sub maybe_new_scope {

#	if the "enter new scope" rule for the current scope fires then
#	    find a scope whose "can enter" fires
#	    push the scope
#	    fire the "on enter" rule for the new scope

    my $ruleset = $rulesets{$rulestack[-1]};
    my $enter_rule = $ruleset->{maybe_push_scope};

    if ( &$enter_rule() ) {
		print "$rulestack[-1].enter_new_scope true\n" if $DEBUG;

		foreach my $rulesetname ( keys %rulesets ) {
		    $ruleset = $rulesets{$rulesetname};
		    my $can_enter_rule = $ruleset->{can_enter};
            if ( &$can_enter_rule() ) {
				print "$rulesetname.can_enter true\n" if $DEBUG;
		
				my $on_enter_rule = $ruleset->{on_enter};
				&$on_enter_rule();
		
				push @rulestack, $rulesetname;
				push @indentstack, $indent;
		    }	    
		}
    }

    return 0;
}

sub maybe_exit_scope {

#	if the "exit scope" rule for the current scope fires then
#	    fire the "on exit" rule for the current scope
#	    (pop)

    my $ruleset = $rulesets{$rulestack[-1]};
    my $maybe_exit_rule = $ruleset->{maybe_exit_scope};

    if ( &$maybe_exit_rule() ) {
		print "$rulestack[-1].maybe_exit_scope true\n" if $DEBUG;
	
		my $on_exit = $ruleset->{on_exit};
	        &$on_exit();
	
		$prevtype = 0;	# reprime the pump for maybe_emit_markup
	
		pop @rulestack;
		pop @indentstack;
	
		return 1;
    }

    return 0;
}