src.org.python.core.buffer.SimpleNIOBuffer Maven / Gradle / Ivy
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package org.python.core.buffer;
import java.nio.ByteBuffer;
import org.python.core.BufferProtocol;
import org.python.core.PyBuffer;
import org.python.core.PyException;
/**
* Buffer API over a read-only one-dimensional java.nio.ByteBuffer of one-byte items.
*/
public class SimpleNIOBuffer extends BaseNIOBuffer {
/**
* Provide an instance of SimpleNIOBuffer with navigation variables initialised,
* for sub-class use. The buffer ({@link #storage}, {@link #index0}), and the {@link #shape}
* array will be initialised from the arguments (which are checked for range). The
* {@link #strides} is set for (one-byte) unit stride. Only the call to
* {@link #checkRequestFlags(int)}, passing the consumer's request flags, really remains for the
* sub-class constructor to do.
*
*
* super(storage.duplicate(), index0, size);
* checkRequestFlags(flags); // Check request is compatible with type
*
*
* @param obj exporting object (or null)
* @param storage the ByteBuffer wrapping the exported object state. NOTE: this
* PyBuffer keeps a reference and may manipulate the position, mark and
* limit hereafter. Use {@link ByteBuffer#duplicate()} to give it an isolated copy.
* @param index0 offset where the data starts in that array (item[0])
* @param size the number of bytes occupied
* @throws NullPointerException if storage is null
* @throws ArrayIndexOutOfBoundsException if index0 and size are
* inconsistent with storage.capacity()
*/
protected SimpleNIOBuffer(BufferProtocol obj, ByteBuffer storage, int index0, int size)
throws PyException, ArrayIndexOutOfBoundsException {
super(storage, CONTIGUITY | SIMPLE, index0, size, 1);
this.obj = obj;
// Check arguments using the "all non-negative" trick
if ((index0 | size | storage.capacity() - (index0 + size)) < 0) {
throw new ArrayIndexOutOfBoundsException();
}
}
/**
* Provide an instance of SimpleNIOBuffer, on a slice of a {@link ByteBuffer},
* meeting the consumer's expectations as expressed in the flags argument, which is
* checked against the capabilities of the buffer type. No reference will be kept to the
* ByteBuffer passed in. (It is duplicated.)
*
* @param flags consumer requirements
* @param obj exporting object (or null)
* @param storage the ByteBuffer wrapping the exported object state
* @param index0 offset where the data starts in that buffer (item[0])
* @param size the number of bytes occupied
* @throws NullPointerException if storage is null
* @throws ArrayIndexOutOfBoundsException if index0 and size are
* inconsistent with storage.length
* @throws PyException {@code BufferError} when expectations do not correspond with the type
*/
public SimpleNIOBuffer(int flags, BufferProtocol obj, ByteBuffer storage, int index0, int size)
throws PyException, ArrayIndexOutOfBoundsException, NullPointerException {
this(obj, storage.duplicate(), index0, size); // Construct checked SimpleNIOBuffer
checkRequestFlags(flags); // Check request is compatible with type
}
/**
* Provide an instance of SimpleNIOBuffer, on the entirety of a {@link ByteBuffer},
* with navigation variables initialised, for sub-class use. The buffer ( {@link #storage},
* {@link #index0}), and the navigation ({@link #shape} array) will be initialised from the
* argument.
*
* @param obj exporting object (or null)
* @param storage the ByteBuffer wrapping the exported object state. NOTE: this
* PyBuffer keeps a reference and may manipulate the position, mark and
* limit hereafter. Use {@link ByteBuffer#duplicate()} to give it an isolated copy.
* @throws NullPointerException if storage is null
*/
protected SimpleNIOBuffer(BufferProtocol obj, ByteBuffer storage) throws NullPointerException {
this(obj, storage, 0, storage.capacity());
}
/**
* Provide an instance of SimpleNIOBuffer, on the entirety of a {@link ByteBuffer},
* meeting the consumer's expectations as expressed in the flags argument, which is
* checked against the capabilities of the buffer type. No reference will be kept to the
* ByteBuffer passed in. (It is duplicated.)
*
* @param flags consumer requirements
* @param obj exporting object (or null)
* @param storage the ByteBuffer wrapping the exported object state
* @throws NullPointerException if storage is null
* @throws PyException {@code BufferError} when expectations do not correspond with the type
*/
public SimpleNIOBuffer(int flags, BufferProtocol obj, ByteBuffer storage) throws PyException,
NullPointerException {
this(obj, storage.duplicate()); // Construct SimpleNIOBuffer on whole ByteBuffer
checkRequestFlags(flags); // Check request is compatible with type
}
/**
* {@inheritDoc}
*
* SimpleNIOBuffer provides an implementation optimised for contiguous bytes in
* one-dimension.
*/
@Override
public int getLen() {
// Simplify for one-dimensional contiguous bytes
return shape[0];
}
@Override
public final int byteIndex(int index) throws IndexOutOfBoundsException {
return index0 + index;
}
// XXX Consider moving to clauses in getBufferSlice(int, int, int, int)
// to avoid delegation loop where that delegates to this but in BaseBuffer the reverse.
@Override
public PyBuffer getBufferSlice(int flags, int start, int count) {
if (count > 0) {
// Translate relative to underlying buffer
int compIndex0 = index0 + start;
// Create the slice from the sub-range of the buffer
return new SimpleView(getRoot(), flags, storage, compIndex0, count);
} else {
// Special case for count==0 where above logic would fail. Efficient too.
return new ZeroByteBuffer.View(getRoot(), flags);
}
}
/**
* {@inheritDoc}
*
* SimpleNIOBuffer provides an implementation for slicing contiguous bytes in one
* dimension. In that case, x(i) = u(r+i) for i = 0..L-1 where u is the underlying
* buffer, and r and L are the start and count with which x was created
* from u. Thus y(k) = u(r+s+km), that is, the composite offset is r+s and
* the stride is m.
*/
@Override
public PyBuffer getBufferSlice(int flags, int start, int count, int stride) {
if (stride == 1 || count < 2) {
// Unstrided slice of simple buffer is special case
return getBufferSlice(flags, start, count);
} else {
// Translate relative to underlying buffer
int compIndex0 = index0 + start;
// Construct a view, taking a lock on the root object (this or this.root)
return new Strided1DNIOBuffer.SlicedView(getRoot(), flags, storage, compIndex0, count,
stride);
}
}
/**
* A SimpleNIOBuffer.SimpleView represents a contiguous subsequence of another
* SimpleNIOBuffer.
*/
static class SimpleView extends SimpleNIOBuffer {
/** The buffer on which this is a slice view */
PyBuffer root;
/**
* Construct a slice of a SimpleNIOBuffer.
*
* @param root buffer which will be acquired and must be released ultimately
* @param flags the request flags of the consumer that requested the slice
* @param storage ByteBuffer wrapping exported data (no reference kept)
* @param offset where the data starts in that buffer (item[0])
* @param count the number of items in the sliced view
*/
public SimpleView(PyBuffer root, int flags, ByteBuffer storage, int offset, int count) {
// Create a new SimpleNIOBuffer on the buffer passed in (part of the root)
super(flags, root.getObj(), storage, offset, count);
// Get a lease on the root PyBuffer
this.root = root.getBuffer(FULL_RO);
}
@Override
protected PyBuffer getRoot() {
return root;
}
}
}