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Parallel programming on the go
/*
* 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 com.github.dm.jrt.function;
import com.github.dm.jrt.util.Reflection;
import org.jetbrains.annotations.NotNull;
import java.util.ArrayList;
import java.util.List;
/**
* Class wrapping a predicate instance.
*
* Created by davide-maestroni on 10/16/2015.
*
* @param the input data type.
*/
public class PredicateWrapper implements Predicate {
private static final LogicalPredicate AND_PREDICATE = new LogicalPredicate();
private static final LogicalPredicate CLOSE_PREDICATE = new LogicalPredicate();
private static final LogicalPredicate NEGATE_PREDICATE = new LogicalPredicate();
private static final LogicalPredicate OPEN_PREDICATE = new LogicalPredicate();
private static final LogicalPredicate OR_PREDICATE = new LogicalPredicate();
private final Predicate mPredicate;
private final List> mPredicates;
/**
* Constructor.
*
* @param predicate the core predicate.
* @param predicates the list of wrapped predicates.
*/
@SuppressWarnings("ConstantConditions")
PredicateWrapper(@NotNull final Predicate predicate,
@NotNull final List> predicates) {
if (predicate == null) {
throw new NullPointerException("the predicate must not be null");
}
if (predicates.isEmpty()) {
throw new IllegalArgumentException("the list of predicates must not be empty");
}
mPredicate = predicate;
mPredicates = predicates;
}
/**
* Returns a composed predicate wrapper that represents a short-circuiting logical AND of this
* predicate and another.
*
* @param other a predicate that will be logically-ANDed with this predicate.
* @return the composed predicate.
*/
@NotNull
public PredicateWrapper and(@NotNull final Predicate other) {
final Class otherClass = other.getClass();
final List> predicates = mPredicates;
final ArrayList> newPredicates =
new ArrayList>(predicates.size() + 4);
newPredicates.add(OPEN_PREDICATE);
newPredicates.addAll(predicates);
newPredicates.add(AND_PREDICATE);
if (otherClass == PredicateWrapper.class) {
newPredicates.addAll(((PredicateWrapper) other).mPredicates);
} else {
newPredicates.add(other);
}
newPredicates.add(CLOSE_PREDICATE);
return new PredicateWrapper(new AndPredicate(mPredicate, other), newPredicates);
}
/**
* Checks if the predicates wrapped by this instance have a static context.
*
* @return whether the predicates have a static context.
*/
public boolean hasStaticContext() {
for (final Predicate predicate : mPredicates) {
if (!Reflection.hasStaticContext(predicate.getClass())) {
return false;
}
}
return true;
}
@Override
public int hashCode() {
int result = 0;
for (final Predicate predicate : mPredicates) {
result = 31 * result + predicate.getClass().hashCode();
}
return result;
}
@Override
public boolean equals(final Object o) {
if (this == o) {
return true;
}
if ((o == null) || (getClass() != o.getClass())) {
return false;
}
final PredicateWrapper that = (PredicateWrapper) o;
final List> thisPredicates = mPredicates;
final List> thatPredicates = that.mPredicates;
final int size = thisPredicates.size();
if (size != thatPredicates.size()) {
return false;
}
for (int i = 0; i < size; ++i) {
if (thisPredicates.get(i).getClass() != thatPredicates.get(i).getClass()) {
return false;
}
}
return true;
}
/**
* Returns a predicate wrapper that represents the logical negation of this predicate.
*
* @return the negated predicate.
*/
@NotNull
@SuppressWarnings("unchecked")
public PredicateWrapper negate() {
final List> predicates = mPredicates;
final int size = predicates.size();
final ArrayList> newPredicates = new ArrayList>(size + 1);
if (size == 1) {
newPredicates.add(NEGATE_PREDICATE);
newPredicates.add(predicates.get(0));
} else {
final Predicate first = predicates.get(0);
if (first == NEGATE_PREDICATE) {
newPredicates.add(predicates.get(1));
} else {
newPredicates.add(first);
for (int i = 1; i < size; ++i) {
final Predicate predicate = predicates.get(i);
if (predicate == NEGATE_PREDICATE) {
++i;
} else if (predicate == OR_PREDICATE) {
newPredicates.add(AND_PREDICATE);
} else if (predicate == AND_PREDICATE) {
newPredicates.add(OR_PREDICATE);
} else {
if ((predicate != OPEN_PREDICATE) && (predicate != CLOSE_PREDICATE)) {
newPredicates.add(NEGATE_PREDICATE);
}
newPredicates.add(predicate);
}
}
}
}
final Predicate predicate = mPredicate;
if (predicate instanceof NegatePredicate) {
return new PredicateWrapper(((NegatePredicate) predicate).mPredicate,
newPredicates);
}
return new PredicateWrapper(new NegatePredicate(predicate), newPredicates);
}
/**
* Returns a composed predicate wrapper that represents a short-circuiting logical OR of this
* predicate and another.
*
* @param other a predicate that will be logically-ORed with this predicate.
* @return the composed predicate.
*/
@NotNull
public PredicateWrapper or(@NotNull final Predicate other) {
final Class otherClass = other.getClass();
final List> predicates = mPredicates;
final ArrayList> newPredicates =
new ArrayList>(predicates.size() + 4);
newPredicates.add(OPEN_PREDICATE);
newPredicates.addAll(predicates);
newPredicates.add(OR_PREDICATE);
if (otherClass == PredicateWrapper.class) {
newPredicates.addAll(((PredicateWrapper) other).mPredicates);
} else {
newPredicates.add(other);
}
newPredicates.add(CLOSE_PREDICATE);
return new PredicateWrapper(new OrPredicate(mPredicate, other), newPredicates);
}
/**
* Predicate implementation logically-ANDing the wrapped ones.
*
* @param the input data type.
*/
private static final class AndPredicate implements Predicate {
private final Predicate mOther;
private final Predicate mPredicate;
/**
* Constructor.
*
* @param predicate the wrapped predicate.
* @param other the other predicate to be logically-ANDed.
*/
private AndPredicate(@NotNull final Predicate predicate,
@NotNull final Predicate other) {
mPredicate = predicate;
mOther = other;
}
public boolean test(final IN in) {
return mPredicate.test(in) && mOther.test(in);
}
}
/**
* Class indicating a logical operation (like AND and OR).
*/
private static class LogicalPredicate implements Predicate