add swap for stdlib string_type

Author: jalvesz

doc/specs/stdlib_math.md

@@ -82,8 +82,8 @@ Elemental function.
 
 #### Argument(s)
 
-`lhs`: scalar or array of any of the intrinsic types `integer`, `real`, `complex`, `logical`, `character` type. This argument is `intent(inout)`.
-`rhs`: scalar or array of any of the intrinsic types `integer`, `real`, `complex`, `logical`, `character` type. This argument is `intent(inout)`.
+`lhs`: scalar or array of any of the intrinsic types `integer`, `real`, `complex`, `logical`, `character`, `string_type` type. This argument is `intent(inout)`.
+`rhs`: scalar or array of any of the intrinsic types `integer`, `real`, `complex`, `logical`, `character`, `string_type` type. This argument is `intent(inout)`.
 
 Note: All arguments must have same `type` and same `kind`.
 

example/math/example_math_swap.f90

@@ -30,4 +30,12 @@ program example_math_swap
         call swap(x,y)
     end block
 
+    block
+        use stdlib_string_type
+        type(string_type) :: x, y
+        x = 'abcde'
+        y = 'fghij'
+        call swap(x,y)
+    end block
+
 end program example_math_swap  

src/stdlib_math.fypp

@@ -51,6 +51,7 @@ module stdlib_math
       #:endfor
       module procedure :: swap_bool
       module procedure :: swap_str
+      module procedure :: swap_stt
     end interface
 
     !> Returns the greatest common divisor of two integers
@@ -550,5 +551,12 @@ contains
         character(len=max(len(lhs),len(rhs))) :: temp
         temp = lhs ; lhs = rhs ; rhs = temp
     end subroutine
+
+    elemental subroutine swap_stt(lhs,rhs)
+        use stdlib_string_type
+        type(string_type), intent(inout) :: lhs, rhs
+        type(string_type) :: temp
+        temp = lhs ; lhs = rhs ; rhs = temp
+    end subroutine
 
 end module stdlib_math

test/math/test_stdlib_math.fypp

@@ -46,6 +46,7 @@ contains
             , new_unittest("swap_c${k1}$", test_swap_c${k1}$) &
             #:endfor
             , new_unittest("swap_str", test_swap_str) &
+            , new_unittest("swap_stt", test_swap_stt) &
 
             !> Tests for arg/argd/argpi
             #:for k1 in CMPLX_KINDS
@@ -322,6 +323,28 @@ contains
         if (allocated(error)) return
     end subroutine test_swap_str
 
+    subroutine test_swap_stt(error)
+        use stdlib_string_type
+        type(error_type), allocatable, intent(out) :: error
+        type(string_type) :: x(2), y(2)
+        
+        x = ['abcde','fghij'] 
+        y = ['fghij','abcde']
+
+        call swap(x,y)
+        
+        call check(error, all( x == ['fghij','abcde'] ) )
+        if (allocated(error)) return
+        call check(error, all( y == ['abcde','fghij']  ) )
+        if (allocated(error)) return
+
+        ! check self swap
+        call swap(x,x)
+        
+        call check(error, all( x == ['fghij','abcde'] ) )
+        if (allocated(error)) return
+    end subroutine test_swap_stt
+
     #:for k1 in CMPLX_KINDS
     subroutine test_arg_${k1}$(error)
         type(error_type), allocatable, intent(out) :: error