fortrangoingonforty/ferp / b43bcce

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Add pattern_len() function for null-terminated pattern handling

Fortran's len_trim() returns 0 for whitespace-only strings, which breaks
patterns like " " (two spaces). This function respects null terminators
to track exact pattern length, falling back to full string length when
no terminator is present.
Authored by mfwolffe <wolffemf@dukes.jmu.edu>
SHA
b43bcce5c8d8e2737ce3ed36e29bbdc3c7682c92
Parents
0d61ac5
Tree
423e3dd

1 changed file

StatusFile+-
M src/ferp_kinds.f90 30 0
src/ferp_kinds.f90modified
@@ -7,6 +7,7 @@ module ferp_kinds
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   public :: i32, i64, dp
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   public :: initial_line_len, max_line_len, max_path_len, max_pattern_len
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+  public :: pattern_len
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   !> Integer kinds
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   integer, parameter :: i32 = int32
@@ -21,4 +22,33 @@ module ferp_kinds
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   integer, parameter :: max_path_len = 4096
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   integer, parameter :: max_pattern_len = 4096
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+contains
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+
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+  pure function pattern_len(pattern) result(plen)
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+    !> Get the true length of a pattern, respecting null terminator if present
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+    !> This allows whitespace-only patterns like "  " to be handled correctly
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+    !> If no null terminator is found, returns the full string length (not len_trim)
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+    !> to properly handle whitespace-only patterns passed with explicit length
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+    character(len=*), intent(in) :: pattern
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+    integer :: plen
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+
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+    integer :: i, slen
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+
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+    slen = len(pattern)
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+    plen = slen
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+
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+    ! Look for null terminator
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+    do i = 1, slen
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+      if (pattern(i:i) == char(0)) then
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+        plen = i - 1
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+        return
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+      end if
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+    end do
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+
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+    ! No null terminator found - return full length
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+    ! (pattern was passed with explicit length, e.g., pattern(1:2))
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+    ! Note: Don't use len_trim here as it would break whitespace patterns
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+
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+  end function pattern_len
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+
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 end module ferp_kinds