cython

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from cython.cimports.cpython.mem import PyMem_Malloc, PyMem_Realloc, PyMem_Free
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@cython.cclass
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class SomeMemory:
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    data: cython.p_double
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    def __cinit__(self, number: cython.size_t):
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        # allocate some memory (uninitialised, may contain arbitrary data)
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        self.data = cython.cast(cython.p_double, PyMem_Malloc(
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            number * cython.sizeof(cython.double)))
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        if not self.data:
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            raise MemoryError()
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    def resize(self, new_number: cython.size_t):
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        # Allocates new_number * sizeof(double) bytes,
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        # preserving the current content and making a best-effort to
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        # reuse the original data location.
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        mem = cython.cast(cython.p_double, PyMem_Realloc(
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            self.data, new_number * cython.sizeof(cython.double)))
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        if not mem:
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            raise MemoryError()
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        # Only overwrite the pointer if the memory was really reallocated.
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        # On error (mem is NULL), the originally memory has not been freed.
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        self.data = mem
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    def __dealloc__(self):
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        PyMem_Free(self.data)  # no-op if self.data is NULL
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