From 850e6582f48afb204e4f1d1710002a3bb6dac0a4 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ian@liberator.relativity.greenend.org.uk>
Date: Thu, 10 Sep 2009 01:52:40 +0100
Subject: [PATCH] Allow %age adjustments to capacity

---
 yarrg/web/check_capacitystring | 68 +++++++++++++++++++++-------------
 yarrg/web/docs                 | 17 ++++++---
 2 files changed, 55 insertions(+), 30 deletions(-)

diff --git a/yarrg/web/check_capacitystring b/yarrg/web/check_capacitystring
index ae1dec4..f001c79 100644
--- a/yarrg/web/check_capacitystring
+++ b/yarrg/web/check_capacitystring
@@ -87,6 +87,19 @@ print STDERR "PAN \`$string'\n";
 	return @mve;
 };
 
+my @mv_names= qw(mass volume);
+my $canon_numeric= $h->{'canon_numeric'}= sub {
+	print STDERR "CANNUM @_\n";
+	my $sep= '';
+	my $out= '';
+	foreach my $ix (qw(0 1)) {
+		next unless defined $_[$ix];
+		$out .= $sep; $sep= ' ';
+		$out .= sprintf "%g%s", $_[$ix], (qw(kg l))[$ix];
+	}
+	return $out;
+};
+
 $h->{'deltas'}= [ ];
 print STDERR "NDELTA0 $#{ $h->{'deltas'} }\n";
 
@@ -96,9 +109,29 @@ while (m/^(.*)(\bminus\b|-|\bplus\b|\+)/) {
 	print STDERR "TERM L=\`$1' M=\`$2' R=\`$''\n";
 	my ($signum,$signopstr)= 
 		$2 =~ m/^p|^\+/ ? (+1,'plus') : (-1,'minus');
-	my (@mve)= $parse_numeric->($rhs, 0);
-	${ $h->{Emsg} }= $mve[2] if defined $mve[2];
-	unshift @{ $h->{'deltas'} }, [ @mve,$signum,$signopstr ];
+	my @mveco;
+	if ($rhs =~ m/^\s*(\d{1,2}(?:\.\d{0,4})?)\%\s*$/) {
+		my $pct= 100.0 + $signum * $1;
+		@mveco= ($pct,$pct,undef);
+		push @mveco, sprintf "%s %g%%", $signopstr, $1;
+		push @mveco, sub {
+			return undef unless defined $_[0];
+			$_[0] * $_[1] / 100.0
+		};
+	} else {
+		@mveco= $parse_numeric->($rhs, 0);
+		if (!defined $mveco[2]) {
+			push @mveco, $signopstr.' '.$canon_numeric->(@mveco);
+			push @mveco, sub {
+				${ $h->{Emsg} }= "Cannot add or subtract".
+					" mass to/from volume"
+					unless defined $_[0];
+				$_[0] + $_[1] * $signum
+			};
+		}
+	}
+	${ $h->{Emsg} }= $mveco[2] if defined $mveco[2];
+	unshift @{ $h->{'deltas'} }, [ @mveco ];
 	print STDERR "NDELTA $#{ $h->{'deltas'} }\n";
 	$_= $lhs;
 }
@@ -143,30 +176,19 @@ $h
 </%args>
 <%perl>
 
-return if length ${ $h->{Emsg} };
-
-my @mv_names= qw(mass volume);
+my $canon_numeric= $h->{'canon_numeric'};
 
-my $canon_numeric= sub {
-	print STDERR "CANNUM @_\n";
-	my $sep= '';
-	my $out= '';
-	foreach my $ix (qw(0 1)) {
-		next unless defined $_[$ix];
-		$out .= $sep; $sep= ' ';
-		$out .= sprintf "%g%s", $_[$ix], (qw(kg l))[$ix];
-	}
-	return $out;
-};
+return if length ${ $h->{Emsg} };
 
 my @mv;
+my @mv_names= qw(mass volume);
 if (@{ $h->{Specs} }) {
 	@mv= @{ $h->{Results}[0] }[1,2];
-	print STDERR "INITIAL VESSEL @mv\n";
 } else {
 	@mv= @{ $h->{'initial'} };
 	${ $h->{Canon} }= $canon_numeric->(@mv);
 }
+print STDERR "INITIAL @mv\n";
 
 print STDERR "NDELTAE $#{ $h->{'deltas'} }\n";
 foreach my $delta (@{ $h->{'deltas'} }) {
@@ -175,14 +197,10 @@ foreach my $delta (@{ $h->{'deltas'} }) {
 	foreach my $ix (qw(0 1)) {
 		next unless defined $delta->[$ix];
 		print STDERR "DELTA I $ix\n";
-		if (!defined $mv[$ix]) {
-			${ $h->{Emsg} }= "Cannot add or subtract".
-				" $mv_names[$ix] to/from $mv_names[!$ix]";
-			return;
-		}
-		$mv[$ix] += $delta->[$ix] * $delta->[3];
+		$mv[$ix] = $delta->[4]->($mv[$ix], $delta->[$ix]);
+		return if length ${ $h->{Emsg} };
 	}
-	${ $h->{Canon} }.= " $delta->[4] ". $canon_numeric->(@$delta);
+	${ $h->{Canon} }.= ' '.$delta->[3];
 }
 
 if (@{ $h->{Specs} } || @{ $h->{'deltas'} }) {
diff --git a/yarrg/web/docs b/yarrg/web/docs
index 24d9f16..48a0062 100755
--- a/yarrg/web/docs
+++ b/yarrg/web/docs
@@ -114,23 +114,30 @@ So you should specify your vessel capacity.  You can enter things
 like:
 <dl>
 <dt>sloop
-<dd>The capacity of a sloop, exactly
+<dd>The capacity of a sloop, leaving no allowance for rum and shot
+<dt>sloop - 1%
+<dd>The capacity of a sloop minus 1%
 <dt>20t 13kl
-<dd>20 tonnes (20,000kg), 13 kilolitres (13,000l)
+<dd>13 tonnes (13,000kg), 20 kilolitres (20,000l)
 <dt>sloop - 100l 100kg
 <dd>The capacity of a sloop minus 100l, minus 100kg
 <dt>2t plus 500kg minus 200kg
 <dd>2300kg, with no limit on volume
 </dl>
+Evaluation is strictly from left to right.
+
+<p>
 
 Formally, the capacity is a list of terms, all but the first preceded
 by one of <kbd>-</kbd>, <kbd>minus</kbd>, <kbd>+</kbd>,
 <kbd>plus</kbd>.  Each term may specify a mass and/or a volume
 (separated by a space), as a number followed (without an intervening
 space) by a unit (<kbd>t</kbd>, <kbd>kg</kbd>, <kbd>kl</kbd> or
-<kbd>l</kbd>).  The first term may be a ship name or abbrevation
-instead.  If the first term specifies only one of mass or volume, all
-the subsequent terms may only adjust that same value.
+<kbd>l</kbd>).  Alternatively each term except the first may specify a
+percentage, which is applied as a percentage change to the answer from
+all the preceding terms.  The first term may be a ship name or
+abbrevation instead.  If the first term specifies only one of mass or
+volume, all the subsequent terms may only adjust that same value.
 
 <h3>Expected losses</h3>
 
-- 
2.30.2