iterator and returns a list containing the returned elements. Iteration on the returned list is guaranteed to produce the elements in the
* same order in which they appeared in the iterator.
*
* @param i a type-specific iterator.
* @return a type-specific list containing the returned elements. */
public static IntList pour( final IntIterator i ) {
return pour( i, Integer.MAX_VALUE );
}
private static class IteratorWrapper extends AbstractIntIterator {
final Iterator i;
public IteratorWrapper( final Iterator i ) {
this.i = i;
}
public boolean hasNext() {
return i.hasNext();
}
public void remove() {
i.remove();
}
public int nextInt() {
return ( ( i.next() ).intValue() );
}
}
/** Wraps a standard iterator into a type-specific iterator.
*
* This method wraps a standard iterator into a type-specific one which will handle the type conversions for you. Of course, any attempt to wrap an iterator returning the instances of the wrong
* class will generate a {@link ClassCastException}. The returned iterator is backed by i: changes to one of the iterators will affect the other, too.
*
*
If i is already type-specific, it will returned and no new object will be generated.
*
* @param i an iterator.
* @return a type-specific iterator backed by i. */
@SuppressWarnings({ "unchecked", "rawtypes" })
public static IntIterator asIntIterator( final Iterator i ) {
if ( i instanceof IntIterator ) return (IntIterator)i;
return new IteratorWrapper( i );
}
private static class ListIteratorWrapper extends AbstractIntListIterator {
final ListIterator i;
public ListIteratorWrapper( final ListIterator i ) {
this.i = i;
}
public boolean hasNext() {
return i.hasNext();
}
public boolean hasPrevious() {
return i.hasPrevious();
}
public int nextIndex() {
return i.nextIndex();
}
public int previousIndex() {
return i.previousIndex();
}
public void set( int k ) {
i.set( ( Integer.valueOf( k ) ) );
}
public void add( int k ) {
i.add( ( Integer.valueOf( k ) ) );
}
public void remove() {
i.remove();
}
public int nextInt() {
return ( ( i.next() ).intValue() );
}
public int previousInt() {
return ( ( i.previous() ).intValue() );
}
}
/** Wraps a standard list iterator into a type-specific list iterator.
*
* This method wraps a standard list iterator into a type-specific one which will handle the type conversions for you. Of course, any attempt to wrap an iterator returning the instances of the
* wrong class will generate a {@link ClassCastException}. The returned iterator is backed by i: changes to one of the iterators will affect the other, too.
*
*
If i is already type-specific, it will returned and no new object will be generated.
*
* @param i a list iterator.
* @return a type-specific list iterator backed by i. */
@SuppressWarnings({ "unchecked", "rawtypes" })
public static IntListIterator asIntIterator( final ListIterator i ) {
if ( i instanceof IntListIterator ) return (IntListIterator)i;
return new ListIteratorWrapper( i );
}
private static class IntervalIterator extends AbstractIntListIterator {
private final int from, to;
int curr;
public IntervalIterator( final int from, final int to ) {
this.from = this.curr = from;
this.to = to;
}
public boolean hasNext() {
return curr < to;
}
public boolean hasPrevious() {
return curr > from;
}
public int nextInt() {
if ( !hasNext() ) throw new NoSuchElementException();
return curr++;
}
public int previousInt() {
if ( !hasPrevious() ) throw new NoSuchElementException();
return --curr;
}
public int nextIndex() {
return curr - from;
}
public int previousIndex() {
return curr - from - 1;
}
public int skip( int n ) {
if ( curr + n <= to ) {
curr += n;
return n;
}
n = to - curr;
curr = to;
return n;
}
public int back( int n ) {
if ( curr - n >= from ) {
curr -= n;
return n;
}
n = curr - from;
curr = from;
return n;
}
}
/** Creates a type-specific list iterator over an interval.
*
*
The type-specific list iterator returned by this method will return the elements from, from+1,…, to-1.
*
* @param from the starting element (inclusive).
* @param to the ending element (exclusive).
* @return a type-specific list iterator enumerating the elements from from to to. */
public static IntListIterator fromTo( final int from, final int to ) {
return new IntervalIterator( from, to );
}
private static class IteratorConcatenator extends AbstractIntIterator {
final IntIterator a[];
int offset, length, lastOffset = -1;
public IteratorConcatenator( final IntIterator a[], int offset, int length ) {
this.a = a;
this.offset = offset;
this.length = length;
advance();
}
private void advance() {
while ( length != 0 ) {
if ( a[ offset ].hasNext() ) break;
length--;
offset++;
}
return;
}
public boolean hasNext() {
return length > 0;
}
public int nextInt() {
if ( !hasNext() ) throw new NoSuchElementException();
int next = a[ lastOffset = offset ].nextInt();
advance();
return next;
}
public void remove() {
if ( lastOffset == -1 ) throw new IllegalStateException();
a[ lastOffset ].remove();
}
public int skip( int n ) {
lastOffset = -1;
int skipped = 0;
while ( skipped < n && length != 0 ) {
skipped += a[ offset ].skip( n - skipped );
if ( a[ offset ].hasNext() ) break;
length--;
offset++;
}
return skipped;
}
}
/** Concatenates all iterators contained in an array.
*
*
This method returns an iterator that will enumerate in order the elements returned by all iterators contained in the given array.
*
* @param a an array of iterators.
* @return an iterator obtained by concatenation. */
public static IntIterator concat( final IntIterator a[] ) {
return concat( a, 0, a.length );
}
/** Concatenates a sequence of iterators contained in an array.
*
*
This method returns an iterator that will enumerate in order the elements returned by a[ offset ], then those returned by a[ offset + 1 ], and so on up to a[
* offset + length - 1 ].
*
* @param a an array of iterators.
* @param offset the index of the first iterator to concatenate.
* @param length the number of iterators to concatenate.
* @return an iterator obtained by concatenation of length elements of a starting at offset. */
public static IntIterator concat( final IntIterator a[], final int offset, final int length ) {
return new IteratorConcatenator( a, offset, length );
}
/** An unmodifiable wrapper class for iterators. */
public static class UnmodifiableIterator extends AbstractIntIterator {
final protected IntIterator i;
public UnmodifiableIterator( final IntIterator i ) {
this.i = i;
}
public boolean hasNext() {
return i.hasNext();
}
public int nextInt() {
return i.nextInt();
}
public Integer next() {
return i.next();
}
}
/** Returns an unmodifiable iterator backed by the specified iterator.
*
* @param i the iterator to be wrapped in an unmodifiable iterator.
* @return an unmodifiable view of the specified iterator. */
public static IntIterator unmodifiable( final IntIterator i ) {
return new UnmodifiableIterator( i );
}
/** An unmodifiable wrapper class for bidirectional iterators. */
public static class UnmodifiableBidirectionalIterator extends AbstractIntBidirectionalIterator {
final protected IntBidirectionalIterator i;
public UnmodifiableBidirectionalIterator( final IntBidirectionalIterator i ) {
this.i = i;
}
public boolean hasNext() {
return i.hasNext();
}
public boolean hasPrevious() {
return i.hasPrevious();
}
public int nextInt() {
return i.nextInt();
}
public int previousInt() {
return i.previousInt();
}
public Integer next() {
return i.next();
}
public Integer previous() {
return i.previous();
}
}
/** Returns an unmodifiable bidirectional iterator backed by the specified bidirectional iterator.
*
* @param i the bidirectional iterator to be wrapped in an unmodifiable bidirectional iterator.
* @return an unmodifiable view of the specified bidirectional iterator. */
public static IntBidirectionalIterator unmodifiable( final IntBidirectionalIterator i ) {
return new UnmodifiableBidirectionalIterator( i );
}
/** An unmodifiable wrapper class for list iterators. */
public static class UnmodifiableListIterator extends AbstractIntListIterator {
final protected IntListIterator i;
public UnmodifiableListIterator( final IntListIterator i ) {
this.i = i;
}
public boolean hasNext() {
return i.hasNext();
}
public boolean hasPrevious() {
return i.hasPrevious();
}
public int nextInt() {
return i.nextInt();
}
public int previousInt() {
return i.previousInt();
}
public int nextIndex() {
return i.nextIndex();
}
public int previousIndex() {
return i.previousIndex();
}
public Integer next() {
return i.next();
}
public Integer previous() {
return i.previous();
}
}
/** Returns an unmodifiable list iterator backed by the specified list iterator.
*
* @param i the list iterator to be wrapped in an unmodifiable list iterator.
* @return an unmodifiable view of the specified list iterator. */
public static IntListIterator unmodifiable( final IntListIterator i ) {
return new UnmodifiableListIterator( i );
}
/** A wrapper promoting the results of a ByteIterator. */
protected static class ByteIteratorWrapper implements IntIterator {
final it.unimi.dsi.fastutil.bytes.ByteIterator iterator;
public ByteIteratorWrapper( final it.unimi.dsi.fastutil.bytes.ByteIterator iterator ) {
this.iterator = iterator;
}
public boolean hasNext() {
return iterator.hasNext();
}
public Integer next() {
return Integer.valueOf( iterator.nextByte() );
}
public int nextInt() {
return iterator.nextByte();
}
public void remove() {
iterator.remove();
}
public int skip( final int n ) {
return iterator.skip( n );
}
}
/** Returns an iterator backed by the specified byte iterator.
*
* @return an iterator backed by the specified byte iterator. */
public static IntIterator wrap( final it.unimi.dsi.fastutil.bytes.ByteIterator iterator ) {
return new ByteIteratorWrapper( iterator );
}
/** A wrapper promoting the results of a ShortIterator. */
protected static class ShortIteratorWrapper implements IntIterator {
final it.unimi.dsi.fastutil.shorts.ShortIterator iterator;
public ShortIteratorWrapper( final it.unimi.dsi.fastutil.shorts.ShortIterator iterator ) {
this.iterator = iterator;
}
public boolean hasNext() {
return iterator.hasNext();
}
public Integer next() {
return Integer.valueOf( iterator.nextShort() );
}
public int nextInt() {
return iterator.nextShort();
}
public void remove() {
iterator.remove();
}
public int skip( final int n ) {
return iterator.skip( n );
}
}
/** Returns an iterator backed by the specified short iterator.
*
* @return an iterator backed by the specified short iterator. */
public static IntIterator wrap( final it.unimi.dsi.fastutil.shorts.ShortIterator iterator ) {
return new ShortIteratorWrapper( iterator );
}
}