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125 lines
3.3 KiB
125 lines
3.3 KiB
4 months ago
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referents = [] # list "object descriptor -> python object"
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freelist = None
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def store(x):
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"Store the object 'x' and returns a new object descriptor for it."
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global freelist
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p = freelist
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if p is None:
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p = len(referents)
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referents.append(x)
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else:
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freelist = referents[p]
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referents[p] = x
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return p
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def discard(p):
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"""Discard (i.e. close) the object descriptor 'p'.
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Return the original object that was attached to 'p'."""
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global freelist
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x = referents[p]
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referents[p] = freelist
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freelist = p
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return x
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class Ref(object):
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"""For use in 'with Ref(x) as ob': open an object descriptor
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and returns it in 'ob', and close it automatically when the
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'with' statement finishes."""
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def __init__(self, x):
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self.x = x
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def __enter__(self):
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self.p = p = store(self.x)
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return p
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def __exit__(self, *args):
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discard(self.p)
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def count_pyobj_alive():
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result = len(referents)
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p = freelist
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while p is not None:
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assert result > 0
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result -= 1
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p = referents[p]
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return result
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# ------------------------------------------------------------
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if __name__ == '__main__':
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import api
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ffi = api.PythonFFI()
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ffi.cdef("""
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typedef int pyobj_t;
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int sum_integers(pyobj_t p_list);
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pyobj_t sum_objects(pyobj_t p_list, pyobj_t p_initial);
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""")
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@ffi.pyexport("int(pyobj_t)")
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def length(p_list):
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list = referents[p_list]
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return len(list)
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@ffi.pyexport("int(pyobj_t, int)")
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def getitem(p_list, index):
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list = referents[p_list]
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return list[index]
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@ffi.pyexport("pyobj_t(pyobj_t)")
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def pyobj_dup(p):
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return store(referents[p])
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@ffi.pyexport("void(pyobj_t)")
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def pyobj_close(p):
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discard(p)
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@ffi.pyexport("pyobj_t(pyobj_t, int)")
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def pyobj_getitem(p_list, index):
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list = referents[p_list]
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return store(list[index])
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@ffi.pyexport("pyobj_t(pyobj_t, pyobj_t)")
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def pyobj_add(p1, p2):
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return store(referents[p1] + referents[p2])
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lib = ffi.verify("""
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typedef int pyobj_t; /* an "object descriptor" number */
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int sum_integers(pyobj_t p_list) {
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/* this a demo function written in C, using the API
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defined above: length() and getitem(). */
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int i, result = 0;
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int count = length(p_list);
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for (i=0; i<count; i++) {
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int n = getitem(p_list, i);
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result += n;
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}
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return result;
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}
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pyobj_t sum_objects(pyobj_t p_list, pyobj_t p_initial) {
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/* same as above, but keeps all additions as Python objects */
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int i;
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int count = length(p_list);
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pyobj_t p1 = pyobj_dup(p_initial);
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for (i=0; i<count; i++) {
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pyobj_t p2 = pyobj_getitem(p_list, i);
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pyobj_t p3 = pyobj_add(p1, p2);
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pyobj_close(p2);
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pyobj_close(p1);
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p1 = p3;
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}
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return p1;
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}
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""")
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with Ref([10, 20, 30, 40]) as p_list:
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print lib.sum_integers(p_list)
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with Ref(5) as p_initial:
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result = discard(lib.sum_objects(p_list, p_initial))
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print result
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assert count_pyobj_alive() == 0
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