Commit | Line | Data |
---|---|---|
a687059c LW |
1 | ;# Usage: &look(*FILEHANDLE,$key,$dict,$fold) |
2 | ||
3 | ;# Sets file position in FILEHANDLE to be first line greater than or equal | |
4 | ;# (stringwise) to $key. Pass flags for dictionary order and case folding. | |
5 | ||
6 | sub look { | |
fe14fcc3 | 7 | local(*FH,$key,$dict,$fold) = @_; |
a687059c LW |
8 | local($max,$min,$mid,$_); |
9 | local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime, | |
10 | $blksize,$blocks) = stat(FH); | |
11 | $blksize = 8192 unless $blksize; | |
12 | $key =~ s/[^\w\s]//g if $dict; | |
55497cff | 13 | $key = lc $key if $fold; |
ac58e20f LW |
14 | $max = int($size / $blksize); |
15 | while ($max - $min > 1) { | |
16 | $mid = int(($max + $min) / 2); | |
17 | seek(FH,$mid * $blksize,0); | |
18 | $_ = <FH> if $mid; # probably a partial line | |
a687059c LW |
19 | $_ = <FH>; |
20 | chop; | |
21 | s/[^\w\s]//g if $dict; | |
55497cff | 22 | $_ = lc $_ if $fold; |
a687059c LW |
23 | if ($_ lt $key) { |
24 | $min = $mid; | |
25 | } | |
26 | else { | |
27 | $max = $mid; | |
28 | } | |
29 | } | |
ac58e20f | 30 | $min *= $blksize; |
a687059c | 31 | seek(FH,$min,0); |
ac58e20f | 32 | <FH> if $min; |
a687059c LW |
33 | while (<FH>) { |
34 | chop; | |
35 | s/[^\w\s]//g if $dict; | |
55497cff | 36 | $_ = lc $_ if $fold; |
a687059c LW |
37 | last if $_ ge $key; |
38 | $min = tell(FH); | |
39 | } | |
40 | seek(FH,$min,0); | |
41 | $min; | |
42 | } | |
43 | ||
44 | 1; |