changed to_title to to_sentence, implemented correct to_title

Author: aman-godara

src/stdlib_ascii.fypp

@@ -19,7 +19,7 @@ module stdlib_ascii
     public :: is_lower, is_upper
 
     ! Character conversion functions
-    public :: to_lower, to_upper, to_title, reverse
+    public :: to_lower, to_upper, to_title, to_sentence, reverse
     public :: to_string
 
     !> Version: experimental
@@ -100,6 +100,13 @@ module stdlib_ascii
         module procedure :: to_title
     end interface to_title
 
+    !> Returns a new character sequence which is the sentence case
+    !> version of the input character sequence
+    !> This method is pure and returns a character sequence
+    interface to_sentence
+        module procedure :: to_sentence
+    end interface to_sentence
+
     !> Returns a new character sequence which is reverse of
     !> the input charater sequence
     !> This method is pure and returns a character sequence
@@ -284,31 +291,58 @@ contains
 
     end function to_upper
 
-    !> Convert character variable to title case
+    !> Converts character sequence to title case
     !> ([Specification](../page/specs/stdlib_ascii.html#to_title))
     !>
     !> Version: experimental
     pure function to_title(string) result(title_string)
         character(len=*), intent(in) :: string
         character(len=len(string)) :: title_string
+        integer :: i
+        logical :: capitalize_switch
+
+        capitalize_switch = .true.
+        do i = 1, len(string)
+            if (is_alpha(string(i:i))) then
+                if (capitalize_switch) then
+                    title_string(i:i) = char_to_upper(string(i:i))
+                    capitalize_switch = .false.
+                else
+                    title_string(i:i) = char_to_lower(string(i:i))
+                end if
+            else
+                title_string(i:i) = string(i:i)
+                capitalize_switch = .true.
+            end if
+        end do
+
+    end function to_title
+
+    !> Converts character sequence to sentence case
+    !> ([Specification](../page/specs/stdlib_ascii.html#to_sentence))
+    !>
+    !> Version: experimental
+    pure function to_sentence(string) result(sentence_string)
+        character(len=*), intent(in) :: string
+        character(len=len(string)) :: sentence_string
         integer :: i, n
 
         n = len(string)
         do i = 1, len(string)
             if (is_alphanum(string(i:i))) then
-                title_string(i:i) = char_to_upper(string(i:i))
+                sentence_string(i:i) = char_to_upper(string(i:i))
                 n = i
                 exit
             else
-                title_string(i:i) = string(i:i)
+                sentence_string(i:i) = string(i:i)
             end if
         end do
 
         do i = n + 1, len(string)
-            title_string(i:i) = char_to_lower(string(i:i))
+            sentence_string(i:i) = char_to_lower(string(i:i))
         end do
 
-    end function to_title
+    end function to_sentence
 
     !> Reverse the character order in the input character variable
     !> ([Specification](../page/specs/stdlib_ascii.html#reverse))

src/stdlib_string_type.fypp

@@ -14,15 +14,15 @@
 !> 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_lower, to_upper_ => to_upper, &
-       & to_title_ => to_title, reverse_ => reverse, to_string
+       & to_title_ => to_title, to_sentence_ => to_sentence, reverse_ => reverse, to_string
     use stdlib_kinds, only : int8, int16, int32, int64
     implicit none
     private
 
     public :: string_type
     public :: len, len_trim, trim, index, scan, verify, repeat, adjustr, adjustl
     public :: lgt, lge, llt, lle, char, ichar, iachar
-    public :: to_lower, to_upper, to_title, reverse
+    public :: to_lower, to_upper, to_title, to_sentence, reverse
     public :: assignment(=)
     public :: operator(>), operator(>=), operator(<), operator(<=)
     public :: operator(==), operator(/=), operator(//)
@@ -122,6 +122,14 @@ module stdlib_string_type
         module procedure :: to_title_string
     end interface to_title
 
+    !> Returns the sentencecase version of the character sequence hold by the input string
+    !>
+    !> This method is Elemental and returns a new string_type instance which holds this
+    !> sentencecase character sequence
+    interface to_sentence
+        module procedure :: to_sentence_string
+    end interface to_sentence
+
     !> Reverses the character sequence hold by the input string
     !> 
     !> This method is Elemental and returns a new string_type instance which holds this
@@ -535,6 +543,15 @@ contains
 
     end function to_title_string
 
+    !> Convert the character sequence hold by the input string to sentence case
+    elemental function to_sentence_string(string) result(sentence_string)
+        type(string_type), intent(in) :: string
+        type(string_type) :: sentence_string
+
+        sentence_string%raw = to_sentence_(maybe(string))
+
+    end function to_sentence_string
+
 
     !> Reverse the character sequence hold by the input string
     elemental function reverse_string(string) result(reversed_string)

src/tests/ascii/test_ascii.f90

@@ -6,7 +6,7 @@ program test_ascii
         whitespace, letters, is_alphanum, is_alpha, is_lower, is_upper, &
         is_digit, is_octal_digit, is_hex_digit, is_white, is_blank, &
         is_control, is_punctuation, is_graphical, is_printable, is_ascii, &
-        to_lower, to_upper, to_title, reverse, LF, TAB, NUL, DEL, &
+        to_lower, to_upper, to_title, to_sentence, reverse, LF, TAB, NUL, DEL, &
         to_string
      use stdlib_kinds, only : int8, int16, int32, int64
 
@@ -73,6 +73,7 @@ program test_ascii
     call test_to_upper_string
     call test_to_lower_string
     call test_to_title_string
+    call test_to_sentence_string
     call test_reverse_string
 
     call test_to_string
@@ -583,26 +584,48 @@ end subroutine test_to_upper_string
 
     subroutine test_to_title_string
         character(len=:), allocatable :: dlc
-        character(len=32), parameter :: input = "tiTLe"
+        character(len=32), parameter :: input = "tHis Is tO bE tiTlEd"
 
-        dlc = to_title("tiTLe")
-        call check(dlc == "Title")
+        dlc = to_title("tHis Is tO bE tiTlEd")
+        call check(dlc == "This Is To Be Titled")
 
         dlc = to_title(input)
         call check(len(dlc) == 32)
-        call check(len_trim(dlc) == 5)
-        call check(trim(dlc) == "Title")
+        call check(len_trim(dlc) == 20)
+        call check(trim(dlc) == "This Is To Be Titled")
 
         dlc = to_title(" s P a C e D !")
-        call check(dlc == " S p a c e d !")
+        call check(dlc == " S P A C E D !")
 
-        dlc = to_title("1st, 2nd, 3rd")
-        call check(dlc == "1st, 2nd, 3rd")
+        dlc = to_title("1st, 2nd, 3rD, 4TH")
+        call check(dlc == "1St, 2Nd, 3Rd, 4Th")
 
         dlc = to_title("""quOTed""")
         call check(dlc == """Quoted""")
     end subroutine test_to_title_string
 
+    subroutine test_to_sentence_string
+        character(len=:), allocatable :: dlc
+        character(len=32), parameter :: input = "tHis iS A seNteNcE."
+
+        dlc = to_sentence("tHis iS A seNteNcE.")
+        call check(dlc == "This is a sentence.")
+
+        dlc = to_sentence(input)
+        call check(len(dlc) == 32)
+        call check(len_trim(dlc) == 19)
+        call check(trim(dlc) == "This is a sentence.")
+
+        dlc = to_sentence(" s P a C e D !")
+        call check(dlc == " S p a c e d !")
+
+        dlc = to_sentence("1st, 2nd, 3rd")
+        call check(dlc == "1st, 2nd, 3rd")
+
+        dlc = to_sentence("""quOTed""")
+        call check(dlc == """Quoted""")
+    end subroutine test_to_sentence_string
+
     subroutine test_reverse_string
         character(len=:), allocatable :: dlc
         character(len=32), parameter :: input = "reversed"

src/tests/string/test_string_functions.f90

@@ -2,7 +2,7 @@
 module test_string_functions
     use stdlib_error, only : check
     use stdlib_string_type, only : string_type, assignment(=), operator(==), &
-                                    to_lower, to_upper, to_title, reverse
+                                    to_lower, to_upper, to_title, to_sentence, reverse
     implicit none
 
 contains
@@ -27,12 +27,21 @@ end subroutine test_to_upper_string
 
     subroutine test_to_title_string
         type(string_type) :: test_string, compare_string
-        test_string = "_#To tiTlE !$%-az09AZ"
-        compare_string = "_#To title !$%-az09az"
+        test_string = "_tO t8iTLE_th!s p#ra$e"
+        compare_string = "_To T8Itle_Th!S P#Ra$E"
 
         call check(to_title(test_string) == compare_string)
 
     end subroutine test_to_title_string
+    
+    subroutine test_to_sentence_string
+        type(string_type) :: test_string, compare_string
+        test_string = "_#To seNtEncE !$%-az09AZ"
+        compare_string = "_#To sentence !$%-az09az"
+
+        call check(to_sentence(test_string) == compare_string)
+
+    end subroutine test_to_sentence_string
 
     subroutine test_reverse_string
         type(string_type) :: test_string, compare_string
@@ -53,6 +62,7 @@ program tester
     call test_to_lower_string
     call test_to_upper_string
     call test_to_title_string
+    call test_to_sentence_string
     call test_reverse_string
 
 end program tester