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1 | package Search::Dict; |
2 | require 5.000; |
3 | require Exporter; |
4 | |
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5 | use strict; |
6 | |
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7 | our $VERSION = '1.02'; |
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8 | our @ISA = qw(Exporter); |
9 | our @EXPORT = qw(look); |
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10 | |
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11 | =head1 NAME |
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12 | |
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13 | Search::Dict, look - search for key in dictionary file |
14 | |
15 | =head1 SYNOPSIS |
16 | |
17 | use Search::Dict; |
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18 | look *FILEHANDLE, $key, $dict, $fold; |
19 | |
20 | use Search::Dict; |
21 | look *FILEHANDLE, $params; |
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22 | |
23 | =head1 DESCRIPTION |
24 | |
25 | Sets file position in FILEHANDLE to be first line greater than or equal |
26 | (stringwise) to I<$key>. Returns the new file position, or -1 if an error |
27 | occurs. |
28 | |
29 | The flags specify dictionary order and case folding: |
30 | |
31 | If I<$dict> is true, search by dictionary order (ignore anything but word |
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32 | characters and whitespace). The default is honour all characters. |
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33 | |
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34 | If I<$fold> is true, ignore case. The default is to honour case. |
35 | |
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36 | If there are only three arguments and the third argument is a hash |
37 | reference, the keys of that hash can have values C<dict>, C<fold>, and |
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38 | C<comp> or C<xfrm> (see below), and their correponding values will be |
39 | used as the parameters. |
40 | |
41 | If a comparison subroutine (comp) is defined, it must return less than zero, |
42 | zero, or greater than zero, if the first comparand is less than, |
43 | equal, or greater than the second comparand. |
44 | |
45 | If a transformation subroutine (xfrm) is defined, its value is used to |
46 | transform the lines read from the filehandle before their comparison. |
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47 | |
48 | =cut |
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49 | |
50 | sub look { |
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51 | my($fh,$key,$dict,$fold) = @_; |
52 | my ($comp, $xfrm); |
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53 | if (@_ == 3 && ref $dict eq 'HASH') { |
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54 | my $params = $dict; |
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55 | $dict = 0; |
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56 | $dict = $params->{dict} if exists $params->{dict}; |
57 | $fold = $params->{fold} if exists $params->{fold}; |
58 | $comp = $params->{comp} if exists $params->{comp}; |
59 | $xfrm = $params->{xfrm} if exists $params->{xfrm}; |
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60 | } |
61 | $comp = sub { $_[0] cmp $_[1] } unless defined $comp; |
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62 | local($_); |
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63 | my(@stat) = stat($fh) |
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64 | or return -1; |
65 | my($size, $blksize) = @stat[7,11]; |
66 | $blksize ||= 8192; |
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67 | $key =~ s/[^\w\s]//g if $dict; |
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68 | $key = lc $key if $fold; |
69 | # find the right block |
70 | my($min, $max) = (0, int($size / $blksize)); |
71 | my $mid; |
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72 | while ($max - $min > 1) { |
73 | $mid = int(($max + $min) / 2); |
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74 | seek($fh, $mid * $blksize, 0) |
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75 | or return -1; |
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76 | <$fh> if $mid; # probably a partial line |
77 | $_ = <$fh>; |
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78 | $_ = $xfrm->($_) if defined $xfrm; |
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79 | chomp; |
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80 | s/[^\w\s]//g if $dict; |
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81 | $_ = lc $_ if $fold; |
82 | if (defined($_) && $comp->($_, $key) < 0) { |
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83 | $min = $mid; |
84 | } |
85 | else { |
86 | $max = $mid; |
87 | } |
88 | } |
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89 | # find the right line |
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90 | $min *= $blksize; |
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91 | seek($fh,$min,0) |
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92 | or return -1; |
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93 | <$fh> if $min; |
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94 | for (;;) { |
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95 | $min = tell($fh); |
96 | defined($_ = <$fh>) |
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97 | or last; |
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98 | $_ = $xfrm->($_) if defined $xfrm; |
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99 | chomp; |
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100 | s/[^\w\s]//g if $dict; |
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101 | $_ = lc $_ if $fold; |
102 | last if $comp->($_, $key) >= 0; |
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103 | } |
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104 | seek($fh,$min,0); |
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105 | $min; |
106 | } |
107 | |
108 | 1; |