perl 3.0 patch #10 patch #9, continued

[p5sagit/p5-mst-13.2.git] / lib / look.pl

;# Usage: &look(*FILEHANDLE,$key,$dict,$fold)

;# Sets file position in FILEHANDLE to be first line greater than or equal
;# (stringwise) to $key.  Pass flags for dictionary order and case folding.

sub look {
    local(*FH,$key,$fold) = @_;
    local($max,$min,$mid,$_);
    local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,
       $blksize,$blocks) = stat(FH);
    $blksize = 8192 unless $blksize;
    $key =~ s/[^\w\s]//g if $dict;
    $key =~ y/A-Z/a-z/ if $fold;
    $max = $size + $blksize - 1;
    $max -= $size % $blksize;
    while ($max - $min > $blksize) {
	$mid = ($max + $min) / 2;
	die "look: internal error"  if $mid % $blksize;
	seek(FH,$mid,0);
	$_ = <FH>;		# probably a partial line
	$_ = <FH>;
	chop;
	s/[^\w\s]//g if $dict;
	y/A-Z/a-z/ if $fold;
	if ($_ lt $key) {
	    $min = $mid;
	}
	else {
	    $max = $mid;
	}
    }
    seek(FH,$min,0);
    while (<FH>) {
	chop;
	s/[^\w\s]//g if $dict;
	y/A-Z/a-z/ if $fold;
	last if $_ ge $key;
	$min = tell(FH);
    }
    seek(FH,$min,0);
    $min;
}

1;