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The GraalVM compiler and the Graal-truffle optimizer.
/*
* Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package org.graalvm.util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.function.Function;
import java.util.function.IntFunction;
import java.util.function.Predicate;
import java.util.function.Supplier;
import org.graalvm.collections.Pair;
/**
* This class contains utility methods for commonly used functional patterns for collections.
*/
public final class CollectionsUtil {
private CollectionsUtil() {
}
/**
* Concatenates two iterables into a single iterable. The iterator exposed by the returned
* iterable does not support {@link Iterator#remove()} even if the input iterables do.
*
* @throws NullPointerException if {@code a} or {@code b} is {@code null}
*/
public static Iterable concat(Iterable a, Iterable b) {
List> l = Arrays.asList(a, b);
return concat(l);
}
/**
* Concatenates multiple iterables into a single iterable. The iterator exposed by the returned
* iterable does not support {@link Iterator#remove()} even if the input iterables do.
*
* @throws NullPointerException if {@code iterables} or any of its elements are {@code null}
*/
public static Iterable concat(List> iterables) {
for (Iterable iterable : iterables) {
Objects.requireNonNull(iterable);
}
return new Iterable<>() {
@Override
public Iterator iterator() {
if (iterables.size() == 0) {
return Collections.emptyIterator();
}
return new Iterator<>() {
final Iterator> cursor = iterables.iterator();
Iterator currentIterator = cursor.next().iterator();
private void advance() {
while (!currentIterator.hasNext() && cursor.hasNext()) {
currentIterator = cursor.next().iterator();
}
}
@Override
public boolean hasNext() {
advance();
return currentIterator.hasNext();
}
@Override
public T next() {
advance();
return currentIterator.next();
}
};
}
};
}
/**
* Returns whether all elements in {@code inputs} match {@code predicate}. May not evaluate
* {@code predicate} on all elements if not necessary for determining the result. If
* {@code inputs} is empty then {@code true} is returned and {@code predicate} is not evaluated.
*
* @return {@code true} if either all elements in {@code inputs} match {@code predicate} or
* {@code inputs} is empty, otherwise {@code false}.
*/
public static boolean allMatch(T[] inputs, Predicate predicate) {
return allMatch(Arrays.asList(inputs), predicate);
}
/**
* Returns whether all elements in {@code inputs} match {@code predicate}. May not evaluate
* {@code predicate} on all elements if not necessary for determining the result. If
* {@code inputs} is empty then {@code true} is returned and {@code predicate} is not evaluated.
*
* @return {@code true} if either all elements in {@code inputs} match {@code predicate} or
* {@code inputs} is empty, otherwise {@code false}.
*/
public static boolean allMatch(Iterable inputs, Predicate predicate) {
for (T t : inputs) {
if (!predicate.test(t)) {
return false;
}
}
return true;
}
/**
* Returns whether any elements in {@code inputs} match {@code predicate}. May not evaluate
* {@code predicate} on all elements if not necessary for determining the result. If
* {@code inputs} is empty then {@code false} is returned and {@code predicate} is not
* evaluated.
*
* @return {@code true} if any elements in {@code inputs} match {@code predicate}, otherwise
* {@code false}.
*/
public static boolean anyMatch(T[] inputs, Predicate predicate) {
return anyMatch(Arrays.asList(inputs), predicate);
}
/**
* Returns whether any elements in {@code inputs} match {@code predicate}. May not evaluate
* {@code predicate} on all elements if not necessary for determining the result. If
* {@code inputs} is empty then {@code false} is returned and {@code predicate} is not
* evaluated.
*
* @return {@code true} if any elements in {@code inputs} match {@code predicate}, otherwise
* {@code false}.
*/
public static boolean anyMatch(Iterable inputs, Predicate predicate) {
for (T t : inputs) {
if (predicate.test(t)) {
return true;
}
}
return false;
}
/**
* Returns a new list consisting of the elements in {@code inputs} that match {@code predicate}.
*
* @return the new list.
*/
public static List filterToList(List inputs, Predicate predicate) {
return filterToList(inputs, predicate, ArrayList::new);
}
/**
* Appends elements of {@code inputs} that match {@code predicate} to the list generated by
* {@code listGenerator}.
*
* @return the list generated by {@code listGenerator}.
*/
public static List filterToList(List inputs, Predicate predicate, Supplier> listGenerator) {
List resultList = listGenerator.get();
for (T t : inputs) {
if (predicate.test(t)) {
resultList.add(t);
}
}
return resultList;
}
/**
* Filters {@code inputs} with {@code predicate}, applies {@code mapper} and adds them in the
* array provided by {@code arrayGenerator}.
*
* @return the array provided by {@code arrayGenerator}.
*/
public static R[] filterAndMapToArray(T[] inputs, Predicate predicate, Function mapper, IntFunction arrayGenerator) {
List resultList = new ArrayList<>();
for (T t : inputs) {
if (predicate.test(t)) {
resultList.add(mapper.apply(t));
}
}
return resultList.toArray(arrayGenerator.apply(resultList.size()));
}
/**
* Applies {@code mapper} on the elements in {@code inputs} and adds them in the array provided
* by {@code arrayGenerator}.
*
* @return the array provided by {@code arrayGenerator}.
*/
public static R[] mapToArray(T[] inputs, Function mapper, IntFunction arrayGenerator) {
return mapToArray(Arrays.asList(inputs), mapper, arrayGenerator);
}
/**
* Applies {@code mapper} on the elements in {@code inputs} and adds them in the array provided
* by {@code arrayGenerator}.
*
* @return the array provided by {@code arrayGenerator}.
*/
public static R[] mapToArray(Collection inputs, Function mapper, IntFunction arrayGenerator) {
R[] result = arrayGenerator.apply(inputs.size());
int idx = 0;
for (T t : inputs) {
result[idx++] = mapper.apply(t);
}
return result;
}
/**
* Applies {@code mapper} on the elements in {@code inputs}, and joins them together separated
* by {@code delimiter}.
*
* @return a new String that is composed from {@code inputs}.
*/
public static String mapAndJoin(T[] inputs, Function mapper, String delimiter) {
return mapAndJoin(Arrays.asList(inputs), mapper, delimiter, "", "");
}
/**
* Applies {@code mapper} on the elements in {@code inputs}, and joins them together separated
* by {@code delimiter} and starting with {@code prefix}.
*
* @return a new String that is composed from {@code inputs}.
*/
public static String mapAndJoin(T[] inputs, Function mapper, String delimiter, String prefix) {
return mapAndJoin(Arrays.asList(inputs), mapper, delimiter, prefix, "");
}
/**
* Applies {@code mapper} on the elements in {@code inputs}, and joins them together separated
* by {@code delimiter} and starting with {@code prefix} and ending with {@code suffix}.
*
* @return a new String that is composed from {@code inputs}.
*/
public static String mapAndJoin(T[] inputs, Function mapper, String delimiter, String prefix, String suffix) {
return mapAndJoin(Arrays.asList(inputs), mapper, delimiter, prefix, suffix);
}
/**
* Applies {@code mapper} on the elements in {@code inputs}, and joins them together separated
* by {@code delimiter}.
*
* @return a new String that is composed from {@code inputs}.
*/
public static String mapAndJoin(Iterable inputs, Function mapper, String delimiter) {
return mapAndJoin(inputs, mapper, delimiter, "", "");
}
/**
* Applies {@code mapper} on the elements in {@code inputs}, and joins them together separated
* by {@code delimiter} and starting with {@code prefix}.
*
* @return a new String that is composed from {@code inputs}.
*/
public static String mapAndJoin(Iterable inputs, Function mapper, String delimiter, String prefix) {
return mapAndJoin(inputs, mapper, delimiter, prefix, "");
}
/**
* Applies {@code mapper} on the elements in {@code inputs}, and joins them together separated
* by {@code delimiter} and starting with {@code prefix} and ending with {@code suffix}.
*
* @return a new String that is composed from {@code inputs}.
*/
public static String mapAndJoin(Iterable inputs, Function mapper, String delimiter, String prefix, String suffix) {
StringBuilder strb = new StringBuilder();
String sep = "";
for (T t : inputs) {
strb.append(sep).append(prefix).append(mapper.apply(t)).append(suffix);
sep = delimiter;
}
return strb.toString();
}
/**
* Combines two iterables into an iterable of pairs with as many elements as the longer
* iterable. Elements are paired in the order of the original iterables. When one of the
* iterators is exhausted, {@code null}s are returned in its place.
*
* @param lhs the first iterable
* @param rhs the second iterable
* @return an iterable of pairs of the input elements
*/
public static Iterable> zipLongest(Iterable lhs, Iterable rhs) {
Iterator lhsIterator = lhs.iterator();
Iterator rhsIterator = rhs.iterator();
return () -> new Iterator<>() {
@Override
public boolean hasNext() {
return lhsIterator.hasNext() || rhsIterator.hasNext();
}
@Override
public Pair next() {
if (lhsIterator.hasNext() && rhsIterator.hasNext()) {
return Pair.create(lhsIterator.next(), rhsIterator.next());
} else if (lhsIterator.hasNext()) {
return Pair.createLeft(lhsIterator.next());
} else {
return Pair.createRight(rhsIterator.next());
}
}
};
}
/**
* Returns an iterable over all pairs of elements.
*
* Suppose that the first iterable returns the elements {@code a1, a2, ..., an} and the second
* iterable returns the elements {@code b1, b2, ..., bm}. Then, the method returns the pairs
* {@code (a1, b1), (a1, b2), ..., (a1, bm), (a2, b1), (a2, b2), ... (an, bm)}.
*
* @param lhs the first iterable (left elements of the {@link Pair})
* @param rhs the second iterable (right elements of the {@link Pair})
* @return an iterable over all pairs of elements
*/
public static Iterable> cartesianProduct(Iterable lhs, Iterable rhs) {
return () -> new Iterator<>() {
private L lhsLast = null;
private final Iterator lhsIterator = lhs.iterator();
private boolean rhsReachedEnd = true;
private Iterator rhsIterator = null;
@Override
public boolean hasNext() {
if (rhsReachedEnd) {
if (!lhsIterator.hasNext()) {
return false;
}
lhsLast = lhsIterator.next();
rhsIterator = rhs.iterator();
rhsReachedEnd = !rhsIterator.hasNext();
return !rhsReachedEnd;
}
return true;
}
@Override
public Pair next() {
if (rhsReachedEnd) {
lhsLast = lhsIterator.next();
rhsIterator = rhs.iterator();
}
R rhsItem = rhsIterator.next();
rhsReachedEnd = !rhsIterator.hasNext();
return Pair.create(lhsLast, rhsItem);
}
};
}
}
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