From aa069a875fec88c112476ab75448df55b2c93a66 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 2 Feb 2014 22:23:25 +0000
Subject: [PATCH] better msgs and default handling

---
 compute | 95 +++++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 65 insertions(+), 30 deletions(-)

diff --git a/compute b/compute
index 222c40f..45076cd 100755
--- a/compute
+++ b/compute
@@ -1,4 +1,12 @@
 #!/usr/bin/perl -w
+#
+# parses some input about ballots and computes the result according
+# to Debian Constitution A.6.
+#
+# usage: .../compute [<input files>...]
+#
+# 
+
 use strict;
 use utf8;
 use autodie;
@@ -19,7 +27,9 @@ our $quorum = 0;
 
 sub addchoice {
     my $choname = shift @_;
-    my $cho = $choices{$choname} = { @_, Index => (scalar @choices) };
+    my $cho = $choices{$choname} = {
+	@_, Index => (scalar @choices)
+    };
     push @choices, $choname;
     return $cho;
 }
@@ -43,30 +53,28 @@ while (<>) {
 	push @invotes_cc, [ $1, "$'" ];
     } elsif (m/^quorum = ([0-9.]+)$/) {
 	$quorum = $1+0.0;
+    } elsif (m/^nodefault$/) {
+	$defcho = { Index => -1 }
     } else {
 	die "invalid input";
     }
 }
 
-$defcho ||= $choices{FD};
-if (!$defcho) {
-    $defcho = addchoice('FD', Desc => "Further Discussion");
-}
-my $defi = $defcho->{Index};
-die "FD has smaj?!" if $defcho->{Smaj};
-
 our @vab;
 # $vab[$ia][$ib] = V(A,B)
 # Actually, it's a list of voters who prefer A to B (A.6(3)(1))
 
 # Go through the voters and construct V(A,B)
 
-print "\nPreference matrix\n";
+print "\nParsing \`simple' style ballots\n";
+# actually, we pre-parse them into @invotes_v
+# since we want to show them as a tally sheet anyway
 
 foreach my $iv (@invotes_cc) {
     $_ = uc $iv->[1];
     foreach my $chn (m/\b\w+\b/g) {
-	$choices{$chn} or addchoice($chn, Desc => "($chn from voter ballot)");
+	next if $choices{$chn};
+	addchoice($chn, Desc => "($chn from voter ballot)");
     }
 }
 
@@ -88,7 +96,7 @@ foreach my $iv (@invotes_cc) {
     foreach (split /\s+/) {
 	foreach (split /=/) {
 	    my $cho = $choices{$_};
-	    $cho or die "unknown option $_ ($voter)";
+	    $cho or die "unknown choice $_ ($voter)";
 	    my $ix = $cho->{Index};
 	    $ranks[$ix] = $rank;
 	}
@@ -103,6 +111,29 @@ foreach my $iv (@invotes_cc) {
     push @invotes_v, [ $vstr, $voter ];
 }
 
+print "\nDetermining default option\n";
+
+if ($defcho && $defcho->{Index} > -1) {
+    print "default option was specified: $choices[$defcho->{Index}]\n";
+} elsif ($defcho) {
+    print "no default option\n";
+} else {
+    foreach my $try (qw(FD SQ NOTA)) {
+	$defcho = $choices{$try};
+	last if $defcho;
+    }
+    if ($defcho) {
+	print "guessed default option was: $choices[$defcho->{Index}]\n";
+    } else {
+	print "could not guess default option, assuming there is none\n";
+    }
+}
+
+my $defi = $defcho->{Index};
+die "FD has smaj?!" if $defcho->{Smaj};
+
+print "\nParsing devotee tally sheet ballots\n";
+
 foreach my $iv (@invotes_v) {
     my ($votestr,$voter) = @$iv;
     eval {
@@ -130,6 +161,8 @@ foreach my $iv (@invotes_v) {
     die "voter $voter $@" if $@;
 }
 
+print "\nPreference matrix\n";
+
 our @ch = map { $choices{$_} } @choices;
 
 # Print the counts V(A,B)
@@ -168,27 +201,29 @@ sub drop ($$) {
     $ch[$i]{Dropped} = $why;
 }
 
-print "\nQuorum A.6(2) (quorum is $quorum)\n";
+if (defined $defi) {
+    print "\nQuorum A.6(2) (quorum is $quorum)\n";
 
-foreach my $i (0..$#choices) {
-    next if $ch[$i]{Dropped};
-    next if $i == $defi;
-    my $v = $vab[$i][$defi];
-    next if $v >= $quorum;
-    drop $i, "quorum ($v < $quorum)";
-}
+    foreach my $i (0..$#choices) {
+	next if $ch[$i]{Dropped};
+	next if $i == $defi;
+	my $v = $vab[$i][$defi];
+	next if $v >= $quorum;
+	drop $i, "quorum ($v < $quorum)";
+    }
 
-print "\nMajority ratio A.6(3)\n";
-
-foreach my $i (0..$#choices) {
-    next if $ch[$i]{Dropped};
-    next if $i == $defi;
-    my $majr = $ch[$i]{Smaj};
-    $majr ||= [1,1]; # A.6(3)(3)
-    my $vad = scalar @{ $vab[$i][$defi] };
-    my $vda = scalar @{ $vab[$defi][$i] };
-    next if $vad * $majr->[1] > $vda * $majr->[0];
-    drop $i, "majority ratio ($vad * $majr->[1] <= $vda * $majr->[0])";
+    print "\nMajority ratio A.6(3)\n";
+
+    foreach my $i (0..$#choices) {
+	next if $ch[$i]{Dropped};
+	next if $i == $defi;
+	my $majr = $ch[$i]{Smaj};
+	$majr ||= [1,1]; # A.6(3)(3)
+	my $vad = scalar @{ $vab[$i][$defi] };
+	my $vda = scalar @{ $vab[$defi][$i] };
+	next if $vad * $majr->[1] > $vda * $majr->[0];
+	drop $i, "majority ratio ($vad * $majr->[1] <= $vda * $majr->[0])";
+    }
 }
 
 print "\nDefeats A.6(4)\n";
-- 
2.30.2