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A general programming library in Java/Android. It's easy to learn and simple to use with concise and powerful APIs.
/*
* Copyright (C) 2016 HaiYang Li
*
* 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.landawn.abacus.util;
import java.util.NoSuchElementException;
import java.util.function.BooleanSupplier;
import java.util.function.DoublePredicate;
import java.util.function.DoubleSupplier;
import java.util.function.Supplier;
import com.landawn.abacus.annotation.Beta;
import com.landawn.abacus.util.u.OptionalDouble;
import com.landawn.abacus.util.stream.DoubleStream;
/**
*
* @author Haiyang Li
* @since 0.8
*/
public abstract class DoubleIterator extends ImmutableIterator {
public static final DoubleIterator EMPTY = new DoubleIterator() {
@Override
public boolean hasNext() {
return false;
}
@Override
public double nextDouble() {
throw new NoSuchElementException();
}
};
/**
*
*
* @return
*/
public static DoubleIterator empty() {//NOSONAR
return EMPTY;
}
/**
*
* @param a
* @return
*/
@SafeVarargs
public static DoubleIterator of(final double... a) {
return N.isNullOrEmpty(a) ? EMPTY : of(a, 0, a.length);
}
/**
*
* @param a
* @param fromIndex
* @param toIndex
* @return
*/
public static DoubleIterator of(final double[] a, final int fromIndex, final int toIndex) {
N.checkFromToIndex(fromIndex, toIndex, a == null ? 0 : a.length);
if (fromIndex == toIndex) {
return EMPTY;
}
return new DoubleIterator() {
private int cursor = fromIndex;
@Override
public boolean hasNext() {
return cursor < toIndex;
}
@Override
public double nextDouble() {
if (cursor >= toIndex) {
throw new NoSuchElementException();
}
return a[cursor++];
}
@Override
public double[] toArray() {
return N.copyOfRange(a, cursor, toIndex);
}
@Override
public DoubleList toList() {
return DoubleList.of(N.copyOfRange(a, cursor, toIndex));
}
};
}
// /**
// * Lazy evaluation.
// *
// * @param arraySupplier
// * @return
// */
// public static DoubleIterator from(final Supplier arraySupplier) {
// N.checkArgNotNull(arraySupplier, "arraySupplier");
//
// return new DoubleIterator() {
// private double[] aar = null;
// private int len = 0;
// private int cur = 0;
// private boolean isInitialized = false;
//
// @Override
// public boolean hasNext() {
// if (!isInitialized) {
// init();
// }
//
// return cur < len;
// }
//
// @Override
// public double nextDouble() {
// if (!isInitialized) {
// init();
// }
//
// if (cur >= len) {
// throw new NoSuchElementException();
// }
//
// return aar[cur++];
// }
//
// private void init() {
// if (!isInitialized) {
// isInitialized = true;
// aar = arraySupplier.get();
// len = N.len(aar);
// }
// }
// };
// }
/**
* Lazy evaluation.
*
* @param iteratorSupplier
* @return
*/
public static DoubleIterator defer(final Supplier iteratorSupplier) {
N.checkArgNotNull(iteratorSupplier, "iteratorSupplier");
return new DoubleIterator() {
private DoubleIterator iter = null;
private boolean isInitialized = false;
@Override
public boolean hasNext() {
if (!isInitialized) {
init();
}
return iter.hasNext();
}
@Override
public double nextDouble() {
if (!isInitialized) {
init();
}
return iter.nextDouble();
}
private void init() {
if (!isInitialized) {
isInitialized = true;
iter = iteratorSupplier.get();
}
}
};
}
/**
* Returns an infinite {@code DoubleIterator}.
*
* @param supplier
* @return
*/
public static DoubleIterator generate(final DoubleSupplier supplier) {
N.checkArgNotNull(supplier);
return new DoubleIterator() {
@Override
public boolean hasNext() {
return true;
}
@Override
public double nextDouble() {
return supplier.getAsDouble();
}
};
}
/**
*
* @param hasNext
* @param supplier
* @return
*/
public static DoubleIterator generate(final BooleanSupplier hasNext, final DoubleSupplier supplier) {
N.checkArgNotNull(hasNext);
N.checkArgNotNull(supplier);
return new DoubleIterator() {
@Override
public boolean hasNext() {
return hasNext.getAsBoolean();
}
@Override
public double nextDouble() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return supplier.getAsDouble();
}
};
}
/**
*
* @return
* @deprecated use nextDouble() instead.
*/
@Deprecated
@Override
public Double next() {
return nextDouble();
}
/**
*
*
* @return
*/
public abstract double nextDouble();
/**
*
*
* @param n
* @return
*/
public DoubleIterator skip(final long n) {
N.checkArgNotNegative(n, "n");
if (n <= 0) {
return this;
}
final DoubleIterator iter = this;
return new DoubleIterator() {
private boolean skipped = false;
@Override
public boolean hasNext() {
if (!skipped) {
skip();
}
return iter.hasNext();
}
@Override
public double nextDouble() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return iter.nextDouble();
}
private void skip() {
long idx = 0;
while (idx++ < n && iter.hasNext()) {
iter.nextDouble();
}
skipped = true;
}
};
}
/**
*
*
* @param count
* @return
*/
public DoubleIterator limit(final long count) {
N.checkArgNotNegative(count, "count");
if (count == 0) {
return DoubleIterator.EMPTY;
}
final DoubleIterator iter = this;
return new DoubleIterator() {
private long cnt = count;
@Override
public boolean hasNext() {
return cnt > 0 && iter.hasNext();
}
@Override
public double nextDouble() {
if (!hasNext()) {
throw new NoSuchElementException();
}
cnt--;
return iter.nextDouble();
}
};
}
/**
*
*
* @param predicate
* @return
*/
public DoubleIterator filter(final DoublePredicate predicate) {
N.checkArgNotNull(predicate, "predicate");
final DoubleIterator iter = this;
return new DoubleIterator() {
private boolean hasNext = false;
private double next = 0;
@Override
public boolean hasNext() {
if (!hasNext) {
while (iter.hasNext()) {
next = iter.nextDouble();
if (predicate.test(next)) {
hasNext = true;
break;
}
}
}
return hasNext;
}
@Override
public double nextDouble() {
if (!hasNext && !hasNext()) {
throw new NoSuchElementException();
}
hasNext = false;
return next;
}
};
}
/**
*
*
* @return
*/
public OptionalDouble first() {
if (hasNext()) {
return OptionalDouble.of(nextDouble());
} else {
return OptionalDouble.empty();
}
}
/**
*
*
* @return
*/
public OptionalDouble last() {
if (hasNext()) {
double next = nextDouble();
while (hasNext()) {
next = nextDouble();
}
return OptionalDouble.of(next);
} else {
return OptionalDouble.empty();
}
}
/**
*
*
* @return
*/
public double[] toArray() {
return toList().trimToSize().array();
}
/**
*
*
* @return
*/
public DoubleList toList() {
final DoubleList list = new DoubleList();
while (hasNext()) {
list.add(nextDouble());
}
return list;
}
/**
*
*
* @return
*/
public DoubleStream stream() {
return DoubleStream.of(this);
}
/**
*
*
* @return
*/
@Beta
public ObjIterator indexed() {
return indexed(0);
}
/**
*
*
* @param startIndex
* @return
*/
@Beta
public ObjIterator indexed(final long startIndex) {
if (startIndex < 0) {
throw new IllegalArgumentException("Invalid start index: " + startIndex);
}
final DoubleIterator iter = this;
return new ObjIterator<>() {
private long idx = startIndex;
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public IndexedDouble next() {
return IndexedDouble.of(iter.nextDouble(), idx++);
}
};
}
/**
*
*
* @param action
* @deprecated
*/
@Override
@Deprecated
public void forEachRemaining(java.util.function.Consumer action) {
super.forEachRemaining(action);
}
/**
*
*
* @param
* @param action
* @throws E
*/
public void foreachRemaining(Throwables.DoubleConsumer action) throws E {//NOSONAR
N.checkArgNotNull(action);
while (hasNext()) {
action.accept(nextDouble());
}
}
/**
*
*
* @param
* @param action
* @throws E
*/
public void foreachIndexed(Throwables.IndexedDoubleConsumer action) throws E {
N.checkArgNotNull(action);
int idx = 0;
while (hasNext()) {
action.accept(idx++, nextDouble());
}
}
}