View of /trunk/pg/lib/Parser/Number.pm

    1 #########################################################################
    2 #
    3 #  Implements the Number class
    4 #
    5 package Parser::Number;
    6 use strict;
    7 our @ISA = qw(Parser::Item);
    8 
    9 $Parser::class->{Number} = 'Parser::Number';
   10 
   11 sub new {
   12   my $self = shift; my $class = ref($self) || $self;
   13   my $equation = shift; my $context = $equation->{context};
   14   my ($value,$ref) = @_;
   15   return $self->Item("Complex",$context)->new($equation,$value,$ref)
   16     if (ref($value) eq 'ARRAY');
   17   $value = $value->value while Value::isReal($value);
   18   my $num = bless {
   19     value => $value + 0, # format the value as a number, just in case
   20     value_string => $value, # for decimal checking, etc.
   21     type => $Value::Type{number}, isConstant => 1,
   22     ref => $ref, equation => $equation,
   23   }, $class;
   24   $num->weaken;
   25   my $x = $num->Package("Real")->make($context,$value);
   26   $num->{isOne}  = 1 if $x eq 1;
   27   $num->{isZero} = 1 if $value == 0;
   28   return $num;
   29 }
   30 
   31 #
   32 #  We know the answers to these, so no need to compute them
   33 #
   34 sub isComplex {0}
   35 sub isNumber {1}
   36 sub isRealNumber {1}
   37 
   38 #
   39 #  Return the value
   40 #
   41 sub eval {(shift)->{value}}
   42 
   43 #
   44 #  If the number is negative, factor it out and
   45 #    try using that in the reductions of the parent objects.
   46 #
   47 sub reduce {
   48   my $self = shift; my $context = $self->context;
   49   my $reduce = $context->{reduction};
   50   if ($reduce->{'-n'} && $self->{value} < 0) {
   51     $self->{value} = -($self->{value});
   52     $self = Parser::UOP::Neg($self);
   53     $self->{op}{isOne} = 1 if $self->Package("Real")->make($context,$self->{op}{value}) eq 1;
   54   }
   55   return $self;
   56 }
   57 
   58 $Parser::reduce->{'-n'} = 1;
   59 
   60 
   61 #
   62 #  Call the Value::Real versions to format numbers
   63 #
   64 sub string {
   65   my $self = shift;
   66   $self->Package("Real")->make($self->context,$self->{value})->string($self->{equation},@_);
   67 }
   68 sub TeX {
   69   my $self = shift;
   70   $self->Package("Real")->make($self->context,$self->{value})->TeX($self->{equation},@_);
   71 }
   72 sub perl {
   73   my $self = shift; my $parens = shift;
   74   my $n = $self->{value};
   75   $n = '('.$n.')' if $parens && $n < 0;
   76   return $n;
   77 }
   78 
   79 ###########################################
   80 
   81 sub NoDecimals {
   82   my $context = shift || Value->context;
   83   $context->flags->set(NumberCheck=>\&_NoDecimals);
   84 }
   85 
   86 sub _NoDecimals {
   87   my $self = shift;
   88   $self->Error("You are not allowed to type decimal numbers in this problem")
   89     unless $self->{value_string} =~ m/^[-+]?[0-9]+$/;
   90 }
   91 
   92 
   93 #########################################################################
   94 
   95 1;