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   1  ;# Usage: &look(*FILEHANDLE,$key,$dict,$fold)
   2  #
   3  # This library is no longer being maintained, and is included for backward
   4  # compatibility with Perl 4 programs which may require it.
   5  #
   6  # In particular, this should not be used as an example of modern Perl
   7  # programming techniques.
   8  #
   9  ;# Sets file position in FILEHANDLE to be first line greater than or equal
  10  ;# (stringwise) to $key.  Pass flags for dictionary order and case folding.
  11  
  12  sub look {
  13      local(*FH,$key,$dict,$fold) = @_;
  14      local($max,$min,$mid,$_);
  15      local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,
  16         $blksize,$blocks) = stat(FH);
  17      $blksize = 8192 unless $blksize;
  18      $key =~ s/[^\w\s]//g if $dict;
  19      $key = lc $key if $fold;
  20      $max = int($size / $blksize);
  21      while ($max - $min > 1) {
  22      $mid = int(($max + $min) / 2);
  23      seek(FH,$mid * $blksize,0);
  24      $_ = <FH> if $mid;        # probably a partial line
  25      $_ = <FH>;
  26      chop;
  27      s/[^\w\s]//g if $dict;
  28      $_ = lc $_ if $fold;
  29      if ($_ lt $key) {
  30          $min = $mid;
  31      }
  32      else {
  33          $max = $mid;
  34      }
  35      }
  36      $min *= $blksize;
  37      seek(FH,$min,0);
  38      <FH> if $min;
  39      while (<FH>) {
  40      chop;
  41      s/[^\w\s]//g if $dict;
  42      $_ = lc $_ if $fold;
  43      last if $_ ge $key;
  44      $min = tell(FH);
  45      }
  46      seek(FH,$min,0);
  47      $min;
  48  }
  49  
  50  1;