AllocatedBuffer.java
// Protocol Buffers - Google's data interchange format
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package com.google.protobuf;
import static com.google.protobuf.Internal.checkNotNull;
import java.nio.ByteBuffer;
/**
* A buffer that was allocated by a {@link BufferAllocator}. For every buffer, it is guaranteed that
* at least one of {@link #hasArray()} or {@link #hasNioBuffer()} will be {@code true}.
*/
@ExperimentalApi
abstract class AllocatedBuffer {
/**
* Indicates whether this buffer contains a backing {@link ByteBuffer} (i.e. it is safe to call
* {@link #nioBuffer()}).
*/
public abstract boolean hasNioBuffer();
/**
* Indicates whether this buffer contains a backing array (i.e. it is safe to call {@link
* #array()}).
*/
public abstract boolean hasArray();
/**
* Returns the {@link ByteBuffer} that backs this buffer <i>(optional operation)</i>.
*
* <p>Call {@link #hasNioBuffer()} before invoking this method in order to ensure that this buffer
* has a backing {@link ByteBuffer}.
*
* @return The {@link ByteBuffer} that backs this buffer
* @throws UnsupportedOperationException If this buffer is not backed by a {@link ByteBuffer}.
*/
public abstract ByteBuffer nioBuffer();
/**
* Returns the byte array that backs this buffer <i>(optional operation)</i>.
*
* <p>Call {@link #hasArray()} before invoking this method in order to ensure that this buffer has
* an accessible backing array.
*
* @return The array that backs this buffer
* @throws java.nio.ReadOnlyBufferException If this buffer is backed by an array but is read-only
* @throws UnsupportedOperationException If this buffer is not backed by an accessible array
*/
public abstract byte[] array();
/**
* Returns the offset within this buffer's backing array of the first element of the buffer
* <i>(optional operation)</i>.
*
* <p>If this buffer is backed by an array then {@link #position()} corresponds to the array index
* {@link #position()} {@code +} {@link #arrayOffset()}.
*
* <p>Invoke the {@link #hasArray hasArray} method before invoking this method in order to ensure
* that this buffer has an accessible backing array.
*
* @return The offset within this buffer's array of the first element of the buffer
* @throws java.nio.ReadOnlyBufferException If this buffer is backed by an array but is read-only
* @throws UnsupportedOperationException If this buffer is not backed by an accessible array
*/
public abstract int arrayOffset();
/**
* Returns this buffer's position.
*
* @return The position of this buffer
*/
public abstract int position();
/**
* Sets this buffer's position.
*
* @param position The new position value; must be non-negative and no larger than the current
* limit
* @return This buffer
* @throws IllegalArgumentException If the preconditions on {@code position} do not hold
*/
public abstract AllocatedBuffer position(int position);
/**
* Returns this buffer's limit.
*
* @return The limit of this buffer
*/
public abstract int limit();
/**
* Returns the number of elements between the current {@link #position()} and the {@link #limit()}
* .
*
* @return The number of elements remaining in this buffer
*/
public abstract int remaining();
/**
* Creates a new {@link AllocatedBuffer} that is backed by the given array. The returned buffer
* will have {@link #hasArray} == {@code true}, {@link #arrayOffset()} == {@code 0}, {@link
* #position()} == {@code 0} and {@link #limit()} equal to the length of {@code bytes}.
*/
public static AllocatedBuffer wrap(byte[] bytes) {
return wrapNoCheck(bytes, 0, bytes.length);
}
/**
* Creates a new {@link AllocatedBuffer} that is backed by the given array. The returned buffer
* will have {@link #hasArray} == {@code true}, {@link #arrayOffset()} == {@code offset}, {@link
* #position()} == {@code 0} and {@link #limit()} == {@code length}.
*/
public static AllocatedBuffer wrap(final byte[] bytes, final int offset, final int length) {
if (offset < 0 || length < 0 || (offset + length) > bytes.length) {
throw new IndexOutOfBoundsException(
String.format("bytes.length=%d, offset=%d, length=%d", bytes.length, offset, length));
}
return wrapNoCheck(bytes, offset, length);
}
/**
* Creates a new {@link AllocatedBuffer} that is backed by the given {@link ByteBuffer}. The
* returned buffer will have {@link #hasNioBuffer} == {@code true}.
*/
public static AllocatedBuffer wrap(final ByteBuffer buffer) {
checkNotNull(buffer, "buffer");
return new AllocatedBuffer() {
@Override
public boolean hasNioBuffer() {
return true;
}
@Override
public ByteBuffer nioBuffer() {
return buffer;
}
@Override
public boolean hasArray() {
return buffer.hasArray();
}
@Override
public byte[] array() {
return buffer.array();
}
@Override
public int arrayOffset() {
return buffer.arrayOffset();
}
@Override
public int position() {
return buffer.position();
}
@Override
public AllocatedBuffer position(int position) {
buffer.position(position);
return this;
}
@Override
public int limit() {
return buffer.limit();
}
@Override
public int remaining() {
return buffer.remaining();
}
};
}
private static AllocatedBuffer wrapNoCheck(
final byte[] bytes, final int offset, final int length) {
return new AllocatedBuffer() {
// Relative to offset.
private int position;
@Override
public boolean hasNioBuffer() {
return false;
}
@Override
public ByteBuffer nioBuffer() {
throw new UnsupportedOperationException();
}
@Override
public boolean hasArray() {
return true;
}
@Override
public byte[] array() {
return bytes;
}
@Override
public int arrayOffset() {
return offset;
}
@Override
public int position() {
return position;
}
@Override
public AllocatedBuffer position(int position) {
if (position < 0 || position > length) {
throw new IllegalArgumentException("Invalid position: " + position);
}
this.position = position;
return this;
}
@Override
public int limit() {
// Relative to offset.
return length;
}
@Override
public int remaining() {
return length - position;
}
};
}
}