All Downloads are FREE. Search and download functionalities are using the official Maven repository.

jersey.repackaged.com.google.common.collect.Ordering Maven / Gradle / Ivy

There is a newer version: 2.22.2
Show newest version
/*
 * Copyright (C) 2007 The Guava Authors
 *
 * 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 jersey.repackaged.com.google.common.collect;

import static jersey.repackaged.com.google.common.base.Preconditions.checkArgument;
import static jersey.repackaged.com.google.common.base.Preconditions.checkNotNull;

import jersey.repackaged.com.google.common.annotations.GwtCompatible;
import jersey.repackaged.com.google.common.annotations.VisibleForTesting;
import jersey.repackaged.com.google.common.base.Function;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.atomic.AtomicInteger;

import javax.annotation.Nullable;

/**
 * A comparator, with additional methods to support common operations. This is
 * an "enriched" version of {@code Comparator}, in the same sense that {@link
 * FluentIterable} is an enriched {@link Iterable}). For example: 
   {@code
 *
 *   if (Ordering.from(comparator).reverse().isOrdered(list)) { ... }}
* * The {@link #from(Comparator)} method returns the equivalent {@code Ordering} * instance for a pre-existing comparator. You can also skip the comparator step * and extend {@code Ordering} directly:
   {@code
 *
 *   Ordering byLengthOrdering = new Ordering() {
 *     public int compare(String left, String right) {
 *       return Ints.compare(left.length(), right.length());
 *     }
 *   };}
* * Except as noted, the orderings returned by the factory methods of this * class are serializable if and only if the provided instances that back them * are. For example, if {@code ordering} and {@code function} can themselves be * serialized, then {@code ordering.onResultOf(function)} can as well. * *

See the Guava User Guide article on * {@code Ordering}. * * @author Jesse Wilson * @author Kevin Bourrillion * @since 2.0 (imported from Google Collections Library) */ @GwtCompatible public abstract class Ordering implements Comparator { // Natural order /** * Returns a serializable ordering that uses the natural order of the values. * The ordering throws a {@link NullPointerException} when passed a null * parameter. * *

The type specification is {@code }, instead of * the technically correct {@code >}, to * support legacy types from before Java 5. */ @GwtCompatible(serializable = true) @SuppressWarnings("unchecked") // TODO(kevinb): right way to explain this?? public static Ordering natural() { return (Ordering) NaturalOrdering.INSTANCE; } // Static factories /** * Returns an ordering based on an existing comparator instance. Note * that there's no need to create a new comparator just to pass it in * here; simply subclass {@code Ordering} and implement its {@code compareTo} * method directly instead. * * @param comparator the comparator that defines the order * @return comparator itself if it is already an {@code Ordering}; otherwise * an ordering that wraps that comparator */ @GwtCompatible(serializable = true) public static Ordering from(Comparator comparator) { return (comparator instanceof Ordering) ? (Ordering) comparator : new ComparatorOrdering(comparator); } /** * Simply returns its argument. * * @deprecated no need to use this */ @GwtCompatible(serializable = true) @Deprecated public static Ordering from(Ordering ordering) { return checkNotNull(ordering); } /** * Returns an ordering that compares objects according to the order in * which they appear in the given list. Only objects present in the list * (according to {@link Object#equals}) may be compared. This comparator * imposes a "partial ordering" over the type {@code T}. Subsequent changes * to the {@code valuesInOrder} list will have no effect on the returned * comparator. Null values in the list are not supported. * *

The returned comparator throws an {@link ClassCastException} when it * receives an input parameter that isn't among the provided values. * *

The generated comparator is serializable if all the provided values are * serializable. * * @param valuesInOrder the values that the returned comparator will be able * to compare, in the order the comparator should induce * @return the comparator described above * @throws NullPointerException if any of the provided values is null * @throws IllegalArgumentException if {@code valuesInOrder} contains any * duplicate values (according to {@link Object#equals}) */ @GwtCompatible(serializable = true) public static Ordering explicit(List valuesInOrder) { return new ExplicitOrdering(valuesInOrder); } /** * Returns an ordering that compares objects according to the order in * which they are given to this method. Only objects present in the argument * list (according to {@link Object#equals}) may be compared. This comparator * imposes a "partial ordering" over the type {@code T}. Null values in the * argument list are not supported. * *

The returned comparator throws a {@link ClassCastException} when it * receives an input parameter that isn't among the provided values. * *

The generated comparator is serializable if all the provided values are * serializable. * * @param leastValue the value which the returned comparator should consider * the "least" of all values * @param remainingValuesInOrder the rest of the values that the returned * comparator will be able to compare, in the order the comparator should * follow * @return the comparator described above * @throws NullPointerException if any of the provided values is null * @throws IllegalArgumentException if any duplicate values (according to * {@link Object#equals(Object)}) are present among the method arguments */ @GwtCompatible(serializable = true) public static Ordering explicit( T leastValue, T... remainingValuesInOrder) { return explicit(Lists.asList(leastValue, remainingValuesInOrder)); } // Ordering singletons /** * Returns an ordering which treats all values as equal, indicating "no * ordering." Passing this ordering to any stable sort algorithm * results in no change to the order of elements. Note especially that {@link * #sortedCopy} and {@link #immutableSortedCopy} are stable, and in the * returned instance these are implemented by simply copying the source list. * *

Example:

   {@code
   *
   *   Ordering.allEqual().nullsLast().sortedCopy(
   *       asList(t, null, e, s, null, t, null))}
* * Assuming {@code t}, {@code e} and {@code s} are non-null, this returns * {@code [t, e, s, t, null, null, null]} regardlesss of the true comparison * order of those three values (which might not even implement {@link * Comparable} at all). * *

Warning: by definition, this comparator is not consistent with * equals (as defined {@linkplain Comparator here}). Avoid its use in * APIs, such as {@link TreeSet#TreeSet(Comparator)}, where such consistency * is expected. * *

The returned comparator is serializable. */ @GwtCompatible(serializable = true) @SuppressWarnings("unchecked") public static Ordering allEqual() { return AllEqualOrdering.INSTANCE; } /** * Returns an ordering that compares objects by the natural ordering of their * string representations as returned by {@code toString()}. It does not * support null values. * *

The comparator is serializable. */ @GwtCompatible(serializable = true) public static Ordering usingToString() { return UsingToStringOrdering.INSTANCE; } /** * Returns an arbitrary ordering over all objects, for which {@code compare(a, * b) == 0} implies {@code a == b} (identity equality). There is no meaning * whatsoever to the order imposed, but it is constant for the life of the VM. * *

Because the ordering is identity-based, it is not "consistent with * {@link Object#equals(Object)}" as defined by {@link Comparator}. Use * caution when building a {@link SortedSet} or {@link SortedMap} from it, as * the resulting collection will not behave exactly according to spec. * *

This ordering is not serializable, as its implementation relies on * {@link System#identityHashCode(Object)}, so its behavior cannot be * preserved across serialization. * * @since 2.0 */ public static Ordering arbitrary() { return ArbitraryOrderingHolder.ARBITRARY_ORDERING; } private static class ArbitraryOrderingHolder { static final Ordering ARBITRARY_ORDERING = new ArbitraryOrdering(); } @VisibleForTesting static class ArbitraryOrdering extends Ordering { @SuppressWarnings("deprecation") // TODO(kevinb): ? private Map uids = Platform.tryWeakKeys(new MapMaker()).makeComputingMap( new Function() { final AtomicInteger counter = new AtomicInteger(0); @Override public Integer apply(Object from) { return counter.getAndIncrement(); } }); @Override public int compare(Object left, Object right) { if (left == right) { return 0; } else if (left == null) { return -1; } else if (right == null) { return 1; } int leftCode = identityHashCode(left); int rightCode = identityHashCode(right); if (leftCode != rightCode) { return leftCode < rightCode ? -1 : 1; } // identityHashCode collision (rare, but not as rare as you'd think) int result = uids.get(left).compareTo(uids.get(right)); if (result == 0) { throw new AssertionError(); // extremely, extremely unlikely. } return result; } @Override public String toString() { return "Ordering.arbitrary()"; } /* * We need to be able to mock identityHashCode() calls for tests, because it * can take 1-10 seconds to find colliding objects. Mocking frameworks that * can do magic to mock static method calls still can't do so for a system * class, so we need the indirection. In production, Hotspot should still * recognize that the call is 1-morphic and should still be willing to * inline it if necessary. */ int identityHashCode(Object object) { return System.identityHashCode(object); } } // Constructor /** * Constructs a new instance of this class (only invokable by the subclass * constructor, typically implicit). */ protected Ordering() {} // Instance-based factories (and any static equivalents) /** * Returns the reverse of this ordering; the {@code Ordering} equivalent to * {@link Collections#reverseOrder(Comparator)}. */ // type parameter lets us avoid the extra in statements like: // Ordering o = Ordering.natural().reverse(); @GwtCompatible(serializable = true) public Ordering reverse() { return new ReverseOrdering(this); } /** * Returns an ordering that treats {@code null} as less than all other values * and uses {@code this} to compare non-null values. */ // type parameter lets us avoid the extra in statements like: // Ordering o = Ordering.natural().nullsFirst(); @GwtCompatible(serializable = true) public Ordering nullsFirst() { return new NullsFirstOrdering(this); } /** * Returns an ordering that treats {@code null} as greater than all other * values and uses this ordering to compare non-null values. */ // type parameter lets us avoid the extra in statements like: // Ordering o = Ordering.natural().nullsLast(); @GwtCompatible(serializable = true) public Ordering nullsLast() { return new NullsLastOrdering(this); } /** * Returns a new ordering on {@code F} which orders elements by first applying * a function to them, then comparing those results using {@code this}. For * example, to compare objects by their string forms, in a case-insensitive * manner, use:
   {@code
   *
   *   Ordering.from(String.CASE_INSENSITIVE_ORDER)
   *       .onResultOf(Functions.toStringFunction())}
*/ @GwtCompatible(serializable = true) public Ordering onResultOf(Function function) { return new ByFunctionOrdering(function, this); } /** * Returns an ordering which first uses the ordering {@code this}, but which * in the event of a "tie", then delegates to {@code secondaryComparator}. * For example, to sort a bug list first by status and second by priority, you * might use {@code byStatus.compound(byPriority)}. For a compound ordering * with three or more components, simply chain multiple calls to this method. * *

An ordering produced by this method, or a chain of calls to this method, * is equivalent to one created using {@link Ordering#compound(Iterable)} on * the same component comparators. */ @GwtCompatible(serializable = true) public Ordering compound( Comparator secondaryComparator) { return new CompoundOrdering(this, checkNotNull(secondaryComparator)); } /** * Returns an ordering which tries each given comparator in order until a * non-zero result is found, returning that result, and returning zero only if * all comparators return zero. The returned ordering is based on the state of * the {@code comparators} iterable at the time it was provided to this * method. * *

The returned ordering is equivalent to that produced using {@code * Ordering.from(comp1).compound(comp2).compound(comp3) . . .}. * *

Warning: Supplying an argument with undefined iteration order, * such as a {@link HashSet}, will produce non-deterministic results. * * @param comparators the comparators to try in order */ @GwtCompatible(serializable = true) public static Ordering compound( Iterable> comparators) { return new CompoundOrdering(comparators); } /** * Returns a new ordering which sorts iterables by comparing corresponding * elements pairwise until a nonzero result is found; imposes "dictionary * order". If the end of one iterable is reached, but not the other, the * shorter iterable is considered to be less than the longer one. For example, * a lexicographical natural ordering over integers considers {@code * [] < [1] < [1, 1] < [1, 2] < [2]}. * *

Note that {@code ordering.lexicographical().reverse()} is not * equivalent to {@code ordering.reverse().lexicographical()} (consider how * each would order {@code [1]} and {@code [1, 1]}). * * @since 2.0 */ @GwtCompatible(serializable = true) // type parameter lets us avoid the extra in statements like: // Ordering> o = // Ordering.natural().lexicographical(); public Ordering> lexicographical() { /* * Note that technically the returned ordering should be capable of * handling not just {@code Iterable} instances, but also any {@code * Iterable}. However, the need for this comes up so rarely * that it doesn't justify making everyone else deal with the very ugly * wildcard. */ return new LexicographicalOrdering(this); } // Regular instance methods // Override to add @Nullable @Override public abstract int compare(@Nullable T left, @Nullable T right); /** * Returns the least of the specified values according to this ordering. If * there are multiple least values, the first of those is returned. The * iterator will be left exhausted: its {@code hasNext()} method will return * {@code false}. * * @param iterator the iterator whose minimum element is to be determined * @throws NoSuchElementException if {@code iterator} is empty * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. * * @since 11.0 */ public E min(Iterator iterator) { // let this throw NoSuchElementException as necessary E minSoFar = iterator.next(); while (iterator.hasNext()) { minSoFar = min(minSoFar, iterator.next()); } return minSoFar; } /** * Returns the least of the specified values according to this ordering. If * there are multiple least values, the first of those is returned. * * @param iterable the iterable whose minimum element is to be determined * @throws NoSuchElementException if {@code iterable} is empty * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. */ public E min(Iterable iterable) { return min(iterable.iterator()); } /** * Returns the lesser of the two values according to this ordering. If the * values compare as 0, the first is returned. * *

Implementation note: this method is invoked by the default * implementations of the other {@code min} overloads, so overriding it will * affect their behavior. * * @param a value to compare, returned if less than or equal to b. * @param b value to compare. * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. */ public E min(@Nullable E a, @Nullable E b) { return (compare(a, b) <= 0) ? a : b; } /** * Returns the least of the specified values according to this ordering. If * there are multiple least values, the first of those is returned. * * @param a value to compare, returned if less than or equal to the rest. * @param b value to compare * @param c value to compare * @param rest values to compare * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. */ public E min( @Nullable E a, @Nullable E b, @Nullable E c, E... rest) { E minSoFar = min(min(a, b), c); for (E r : rest) { minSoFar = min(minSoFar, r); } return minSoFar; } /** * Returns the greatest of the specified values according to this ordering. If * there are multiple greatest values, the first of those is returned. The * iterator will be left exhausted: its {@code hasNext()} method will return * {@code false}. * * @param iterator the iterator whose maximum element is to be determined * @throws NoSuchElementException if {@code iterator} is empty * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. * * @since 11.0 */ public E max(Iterator iterator) { // let this throw NoSuchElementException as necessary E maxSoFar = iterator.next(); while (iterator.hasNext()) { maxSoFar = max(maxSoFar, iterator.next()); } return maxSoFar; } /** * Returns the greatest of the specified values according to this ordering. If * there are multiple greatest values, the first of those is returned. * * @param iterable the iterable whose maximum element is to be determined * @throws NoSuchElementException if {@code iterable} is empty * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. */ public E max(Iterable iterable) { return max(iterable.iterator()); } /** * Returns the greater of the two values according to this ordering. If the * values compare as 0, the first is returned. * *

Implementation note: this method is invoked by the default * implementations of the other {@code max} overloads, so overriding it will * affect their behavior. * * @param a value to compare, returned if greater than or equal to b. * @param b value to compare. * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. */ public E max(@Nullable E a, @Nullable E b) { return (compare(a, b) >= 0) ? a : b; } /** * Returns the greatest of the specified values according to this ordering. If * there are multiple greatest values, the first of those is returned. * * @param a value to compare, returned if greater than or equal to the rest. * @param b value to compare * @param c value to compare * @param rest values to compare * @throws ClassCastException if the parameters are not mutually * comparable under this ordering. */ public E max( @Nullable E a, @Nullable E b, @Nullable E c, E... rest) { E maxSoFar = max(max(a, b), c); for (E r : rest) { maxSoFar = max(maxSoFar, r); } return maxSoFar; } /** * Returns the {@code k} least elements of the given iterable according to * this ordering, in order from least to greatest. If there are fewer than * {@code k} elements present, all will be included. * *

The implementation does not necessarily use a stable sorting * algorithm; when multiple elements are equivalent, it is undefined which * will come first. * * @return an immutable {@code RandomAccess} list of the {@code k} least * elements in ascending order * @throws IllegalArgumentException if {@code k} is negative * @since 8.0 */ public List leastOf(Iterable iterable, int k) { if (iterable instanceof Collection) { Collection collection = (Collection) iterable; if (collection.size() <= 2L * k) { // In this case, just dumping the collection to an array and sorting is // faster than using the implementation for Iterator, which is // specialized for k much smaller than n. @SuppressWarnings("unchecked") // c only contains E's and doesn't escape E[] array = (E[]) collection.toArray(); Arrays.sort(array, this); if (array.length > k) { array = ObjectArrays.arraysCopyOf(array, k); } return Collections.unmodifiableList(Arrays.asList(array)); } } return leastOf(iterable.iterator(), k); } /** * Returns the {@code k} least elements from the given iterator according to * this ordering, in order from least to greatest. If there are fewer than * {@code k} elements present, all will be included. * *

The implementation does not necessarily use a stable sorting * algorithm; when multiple elements are equivalent, it is undefined which * will come first. * * @return an immutable {@code RandomAccess} list of the {@code k} least * elements in ascending order * @throws IllegalArgumentException if {@code k} is negative * @since 14.0 */ public List leastOf(Iterator elements, int k) { checkNotNull(elements); checkArgument(k >= 0, "k (%s) must be nonnegative", k); if (k == 0 || !elements.hasNext()) { return ImmutableList.of(); } else if (k >= Integer.MAX_VALUE / 2) { // k is really large; just do a straightforward sorted-copy-and-sublist ArrayList list = Lists.newArrayList(elements); Collections.sort(list, this); if (list.size() > k) { list.subList(k, list.size()).clear(); } list.trimToSize(); return Collections.unmodifiableList(list); } /* * Our goal is an O(n) algorithm using only one pass and O(k) additional * memory. * * We use the following algorithm: maintain a buffer of size 2*k. Every time * the buffer gets full, find the median and partition around it, keeping * only the lowest k elements. This requires n/k find-median-and-partition * steps, each of which take O(k) time with a traditional quickselect. * * After sorting the output, the whole algorithm is O(n + k log k). It * degrades gracefully for worst-case input (descending order), performs * competitively or wins outright for randomly ordered input, and doesn't * require the whole collection to fit into memory. */ int bufferCap = k * 2; @SuppressWarnings("unchecked") // we'll only put E's in E[] buffer = (E[]) new Object[bufferCap]; E threshold = elements.next(); buffer[0] = threshold; int bufferSize = 1; // threshold is the kth smallest element seen so far. Once bufferSize >= k, // anything larger than threshold can be ignored immediately. while (bufferSize < k && elements.hasNext()) { E e = elements.next(); buffer[bufferSize++] = e; threshold = max(threshold, e); } while (elements.hasNext()) { E e = elements.next(); if (compare(e, threshold) >= 0) { continue; } buffer[bufferSize++] = e; if (bufferSize == bufferCap) { // We apply the quickselect algorithm to partition about the median, // and then ignore the last k elements. int left = 0; int right = bufferCap - 1; int minThresholdPosition = 0; // The leftmost position at which the greatest of the k lower elements // -- the new value of threshold -- might be found. while (left < right) { int pivotIndex = (left + right + 1) >>> 1; int pivotNewIndex = partition(buffer, left, right, pivotIndex); if (pivotNewIndex > k) { right = pivotNewIndex - 1; } else if (pivotNewIndex < k) { left = Math.max(pivotNewIndex, left + 1); minThresholdPosition = pivotNewIndex; } else { break; } } bufferSize = k; threshold = buffer[minThresholdPosition]; for (int i = minThresholdPosition + 1; i < bufferSize; i++) { threshold = max(threshold, buffer[i]); } } } Arrays.sort(buffer, 0, bufferSize, this); bufferSize = Math.min(bufferSize, k); return Collections.unmodifiableList( Arrays.asList(ObjectArrays.arraysCopyOf(buffer, bufferSize))); // We can't use ImmutableList; we have to be null-friendly! } private int partition( E[] values, int left, int right, int pivotIndex) { E pivotValue = values[pivotIndex]; values[pivotIndex] = values[right]; values[right] = pivotValue; int storeIndex = left; for (int i = left; i < right; i++) { if (compare(values[i], pivotValue) < 0) { ObjectArrays.swap(values, storeIndex, i); storeIndex++; } } ObjectArrays.swap(values, right, storeIndex); return storeIndex; } /** * Returns the {@code k} greatest elements of the given iterable according to * this ordering, in order from greatest to least. If there are fewer than * {@code k} elements present, all will be included. * *

The implementation does not necessarily use a stable sorting * algorithm; when multiple elements are equivalent, it is undefined which * will come first. * * @return an immutable {@code RandomAccess} list of the {@code k} greatest * elements in descending order * @throws IllegalArgumentException if {@code k} is negative * @since 8.0 */ public List greatestOf(Iterable iterable, int k) { // TODO(kevinb): see if delegation is hurting performance noticeably // TODO(kevinb): if we change this implementation, add full unit tests. return reverse().leastOf(iterable, k); } /** * Returns the {@code k} greatest elements from the given iterator according to * this ordering, in order from greatest to least. If there are fewer than * {@code k} elements present, all will be included. * *

The implementation does not necessarily use a stable sorting * algorithm; when multiple elements are equivalent, it is undefined which * will come first. * * @return an immutable {@code RandomAccess} list of the {@code k} greatest * elements in descending order * @throws IllegalArgumentException if {@code k} is negative * @since 14.0 */ public List greatestOf(Iterator iterator, int k) { return reverse().leastOf(iterator, k); } /** * Returns a copy of the given iterable sorted by this ordering. The input is * not modified. The returned list is modifiable, serializable, and has random * access. * *

Unlike {@link Sets#newTreeSet(Iterable)}, this method does not discard * elements that are duplicates according to the comparator. The sort * performed is stable, meaning that such elements will appear in the * resulting list in the same order they appeared in the input. * * @param iterable the elements to be copied and sorted * @return a new list containing the given elements in sorted order */ public List sortedCopy(Iterable iterable) { @SuppressWarnings("unchecked") // does not escape, and contains only E's E[] array = (E[]) Iterables.toArray(iterable); Arrays.sort(array, this); return Lists.newArrayList(Arrays.asList(array)); } /** * Returns an immutable copy of the given iterable sorted by this * ordering. The input is not modified. * *

Unlike {@link Sets#newTreeSet(Iterable)}, this method does not discard * elements that are duplicates according to the comparator. The sort * performed is stable, meaning that such elements will appear in the * resulting list in the same order they appeared in the input. * * @param iterable the elements to be copied and sorted * @return a new immutable list containing the given elements in sorted order * @throws NullPointerException if {@code iterable} or any of its elements is * null * @since 3.0 */ public ImmutableList immutableSortedCopy( Iterable iterable) { @SuppressWarnings("unchecked") // we'll only ever have E's in here E[] elements = (E[]) Iterables.toArray(iterable); for (E e : elements) { checkNotNull(e); } Arrays.sort(elements, this); return ImmutableList.asImmutableList(elements); } /** * Returns {@code true} if each element in {@code iterable} after the first is * greater than or equal to the element that preceded it, according to this * ordering. Note that this is always true when the iterable has fewer than * two elements. */ public boolean isOrdered(Iterable iterable) { Iterator it = iterable.iterator(); if (it.hasNext()) { T prev = it.next(); while (it.hasNext()) { T next = it.next(); if (compare(prev, next) > 0) { return false; } prev = next; } } return true; } /** * Returns {@code true} if each element in {@code iterable} after the first is * strictly greater than the element that preceded it, according to * this ordering. Note that this is always true when the iterable has fewer * than two elements. */ public boolean isStrictlyOrdered(Iterable iterable) { Iterator it = iterable.iterator(); if (it.hasNext()) { T prev = it.next(); while (it.hasNext()) { T next = it.next(); if (compare(prev, next) >= 0) { return false; } prev = next; } } return true; } /** * {@link Collections#binarySearch(List, Object, Comparator) Searches} * {@code sortedList} for {@code key} using the binary search algorithm. The * list must be sorted using this ordering. * * @param sortedList the list to be searched * @param key the key to be searched for */ public int binarySearch(List sortedList, @Nullable T key) { return Collections.binarySearch(sortedList, key, this); } /** * Exception thrown by a {@link Ordering#explicit(List)} or {@link * Ordering#explicit(Object, Object[])} comparator when comparing a value * outside the set of values it can compare. Extending {@link * ClassCastException} may seem odd, but it is required. */ // TODO(kevinb): make this public, document it right @VisibleForTesting static class IncomparableValueException extends ClassCastException { final Object value; IncomparableValueException(Object value) { super("Cannot compare value: " + value); this.value = value; } private static final long serialVersionUID = 0; } // Never make these public static final int LEFT_IS_GREATER = 1; static final int RIGHT_IS_GREATER = -1; }