`3259a58`

Fix alternation pattern parsing with null terminators

Add null terminators when storing parsed alternatives in the
Aho-Corasick optimization path. Without this, alternatives like
"hello" stored in fixed-length arrays would have incorrect lengths.

Authored by mfwolffe <wolffemf@dukes.jmu.edu> 4 months ago

SHA: 3259a5837fd0dcec5afffe34e3d7ff9281e927ea
Parents: 6a04d1a
Tree: 8785b2c

1 changed file

Status	File	+	-
M	`src/regex/regex_optimizer.f90`	17	4

src/regex/regex_optimizer.f90modified

    use regex_types
    use regex_charclass
    use aho_corasick
 +  use ferp_kinds, only: pattern_len
    implicit none
    private
      is_simple = .true.
      num_alt = 0
 -    pat_len = len_trim(pattern)
 +    pat_len = pattern_len(pattern)  ! Use pattern_len to preserve whitespace patterns
      if (pat_len == 0) then
        is_simple = .false.
                return
              end if
              alternatives(num_alt) = pattern(alt_start:alt_start+alt_len-1)
 +            ! Add null terminator to preserve exact length
 +            if (alt_len < len(alternatives(num_alt))) then
 +              alternatives(num_alt)(alt_len+1:alt_len+1) = char(0)
 +            end if
            else
              ! Empty alternative - still valid
              num_alt = num_alt + 1
 -            alternatives(num_alt) = ''
 +            alternatives(num_alt) = char(0)
            end if
            alt_start = i + 1
            alt_len = 0
                return
              end if
              alternatives(num_alt) = pattern(alt_start:alt_start+alt_len-1)
 +            ! Add null terminator to preserve exact length
 +            if (alt_len < len(alternatives(num_alt))) then
 +              alternatives(num_alt)(alt_len+1:alt_len+1) = char(0)
 +            end if
            else
              num_alt = num_alt + 1
 -            alternatives(num_alt) = ''
 +            alternatives(num_alt) = char(0)
            end if
            alt_start = i + 1
            alt_len = 0
        end if
        if (alt_len > 0) then
          alternatives(num_alt) = pattern(alt_start:alt_start+alt_len-1)
 +        ! Add null terminator to preserve exact length
 +        if (alt_len < len(alternatives(num_alt))) then
 +          alternatives(num_alt)(alt_len+1:alt_len+1) = char(0)
 +        end if
        else
 -        alternatives(num_alt) = ''
 +        alternatives(num_alt) = char(0)
        end if
      end if