Issue #2396: backport the memoryview object.

3 files changed, 90 insertions, 14 deletions

diff --git a/Include/Python.h b/Include/Python.h
index 1a05116..7af6b13 100644
--- a/Include/Python.h
+++ b/Include/Python.h
@@ -92,7 +92,7 @@
 #endif
 #include "rangeobject.h"
 #include "stringobject.h"
-/* #include "memoryobject.h" */
+#include "memoryobject.h"
 #include "bufferobject.h"
 #include "bytesobject.h"
 #include "bytearrayobject.h"
diff --git a/Include/memoryobject.h b/Include/memoryobject.h
new file mode 100644
index 0000000..bf0b621
--- /dev/null
+++ b/Include/memoryobject.h
@@ -0,0 +1,74 @@
+/* Memory view object. In Python this is available as "memoryview". */
+
+#ifndef Py_MEMORYOBJECT_H
+#define Py_MEMORYOBJECT_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+PyAPI_DATA(PyTypeObject) PyMemoryView_Type;
+
+#define PyMemoryView_Check(op) (Py_TYPE(op) == &PyMemoryView_Type)
+
+/* Get a pointer to the underlying Py_buffer of a memoryview object. */
+#define PyMemoryView_GET_BUFFER(op) (&((PyMemoryViewObject *)(op))->view)
+/* Get a pointer to the PyObject from which originates a memoryview object. */
+#define PyMemoryView_GET_BASE(op) (((PyMemoryViewObject *)(op))->view.obj)
+
+
+PyAPI_FUNC(PyObject *) PyMemoryView_GetContiguous(PyObject *base, 
+						  int buffertype, 
+						  char fort);
+
+    /* Return a contiguous chunk of memory representing the buffer
+       from an object in a memory view object.  If a copy is made then the
+       base object for the memory view will be a *new* bytes object. 
+       
+       Otherwise, the base-object will be the object itself and no 
+       data-copying will be done. 
+
+       The buffertype argument can be PyBUF_READ, PyBUF_WRITE,
+       PyBUF_SHADOW to determine whether the returned buffer
+       should be READONLY, WRITABLE, or set to update the
+       original buffer if a copy must be made.  If buffertype is
+       PyBUF_WRITE and the buffer is not contiguous an error will
+       be raised.  In this circumstance, the user can use
+       PyBUF_SHADOW to ensure that a a writable temporary
+       contiguous buffer is returned.  The contents of this
+       contiguous buffer will be copied back into the original
+       object after the memoryview object is deleted as long as
+       the original object is writable and allows setting an
+       exclusive write lock. If this is not allowed by the
+       original object, then a BufferError is raised.
+       
+       If the object is multi-dimensional and if fortran is 'F',
+       the first dimension of the underlying array will vary the
+       fastest in the buffer.  If fortran is 'C', then the last
+       dimension will vary the fastest (C-style contiguous).  If
+       fortran is 'A', then it does not matter and you will get
+       whatever the object decides is more efficient.  
+
+       A new reference is returned that must be DECREF'd when finished.
+    */
+
+PyAPI_FUNC(PyObject *) PyMemoryView_FromObject(PyObject *base);
+
+PyAPI_FUNC(PyObject *) PyMemoryView_FromBuffer(Py_buffer *info);
+    /* create new if bufptr is NULL 
+        will be a new bytesobject in base */
+
+
+/* The struct is declared here so that macros can work, but it shouldn't
+   be considered public. Don't access those fields directly, use the macros
+   and functions instead! */
+typedef struct {
+    PyObject_HEAD
+    PyObject *base;
+    Py_buffer view;
+} PyMemoryViewObject;
+
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_MEMORYOBJECT_H */
diff --git a/Include/object.h b/Include/object.h
index c40d3620..cfca64f 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -159,21 +159,23 @@ typedef Py_ssize_t (*writebufferproc)(PyObject *, Py_ssize_t, void **);
 typedef Py_ssize_t (*segcountproc)(PyObject *, Py_ssize_t *);
 typedef Py_ssize_t (*charbufferproc)(PyObject *, Py_ssize_t, char **);
 
-/* Py3k buffer interface */
 
+/* Py3k buffer interface */
 typedef struct bufferinfo {
-	void *buf;
-	PyObject *obj;        /* borrowed reference */
-        Py_ssize_t len;
-        Py_ssize_t itemsize;  /* This is Py_ssize_t so it can be
-                                 pointed to by strides in simple case.*/
-        int readonly;
-        int ndim;
-        char *format;
-        Py_ssize_t *shape;
-        Py_ssize_t *strides;
-        Py_ssize_t *suboffsets;
-        void *internal;
+	void *buf;   
+	PyObject *obj;        /* owned reference */
+	Py_ssize_t len;
+	Py_ssize_t itemsize;  /* This is Py_ssize_t so it can be 
+			         pointed to by strides in simple case.*/
+	int readonly;
+	int ndim;
+	char *format;
+	Py_ssize_t *shape;
+	Py_ssize_t *strides;
+	Py_ssize_t *suboffsets;
+	Py_ssize_t smalltable[2];  /* static store for shape and strides of
+				      mono-dimensional buffers. */
+	void *internal;
 } Py_buffer;
 
 typedef int (*getbufferproc)(PyObject *, Py_buffer *, int);