Merge branch 'u/stumpc5/have_libgap_permutation_to_sage_use_permutati…

…on_instead_of_permutation_group_element' of git://trac.sagemath.org/sage into u/tscrim/libgap_to_sage_permutation_construction-25609

src/sage/groups/perm_gps/permgroup.py

@@ -104,7 +104,6 @@
 - Javier Lopez Pena (2013): Added conjugacy classes.
 
 - Sebastian Oehms (2018): added _coerce_map_from_ in order to use isomorphism coming up with as_permutation_group method (Trac #25706)
-
 - Christian Stump (2018): Added alternative implementation of strong_generating_system directly using GAP.
 
 REFERENCES:

src/sage/libs/gap/element.pyx

@@ -29,6 +29,9 @@ from sage.structure.sage_object cimport SageObject
 from sage.structure.parent import Parent
 from sage.rings.all import ZZ, QQ, RDF
 
+from sage.groups.perm_gps.permgroup_element cimport PermutationGroupElement
+from sage.combinat.permutation import Permutation
+
 decode_type_number = {
     libGAP_T_INT: 'T_INT (integer)',
     libGAP_T_INTPOS: 'T_INTPOS (positive integer)',
@@ -2786,24 +2789,35 @@ cdef class GapElement_Permutation(GapElement):
         <type 'sage.libs.gap.element.GapElement_Permutation'>
     """
 
-    def sage(self):
+    def sage(self, parent=None):
         r"""
         Return the Sage equivalent of the :class:`GapElement`
 
+        If the permutation group is given as parent, this method is
+        *much* faster.
+
         EXAMPLES::
 
             sage: perm_gap = libgap.eval('(1,5,2)(4,3,8)');  perm_gap
             (1,5,2)(3,8,4)
             sage: perm_gap.sage()
+            [5, 1, 8, 3, 2, 6, 7, 4]
+            sage: type(_)
+            <class 'sage.combinat.permutation.StandardPermutations_all_with_category.element_class'>
+            sage: perm_gap.sage(PermutationGroup([(1,2),(1,2,3,4,5,6,7,8)]))
             (1,5,2)(3,8,4)
             sage: type(_)
             <type 'sage.groups.perm_gps.permgroup_element.PermutationGroupElement'>
         """
-        from sage.groups.perm_gps.permgroup_element import PermutationGroupElement
-        libgap = self.parent()
-        return PermutationGroupElement(libgap.ListPerm(self).sage())
+        cdef PermutationGroupElement one_c
 
+        libgap = self.parent()
+        lst = libgap.ListPerm(self)
 
+        if parent is None:
+            return Permutation(lst.sage(), check_input=False)
+        else:
+            return parent.one()._generate_new_GAP(lst)
 
 ############################################################################
 ### GapElement_Record ######################################################