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 $key.  Pass flags for dictionary order and case folding.
11
12sub look {
13    local(*FH,$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
501;
51