added interface for to_lower, to_upper, to_title, reverse functions

Author: aman-godara

src/stdlib_ascii.f90

@@ -64,6 +64,36 @@ module stdlib_ascii
     character(len=*), public, parameter :: lowercase = letters(27:) !! a .. z
     character(len=*), public, parameter :: whitespace = " "//TAB//VT//CR//LF//FF !! ASCII _whitespace
 
+
+    !> Convert character variable to lower case
+    !>
+    !> This method is pure and returns a character sequence
+    interface to_lower
+        module procedure :: to_lower
+    end interface to_lower
+
+    !> Convert character variable to upper case
+    !>
+    !> This method is pure and returns a character sequence
+    interface to_upper
+        module procedure :: to_upper
+    end interface to_upper
+
+    !> Convert character variable to title case
+    !>
+    !> This method is pure and returns a character sequence
+    interface to_title
+        module procedure :: to_title
+    end interface to_title
+
+    !> Reverse the character order in the input character variable
+    !>
+    !> This method is pure and returns a character sequence
+    interface reverse
+        module procedure :: reverse
+    end interface reverse
+    
+
 contains
 
     !> Checks whether `c` is an ASCII letter (A .. Z, a .. z).

src/stdlib_string_type.f90

@@ -12,11 +12,13 @@
 !>
 !> The specification of this module is available [here](../page/specs/stdlib_string_type.html).
 module stdlib_string_type
+    use stdlib_ascii, only: to_lower, to_upper, to_title, reverse
+
     implicit none
     private
-
+    
     public :: string_type
-    public :: len, len_trim, trim, index, scan, verify, repeat, adjustr, adjustl
+    public :: len, len_trim, trim, index, scan, verify, repeat, adjustr, adjustl, to_lower, to_upper, to_title, reverse
     public :: lgt, lge, llt, lle, char, ichar, iachar
     public :: assignment(=)
     public :: operator(>), operator(>=), operator(<), operator(<=)
@@ -89,6 +91,34 @@ module stdlib_string_type
         module procedure :: repeat_string
     end interface repeat
 
+    !> 
+    !>
+    !>
+    interface to_lower
+        module procedure :: to_lower_string
+    end interface to_lower
+
+    !>
+    !>
+    !>
+    interface to_upper
+        module procedure :: to_upper_string
+    end interface to_upper
+
+    !>
+    !>
+    !>
+    interface to_title
+        module procedure :: to_title_string
+    end interface to_title
+
+    !>
+    !>
+    !>
+    interface reverse
+        module procedure :: reverse_string
+    end interface reverse
+
     !> Return the character sequence represented by the string.
     !>
     !> This method is elemental and returns a scalar character value.
@@ -447,6 +477,42 @@ elemental function repeat_string(string, ncopies) result(repeated_string)
     end function repeat_string
 
 
+    elemental function to_lower_string(string) result(lowered_string)
+        type(string_type), intent(in) :: string
+        type(string_type) :: lowered_string
+
+        lowered_string%raw = to_lower(string%raw)
+
+    end function to_lower_string
+
+
+    elemental function to_upper_string(string) result(uppered_string)
+        type(string_type), intent(in) :: string
+        type(string_type) :: uppered_string
+
+        uppered_string%raw = to_upper(string%raw)
+
+    end function to_upper_string
+
+
+    elemental function to_title_string(string) result(titled_string)
+        type(string_type), intent(in) :: string
+        type(string_type) :: titled_string
+
+        titled_string%raw = to_title(string%raw)
+
+    end function to_title_string
+
+
+    elemental function reverse_string(string) result(reversed_string)
+        type(string_type), intent(in) :: string
+        type(string_type) :: reversed_string
+
+        reversed_string%raw = reverse(string%raw)
+
+    end function reverse_string
+
+
     !> Position of a sequence of character within a character sequence.
     !> In this version both character sequences are represented by a string.
     elemental function index_string_string(string, substring, back) result(pos)