an example for using boost::unordered_map in Cython.

setup.py

from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext

ext_modules = [
        Extension("test_um",
            ["test_um.pyx"],
            include_dirs=["/usr/local/include/boost"],
            library_dirs=["/usr/local/lib"],
            language="c++")
        ]

setup(
    name="hello boost::unordered_map",
    cmdclass = {'build_ext': build_ext},
    ext_modules = ext_modules
)

test_um.pyx

from cython.operator cimport dereference as deref, preincrement as inc
from libcpp.string cimport string
from libcpp.pair cimport pair

cdef extern from "<boost/unordered_map.hpp>" namespace "boost":
    cdef cppclass unordered_map[K, T]: # K: key_type, T: mapped_type
        cppclass iterator:
            pair& operator*()
            bint operator==(iterator)
            bint operator!=(iterator)
        unordered_map()
        bint empty()
        size_t size()
        iterator begin()
        iterator end()
        pair emplace(K, T)
        iterator find(K)
        void clear()
        size_t count(K)
        T& operator[](K)
 
def test():
    cdef unordered_map[int, int] *v = new unordered_map[int, int]()
    v.emplace(1, 1)
    v.emplace(2, 2)
    v.emplace(3, 100)
    cdef unordered_map[int, int].iterator it = v.find(3)
    return <int>deref(it).second

Thanks for sharing!

To use this I had to slightly change two function signatures:

cdef extern from "<boost/unordered_map.hpp>" namespace "boost":
    cdef cppclass unordered_map[K, T]: # K: key_type, T: mapped_type
        cppclass iterator:
            pair[K,T]& operator*()
            # ...
        pair[K,T] emplace(K, T)
        # ...