Merge pull request #1025 from Alex-Jordan/reduce-mnx

reduction rule for m(nx)->(mn)x

Author: drgrice1

lib/Parser/BOP.pm

@@ -302,6 +302,32 @@ sub swapOps {
 	return $self;
 }
 
+#
+#  Change an association "(a bop b) bop c" to "a bop (b bop c)" or vice versa
+#  argument $dir should be 'left' or 'right'
+#  'left'  for "a bop (b bop c)" to become "(a bop b) bop c"
+#  'right' for "(a bop b) bop c" to become "a bop (b bop c)"
+#  Assumes the calling entity verified it is appropriate to associate
+#
+sub associateOps {
+	my $self = shift;
+	my $dir  = shift;
+	if ($dir eq 'left') {
+		return $self->Item('BOP')->new(
+			$self->{equation}, $self->{bop},
+			$self->Item('BOP')->new($self->{equation}, $self->{bop}, $self->{lop}, $self->{rop}{lop})->reduce,
+			$self->{rop}{rop}
+		)->reduce;
+	} else {
+		return $self->Item('BOP')->new(
+			$self->{equation},
+			$self->{lop}{bop},
+			$self->{lop}{lop},
+			$self->Item('BOP')->new($self->{equation}, $self->{bop}, $self->{lop}{rop}, $self->{rop})
+		)->reduce;
+	}
+}
+
 #
 #  Get the variables from the two operands
 #

lib/Parser/BOP/multiply.pm

@@ -68,6 +68,11 @@ sub _reduce {
 	$self->swapOps
 		if (($self->{rop}->class eq 'Number' && $self->{lop}->class ne 'Number' && $reduce->{'x*n'})
 			|| ($self->{lop}->class eq 'Function' && $self->{rop}->class ne 'Function' && $reduce->{'fn*x'}));
+	$self = $self->associateOps('left')
+		if ($reduce->{'m*(n*x)'}
+			&& $self->{lop}->class eq 'Number'
+			&& $self->{rop}->isa('Parser::BOP::multiply')
+			&& $self->{rop}{lop}->class eq 'Number');
 	return $self;
 }
 
@@ -78,14 +83,15 @@ sub makeNeg {
 	return $self;
 }
 
-$Parser::reduce->{'1*x'}    = 1;
-$Parser::reduce->{'x*1'}    = 1;
-$Parser::reduce->{'0*x'}    = 1;
-$Parser::reduce->{'x*0'}    = 1;
-$Parser::reduce->{'(-x)*y'} = 1;
-$Parser::reduce->{'x*(-y)'} = 1;
-$Parser::reduce->{'x*n'}    = 1;
-$Parser::reduce->{'fn*x'}   = 1;
+$Parser::reduce->{'1*x'}     = 1;
+$Parser::reduce->{'x*1'}     = 1;
+$Parser::reduce->{'0*x'}     = 1;
+$Parser::reduce->{'x*0'}     = 1;
+$Parser::reduce->{'(-x)*y'}  = 1;
+$Parser::reduce->{'x*(-y)'}  = 1;
+$Parser::reduce->{'x*n'}     = 1;
+$Parser::reduce->{'fn*x'}    = 1;
+$Parser::reduce->{'m*(n*x)'} = 1;
 
 sub string {
 	my ($self, $precedence, $showparens, $position, $outerRight) = @_;