Index: perl/lib/BarnOwl/Completion.pm
===================================================================
--- perl/lib/BarnOwl/Completion.pm	(revision 8eac1a5be01a70875c0d351ef12d9ab5f2cc0b76)
+++ perl/lib/BarnOwl/Completion.pm	(revision 8eac1a5be01a70875c0d351ef12d9ab5f2cc0b76)
@@ -0,0 +1,20 @@
+use warnings;
+use strict;
+
+=head1 NAME
+
+BarnOwl::Completion
+
+=head1 DESCRIPTION
+
+Hooks for tab-completion support in BarnOwl.
+
+=cut
+
+package BarnOwl::Completion;
+
+use BarnOwl::Completion::Context;
+
+
+
+1;
Index: perl/lib/BarnOwl/Completion/Context.pm
===================================================================
--- perl/lib/BarnOwl/Completion/Context.pm	(revision 8eac1a5be01a70875c0d351ef12d9ab5f2cc0b76)
+++ perl/lib/BarnOwl/Completion/Context.pm	(revision 8eac1a5be01a70875c0d351ef12d9ab5f2cc0b76)
@@ -0,0 +1,131 @@
+use warnings;
+use strict;
+
+=head1 NAME
+
+BarnOwl::Completion::Context
+
+=head1 DESCRIPTION
+
+BarnOwl::Completion::Context is the context that is passed to a
+completion function by BarnOwl. It contains information on the text
+being completed.
+
+=head1 METHODS
+
+=head2 line
+
+The entire command-line currently being completed.
+
+=head2 point
+
+The index of the cursor in C<line>, in the range C<[0,len($line)]>.
+
+=head2 words
+
+The current command-line, tokenized according to BarnOwl's
+tokenization rules, as an array reference.
+
+=head2 word
+
+The current word the point is sitting in, as an index into C<words>.
+
+=head2 word_point
+
+The index of the point within C<$words->[$word]>.
+
+=cut
+
+package BarnOwl::Completion::Context;
+
+use base qw(Class::Accessor::Fast);
+
+__PACKAGE__->mk_ro_accessors(qw(line point words word word_point));
+
+sub new {
+    my $class = shift;
+    my $before_point = shift;
+    my $after_point = shift;
+
+    my $line  = $before_point . $after_point;
+    my $point = length ($before_point);
+    my ($words, $word, $word_point) = tokenize($line, $point);
+
+    my $self = {
+        line  => $line,
+        point => $point,
+        words => $words,
+        word  => $word,
+        word_point => $word_point
+       };
+    return bless($self, $class);
+}
+
+=for doc
+
+Ideally, this should use the same codepath we use to /actually/
+tokenize commands, but for now, make sure this is kept in sync with
+owl_parseline in util.c
+
+Unlike owl_parseline, we always return a result, even in the presence
+of parse errors, since we may be called on incomplete command-lines.
+
+The owl_parseline rules are:
+
+* Tokenize on ' ' and '\t'
+* ' and " are quote characters
+* \ has no effect
+
+=cut
+
+my $boring = qr{[^'" \t]};
+my $quote  = qr{['"]};
+my $space  = qr{[ \t]};
+
+sub tokenize {
+    my $line = shift;
+    my $point = shift;
+
+    my @words = ();
+    my $cword = 0;
+    my $word_point;
+
+    my $word = '';
+    my $skipped = 0;
+
+    pos($line) = 0;
+    while(pos($line) < length($line)) {
+        if($line =~ m{\G ($boring+) }gcx) {
+            $word .= $1;
+        } elsif ($line =~ m{\G ($quote)}gcx) {
+            my $chr = $1;
+            $skipped++ if pos($line) > $point;
+            if($line =~ m{\G ([^$chr]*) $chr}gcx) {
+                $word .= $1;
+                $skipped++ if pos($line) > $point;
+            } else {
+                $word .= substr($line, pos($line));
+                pos($line) = length($line);
+            }
+        }
+
+        if ($line =~ m{\G ($space+|$)}gcx) {
+            my $wend = pos($line) - length($1);
+            push @words, $word;
+            $cword++ unless $wend >= $point;
+            if ($wend >= $point && !defined($word_point)) {
+                $word_point = length($word) - ($wend - $point) + $skipped;
+            }
+            $word = '';
+            $skipped = 0;
+        }
+    }
+
+    if(length($word)) { die("Internal error, leftover=$word"); }
+
+    $word_point = 0 unless defined($word_point);
+
+    return (\@words, $cword, $word_point);
+}
+
+1;
