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lib/Acme/AlgebraicToRPN.pm  view on Meta::CPAN

    $rpn =~ s/\s//g;
    ./_Eval($rpn);
    my @result = ./_Cleanup();
    # reset, ready for next equation
    $.stack = [];
    return @result;
}

=head2 B<rpn_as_string>

  $stack = $al->rpn($expr);

Same as B<rpn>, but returns as a comma-separated list. Split on
commas, and you have your stack to be processed.

=cut

sub rpn_as_string {
    my ($self, $algebraic) = @_;
    my @result = ./rpn($algebraic);
    return join(",", @result);
}

sub _Cleanup {
    my ($self) = @_;
    my @Stack;
    map {
        $_ =~ s/^,//;
        if ($_ ne '') {
            my (@c) = split(',', $_);
            if (@c) {
                s/\s//g foreach @c;
                push(@Stack, @c);
            }
            else {
                push(@Stack, $_);
            }
        }
    } @{$.stack};
    return @Stack;
}

sub _Eval {
    my ($self, $expr) = @_;
    return unless defined $expr;
    #print "Evaling $expr\n";
    if ($expr =~ /(.+?),(.+)/) {
        my $L = $1;
        my $R = $2;
        if ($L =~ /^\w+$/ && $R =~ /$RE{balanced}{-parens=>'()'}/) {
            #print "HERE $L\n";
            push(@{$.stack}, $L);
        }
    }

    if ($expr =~ /(\w+)($RE{balanced}{-parens=>'()'})(.*)/) {
        my $op = $1;
        my $p  = $2;
        my $r  = $3;
        my $core = substr($p, 1, length($p)-2);
        if (defined $.userFunc && defined $.userFunc{$op}) {
            # count # of commas in arg list
            my $na = $core =~ tr/,/,/;
            # bump by one
            $na++;
            # add # of aguments on
            $core = qq($core,$na);
        }
        ./_Eval($core);
        push(@{$.stack}, $core) 
            unless $core =~ /$RE{balanced}{-parens=>'()'}/;
        push(@{$.stack}, $op);
        ./_Eval($r) 
            if defined $r && $r =~ /$RE{balanced}{-parens=>'()'}/;
        push(@{$.stack}, $r) 
            if defined $r && !($r =~ /$RE{balanced}{-parens=>'()'}/);
    }
}

=head2 B<check>

  $ok = $al->check(\@stack, @expected);

Checks result of RPN conversion. @stack is what the B<rpn> function
returned, and @expected is what you expected the result to be. This
is kind of a diagnostic routine for testing.

Returns 1 if both @stack and @expected were the same, 0 if not.

=cut

sub check {
    my ($self, $ref, @result) = @_;
    my @shouldbe = @$ref;
    return 0 unless @shouldbe == @result;
    my $same = 1;
    map {
        my $sb = shift(@shouldbe);
        $same = 0 unless $sb eq $_;
    } @result;
    return $same;
}

1; # End of Acme::AlgebraicToRPN