Line data    Source code

       1              : !> Utility functions and types for the HSD parser
       2              : module hsd_utils
       3              :   use hsd_constants, only: dp
       4              :   implicit none (type, external)
       5              :   private
       6              : 
       7              :   public :: string_buffer_t
       8              :   public :: to_lower
       9              : 
      10              :   !> Initial buffer capacity
      11              :   integer, parameter :: BUFFER_INITIAL_CAPACITY = 256
      12              : 
      13              :   !> String buffer for efficient string building
      14              :   !>
      15              :   !> Avoids O(n²) string concatenation by pre-allocating buffer space
      16              :   !> and growing geometrically when needed.
      17              :   type :: string_buffer_t
      18              :     character(len=:), allocatable :: buffer
      19              :     integer :: length = 0
      20              :     integer :: capacity = 0
      21              :   contains
      22              :     procedure :: init => buffer_init
      23              :     procedure :: append_char => buffer_append_char
      24              :     procedure :: append_str => buffer_append_str
      25              :     procedure :: get_string => buffer_get_string
      26              :     procedure :: clear => buffer_clear
      27              :   end type string_buffer_t
      28              : 
      29              : contains
      30              : 
      31              :   !> Initialize the string buffer with given or default capacity
      32         2801 :   subroutine buffer_init(self)
      33              :     class(string_buffer_t), intent(inout) :: self
      34              : 
      35         2801 :     self%capacity = BUFFER_INITIAL_CAPACITY
      36            4 :     if (allocated(self%buffer)) deallocate(self%buffer)
      37         2801 :     allocate(character(len=self%capacity) :: self%buffer)
      38         2801 :     self%length = 0
      39              : 
      40         2801 :   end subroutine buffer_init
      41              : 
      42              :   !> Append a single character to the buffer
      43        28758 :   subroutine buffer_append_char(self, ch)
      44              :     class(string_buffer_t), intent(inout) :: self
      45              :     character(len=1), intent(in) :: ch
      46              : 
      47        28758 :     character(len=:), allocatable :: new_buffer
      48        28758 :     integer :: new_capacity
      49              : 
      50              :     ! Initialize if needed
      51        28758 :     if (self%capacity == 0) call self%init()
      52              : 
      53              :     ! Grow buffer if needed (double capacity)
      54        28758 :     if (self%length >= self%capacity) then
      55            5 :       new_capacity = self%capacity * 2
      56            5 :       allocate(character(len=new_capacity) :: new_buffer)
      57            5 :       new_buffer(1:self%length) = self%buffer(1:self%length)
      58            5 :       call move_alloc(new_buffer, self%buffer)
      59            5 :       self%capacity = new_capacity
      60              :     end if
      61              : 
      62        28758 :     self%length = self%length + 1
      63        28758 :     self%buffer(self%length:self%length) = ch
      64              : 
      65        31559 :   end subroutine buffer_append_char
      66              : 
      67              :   !> Append a string to the buffer
      68         2334 :   subroutine buffer_append_str(self, str)
      69              :     class(string_buffer_t), intent(inout) :: self
      70              :     character(len=*), intent(in) :: str
      71              : 
      72         2334 :     character(len=:), allocatable :: new_buffer
      73         2334 :     integer :: new_capacity, str_len
      74              : 
      75         2334 :     str_len = len(str)
      76            0 :     if (str_len == 0) return
      77              : 
      78              :     ! Initialize if needed
      79         2334 :     if (self%capacity == 0) call self%init()
      80              : 
      81              :     ! Grow buffer if needed
      82         2334 :     if (self%length + str_len > self%capacity) then
      83            7 :       new_capacity = max(self%capacity * 2, self%length + str_len)
      84            7 :       allocate(character(len=new_capacity) :: new_buffer)
      85            7 :       new_buffer(1:self%length) = self%buffer(1:self%length)
      86            7 :       call move_alloc(new_buffer, self%buffer)
      87            7 :       self%capacity = new_capacity
      88              :     end if
      89              : 
      90         2334 :     self%buffer(self%length+1:self%length+str_len) = str
      91         2334 :     self%length = self%length + str_len
      92              : 
      93        31092 :   end subroutine buffer_append_str
      94              : 
      95              :   !> Get the accumulated string
      96         2801 :   function buffer_get_string(self) result(str)
      97              :     class(string_buffer_t), intent(in) :: self
      98              :     character(len=:), allocatable :: str
      99              : 
     100         2801 :     if (self%length > 0) then
     101         2797 :       str = self%buffer(1:self%length)
     102              :     else
     103            4 :       str = ""
     104              :     end if
     105              : 
     106         2334 :   end function buffer_get_string
     107              : 
     108              :   !> Clear the buffer for reuse (keeps capacity)
     109            3 :   subroutine buffer_clear(self)
     110              :     class(string_buffer_t), intent(inout) :: self
     111            3 :     self%length = 0
     112         2801 :   end subroutine buffer_clear
     113              : 
     114              :   !> Convert a string to lowercase
     115       552203 :   pure function to_lower(str) result(lower)
     116              :     character(len=*), intent(in) :: str
     117              :     character(len=len(str)) :: lower
     118       552203 :     integer :: i, ic
     119              : 
     120      5383248 :     do i = 1, len(str)
     121      4831045 :       ic = ichar(str(i:i))
     122      5383248 :       if (ic >= 65 .and. ic <= 90) then
     123         3036 :         lower(i:i) = char(ic + 32)
     124              :       else
     125      4828009 :         lower(i:i) = str(i:i)
     126              :       end if
     127              :     end do
     128      1104409 :   end function to_lower
     129              : 
     130       552203 : end module hsd_utils