submatrix_types: use sort from util

Instead of implementing a custom quicksort, we can use sort from util.
qsort_two is still required within submatrix_dissection. However, this
is a very specific use case so we can make it a private part of
submatrix_dissection and get rid of submatrix_methods entirely.

src/submatrix_dissection.F

@@ -51,7 +51,6 @@ MODULE submatrix_dissection
                                               mp_send,&
                                               mp_wait
    USE kinds,                           ONLY: dp
-   USE submatrix_methods,               ONLY: qsort_two
    USE submatrix_types,                 ONLY: buffer_type,&
                                               bufptr_type,&
                                               intBuffer_type,&
@@ -819,4 +818,58 @@ SUBROUTINE submatrix_communicate_results(this, resultmat)
 
    END SUBROUTINE submatrix_communicate_results
 
+! **************************************************************************************************
+!> \brief sort two integer arrays using quicksort, using the second list as second-level sorting criterion
+!> \param arr_a - first input array
+!> \param arr_b - second input array
+!> \param left - left boundary of region to be sorted
+!> \param right - right boundary of region to be sorted
+! **************************************************************************************************
+   RECURSIVE PURE SUBROUTINE qsort_two(arr_a, arr_b, left, right)
+
+      INTEGER, DIMENSION(:), INTENT(inout)               :: arr_a, arr_b
+      INTEGER, INTENT(in)                                :: left, right
+
+      INTEGER                                            :: i, j, pivot_a, pivot_b, tmp
+
+      IF (right - left .LT. 1) RETURN
+
+      i = left
+      j = right - 1
+      pivot_a = arr_a(right)
+      pivot_b = arr_b(right)
+
+      DO
+         DO WHILE ((arr_a(i) .LT. pivot_a) .OR. ((arr_a(i) .EQ. pivot_a) .AND. (arr_b(i) .LT. pivot_b)))
+            i = i + 1
+         ENDDO
+         DO WHILE ((j .GT. i) .AND. ((arr_a(j) .GT. pivot_a) .OR. ((arr_a(j) .EQ. pivot_a) .AND. (arr_b(j) .GE. pivot_b))))
+            j = j - 1
+         ENDDO
+         IF (i .LT. j) THEN
+            tmp = arr_a(i)
+            arr_a(i) = arr_a(j)
+            arr_a(j) = tmp
+            tmp = arr_b(i)
+            arr_b(i) = arr_b(j)
+            arr_b(j) = tmp
+         ELSE
+            EXIT
+         ENDIF
+      ENDDO
+
+      IF ((arr_a(i) .GT. pivot_a) .OR. (arr_a(i) .EQ. pivot_a .AND. arr_b(i) .GT. pivot_b)) THEN
+         tmp = arr_a(i)
+         arr_a(i) = arr_a(right)
+         arr_a(right) = tmp
+         tmp = arr_b(i)
+         arr_b(i) = arr_b(right)
+         arr_b(right) = tmp
+      ENDIF
+
+      IF (i - 1 .GT. left) CALL qsort_two(arr_a, arr_b, left, i - 1)
+      IF (i + 1 .LT. right) CALL qsort_two(arr_a, arr_b, i + 1, right)
+
+   END SUBROUTINE qsort_two
+
 END MODULE submatrix_dissection

src/submatrix_types.F

@@ -6,7 +6,7 @@
 MODULE submatrix_types
 
    USE kinds,                           ONLY: dp
-   USE submatrix_methods,               ONLY: qsort
+   USE util,                            ONLY: sort
 
    IMPLICIT NONE
    PRIVATE
@@ -199,9 +199,10 @@ END FUNCTION set_getall
 !> \brief update internal list of set elements
 !> \param this - instance of extendable vector
 ! **************************************************************************************************
-   PURE SUBROUTINE set_update_sorted(this)
-      CLASS(set_type), INTENT(INOUT)   :: this
-      INTEGER                          :: i, idx
+   SUBROUTINE set_update_sorted(this)
+      CLASS(set_type), INTENT(INOUT)     :: this
+      INTEGER                            :: i, idx
+      INTEGER, DIMENSION(:), ALLOCATABLE :: tmp
 
       IF (ALLOCATED(this%sorted)) DEALLOCATE (this%sorted)
       ALLOCATE (this%sorted(this%elements))
@@ -214,7 +215,9 @@ PURE SUBROUTINE set_update_sorted(this)
          ENDIF
       ENDDO
 
-      CALL qsort(this%sorted, 1, this%elements)
+      ALLOCATE (tmp(this%elements))
+      CALL sort(this%sorted, this%elements, tmp)
+      DEALLOCATE (tmp)
 
       this%sorted_up_to_date = .TRUE.
    END SUBROUTINE set_update_sorted