[pypy-commit] pypy PyBuffer: Create BufferViewND to avoid mutating the memoryview in _cast_to_ND()

[rlamy]

Author: Ronan Lamy <ronan.lamy at gmail.com>
Branch: PyBuffer
Changeset: r90843:dbc12a5f29c5
Date: 2017-03-28 15:54 +0100
http://bitbucket.org/pypy/pypy/changeset/dbc12a5f29c5/

Log:	Create BufferViewND to avoid mutating the memoryview in
	_cast_to_ND()

diff --git a/pypy/objspace/std/memoryobject.py b/pypy/objspace/std/memoryobject.py
--- a/pypy/objspace/std/memoryobject.py
+++ b/pypy/objspace/std/memoryobject.py
@@ -547,11 +547,11 @@
 
         origfmt = self.getformat()
         newbuf = self._cast_to_1D(space, buf, origfmt, fmt)
-        mv = W_MemoryView(newbuf, newbuf.getformat(), newbuf.getitemsize())
         if w_shape:
             fview = space.fixedview(w_shape)
             shape = [space.int_w(w_obj) for w_obj in fview]
-            mv._cast_to_ND(space, shape, ndim)
+            newbuf = self._cast_to_ND(space, newbuf, shape, ndim)
+        mv = W_MemoryView(newbuf, newbuf.getformat(), newbuf.getitemsize())
         return mv
 
     def _init_flags(self):
@@ -634,19 +634,16 @@
 
         return None
 
-    def _cast_to_ND(self, space, shape, ndim):
-        buf = self.buf
+    def _cast_to_ND(self, space, buf, shape, ndim):
         length = itemsize = buf.getitemsize()
         for i in range(ndim):
             length *= shape[i]
-        if length != self.buf.getlength():
+        if length != buf.getlength():
             raise oefmt(space.w_TypeError,
                         "memoryview: product(shape) * itemsize != buffer size")
 
-        self.ndim = ndim
-        self.shape = shape
-        self.strides = self._strides_from_shape(shape, itemsize)
-        self._init_flags()
+        strides = self._strides_from_shape(shape, itemsize)
+        return BufferViewND(buf, ndim, shape, strides)
 
     @staticmethod
     def _strides_from_shape(shape, itemsize):
@@ -813,3 +810,55 @@
 
     def getstrides(self):
         return self.strides
+
+class BufferViewND(Buffer):
+    def __init__(self, parent, ndim, shape, strides):
+        assert parent.getndim() == 1
+        assert len(shape) == len(strides) == ndim
+        self.parent = parent
+        self.readonly = parent.readonly
+        self.ndim = ndim
+        self.shape = shape
+        self.strides = strides
+
+    def getlength(self):
+        return self.parent.getlength()
+
+    def as_str(self):
+        return self.parent.as_str()
+
+    def as_str_and_offset_maybe(self):
+        return self.parent.as_str_and_offset_maybe()
+
+    def as_binary(self):
+        return self.parent.as_binary()
+
+    def getitem(self, index):
+        return self.parent.getitem(index)
+
+    def setitem(self, index, char):
+        self.parent.setitem(index, char)
+
+    def getslice(self, start, stop, step, size):
+        return self.parent.getslice(start, stop, step, size)
+
+    def setslice(self, start, string):
+        self.parent.setslice(start, string)
+
+    def get_raw_address(self):
+        return self.parent.get_raw_address()
+
+    def getformat(self):
+        return self.parent.getformat()
+
+    def getitemsize(self):
+        return self.parent.getitemsize()
+
+    def getndim(self):
+        return self.ndim
+
+    def getshape(self):
+        return self.shape
+
+    def getstrides(self):
+        return self.strides