/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.nio;
import java.util.Arrays;
/**
* A buffer of doubles.
* <p>
* A double buffer can be created in either one of the following ways:
* <ul>
* <li>{@link #allocate(int) Allocate} a new double array and create a buffer
* based on it;</li>
* <li>{@link #wrap(double[]) Wrap} an existing double array to create a new
* buffer;</li>
* <li>Use
* {@link java.nio.ByteBuffer#asDoubleBuffer() ByteBuffer.asDoubleBuffer} to
* create a double buffer based on a byte buffer.</li>
* </ul>
*/
public abstract class DoubleBuffer extends Buffer implements
Comparable<DoubleBuffer> {
/**
* Creates a double buffer based on a newly allocated double array.
*
* @param capacity
* the capacity of the new buffer.
* @return the created double buffer.
* @throws IllegalArgumentException
* if {@code capacity} is less than zero.
*/
public static DoubleBuffer allocate(int capacity) {
if (capacity < 0) {
throw new IllegalArgumentException("capacity < 0: " + capacity);
}
return new ReadWriteDoubleArrayBuffer(capacity);
}
/**
* Creates a new double buffer by wrapping the given double array.
* <p>
* Calling this method has the same effect as
* {@code wrap(array, 0, array.length)}.
*
* @param array
* the double array which the new buffer will be based on.
* @return the created double buffer.
*/
public static DoubleBuffer wrap(double[] array) {
return wrap(array, 0, array.length);
}
/**
* Creates a new double buffer by wrapping the given double array.
* <p>
* The new buffer's position will be {@code start}, limit will be
* {@code start + doubleCount}, capacity will be the length of the array.
*
* @param array
* the double array which the new buffer will be based on.
* @param start
* the start index, must not be negative and not greater than
* {@code array.length}.
* @param doubleCount
* the length, must not be negative and not greater than
* {@code array.length - start}.
* @return the created double buffer.
* @exception IndexOutOfBoundsException
* if either {@code start} or {@code doubleCount} is invalid.
*/
public static DoubleBuffer wrap(double[] array, int start, int doubleCount) {
Arrays.checkOffsetAndCount(array.length, start, doubleCount);
DoubleBuffer buf = new ReadWriteDoubleArrayBuffer(array);
buf.position = start;
buf.limit = start + doubleCount;
return buf;
}
DoubleBuffer(int capacity) {
super(3, capacity, null);
}
public final double[] array() {
return protectedArray();
}
public final int arrayOffset() {
return protectedArrayOffset();
}
/**
* Returns a read-only buffer that shares its content with this buffer.
* <p>
* The returned buffer is guaranteed to be a new instance, even if this
* buffer is read-only itself. The new buffer's position, limit, capacity
* and mark are the same as this buffer's.
* <p>
* The new buffer shares its content with this buffer, which means that this
* buffer's change of content will be visible to the new buffer. The two
* buffer's position, limit and mark are independent.
*
* @return a read-only version of this buffer.
*/
public abstract DoubleBuffer asReadOnlyBuffer();
/**
* Compacts this double buffer.
* <p>
* The remaining doubles will be moved to the head of the buffer, staring
* from position zero. Then the position is set to {@code remaining()}; the
* limit is set to capacity; the mark is cleared.
*
* @return this buffer.
* @exception ReadOnlyBufferException
* if no changes may be made to the contents of this buffer.
*/
public abstract DoubleBuffer compact();
/**
* Compare the remaining doubles of this buffer to another double buffer's
* remaining doubles.
*
* @param otherBuffer
* another double buffer.
* @return a negative value if this is less than {@code other}; 0 if this
* equals to {@code other}; a positive value if this is greater
* than {@code other}.
* @exception ClassCastException
* if {@code other} is not a double buffer.
*/
public int compareTo(DoubleBuffer otherBuffer) {
int compareRemaining = (remaining() < otherBuffer.remaining()) ? remaining()
: otherBuffer.remaining();
int thisPos = position;
int otherPos = otherBuffer.position;
double thisDouble, otherDouble;
while (compareRemaining > 0) {
thisDouble = get(thisPos);
otherDouble = otherBuffer.get(otherPos);
// checks for double and NaN inequality
if ((thisDouble != otherDouble)
&& ((thisDouble == thisDouble) || (otherDouble == otherDouble))) {
return thisDouble < otherDouble ? -1 : 1;
}
thisPos++;
otherPos++;
compareRemaining--;
}
return remaining() - otherBuffer.remaining();
}
/**
* Returns a duplicated buffer that shares its content with this buffer.
* <p>
* The duplicated buffer's position, limit, capacity and mark are the same
* as this buffer's. The duplicated buffer's read-only property and byte
* order are the same as this buffer's, too.
* <p>
* The new buffer shares its content with this buffer, which means either
* buffer's change of content will be visible to the other. The two buffer's
* position, limit and mark are independent.
*
* @return a duplicated buffer that shares its content with this buffer.
*/
public abstract DoubleBuffer duplicate();
/**
* Checks whether this double buffer is equal to another object. If {@code
* other} is not a {@code DoubleBuffer} then {@code false} is returned.
*
* <p>Two double buffers are equal if their remaining doubles are equal.
* Position, limit, capacity and mark are not considered.
*
* <p>This method considers two doubles {@code a} and {@code b} to be equal
* if {@code a == b} or if {@code a} and {@code b} are both {@code NaN}.
* Unlike {@link Double#equals}, this method considers {@code -0.0} and
* {@code +0.0} to be equal.
*
* @param other
* the object to compare with this double buffer.
* @return {@code true} if this double buffer is equal to {@code other},
* {@code false} otherwise.
*/
@Override
public boolean equals(Object other) {
if (!(other instanceof DoubleBuffer)) {
return false;
}
DoubleBuffer otherBuffer = (DoubleBuffer) other;
if (remaining() != otherBuffer.remaining()) {
return false;
}
int myPosition = position;
int otherPosition = otherBuffer.position;
boolean equalSoFar = true;
while (equalSoFar && (myPosition < limit)) {
double a = get(myPosition++);
double b = otherBuffer.get(otherPosition++);
equalSoFar = a == b || (a != a && b != b);
}
return equalSoFar;
}
/**
* Returns the double at the current position and increases the position by
* 1.
*
* @return the double at the current position.
* @exception BufferUnderflowException
* if the position is equal or greater than limit.
*/
public abstract double get();
/**
* Reads doubles from the current position into the specified double array
* and increases the position by the number of doubles read.
* <p>
* Calling this method has the same effect as
* {@code get(dst, 0, dst.length)}.
*
* @param dst
* the destination double array.
* @return this buffer.
* @exception BufferUnderflowException
* if {@code dst.length} is greater than {@code remaining()}.
*/
public DoubleBuffer get(double[] dst) {
return get(dst, 0, dst.length);
}
/**
* Reads doubles from the current position into the specified double array,
* starting from the specified offset, and increases the position by the
* number of doubles read.
*
* @param dst
* the target double array.
* @param dstOffset
* the offset of the double array, must not be negative and not
* greater than {@code dst.length}.
* @param doubleCount
* the number of doubles to read, must be no less than zero and
* not greater than {@code dst.length - dstOffset}.
* @return this buffer.
* @exception IndexOutOfBoundsException
* if either {@code dstOffset} or {@code doubleCount} is invalid.
* @exception BufferUnderflowException
* if {@code doubleCount} is greater than {@code remaining()}.
*/
public DoubleBuffer get(double[] dst, int dstOffset, int doubleCount) {
Arrays.checkOffsetAndCount(dst.length, dstOffset, doubleCount);
if (doubleCount > remaining()) {
throw new BufferUnderflowException();
}
for (int i = dstOffset; i < dstOffset + doubleCount; ++i) {
dst[i] = get();
}
return this;
}
/**
* Returns a double at the specified index; the position is not changed.
*
* @param index
* the index, must not be negative and less than limit.
* @return a double at the specified index.
* @exception IndexOutOfBoundsException
* if index is invalid.
*/
public abstract double get(int index);
public final boolean hasArray() {
return protectedHasArray();
}
/**
* Calculates this buffer's hash code from the remaining chars. The
* position, limit, capacity and mark don't affect the hash code.
*
* @return the hash code calculated from the remaining chars.
*/
@Override
public int hashCode() {
int myPosition = position;
int hash = 0;
long l;
while (myPosition < limit) {
l = Double.doubleToLongBits(get(myPosition++));
hash = hash + ((int) l) ^ ((int) (l >> 32));
}
return hash;
}
/**
* Indicates whether this buffer is direct. A direct buffer will try its
* best to take advantage of native memory APIs and it may not stay in the
* Java heap, so it is not affected by garbage collection.
* <p>
* A double buffer is direct if it is based on a byte buffer and the byte
* buffer is direct.
*
* @return {@code true} if this buffer is direct, {@code false} otherwise.
*/
public abstract boolean isDirect();
/**
* Returns the byte order used by this buffer when converting doubles
* from/to bytes.
* <p>
* If this buffer is not based on a byte buffer, then this always returns
* the platform's native byte order.
*
* @return the byte order used by this buffer when converting doubles
* from/to bytes.
*/
public abstract ByteOrder order();
/**
* Child class implements this method to realize {@code array()}.
*
* @see #array()
*/
abstract double[] protectedArray();
/**
* Child class implements this method to realize {@code arrayOffset()}.
*
* @see #arrayOffset()
*/
abstract int protectedArrayOffset();
/**
* Child class implements this method to realize {@code hasArray()}.
*
* @see #hasArray()
*/
abstract boolean protectedHasArray();
/**
* Writes the given double to the current position and increases the
* position by 1.
*
* @param d
* the double to write.
* @return this buffer.
* @exception BufferOverflowException
* if position is equal or greater than limit.
* @exception ReadOnlyBufferException
* if no changes may be made to the contents of this buffer.
*/
public abstract DoubleBuffer put(double d);
/**
* Writes doubles from the given double array to the current position and
* increases the position by the number of doubles written.
* <p>
* Calling this method has the same effect as
* {@code put(src, 0, src.length)}.
*
* @param src
* the source double array.
* @return this buffer.
* @exception BufferOverflowException
* if {@code remaining()} is less than {@code src.length}.
* @exception ReadOnlyBufferException
* if no changes may be made to the contents of this buffer.
*/
public final DoubleBuffer put(double[] src) {
return put(src, 0, src.length);
}
/**
* Writes doubles from the given double array, starting from the specified
* offset, to the current position and increases the position by the number
* of doubles written.
*
* @param src
* the source double array.
* @param srcOffset
* the offset of double array, must not be negative and not
* greater than {@code src.length}.
* @param doubleCount
* the number of doubles to write, must be no less than zero and
* not greater than {@code src.length - srcOffset}.
* @return this buffer.
* @exception BufferOverflowException
* if {@code remaining()} is less than {@code doubleCount}.
* @exception IndexOutOfBoundsException
* if either {@code srcOffset} or {@code doubleCount} is invalid.
* @exception ReadOnlyBufferException
* if no changes may be made to the contents of this buffer.
*/
public DoubleBuffer put(double[] src, int srcOffset, int doubleCount) {
Arrays.checkOffsetAndCount(src.length, srcOffset, doubleCount);
if (doubleCount > remaining()) {
throw new BufferOverflowException();
}
for (int i = srcOffset; i < srcOffset + doubleCount; ++i) {
put(src[i]);
}
return this;
}
/**
* Writes all the remaining doubles of the {@code src} double buffer to this
* buffer's current position, and increases both buffers' position by the
* number of doubles copied.
*
* @param src
* the source double buffer.
* @return this buffer.
* @exception BufferOverflowException
* if {@code src.remaining()} is greater than this buffer's
* {@code remaining()}.
* @exception IllegalArgumentException
* if {@code src} is this buffer.
* @exception ReadOnlyBufferException
* if no changes may be made to the contents of this buffer.
*/
public DoubleBuffer put(DoubleBuffer src) {
if (src == this) {
throw new IllegalArgumentException("src == this");
}
if (src.remaining() > remaining()) {
throw new BufferOverflowException();
}
double[] doubles = new double[src.remaining()];
src.get(doubles);
put(doubles);
return this;
}
/**
* Write a double to the specified index of this buffer and the position is
* not changed.
*
* @param index
* the index, must not be negative and less than the limit.
* @param d
* the double to write.
* @return this buffer.
* @exception IndexOutOfBoundsException
* if index is invalid.
* @exception ReadOnlyBufferException
* if no changes may be made to the contents of this buffer.
*/
public abstract DoubleBuffer put(int index, double d);
/**
* Returns a sliced buffer that shares its content with this buffer.
* <p>
* The sliced buffer's capacity will be this buffer's {@code remaining()},
* and its zero position will correspond to this buffer's current position.
* The new buffer's position will be 0, limit will be its capacity, and its
* mark is cleared. The new buffer's read-only property and byte order are
* the same as this buffer's.
* <p>
* The new buffer shares its content with this buffer, which means either
* buffer's change of content will be visible to the other. The two buffer's
* position, limit and mark are independent.
*
* @return a sliced buffer that shares its content with this buffer.
*/
public abstract DoubleBuffer slice();
}