tree_graph__shorthand Subroutine

   pure subroutine tree_graph__shorthand(self)
      use :: forgex_utf8_m, only: ichar_utf8
      implicit none
      class(tree_t), intent(inout) :: self
      type(tree_node_t) :: node
      type(segment_t), allocatable :: seglist(:)
      type(segment_t) :: seg
      character(:), allocatable :: chara


      select case (trim(self%tape%token_char))
      case (ESCAPE_T)
         node = make_atom(SEG_TAB)
         call self%register_connector(node, terminal, terminal)
         return

      case (ESCAPE_N)
         call self%crlf()
         return

      case (ESCAPE_R)
         node = make_atom(SEG_CR)
         call self%register_connector(node, terminal, terminal)
         return

      case (ESCAPE_D)
         node = make_atom(SEG_DIGIT)
         call self%register_connector(node, terminal, terminal)
         return

      case (ESCAPE_D_CAPITAL)
         call node%c%add(SEG_DIGIT)
         call node%c%invert()
         ! allocate(seglist(1))
         ! seglist(1) = SEG_DIGIT
         ! call invert_segment_list(seglist)

      case (ESCAPE_W)
         call node%c%add(SEG_LOWERCASE)
         call node%c%add(SEG_UNDERSCORE)
         call node%c%add(SEG_DIGIT)
         call node%c%add(SEG_UPPERCASE)

         ! allocate(seglist(4))
         ! seglist(1) = SEG_LOWERCASE
         ! seglist(2) = SEG_UPPERCASE
         ! seglist(3) = SEG_DIGIT
         ! seglist(4) = SEG_UNDERSCORE

      case (ESCAPE_W_CAPITAL)
         call node%c%add(SEG_LOWERCASE)
         call node%c%add(SEG_UNDERSCORE)
         call node%c%add(SEG_DIGIT)
         call node%c%add(SEG_UPPERCASE)
         call node%c%invert()
         ! allocate(seglist(4))
         ! seglist(1) = SEG_LOWERCASE
         ! seglist(2) = SEG_UPPERCASE
         ! seglist(3) = SEG_DIGIT
         ! seglist(4) = SEG_UNDERSCORE
         ! call invert_segment_list(seglist)

      case (ESCAPE_S)
         call node%c%add([SEG_SPACE, SEG_TAB, SEG_CR, SEG_LF, SEG_FF, SEG_ZENKAKU_SPACE])

         ! allocate(seglist(6))
         ! seglist(1) = SEG_SPACE
         ! seglist(2) = SEG_TAB
         ! seglist(3) = SEG_CR
         ! seglist(4) = SEG_LF
         ! seglist(5) = SEG_FF
         ! seglist(6) = SEG_ZENKAKU_SPACE

      case (ESCAPE_S_CAPITAL)
         call node%c%add([SEG_SPACE, SEG_TAB, SEG_CR, SEG_LF, SEG_FF, SEG_ZENKAKU_SPACE])
         call node%c%invert()

         ! allocate(seglist(6))
         ! seglist(1) = SEG_SPACE
         ! seglist(2) = SEG_TAB
         ! seglist(3) = SEG_CR
         ! seglist(4) = SEG_LF
         ! seglist(5) = SEG_FF
         ! seglist(6) = SEG_ZENKAKU_SPACE
         ! call invert_segment_list(seglist)

      case (ESCAPE_X)
         ! Error handling for x escape sequence is handled by hex2seg.
         call self%hex2seg(seglist)
         if (.not. self%is_valid) return
         ! It is not necessary to call self%tape%get_token() procedure.
         call node%c%add(seglist)

      case (ESCAPE_P)
         call self%property(seglist)
         if (.not. self%is_valid) return

      case (EMPTY_CHAR)
         self%code = SYNTAX_ERR_ESCAPED_SYMBOL_MISSING
         self%is_valid = .false.
         return
      case (SYMBOL_LSBK, SYMBOL_RSBK, &
            SYMBOL_LCRB, SYMBOL_RCRB, &
            SYMBOL_LPAR, SYMBOL_RPAR, &
            SYMBOL_DOLL, SYMBOL_BSLH, &
            SYMBOL_VBAR, SYMBOL_DOT, &
            SYMBOL_QUES, SYMBOL_CRET, &
            SYMBOL_STAR, SYMBOL_PLUS, &
            SYMBOL_HYPN)
         chara = self%tape%token_char
         seg = segment_t(ichar_utf8(chara), ichar_utf8(chara))
         node%op = op_char

         call node%c%add(seg)
         call self%register_connector(node, terminal, terminal)
         return

      case default
         self%code = SYNTAX_ERR_ESCAPED_SYMBOL_INVALID
         self%is_valid = .false.
         ! chara = self%tape%token_char
         ! seg = segment_t(ichar_utf8(chara), ichar_utf8(chara))
         ! node = make_atom(seg)
         ! call self%register_connector(node, terminal, terminal)
         return
      end select

      ! allocate(node%c(size(seglist, dim=1)))
      ! This size function is safe because it is always allocated 
      ! to the non-returned branches of the select case above.

      ! node%c(:) = seglist(:)
      node%op = op_char

      call self%register_connector(node, terminal, terminal)

      ! deallocate(seglist)

   end subroutine tree_graph__shorthand