/*
* Copyright (c) 2011, 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).
*
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* 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
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package java.util.functions;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
/**
* Static utility methods pertaining to {@code Predicate} instances.
*
*
All of the returned predicates are serializable if given serializable
* parameters.
*/
public final class Predicates {
/**
* a predicate that evaluates to {@code true} if the reference
* being tested is {@code null}.
*/
public static final Predicate IS_NULL = #{Object t -> t == null};
/**
* a predicate that evaluates to {@code true} if the reference
* being tested is not {@code null}.
*/
public static final Predicate NON_NULL = #{Object t -> t != null};
/**
* a predicate who's result is always {@code false}.
*/
public static final Predicate FALSE = #{Object t -> false};
/**
* a predicate who's result is always {@code true}.
*/
public static final Predicate TRUE = #{Object t -> true};
/**
* singleton utils
*/
private Predicates() {
throw new AssertionError("No instances!");
}
/**
* Returns a predicate that evaluates to {@code true} if the reference
* being tested is {@code null}.
*
* @return a predicate that evaluates to {@code true} if the reference
* being tested is {@code null}
*/
public static Predicate isNull() {
return (Predicate) IS_NULL;
}
/**
* Returns a predicate that evaluates to {@code true} if the reference
* being tested is non-{@code null}.
*
* @return a predicate that evaluates to {@code true} if the reference
* being tested is is non-{@code null}
*/
public static Predicate nonNull() {
return (Predicate) NON_NULL;
}
/**
* Returns a predicate who's result is always {@code false}.
*
* @return a predicate who's result is always {@code false}.
*/
public static Predicate alwaysFalse() {
return (Predicate) FALSE;
}
/**
* Returns a predicate who's result is always {@code true}.
*
* @return a predicate who's result is always {@code true}.
*/
public static Predicate alwaysTrue() {
return (Predicate) TRUE;
}
/**
* Returns a predicate that evaluates to {@code true} if the object being
* tested is an instance of the provided class. If the object being tested
* is {@code null} this predicate evaluates to {@code false}.
*
* @param clazz The target class to be matched by the predicate.
* @return a predicate that evaluates to {@code true} if the object being
* tested is an instance of the provided class
*/
public static Predicate instanceOf(Class> clazz) {
return #{Object o -> clazz.isInstance(o)};
}
/**
* Returns a predicate that who's result is {@code target == object}.
*
* @param the type of predicate values.
* @param t The target value to be compared for identity equality.
* @return a predicate that who's result is {@code target == object}
*/
public static Predicate isSame(T target) {
return #{T t -> t == target};
}
/**
* Returns a predicate who's result matches
* {@code Objects.equals(target, t)}.
*
* @param the type of predicate values.
* @param t The target value to be compared for equality.
* @return a predicate who's result matches {@code Objects.equals(target, t)}
*/
public static Predicate isEqual(T target) {
if (null == target)
return Predicates.isNull();
else
return #{T t -> target.equals(t)};
}
/**
* Creates a predicate that evaluates to {@code true} if the tested object
* is a member of the provided collection. The collection is not defensively
* copied so changes to it will alter the behavior of the predicate.
*
* @param Type of predicate values.
* @param target the collection against which objects will be tested.
* @return a predicate that evaluates to {@code true} if the tested object
* is a member of the provided collection. The collection is not defensively
* copied so changes to it will alter the behavior of the predicate.
*/
public static Predicate contains(Collection extends T> target) {
return #{T t -> target.contains(t)};
}
/**
* Creates a predicate that is a composition of a mapper and a predicate.
* The returned predicate's result is {@code predicate.eval(mapper.map(t))}.
*
* @return the composition of the provided mapper and predicate
*/
public static Predicate compose(
Predicate predicate, Mapper mapper) {
return #{T t -> predicate.eval(mapper.map(t))};
}
/**
* Returns a predicate that evaluates to {@code true} if the provided
* predicate evaluates to {@code false}
*
* @param the type of values evaluated by the predicate.
* @param predicate The predicate to be evaluated.
* @return A predicate who's result is the logical inverse of the provided
* predicate.
*/
public static > Predicate negate(
P predicate) {
return #{T t -> !predicate.eval(t)};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param first initial component predicate to be evaluated.
* @param second additional component predicate to be evaluated.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
public static > Predicate and(
Predicate first, P second) {
if((null != first) && (first == second)) {
return (Predicate) first;
}
Objects.requireNonNull(first);
Objects.requireNonNull(second);
return #{T t -> first.eval(t) && second.eval(t)};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
public static > Predicate and(
Iterable components) {
List
predicates = safeCopyOf(components);
if(predicates.isEmpty()) {
throw new IllegalArgumentException("no predicates");
}
return #{T t ->
for(P predicate : predicates) {
if(!predicate.eval(t)) {
return false;
}
}
return true;};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
static > Predicate and(
P first, Iterable components) {
List
predicates = safeCopyOf(first, components);
return #{T t ->
for(P predicate : predicates) {
if(!predicate.eval(t)) {
return false;
}
}
return true;};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
@SafeVarargs
public static > Predicate and(
P... components) {
P[] predicates = safeCopyOf(components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return #{T t ->
for(P predicate : predicates) {
if(!predicate.eval(t)) {
return false;
}
}
return true;};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param first first predicate to be evaluated.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
@SafeVarargs
static > Predicate and(
P first, P... components) {
P[] predicates = safeCopyOf(first, components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return #{T t ->
for(P predicate : predicates) {
if(!predicate.eval(t)) {
return false;
}
}
return true;};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param first initial component predicate to be evaluated.
* @param second additional component predicate to be evaluated.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
public static > Predicate or(
Predicate first, P second) {
if((null != first) && (first == second)) {
return first;
}
Objects.requireNonNull(first);
Objects.requireNonNull(second);
return #{T t -> first.eval(t) || second.eval(t)};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
public static > Predicate or(
Iterable components) {
List
predicates = safeCopyOf(components);
if(predicates.isEmpty()) {
throw new IllegalArgumentException("no predicates");
}
return #{T t ->
for(P predicate : predicates) {
if(predicate.eval(t)) {
return true;
}
}
return false;};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
static > Predicate or(
P first, Iterable components) {
List
predicates = safeCopyOf(first, components);
return #{T t ->
for(P predicate : predicates) {
if(predicate.eval(t)) {
return true;
}
}
return false;};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
@SafeVarargs
public static > Predicate or(
P... components) {
P[] predicates = safeCopyOf(components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return #{T t ->
for(P predicate : predicates) {
if(predicate.eval(t)) {
return true;
}
}
return false;};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
@SafeVarargs
static > Predicate or(
Predicate first, P... components) {
P[] predicates = safeCopyOf((P) first, components);
return #{T t ->
for(P predicate : predicates) {
if(predicate.eval(t)) {
return true;
}
}
return false;};
}
/**
* Returns a predicate that evaluates to {@code true} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param first initial component predicate to be evaluated.
* @param second additional component predicate to be evaluated.
* @return a predicate that evaluates to {@code true} if all or none of the
* component predicates evaluate to {@code true}
*/
public static > Predicate xor(
Predicate first, P second) {
if((null != first) && (first == second)) {
return #{T t -> false};
}
Objects.requireNonNull(first);
Objects.requireNonNull(second);
return #{T t -> first.eval(t) ^ second.eval(t)};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
public static > Predicate xor(
Iterable components) {
List
predicates = safeCopyOf(components);
if(predicates.isEmpty()) {
throw new IllegalArgumentException("no predicates");
}
return #{T t ->
Boolean initial = null;
for (P predicate : predicates) {
if (null == initial) {
initial = predicate.eval(t);
} else {
if (!(initial ^ predicate.eval(t))) {
return true;
}
}
}
return false;};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
@SafeVarargs
public static > Predicate xor(P... components) {
P[] predicates = safeCopyOf(components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return #{T t ->
Boolean initial = null;
for (P predicate : predicates) {
if (null == initial) {
initial = predicate.eval(t);
} else {
if (!(initial ^ predicate.eval(t))) {
return true;
}
}
}
return false;};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
@SafeVarargs
static > Predicate xor(
Predicate first,
P... components) {
P[] predicates = safeCopyOf((P) first, components);
return #{T t ->
Boolean initial = null;
for (P predicate : predicates) {
if (null == initial) {
initial = predicate.eval(t);
} else {
if (!(initial ^ predicate.eval(t))) {
return true;
}
}
}
return false;};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
static > Predicate xor(
Predicate first,
Iterable components) {
List
predicates = safeCopyOf((P) first, components);
return #{T t ->
Boolean initial = null;
for (P predicate : predicates) {
if (null == initial) {
initial = predicate.eval(t);
} else {
if (!(initial ^ predicate.eval(t))) {
return true;
}
}
}
return false;};
}
// XXX mduigou These need to be moved somewhere.
@SafeVarargs
static T[] safeCopyOf(T... array) {
T[] copy = Arrays.copyOf(array, array.length);
for(T each : copy) {
Objects.requireNonNull(each);
}
return copy;
}
@SafeVarargs
static T[] safeCopyOf(T first, T... array) {
T[] copy = (T[]) Array.newInstance(array.getClass().getComponentType(), array.length + 1);
copy[0] = Objects.requireNonNull(first);
System.arraycopy(array, 0, copy, 1, array.length);
for(T each : copy) {
Objects.requireNonNull(each);
}
return copy;
}
static List safeCopyOf(T first, Iterable iterable) {
ArrayList list = new ArrayList<>();
list.add(Objects.requireNonNull(first));
for (T element : iterable) {
list.add(Objects.requireNonNull(element));
}
return list;
}
static List safeCopyOf(Iterable iterable) {
ArrayList list = new ArrayList<>();
for (T element : iterable) {
list.add(Objects.requireNonNull(element));
}
return list;
}
}