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lib/Math/SymbolicX/Calculator.pm  view on Meta::CPAN

use warnings;

use Params::Util qw/_INSTANCE/;

use Math::Symbolic ();
use Math::Symbolic::Custom::Transformation;
require Math::SymbolicX::Calculator::Command;

our $VERSION = '0.02';

use vars qw/$Identifier_Regex/;
$Identifier_Regex = qr/[a-zA-Z][a-zA-Z_0-9]*/;

=encoding utf8

=head1 NAME

Math::SymbolicX::Calculator - A representation of a Symbolic Calculator

=head1 SYNOPSIS

  # You probably want to use on of the interfaces instead such as
  # Math::SymbolicX::Calculator::Interface::Shell

  use Math::SymbolicX::Calculator;
  my $calc = Math::SymbolicX::Calculator->new();
  my $cmd = $calc->new_command(...);
  # ...
  $calc->execute($cmd);

=head1 DESCRIPTION

This class represents the state of a symbolic calculator. It is mainly
a glorified state hash of variables and their contents.

It can execute commands which are represented by
L<Math::SymbolicX::Calculator::Command> objects and which operate
on the symbol table on some way.

Any slot of the symbol table may either contain a L<Math::Symbolic> tree
or a L<Math::Symbolic::Custom::Transformation> object.

=head1 METHODS

=cut

=head2 new

Returns a new Calculator object.

=cut

sub new {
    my $proto = shift;
    my $class = ref($proto)||$proto;

    my $self = {
        stash => {},
        history => [],
    };
    bless $self => $class;

    return $self;
}


=head2 new_command

This method is a short-cut to
L<Math::SymbolicX::Calculator::Command>'s C<new> method and
creates a new command object which can be executed using the
Calculator object.

=cut

sub new_command {
    my $self = shift;
    return Math::SymbolicX::Calculator::Command->new(@_);
}

=head2 execute

Executes the command given as first argument. The command should be a
L<Math::SymbolicX::Calculator::Command> object. Returns any
return values of the command's execution. (This may be a list!)

=cut

sub execute {
    my $self = shift;
    my $cmd = shift;
    
    my @output = $cmd->_execute($self);
    return @output;
}

=head2 stash

Accesses the symbol table hash with the symbol name given as first
argument. Valid symbol names match the regex C</[A-Za-z][A-Za-z0-9_]*/>.

(This is read only.)

=cut

sub stash {
    my $self = shift;
    my $sym = shift;
    return $self->{stash}{$sym};
}

=head2 get_transformation

First argument must be a symbol name. Accesses the Calculator symbol table
to fetch a transformation from it that is saved as the symbol.

If the smybol table contains a transformation in the specified slot,
that transformation is returned.

If it contains a formula, it manufactures a transformation from that
formula which amounts to replacing the specified symbol with