combine

   1 #!/usr/bin/perl
   2
   3 =head1 NAME
   4
   5 combine - combine sets of lines from two files using boolean operations
   6
   7 =head1 SYNOPSIS
   8
   9 combine file1 and file2
  10
  11 combine file1 not file2
  12
  13 combine file1 or file2
  14
  15 combine file1 xor file2
  16
  17 _ file1 and file2 _
  18
  19 _ file1 not file2 _
  20
  21 _ file1 or file2 _
  22
  23 _ file1 xor file2 _
  24
  25 =head1 DESCRIPTION
  26
  27 B<combine> combines the lines in two files. Depending on the boolean
  28 operation specified, the contents will be combined in different ways:
  29
  30 =over 4
  31
  32 =item and
  33
  34 Outputs lines that are in file1 if they are also present in file2.
  35
  36 =item not
  37
  38 Outputs lines that are in file1 but not in file2.
  39
  40 =item or
  41
  42 Outputs lines that are in file1 or file2.
  43
  44 =item xor
  45
  46 Outputs lines that are in either file1 or file2, but not in both files.
  47
  48 =back
  49
  50 "-" can be specified for either file to read stdin for that file.
  51
  52 The input files need not be sorted, and the lines are output in the order
  53 they occur in file1 (followed by the order they occur in file2 for the two
  54 "or" operations). Bear in mind that this means that the operations are not
  55 commutative; "a and b" will not necessarily be the same as "b and a". To
  56 obtain commutative behavior sort and uniq the result.
  57
  58 Note that this program can be installed as "_" to allow for the syntactic
  59 sugar shown in the latter half of the synopsis (similar to the test/[
  60 command). It is not currently installed as "_" by default, but you can
  61 alias it to that if you like.
  62
  63 =head1 SEE ALSO
  64
  65 join(1)
  66
  67 =head1 AUTHOR
  68
  69 Copyright 2006 by Joey Hess <id@joeyh.name>
  70
  71 Licensed under the GNU GPL.
  72
  73 =cut
  74
  75 use warnings;
  76 use strict;
  77
  78 sub filemap {
  79         my $file=shift;
  80         my $sub=shift;
  81
  82         open (IN, $file) || die "$file: $!\n";
  83         while (<IN>) {
  84                 chomp;
  85                 $sub->();
  86         }
  87         close IN;
  88 }
  89
  90 sub hashify {
  91         my $file=shift;
  92
  93         my %seen;
  94         filemap $file, sub { $seen{$_}++ };
  95         return \%seen;
  96 }
  97
  98 sub compare_or {
  99         my ($file1, $file2) = @_;
 100
 101         filemap $file1, sub { print "$_\n" };
 102         filemap $file2, sub { print "$_\n" };
 103 }
 104
 105 sub compare_xor {
 106         my ($file1, $file2) = @_;
 107
 108         my (@lines2, %seen2);
 109         filemap $file2,
 110                 sub {
 111                         push @lines2, $_;
 112                         $seen2{$_} = 1;
 113                 };
 114
 115         # Print all lines in file1 that are not in file2,
 116         # and mark lines that are in both files by setting
 117         # their value in %seen2 to 0.
 118         filemap $file1,
 119                 sub {
 120                         if (exists $seen2{$_}) {
 121                                 $seen2{$_} = 0;
 122                         }
 123                         else {
 124                                 print "$_\n";
 125                         }
 126                 };
 127
 128         # Print all lines that are in file2 but not in file1.
 129         # The value of these lines in seen2 is set to 1.
 130         foreach (@lines2) {
 131                 print "$_\n" if $seen2{$_};
 132         }
 133 }
 134
 135 sub compare_not {
 136         my ($file1, $file2) = @_;
 137
 138         my $seen=hashify($file2);
 139         filemap $file1, sub { print "$_\n" unless $seen->{$_} };
 140 }
 141
 142 sub compare_and {
 143         my ($file1, $file2) = @_;
 144
 145         my $seen=hashify($file2);
 146         filemap $file1, sub { print "$_\n" if $seen->{$_} };
 147 }
 148
 149 if (@ARGV >= 4 && $ARGV[3] eq "_") {
 150         delete $ARGV[3];
 151 }
 152
 153 if (@ARGV != 3) {
 154         die "Usage: combine file1 OP file2\n";
 155 }
 156
 157 my $file1=shift;
 158 my $op=lc shift;
 159 my $file2=shift;
 160
 161 if ($::{"compare_$op"}) {
 162         no strict 'refs';
 163         "compare_$op"->($file1, $file2);
 164 }
 165 else {
 166         die "unknown operation, $op\n";
 167 }