8000 MAINT: Improve memory usage in PEP3118 format parsing by eric-wieser · Pull Request #11535 · numpy/numpy · GitHub
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MAINT: Improve memory usage in PEP3118 format parsing #11535

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Merged
merged 1 commit into from
Aug 4, 2018
Merged

MAINT: Improve memory usage in PEP3118 format parsing #11535

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66 changes: 33 additions & 33 deletions numpy/core/_internal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -444,46 +444,46 @@ def _view_is_safe(oldtype, newtype):
}
_pep3118_standard_typechars = ''.join(_pep3118_standard_map.keys())

def _dtype_from_pep3118(spec):

class Stream(object):
def __init__(self, s):
self.s = s
self.byteorder = '@'
class _Stream(object):
def __init__(self, s):
self.s = s
self.byteorder = '@'

def advance(self, n):
res = self.s[:n]
self.s = self.s[n:]
return res
def advance(self, n):
res = self.s[:n]
self.s = self.s[n:]
return res

def consume(self, c):
if self.s[:len(c)] == c:
self.advance(len(c))
return True
return False

def consume_until(self, c):
if callable(c):
i = 0
while i < len(self.s) and not c(self.s[i]):
i = i + 1
return self.advance(i)
else:
i = self.s.index(c)
res = self.advance(i)
self.advance(len(c))
return res
def consume(self, c):
if self.s[:len(c)] == c:
self.advance(len(c))
return True
return False

@property
def next(self):
return self.s[0]
def consume_until(self, c):
if callable(c):
i = 0
while i < len(self.s) and not c(self.s[i]):
i = i + 1
return self.advance(i)
else:
i = self.s.index(c)
res = self.advance(i)
self.advance(len(c))
return res

def __bool__(self):
return bool(self.s)
__nonzero__ = __bool__
@property
def next(self):
return self.s[0]

stream = Stream(spec)
def __bool__(self):
return bool(self.s)
__nonzero__ = __bool__


def _dtype_from_pep3118(spec):
stream = _Stream(spec)
dtype, align = __dtype_from_pep3118(stream, is_subdtype=False)
return dtype

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20 changes: 20 additions & 0 deletions numpy/tests/test_ctypeslib.py
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Original file line number Diff line number Diff line change
Expand Up @@ -170,3 +170,23 @@ def check(x):
check(as_array(pointer(c_array), shape=()))
check(as_array(pointer(c_array[0]), shape=(2,)))
check(as_array(pointer(c_array[0][0]), shape=(2, 3)))

def test_reference_cycles(self):
# related to gh-6511
import ctypes

# create array to work with
# don't use int/long to avoid running into bpo-10746
N = 100
a = np.arange(N, dtype=np.short)

# get pointer to array
pnt = np.ctypeslib.as_ctypes(a)

with np.testing.assert_no_gc_cycles():
# decay the array above to a pointer to its first element
newpnt = ctypes.cast(pnt, ctypes.POINTER(ctypes.c_short))
# and construct an array using this data
b = np.ctypeslib.as_array(newpnt, (N,))
# now delete both, which should cleanup both objects
del newpnt, b
0