Package org.python.core

Class Py2kBuffer

java.lang.Object
org.python.core.PyObject
org.python.core.PySequence
org.python.core.Py2kBuffer
All Implemented Interfaces:
Serializable, BufferProtocol
public class Py2kBuffer extends PySequence implements BufferProtocol
Implementation of the Python buffer type. buffer is being superseded in Python 2.7 by memoryview, and is provided here to support legacy Python code. Use memoryview if you can.

buffer and memoryview both wrap the same Jython buffer API: that designed for memoryview. In CPython, a new C API (which Jython's resembles) was introduced with memoryview. Because of this, buffer and memoryview may be supplied as arguments in the same places, and will accept as arguments the same (one-dimensional byte-array) types. Their behaviour differs as detailed in the documentation.

See Also:

  • Field Details

    • TYPE

      public static final PyType TYPE

  • Constructor Details

    • Py2kBuffer

      public Py2kBuffer(BufferProtocol object, int offset, int size)
      Construct a Py2kBuffer from an object supporting the BufferProtocol. The buffer takes no lease on the PyBuffer at present, but for each action performed obtains a new one and releases it. (Major difference from memoryview.) Note that when size=-1 is given, the buffer reflects the changing size of the underlying object.
      Parameters:
      object - the object on which this is to be a buffer.
      offset - into the array exposed by the object (0 for start).
      size - of the slice or -1 for all of the object.

  • Method Details

    • __len__

      public int __len__()
      Description copied from class: PyObject
      Equivalent to the standard Python __len__ method. Part of the mapping discipline.
      Overrides:
      __len__ in class PyObject
      Returns:
      the length of the object

    • __repr__

      public PyString __repr__()
      Description copied from class: PyObject
      Equivalent to the standard Python __repr__ method. Each sub-class of PyObject is likely to re-define this method to provide for its own reproduction.
      Overrides:
      __repr__ in class PyObject

    • __str__

      public PyString __str__()
      Description copied from class: PyObject
      Equivalent to the standard Python __str__ method. The default implementation (in PyObject) calls PyObject.__repr__(), making it unnecessary to override __str__ in sub-classes of PyObject where both forms are the same. A common choice is to provide the same implementation to __str__ and toString, for consistency in the printed form of objects between Python and Java.
      Overrides:
      __str__ in class PyObject

    • toString

      public String toString()
      Overrides:
      toString in class PyObject

    • __add__

      public PyObject __add__(PyObject other)
      Equivalent to the standard Python __add__ method. A buffer implements this as concatenation and returns a str (PyString) result.
      Overrides:
      __add__ in class PyObject
      Parameters:
      other - the object to perform this binary operation with (the right-hand operand).
      Returns:
      the result of the add, or null if this operation is not defined.

    • __mul__

      public PyObject __mul__(PyObject o)
      Equivalent to the standard Python __mul__ method. On a buffer it returns a str containing the buffer contents n times.
      Overrides:
      __mul__ in class PyObject
      Parameters:
      o - the object to perform this binary operation with (the right-hand operand).
      Returns:
      the result of the mul, or null if this operation is not defined

    • __rmul__

      public PyObject __rmul__(PyObject o)
      Equivalent to the standard Python __rmul__ method. On a buffer it returns a str containing the buffer contents n times.
      Overrides:
      __rmul__ in class PyObject
      Parameters:
      o - the object to perform this binary operation with (the left-hand operand).
      Returns:
      the result of the mul, or null if this operation is not defined.

    • getBuffer

      public PyBuffer getBuffer(int flags)
      Method by which the consumer requests the buffer from the exporter. The consumer provides information on its ability to understand buffer navigation. Each consumer requesting a buffer in this way, when it has finished using it, should make a corresponding call to PyBuffer.release() on the buffer it obtained, or PyBuffer.close() using try-with-resources, since some objects alter their behaviour while buffers are exported.

      The PyBuffer returned from this method is provided directly by the underlying object on which this buffer was constructed, taking account of the slicing arguments (offset and size), if these were given when the buffer was constructed.

      Specified by:
      getBuffer in interface BufferProtocol
      Parameters:
      flags - specifying features demanded and the navigational capabilities of the consumer
      Returns:
      exported buffer

    • pyset

      public void pyset(int index, PyObject value) throws PyException
      Sets the indexed element of the buffer to the given value, treating the operation as assignment to a slice of length one. This is different from the same operation on a byte array, where the assigned value must be an int: here it must have the buffer API and length one. This is an extension point called by PySequence in its implementation of PySequence.__setitem__(int, org.python.core.PyObject) It is guaranteed by PySequence that the index is within the bounds of the buffer. Any other clients calling pyset(int, PyObject) must make the same guarantee.
      Parameters:
      index - index of the element to set.
      value - to set this element to, regarded as a buffer of length one unit.
      Throws:
      PyException - AttributeError if value cannot be converted to an integer
      PyException - ValueError if value<0 or value%gt;255