#!/usr/bin/perl
package SexprNode;

use strict; use warnings;

sub new {
    my $class = shift;
    my $sexprnode = {_succ => [], _pred => undef, _label => shift, _start => -1, _end=> -1};
    bless $sexprnode, $class;
    return $sexprnode;
}

sub label {
    my $sexrpn = shift;
    return $sexrpn->{_label};
}

sub attachsexprn {
    my $predn = shift;
    my $succn = shift;
    push @{$predn->{_succ}}, $succn;
    $succn->{_pred} = $predn;
}

sub DESTROY {
    my $sexprn = shift;
    foreach my $n (@{$sexprn->{_succ}}){
	$n->DESTROY;
    }
    $sexprn->{_succ} = undef;
    $sexprn->{_pred} = undef;
}

sub dfs {
	my $sexprn = shift;
	if (defined($sexprn->{_succ})){
		return ($sexprn, map { $_->dfs } @{$sexprn->{_succ}});
	}else{
		return $sexprn;
	}
}
sub prettystring {
	my $sexprn = shift;
	my $indent = shift;
	my $prettys;
	if (!@{$sexprn->{_succ}}){
		$prettys .= '(' . $sexprn->{_label} . ') ';
	}else{
		$prettys = '(' . $sexprn->{_label} . ' ';
		my $whitespace = '';
		foreach my $n (@{$sexprn->{_succ}}){
			if (!@{$n->{_succ}}){
				$prettys .= $whitespace . $n->prettystring('');
				$whitespace = '';
			}else{
				$whitespace = "\n" . $indent;
				$prettys .= $whitespace . $n->prettystring($indent . '  ');
			}
		}
		$prettys .= ')';
	}
	return $prettys;
}
1;