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SimpleBuffer.java
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package org.python.core.buffer;
import org.python.core.BufferProtocol;
import org.python.core.PyBuffer;
import org.python.core.PyException;
import org.python.core.util.StringUtil;
/**
* Buffer API over a read-only one-dimensional array of one-byte items.
*/
public class SimpleBuffer extends BaseArrayBuffer {
/**
* Provide an instance of <code>SimpleBuffer</code> 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 not checked for range). The
* {@link #strides} is set for a one-byte stride. Only the call to
* {@link #checkRequestFlags(int)}, passing the consumer's request flags really remains for the
* sub-class constructor to do.
*
* <pre>
* super(storage, index0, size);
* checkRequestFlags(flags); // Check request is compatible with type
* </pre>
*
* @param obj exporting object (or <code>null</code>)
* @param storage the array of bytes storing the implementation of the exporting object
* @param index0 offset where the data starts in that array (item[0])
* @param size the number of bytes occupied
* @throws NullPointerException if <code>storage</code> is null
*/
protected SimpleBuffer(BufferProtocol obj, byte[] storage, int index0, int size)
throws PyException, ArrayIndexOutOfBoundsException {
super(storage, CONTIGUITY | SIMPLE, index0, size, 1);
this.obj = obj;
}
/**
* Provide an instance of <code>SimpleBuffer</code>, on a slice of a byte array, meeting the
* consumer's expectations as expressed in the <code>flags</code> argument, which is checked
* against the capabilities of the buffer type.
*
* @param flags consumer requirements
* @param obj exporting object (or <code>null</code>)
* @param storage the array of bytes storing the implementation of the exporting object
* @param index0 offset where the data starts in that array (item[0])
* @param size the number of bytes occupied
* @throws NullPointerException if <code>storage</code> is null
* @throws ArrayIndexOutOfBoundsException if <code>index0</code> and <code>size</code> are
* inconsistent with <code>storage.length</code>
* @throws PyException {@code BufferError} when expectations do not correspond with the type
*/
public SimpleBuffer(int flags, BufferProtocol obj, byte[] storage, int index0, int size)
throws PyException, ArrayIndexOutOfBoundsException, NullPointerException {
this(obj, storage, index0, size); // Construct checked SimpleBuffer
checkRequestFlags(flags); // Check request is compatible with type
// Check arguments using the "all non-negative" trick
if ((index0 | size | storage.length - (index0 + size)) < 0) {
throw new ArrayIndexOutOfBoundsException();
}
}
/**
* Provide an instance of <code>SimpleBuffer</code>, on the entirety of a byte array, 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
* array argument.
*
* @param obj exporting object (or <code>null</code>)
* @param storage the array of bytes storing the implementation of the exporting object
* @throws NullPointerException if <code>storage</code> is null
*/
protected SimpleBuffer(BufferProtocol obj, byte[] storage) throws NullPointerException {
this(obj, storage, 0, storage.length);
}
/**
* Provide an instance of <code>SimpleBuffer</code>, on the entirety of a byte array, meeting
* the consumer's expectations as expressed in the <code>flags</code> argument, which is checked
* against the capabilities of the buffer type.
*
* @param flags consumer requirements
* @param obj exporting object (or <code>null</code>)
* @param storage the array of bytes storing the implementation of the exporting object
* @throws NullPointerException if <code>storage</code> is null
* @throws PyException {@code BufferError} when expectations do not correspond with the type
*/
public SimpleBuffer(int flags, BufferProtocol obj, byte[] storage) throws PyException,
NullPointerException {
this(obj, storage); // Construct SimpleBuffer on whole array
checkRequestFlags(flags); // Check request is compatible with type
}
/**
* {@inheritDoc}
* <p>
* <code>SimpleBuffer</code> provides an implementation optimised for contiguous bytes in
* one-dimension.
*/
@Override
public int getLen() {
// Simplify for one-dimensional contiguous bytes
return shape[0];
}
/**
* {@inheritDoc}
* <p>
* In <code>SimpleBuffer</code> the calculation is specialised for one dimension, no striding,
* and an item size of 1.
*/
@Override
public int byteIndex(int index) throws IndexOutOfBoundsException {
if (index < 0 || index >= shape[0]) {
throw new 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}
* <p>
* <code>SimpleBuffer</code> provides an implementation for slicing contiguous bytes in one
* dimension. In that case, <i>x(i) = u(r+i)</i> for <i>i = 0..L-1</i> where u is the underlying
* buffer, and <i>r</i> and <i>L</i> are the start and count with which <i>x</i> was created
* from <i>u</i>. Thus <i>y(k) = u(r+s+km)</i>, that is, the composite offset is <i>r+s</i> and
* the stride is <i>m</i>.
*/
@Override
public PyBuffer getBufferSlice(int flags, int start, int count, int stride) {
if (stride == 1 || count < 2) {
// Unstrided slice of simple buffer is itself simple
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 Strided1DBuffer.SlicedView(getRoot(), flags, storage, compIndex0, count,
stride);
}
}
@SuppressWarnings("deprecation")
@Override
public Pointer getPointer(int index) throws IndexOutOfBoundsException {
return new Pointer(storage, index0 + index);
}
@SuppressWarnings("deprecation")
@Override
public Pointer getPointer(int... indices) throws IndexOutOfBoundsException {
checkDimension(indices.length);
return getPointer(indices[0]);
}
@Override
public String toString() {
// For contiguous bytes in one dimension we can avoid the intAt() calls
return StringUtil.fromBytes(storage, index0, shape[0]);
}
/**
* A <code>SimpleBuffer.SimpleView</code> represents a contiguous subsequence of another
* <code>SimpleBuffer</code>.
*/
static class SimpleView extends SimpleBuffer {
/** The buffer on which this is a slice view */
PyBuffer root;
/**
* Construct a slice of a SimpleBuffer.
*
* @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 the array of bytes storing the implementation of the exporting object
* @param offset where the data starts in that array (item[0])
* @param size the number of bytes occupied
*/
public SimpleView(PyBuffer root, int flags, byte[] storage, int offset, int size) {
// Create a new SimpleBuffer on the buffer passed in (part of the root)
super(flags, root.getObj(), storage, offset, size);
// Get a lease on the root PyBuffer
this.root = root.getBuffer(FULL_RO);
}
@Override
protected PyBuffer getRoot() {
return root;
}
}
}