Use the optval function in the sorting routines

The optval function replaces some nested if statemens and allows to
remove the reverse_ variable which is a clone of the optional reverse
variable.

Author: Carl Burkert

src/stdlib_sorting.fypp

@@ -123,6 +123,8 @@ module stdlib_sorting
         dp,                 &
         qp
 
+    use stdlib_optval, only: optval
+
     use stdlib_string_type, only: string_type, assignment(=), operator(>), &
         operator(>=), operator(<), operator(<=)
 

src/stdlib_sorting_ord_sort.fypp

@@ -75,12 +75,7 @@ contains
         ${t3}$, intent(out), optional :: work(0:)
         logical, intent(in), optional :: reverse
 
-        logical :: reverse_
-
-        reverse_ = .false.
-        if(present(reverse)) reverse_ = reverse
-
-        if (reverse_) then
+        if (optval(reverse, .false.)) then
             call ${name1}$_decrease_ord_sort(array, work)
         else
             call ${name1}$_increase_ord_sort(array, work)

src/stdlib_sorting_sort.fypp

@@ -78,12 +78,7 @@ contains
             ${t1}$, intent(inout) :: array(0:)
             logical, intent(in), optional            :: reverse
 
-            logical :: reverse_
-
-            reverse_ = .false.
-            if(present(reverse)) reverse_ = reverse
-
-            if(reverse_)then
+            if(optval(reverse, .false.))then
              call ${name1}$_decrease_sort(array)
             else
              call ${name1}$_increase_sort(array)

src/stdlib_sorting_sort_index.fypp

@@ -107,10 +107,8 @@ contains
             index(i) = i+1
         end do
 
-        if ( present(reverse) ) then
-            if ( reverse ) then
-                call reverse_segment( array, index )
-            end if
+        if ( optval(reverse, .false.) ) then
+            call reverse_segment( array, index )
         end if
 
 ! If necessary allocate buffers to serve as scratch memory.
@@ -148,10 +146,8 @@ contains
             end if
         end if
 
-        if ( present(reverse) ) then
-            if ( reverse ) then
-                call reverse_segment( array, index )
-            end if
+        if ( optval(reverse, .false.) ) then
+            call reverse_segment( array, index )
         end if
 
     contains