[WWcvs] pg: Added isReduced method to tell if a Union, Set or Interval is

[dpvc v. a. <we...@ma...>]

Log Message:
-----------
Added isReduced method to tell if a Union, Set or Interval is already
reduced.  Fixed up sort to use CORE::sort, and added sort and reduce
to Intervals, which do nothing, but are there for consistency.

Modified Files:
--------------
    pg/lib/Value:
        Interval.pm
        Set.pm
        Union.pm

Revision Data
-------------
Index: Set.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Value/Set.pm,v
retrieving revision 1.5
retrieving revision 1.6
diff -Llib/Value/Set.pm -Llib/Value/Set.pm -u -r1.5 -r1.6
--- lib/Value/Set.pm
+++ lib/Value/Set.pm
@@ -186,6 +186,11 @@
   return scalar(@l) - scalar(@r);
 }
 
+############################################
+#
+#  Utility routines
+#
+
 #
 #  Remove redundant values
 #
@@ -201,11 +206,20 @@
 }
 
 #
+#  True if the set is reduced
+#
+sub isReduced {
+  my $self = shift;
+  return 1 if $self->{isReduced} || $self->length < 2;
+  return $self->reduce->length == $self->length;
+}
+
+#
 #  Sort the data for a set
 #
 sub sort {
   my $self = shift;
-  return $self->make(sort {$a <=> $b} $self->value);
+  return $self->make(CORE::sort {$a <=> $b} $self->value);
 }
 
 ###########################################################################
Index: Interval.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Value/Interval.pm,v
retrieving revision 1.24
retrieving revision 1.25
diff -Llib/Value/Interval.pm -Llib/Value/Interval.pm -u -r1.24 -r1.25
--- lib/Value/Interval.pm
+++ lib/Value/Interval.pm
@@ -225,6 +225,15 @@
   return $l->{close} cmp $r->{close};
 }
 
+############################################
+#
+#  Utility routines
+#
+
+sub reduce {shift}
+sub isReduced {1}
+sub sort {shift}
+
 ###########################################################################
 
 1;
Index: Union.pm
===================================================================
RCS file: /webwork/cvs/system/pg/lib/Value/Union.pm,v
retrieving revision 1.18
retrieving revision 1.19
diff -Llib/Value/Union.pm -Llib/Value/Union.pm -u -r1.18 -r1.19
--- lib/Value/Union.pm
+++ lib/Value/Union.pm
@@ -201,9 +201,12 @@
 
 ############################################
 #
-#  Reduce unions to simplest form
+#  Utility routines
 #
 
+#
+#  Reduce unions to simplest form
+#
 sub reduce {
   my $self = shift;
   return $self if $self->{isReduced} || $self->length < 2;
@@ -245,7 +248,21 @@
   return $pkg->make(@union)->with(isReduced=>1);
 }
 
-############################################
+#
+#  True if a union is reduced
+#
+sub isReduced {
+  my $self = shift;
+  return 1 if $self->{isReduced} || $self->length < 2;
+  my $reduced = $self->reduce;
+  return unless $reduced->type eq 'Union' && $reduced->length == $self->length;
+  my @R = $reduced->sort->value; my @S = $self->sort->value;
+  foreach my $i (0..$#R) {
+    return unless $R[$i] == $S[$i] && $R[$i]->length == $S[$i]->length;
+  }
+  return 1;
+}
+
 #
 #  Sort a union lexicographically
 #