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Commit 1fc34d3b authored by Mark Florisson's avatar Mark Florisson
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Allow casting C arrays to cython.arrays & direct assignment to memoryviews

parent 538fa670
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Showing with 126 additions and 36 deletions
Cython/Compiler/ExprNodes.py
View file @ 1fc34d3b
......@@ -636,6 +636,9 @@ class ExprNode(Node):
if not src.type.is_memoryviewslice:
if src.type.is_pyobject:
src = CoerceToMemViewSliceNode(src, dst_type, env)
elif src.type.is_array:
src = CythonArrayNode.from_carray(src, env).coerce_to(
dst_type, env)
else:
error(self.pos,
"Cannot convert '%s' to memoryviewslice" %
......@@ -6763,7 +6766,7 @@ ERR_START = "Start may not be given"
ERR_NOT_STOP = "Stop must be provided to indicate shape"
ERR_STEPS = ("Strides may only be given to indicate contiguity. "
"Consider slicing it after conversion")
ERR_NOT_POINTER = "Can only create cython.array from pointer"
ERR_NOT_POINTER = "Can only create cython.array from pointer or array"
ERR_BASE_TYPE = "Pointer base type does not match cython.array base type"
class CythonArrayNode(ExprNode):
......@@ -6779,6 +6782,12 @@ class CythonArrayNode(ExprNode):
and less work. Acquiring a memoryviewslice from this will be just as
efficient. ExprNode.coerce_to() will do the additional typecheck on
self.compile_time_type
This also handles <int[:, :]> my_c_array
operand ExprNode the thing we're casting
base_type_node MemoryViewSliceTypeNode the cast expression node
"""
subexprs = ['operand', 'shapes']
......@@ -6786,20 +6795,61 @@ class CythonArrayNode(ExprNode):
shapes = None
is_temp = True
mode = "c"
array_dtype = None
shape_type = PyrexTypes.c_py_ssize_t_type
def analyse_types(self, env):
import MemoryView
self.operand.analyse_types(env)
if self.array_dtype:
array_dtype = self.array_dtype
else:
array_dtype = self.base_type_node.base_type_node.analyse(env)
axes = self.base_type_node.axes
MemoryView.validate_memslice_dtype(self.pos, array_dtype)
self.type = error_type
self.shapes = []
ndim = len(axes)
# Base type of the pointer or C array we are converting
base_type = self.operand.type
# Dimension sizes of C array
array_dimension_sizes = []
if base_type.is_array:
while base_type.is_array:
array_dimension_sizes.append(base_type.size)
base_type = base_type.base_type
else:
base_type = base_type.base_type
for axis_no, axis in enumerate(self.base_type_node.axes):
if not self.operand.type.is_ptr and not self.operand.type.is_array:
return error(self.operand.pos, ERR_NOT_POINTER)
elif not base_type.same_as(array_dtype):
return error(self.operand.pos, ERR_BASE_TYPE)
elif self.operand.type.is_array and len(array_dimension_sizes) != ndim:
return error(self.operand.pos,
"Expected %d dimensions, array has %d dimensions" %
(ndim, len(array_dimension_sizes)))
# Verify the start, stop and step values
# In case of a C array, use the size of C array in each dimension to
# get an automatic cast
for axis_no, axis in enumerate(axes):
if not axis.start.is_none:
return error(axis.start.pos, ERR_START)
if axis.stop.is_none:
if array_dimension_sizes:
dimsize = array_dimension_sizes[axis_no]
axis.stop = IntNode(self.pos, value=dimsize,
constant_result=dimsize,
type=PyrexTypes.c_int_type)
else:
return error(axis.pos, ERR_NOT_STOP)
axis.stop.analyse_types(env)
......@@ -6812,7 +6862,7 @@ class CythonArrayNode(ExprNode):
if not axis.stop.type.is_int:
return error(axis.stop.pos, "Expected an integer type")
first_or_last = axis_no in (0, len(self.base_type_node.axes) - 1)
first_or_last = axis_no in (0, ndim - 1)
if not axis.step.is_none and first_or_last:
axis.step.analyse_types(env)
if (not axis.step.type.is_int and axis.step.is_literal and not
......@@ -6828,31 +6878,17 @@ class CythonArrayNode(ExprNode):
elif axis.step and not first_or_last:
return error(axis.step.pos, ERR_STEPS)
self.operand.analyse_types(env)
array_dtype = self.base_type_node.base_type_node.analyse(env)
MemoryView.validate_memslice_dtype(self.pos, array_dtype)
if not self.operand.type.is_ptr:
return error(self.operand.pos, ERR_NOT_POINTER)
elif not self.operand.type.base_type.same_as(array_dtype):
return error(self.operand.pos, ERR_BASE_TYPE)
if not self.operand.is_name:
self.operand = self.operand.coerce_to_temp(env)
axes = [('direct', 'follow')] * len(self.base_type_node.axes)
axes = [('direct', 'follow')] * len(axes)
if self.mode == "fortran":
axes[0] = ('direct', 'contig')
else:
axes[-1] = ('direct', 'contig')
self.coercion_type = PyrexTypes.MemoryViewSliceType(array_dtype, axes)
#self.type = py_object_type
self.type = self.get_cython_array_type(env)
assert self.type
MemoryView.use_cython_array_utility_code(env)
env.use_utility_code(MemoryView.typeinfo_to_format_code)
......@@ -6881,6 +6917,7 @@ class CythonArrayNode(ExprNode):
itemsize = "sizeof(%s)" % dtype.declaration_code("")
type_info = Buffer.get_type_information_cname(code, dtype)
if self.operand.type.is_ptr:
code.putln("if (!%s) {" % self.operand.result())
code.putln( 'PyErr_SetString(PyExc_ValueError,'
'"Cannot create cython.array from NULL pointer");')
......@@ -6914,6 +6951,29 @@ class CythonArrayNode(ExprNode):
dispose(shapes_temp)
dispose(format_temp)
@classmethod
def from_carray(cls, src_node, env):
"""
Given a C array type, return a CythonArrayNode
"""
pos = src_node.pos
base_type = src_node.type
none_node = NoneNode(pos)
axes = []
while base_type.is_array:
axes.append(SliceNode(pos, start=none_node, stop=none_node,
step=none_node))
base_type = base_type.base_type
axes[-1].step = IntNode(pos, value="1", is_c_literal=True)
memslicenode = Nodes.MemoryViewSliceTypeNode(pos, axes=axes,
base_type_node=base_type)
result = CythonArrayNode(pos, base_type_node=memslicenode,
operand=src_node, array_dtype=base_type)
result.analyse_types(env)
return result
class SizeofNode(ExprNode):
# Abstract base class for sizeof(x) expression nodes.
......
docs/src/userguide/memoryviews.rst
View file @ 1fc34d3b
......@@ -193,11 +193,15 @@ It also takes an optional argument `mode` ('c' or 'fortran') and a boolean `allo
# define a function that can deallocate the data (if needed)
my_array.callback_free_data = free
You can also cast pointers to arrays::
You can also cast pointers to array, or C arrays to arrays::
cdef cython.array my_array = <int[:10, :2]> my_data_pointer
cdef cython.array my_array = <int[:, :]> my_c_array
Of course, you can also immidiately assign a cython.array to a typed memoryview slice.
Of course, you can also immediately assign a cython.array to a typed memoryview slice. A C array
may be assigned directly to a memoryview slice::
cdef int[:, ::1] myslice = my_2d_c_array
The arrays are indexable and slicable from Python space just like memoryview objects, and have the same
attributes as memoryview objects.
......
tests/run/cythonarray.pyx
View file @ 1fc34d3b
......@@ -64,7 +64,6 @@ def dont_allocate_buffer():
"""
cdef cy.array result = cy.array((10, 10), itemsize=sizeof(int), format='i', allocate_buffer=False)
assert result.data == NULL
result.data = <char *> 1
result.callback_free_data = callback
result = None
......@@ -115,7 +114,7 @@ cdef int *getp(int dim1=10, int dim2=10) except NULL:
return p
cdef void callback_free_data(char *p):
cdef void callback_free_data(void *p):
print 'callback free data called'
free(p)
......@@ -126,11 +125,14 @@ def test_array_from_pointer():
69
c
getp()
callback free data called
fortran
getp()
56
getp()
56
getp()
119
callback free data called
"""
cdef int *p = getp()
......@@ -139,14 +141,38 @@ def test_array_from_pointer():
print c_arr[6, 9]
print c_arr.mode
print (<int[:10:1, :10]> getp()).mode
c_arr = (<int[:10:1, :10]> getp())
print c_arr.mode
c_arr.callback_free_data = free
cdef int[:, ::1] mslice = <int[:10, :10]> getp()
c_arr = <int[:10, :10]> getp()
c_arr.callback_free_data = free
cdef int[:, ::1] mslice = c_arr
print mslice[5, 6]
print (<int[:12, :10]> getp(12, 10))[5, 6]
# There is a reference cycle between the array object to its memoryview
# object that it keeps
del c_arr
import gc
gc.collect()
c_arr = <int[:12, :10]> getp(12, 10)
c_arr.callback_free_data = free
print c_arr[5, 6]
cdef int m = 12
cdef int n = 10
c_arr = <int[:m, :n]> getp(m, n)
c_arr.callback_free_data = callback_free_data
print c_arr[m - 1, n - 1]
def test_cyarray_from_carray():
"""
>>> test_cyarray_from_carray()
0 8 21
0 8 21
"""
cdef int a[7][8]
for i in range(7):
for j in range(8):
a[i][j] = i * 8 + j
cdef int[:, :] mslice = <int[:, :]> a
print mslice[0, 0], mslice[1, 0], mslice[2, 5]
mslice = a
print mslice[0, 0], mslice[1, 0], mslice[2, 5]
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