Add const at to map

Cython/Includes/libcpp/map.pxd

@@ -39,6 +39,7 @@ cdef extern from "<map>" namespace "std" nogil:
         bint operator<=(map&, map&)
         bint operator>=(map&, map&)
         U& at(const T&) except +
+        const U& const_at "at"(const T&) except +
         iterator begin()
         const_iterator const_begin "begin" ()
         void clear()

tests/run/cpp_stl_cpp11.pyx

@@ -9,6 +9,7 @@ from libcpp.queue cimport queue
 from libcpp.queue cimport priority_queue
 from libcpp.vector cimport vector
 from libcpp.pair cimport pair
+from libcpp.map cimport map
 
 
 def test_vector_functionality():
@@ -58,6 +59,19 @@ def test_priority_queue_functionality():
     return "pass"
 
 
+def test_map_functionality():
+    """
+    >>> test_map_functionality()
+    'pass'
+    """
+    cdef:
+        map[int, const void*] int_map
+        const void* data
+    int_map[77] = NULL
+    data = int_map.const_at(77)
+    return "pass"
+
+
 def test_unordered_map_functionality():
     """
     >>> test_unordered_map_functionality()