Merge pull request #319 from Marlin-Na/pycapsule

Pass symengine object with PyCapsule

Author: isuruf

symengine/lib/symengine.pxd

@@ -1064,3 +1064,7 @@ cdef extern from "<symengine/solve.h>" namespace "SymEngine":
 cdef extern from "<symengine/printers.h>" namespace "SymEngine":
     string ccode(const Basic &x) nogil except +
     string latex(const Basic &x) nogil except +
+
+## Defined in 'symengine/cwrapper.cpp'
+cdef struct CRCPBasic:
+    rcp_const_basic m

symengine/lib/symengine_wrapper.pyx

@@ -3,7 +3,7 @@ cimport symengine
 from symengine cimport (RCP, pair, map_basic_basic, umap_int_basic,
     umap_int_basic_iterator, umap_basic_num, umap_basic_num_iterator,
     rcp_const_basic, std_pair_short_rcp_const_basic,
-    rcp_const_seriescoeffinterface)
+    rcp_const_seriescoeffinterface, CRCPBasic)
 from libcpp cimport bool as cppbool
 from libcpp.string cimport string
 from libcpp.vector cimport vector
@@ -20,6 +20,7 @@ import warnings
 from symengine.compatibility import is_sequence
 import os
 import sys
+from cpython.pycapsule cimport PyCapsule_GetPointer
 
 if sys.version_info[0] == 2:
     from collections import MutableMapping
@@ -38,6 +39,15 @@ include "config.pxi"
 class SympifyError(Exception):
     pass
 
+cpdef object capsule_to_basic(object capsule):
+    cdef CRCPBasic *p = <CRCPBasic*>PyCapsule_GetPointer(capsule, NULL)
+    return c2py(p.m)
+
+cpdef void assign_to_capsule(object capsule, object value):
+    cdef CRCPBasic *p_cap = <CRCPBasic*>PyCapsule_GetPointer(capsule, NULL)
+    cdef Basic v = sympify(value)
+    p_cap.m = v.thisptr
+
 cdef object c2py(rcp_const_basic o):
     cdef Basic r
     if (symengine.is_a_Add(deref(o))):