Commit | Line | Data |
a0d0e21e |
1 | package Search::Dict; |
2 | require 5.000; |
3 | require Exporter; |
4 | |
5 | @ISA = qw(Exporter); |
6 | @EXPORT = qw(look); |
7 | |
8 | # Usage: look(*FILEHANDLE,$key,$dict,$fold) |
9 | |
10 | # Sets file position in FILEHANDLE to be first line greater than or equal |
11 | # (stringwise) to $key. Pass flags for dictionary order and case folding. |
12 | |
13 | sub look { |
14 | local(*FH,$key,$dict,$fold) = @_; |
15 | local($max,$min,$mid,$_); |
16 | local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime, |
17 | $blksize,$blocks) = stat(FH); |
18 | $blksize = 8192 unless $blksize; |
19 | $key =~ s/[^\w\s]//g if $dict; |
20 | $key =~ tr/A-Z/a-z/ if $fold; |
21 | $max = int($size / $blksize); |
22 | while ($max - $min > 1) { |
23 | $mid = int(($max + $min) / 2); |
24 | seek(FH,$mid * $blksize,0); |
25 | $_ = <FH> if $mid; # probably a partial line |
26 | $_ = <FH>; |
27 | chop; |
28 | s/[^\w\s]//g if $dict; |
29 | tr/A-Z/a-z/ if $fold; |
30 | if ($_ lt $key) { |
31 | $min = $mid; |
32 | } |
33 | else { |
34 | $max = $mid; |
35 | } |
36 | } |
37 | $min *= $blksize; |
38 | seek(FH,$min,0); |
39 | <FH> if $min; |
40 | while (<FH>) { |
41 | chop; |
42 | s/[^\w\s]//g if $dict; |
43 | y/A-Z/a-z/ if $fold; |
44 | last if $_ ge $key; |
45 | $min = tell(FH); |
46 | } |
47 | seek(FH,$min,0); |
48 | $min; |
49 | } |
50 | |
51 | 1; |
52 | |