refac(depth_first_search): rm unneeded local vars

Author: Damian Rouson

src/dag_s.f90

@@ -38,7 +38,8 @@ pure module function topological_sort(dag) result(order)
       integer, allocatable :: discovered(:)
       integer v
 
-      allocate(discovered(0), searched_and_ordered%o(0), searched_and_ordered%s(0))
+      allocate(discovered(0))
+      searched_and_ordered = searched_and_ordered_t(s = [integer::], o = [integer::])
 
       do v = 1, size(dag%vertices)
         if (.not. any(v == searched_and_ordered%s)) then
@@ -52,33 +53,28 @@ pure module function topological_sort(dag) result(order)
 
   contains
 
-    pure recursive function depth_first_search(v, d, o) result(result_)
+    pure recursive function depth_first_search(v, d, o) result(hybrid)
       integer, intent(in) :: v
       integer, intent(in), dimension(:) :: d, o
-      type(searched_and_ordered_t) result_
+      type(searched_and_ordered_t) hybrid
 
       call assert(.not. any(v == d), "depth_first_search: cycle detected", intrinsic_array_t([v,d]))
 
       block
-        integer, allocatable :: dependencies(:), d_local(:)
+        integer, allocatable :: dependencies(:)
         integer w
-        type(searched_and_ordered_t) hybrid
 
         hybrid = searched_and_ordered_t(s = [integer::], o = o)
         dependencies = dag%depends_on(v)
 
-        allocate(d_local(0))
-
-        do w = 1, size(dependencies)
-          if (.not. any(dependencies(w) == hybrid%s)) then
-            hybrid = depth_first_search(dependencies(w), [d, v], hybrid%o)
-            d_local = [d_local, hybrid%s]
-            hybrid%s = d_local
-          end if
+        do concurrent(w = 1:size(dependencies))
+          associate(w_dependencies => dependencies(w))
+            if (.not. any(w_dependencies == hybrid%s)) hybrid = depth_first_search(w_dependencies, [d, v], hybrid%o)
+          end associate
         end do
 
         if (.not. any(v == hybrid%o)) hybrid%o = [v, hybrid%o]
-        result_ = searched_and_ordered_t(s = [v, hybrid%s], o = hybrid%o)
+        hybrid = searched_and_ordered_t(s = [v, hybrid%s], o = hybrid%o)
       end block
 
     end function