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Math functions for BigDecimal.
package ch.obermuhlner.math.big.stream;
import java.util.Comparator;
import java.util.Spliterator;
import java.util.Spliterators.AbstractSpliterator;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import ch.obermuhlner.math.big.BigFloat;
import ch.obermuhlner.math.big.BigFloat.Context;
/**
* Provides constructor methods for streams of {@link BigFloat} elements.
*/
public class BigFloatStream {
/**
* Returns a sequential ordered {@code Stream} from {@code startInclusive}
* (inclusive) to {@code endExclusive} (exclusive) by an incremental {@code step}.
*
* An equivalent sequence of increasing values can be produced
* sequentially using a {@code for} loop as follows:
*
for (BigFloat i = startInclusive; i.isLessThan(endExclusive); i = i.add(step)) {
// ...
}
*
* @param startInclusive the (inclusive) initial value
* @param endExclusive the exclusive upper bound
* @param step the step between elements
* @return a sequential {@code Stream}
*/
public static Stream range(BigFloat startInclusive, BigFloat endExclusive, BigFloat step) {
if (step.isZero()) {
throw new IllegalArgumentException("invalid step: 0");
}
if (endExclusive.subtract(startInclusive).signum() != step.signum()) {
return Stream.empty();
}
return StreamSupport.stream(new BigFloatSpliterator(startInclusive, endExclusive, false, step), false);
}
/**
* Returns a sequential ordered {@code Stream} from {@code startInclusive}
* (inclusive) to {@code endExclusive} (exclusive) by an incremental {@code step}.
*
* {@link Context#valueOf(long)} is used to convert the {@code long} values.
*
* @param startInclusive the (inclusive) initial value
* @param endExclusive the exclusive upper bound
* @param step the step between elements
* @param context the {@link Context} used to convert the {@code long} values
* @return a sequential {@code Stream}
* @see #range(BigFloat, BigFloat, BigFloat)
*/
public static Stream range(long startInclusive, long endExclusive, long step, Context context) {
return range(context.valueOf(startInclusive), context.valueOf(endExclusive), context.valueOf(step));
}
/**
* Returns a sequential ordered {@code Stream} from {@code startInclusive}
* (inclusive) to {@code endExclusive} (exclusive) by an incremental {@code step}.
*
* {@link Context#valueOf(double)} is used to convert the {@code double} values.
*
* @param startInclusive the (inclusive) initial value
* @param endExclusive the exclusive upper bound
* @param step the step between elements
* @param context the {@link Context} used to convert the {@code double} values
* @return a sequential {@code Stream}
* @see #range(BigFloat, BigFloat, BigFloat)
*/
public static Stream range(double startInclusive, double endExclusive, double step, Context context) {
return range(context.valueOf(startInclusive), context.valueOf(endExclusive), context.valueOf(step));
}
/**
* Returns a sequential ordered {@code Stream} from {@code startInclusive}
* (inclusive) to {@code endInclusive} (inclusive) by an incremental {@code step}.
*
* An equivalent sequence of increasing values can be produced
* sequentially using a {@code for} loop as follows:
*
for (BigFloat i = startInclusive; i.isLessThanOrEqual(endInclusive); i = i.add(step)) {
//...
}
*
* @param startInclusive the (inclusive) initial value
* @param endInclusive the inclusive upper bound
* @param step the step between elements
* @return a sequential {@code Stream}
*/
public static Stream rangeClosed(BigFloat startInclusive, BigFloat endInclusive, BigFloat step) {
if (step.isZero()) {
throw new IllegalArgumentException("invalid step: 0");
}
if (endInclusive.subtract(startInclusive).signum() == -step.signum()) {
return Stream.empty();
}
return StreamSupport.stream(new BigFloatSpliterator(startInclusive, endInclusive, true, step), false);
}
/**
* Returns a sequential ordered {@code Stream} from {@code startInclusive}
* (inclusive) to {@code endInclusive} (inclusive) by an incremental {@code step}.
*
* {@link Context#valueOf(long)} is used to convert the {@code long} values.
*
* @param startInclusive the (inclusive) initial value
* @param endInclusive the inclusive upper bound
* @param step the step between elements
* @param context the {@link Context} used to convert the {@code long} values
* @return a sequential {@code Stream}
* @see #rangeClosed(BigFloat, BigFloat, BigFloat)
*/
public static Stream rangeClosed(long startInclusive, long endInclusive, long step, Context context) {
return rangeClosed(context.valueOf(startInclusive), context.valueOf(endInclusive), context.valueOf(step));
}
/**
* Returns a sequential ordered {@code Stream} from {@code startInclusive}
* (inclusive) to {@code endInclusive} (inclusive) by an incremental {@code step}.
*
* {@link Context#valueOf(double)} is used to convert the {@code double} values.
*
* @param startInclusive the (inclusive) initial value
* @param endInclusive the inclusive upper bound
* @param step the step between elements
* @param context the {@link Context} used to convert the {@code double} values
* @return a sequential {@code Stream}
* @see #rangeClosed(BigFloat, BigFloat, BigFloat)
*/
public static Stream rangeClosed(double startInclusive, double endInclusive, double step, Context context) {
return rangeClosed(context.valueOf(startInclusive), context.valueOf(endInclusive), context.valueOf(step));
}
private static class BigFloatSpliterator extends AbstractSpliterator {
private BigFloat value;
private BigFloat step;
private long count;
public BigFloatSpliterator(BigFloat startInclusive, BigFloat step, long count) {
super(count,
Spliterator.SIZED | Spliterator.SUBSIZED | Spliterator.DISTINCT | Spliterator.IMMUTABLE | Spliterator.NONNULL | Spliterator.ORDERED | Spliterator.SORTED);
this.value = startInclusive;
this.step = step;
this.count = count;
}
public BigFloatSpliterator(BigFloat startInclusive, BigFloat end, boolean inclusive, BigFloat step) {
this(startInclusive, step, estimatedCount(startInclusive, end, inclusive, step));
}
private static long estimatedCount(BigFloat startInclusive, BigFloat end, boolean inclusive, BigFloat step) {
BigFloat count = end.subtract(startInclusive).divide(step);
long result = count.toLong();
if (count.getFractionalPart().signum() != 0) {
result++;
} else {
if (inclusive) {
result++;
}
}
return result;
}
@Override
public Comparator getComparator() {
if (step.signum() < 0) {
return Comparator.reverseOrder();
}
return null;
}
@Override
public boolean tryAdvance(Consumer action) {
if (count == 0) {
return false;
}
action.accept(value);
value = value.add(step);
count--;
return true;
}
@Override
public void forEachRemaining(Consumer action) {
while (count > 0) {
action.accept(value);
value = value.add(step);
count--;
}
}
@Override
public Spliterator trySplit() {
long firstHalfCount = count / 2;
if (firstHalfCount == 0) {
return null;
}
long secondHalfCount = count - firstHalfCount;
count = firstHalfCount;
BigFloat startSecondHalf = value.add(step.multiply(firstHalfCount));
return new BigFloatSpliterator(startSecondHalf, step, secondHalfCount);
}
}
}