public class SimpleStringBuffer extends SimpleBuffer
ByteBuffer or
PyBuffer.Pointer result), and therefore this class must create a byte array from the
String for them. However, it defers creation of a byte array until that part of the API is
actually used. Where possible, this class overrides those methods in SimpleBuffer that would
otherwise access the byte array attribute to use the String instead.PyBuffer.PointerANY_CONTIGUOUS, AS_ARRAY, C_CONTIGUOUS, CONTIG, CONTIG_RO, CONTIGUITY, F_CONTIGUOUS, FORMAT, FULL, FULL_RO, INDIRECT, IS_C_CONTIGUOUS, IS_F_CONTIGUOUS, MAX_NDIM, NAVIGATION, ND, RECORDS, RECORDS_RO, SIMPLE, STRIDED, STRIDED_RO, STRIDES, WRITABLE| Constructor and Description |
|---|
SimpleStringBuffer(int flags,
BufferProtocol obj,
String bufString)
Provide an instance of SimpleStringBuffer meeting the consumer's expectations as expressed in
the flags argument.
|
| Modifier and Type | Method and Description |
|---|---|
byte |
byteAtImpl(int index)
Retrieve the byte at the given index in the underlying storage treated as a flat sequence of
bytes.
|
int |
byteIndex(int index)
Convert an item index (for a one-dimensional buffer) to an absolute byte index in the storage
shared by the exporter.
|
void |
copyTo(int srcIndex,
byte[] dest,
int destPos,
int count)
Copy a simple slice of the buffer-view to the destination byte array, defined by a starting
item-index in the source buffer and the
count of items to copy. |
PyBuffer.Pointer |
getBuf()
Return a structure describing the slice of a byte array that holds the data being exported to
the consumer.
|
PyBuffer |
getBufferSlice(int flags,
int start,
int count)
Equivalent to
PyBuffer.getBufferSlice(int, int, int, int) with stride 1. |
PyBuffer |
getBufferSlice(int flags,
int start,
int count,
int stride)
Get a
PyBuffer that represents a slice of the current one described in terms of
a start index, number of items to include in the slice, and the stride in the current buffer. |
int |
getLen()
The total number of bytes represented by the view, which will be the product of the elements of the
shape array, and the item size in bytes. |
PyBuffer.Pointer |
getPointer(int... indices)
Return a structure describing the position in a byte array of a single item from the data
being exported to the consumer, in the case that array may be multi-dimensional.
|
PyBuffer.Pointer |
getPointer(int index)
Return a structure describing the position in a byte array of a single item from the data
being exported to the consumer.
|
String |
toString()
The
toString() method of a SimpleStringBuffer simply produces the
underlying String. |
byteIndex, copyFrom, copyFromisContiguousbyteAt, byteAt, close, copyTo, getBuffer, getBufferAgain, getFormat, getItemsize, getNdim, getNIOByteBuffer, getObj, getShape, getStrides, getSuboffsets, hasArray, intAt, intAt, isReadonly, isReleased, release, storeAt, storeAtpublic SimpleStringBuffer(int flags,
BufferProtocol obj,
String bufString)
flags - consumer requirementsobj - exporting object (or null)bufString - storing the implementation of the objectpublic int getLen()
shape array, and the item size in bytes.
SimpleBuffer provides an implementation optimised for contiguous bytes in
one-dimension.
This method uses String.length() rather than create an actual byte buffer.
getLen in interface PyBUFgetLen in class SimpleBufferpublic final byte byteAtImpl(int index)
BaseBuffer.index0, BaseBuffer.shape, BaseBuffer.strides,
and the item size. The caller is responsible for validating the original item-index and
raising (typically) an IndexOutOfBoundsException. Misuse of this method may
still result in unchecked exceptions characteristic of the storage implementation.
This method uses String.charAt(int) rather than create an actual byte buffer.
index - byte-index of location to retrievepublic final int byteIndex(int index)
PyBuffer is a linearly-indexed
sequence of bytes, although it may not actually be a heap-allocated Java byte[]
object. The purpose of this method is to allow the exporter to define the relationship
between the item index (as used in PyBuffer.byteAt(int)) and the byte-index (as used with the
ByteBuffer returned by PyBuffer.getNIOByteBuffer()). See
PyBuffer.byteIndex(int[]) for discussion of the multi-dimensional case.
In SimpleBuffer the calculation is specialised for one dimension, no striding,
and an item size of 1.
In SimpleStringBuffer we can simply return the argument.
byteIndex in interface PyBufferbyteIndex in class SimpleBufferindex - item-index from consumerpublic void copyTo(int srcIndex,
byte[] dest,
int destPos,
int count)
throws IndexOutOfBoundsException
count of items to copy. This may validly
be done only for a one-dimensional buffer, as the meaning of the starting item-index is
otherwise not defined. count*itemsize bytes will be occupied in the destination.
The default implementation in BaseBuffer deals with the general one-dimensional
case of arbitrary item size and stride, but is unable to optimise access to sequential bytes.
The implementation in BaseArrayBuffer deals with the general one-dimensional
case of arbitrary item size and stride.
This method uses String.charAt(int) rather than create an actual byte buffer.
copyTo in interface PyBuffercopyTo in class BaseArrayBuffersrcIndex - starting item-index in the source bufferdest - destination byte arraydestPos - byte-index in the destination array of the source item [0,...]count - number of items to copyIndexOutOfBoundsException - if access out of bounds in source or destinationpublic PyBuffer getBufferSlice(int flags, int start, int count)
PyBuffer.getBufferSlice(int, int, int, int) with stride 1.
The SimpleStringBuffer implementation avoids creation of a byte buffer.
getBufferSlice in interface PyBuffergetBufferSlice in class SimpleBufferflags - specifying features demanded and the navigational capabilities of the consumerstart - index in the current buffercount - number of items in the required slicepublic PyBuffer getBufferSlice(int flags, int start, int count, int stride)
PyBuffer that represents a slice of the current one described in terms of
a start index, number of items to include in the slice, and the stride in the current buffer.
A consumer that obtains a PyBuffer with getBufferSlice must release
it with PyBuffer.release() just as if it had been obtained with
PyBuffer.getBuffer(int)
Suppose that x(i) denotes the ith element of the current buffer, that is, the
byte retrieved by this.byteAt(i) or the unit indicated by
this.getPointer(i). A request for a slice where start = s,
count = N and stride = m, results in a buffer
y such that y(k) = x(s+km) where k=0..(N-1). In Python terms, this is
the slice x[s : s+(N-1)m+1 : m] (if m>0) or the slice x[s : s+(N-1)m-1 :
m] (if m<0). Implementations should check that this range is entirely within
the current buffer.
In a simple buffer backed by a contiguous byte array, the result is a strided PyBuffer on the
same storage but where the offset is adjusted by s and the stride is as supplied. If
the current buffer is already strided and/or has an item size larger than single bytes, the
new start index, count and stride will be translated
from the arguments given, through this buffer's stride and item size. The caller always
expresses start and strides in terms of the abstract view of this
buffer.
SimpleBuffer 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.
The SimpleStringBuffer implementation creates an actual byte buffer.
getBufferSlice in interface PyBuffergetBufferSlice in class SimpleBufferflags - specifying features demanded and the navigational capabilities of the consumerstart - index in the current buffercount - number of items in the required slicestride - index-distance in the current buffer between consecutive items in the slicepublic PyBuffer.Pointer getBuf()
obj has type BufferProtocol:
PyBuffer a = obj.getBuffer(PyBUF.SIMPLE); int itemsize = a.getItemsize(); PyBuffer.Pointer b = a.getBuf();the item with index
k is in the array b.storage at index
[b.offset + k*itemsize] to [b.offset + (k+1)*itemsize - 1]
inclusive. And if itemsize==1, the item is simply the byte
b.storage[b.offset + k]
If the buffer is multidimensional or non-contiguous, storage[offset] is still
the (first byte of) the item at index [0] or [0,...,0]. However, it is necessary to navigate
b.storage using the shape, strides and maybe
suboffsets provided by the API.
BaseArrayBuffer provides a reference to the storage array even when the buffer
is intended not to be writable. There can be no enforcement of read-only character once a
reference to the byte array has been handed out.
This method creates an actual byte array from the underlying String if none yet exists.
getBuf in interface PyBuffergetBuf in class BaseArrayBufferpublic PyBuffer.Pointer getPointer(int index)
obj has type BufferProtocol:
int k = ... ; PyBuffer a = obj.getBuffer(PyBUF.FULL); int itemsize = a.getItemsize(); PyBuffer.Pointer b = a.getPointer(k);the item with index
k is in the array b.storage at index
[b.offset] to [b.offset + itemsize - 1] inclusive. And if
itemsize==1, the item is simply the byte b.storage[b.offset]
Essentially this is a method for computing the offset of a particular index. The client is
free to navigate the underlying buffer b.storage without respecting these
boundaries.
This method creates an actual byte array from the underlying String if none yet exists.
getPointer in interface PyBuffergetPointer in class SimpleBufferindex - in the buffer to position the pointerpublic PyBuffer.Pointer getPointer(int... indices)
obj
has type BufferProtocol:
int i, j, k; // ... calculation that assigns i, j, k PyBuffer a = obj.getBuffer(PyBUF.FULL); int itemsize = a.getItemsize(); PyBuffer.Pointer b = a.getPointer(i,j,k);the item with index
[i,j,k] is in the array b.storage at index
[b.offset] to [b.offset + itemsize - 1] inclusive. And if
itemsize==1, the item is simply the byte b.storage[b.offset]
Essentially this is a method for computing the offset of a particular index. The client is
free to navigate the underlying buffer b.storage without respecting these
boundaries. If the buffer is non-contiguous, the above description is still valid (since a
multi-byte item must itself be contiguously stored), but in any additional navigation of
b.storage[] to other items, the client must use the shape, strides and
sub-offsets provided by the API. Normally one starts b = a.getBuf() in order to
establish the offset of index [0,...,0].
This method creates an actual byte array from the underlying String if none yet exists.
getPointer in interface PyBuffergetPointer in class SimpleBufferindices - multidimensional index at which to position the pointerpublic String toString()
toString() method of a SimpleStringBuffer simply produces the
underlying String.toString in interface PyBuffertoString in class SimpleBuffer