############################
### ALF reader interface ###
############################

sub ALF_CreateData {	local($parent) = @_;	### creates ALF database from lexical tokens, using $parent as root and name generator. Returns true
	print("# System Message:\tstarted adding contents to ALF database \47$parent\47 ",&DateTime,"\n");
	local $firstline = $ALF_FirstLine{$parent};
	local $token = $firstline? $ALF_ParserIndex[$firstline-1] + 2 : 0;
	&AutoNameStart($parent,$AutoNameCount);
	$ALF_Children{$parent} = &CreateArray() unless defined($ALF_Children{$parent});
	&StringMatch($ALF_ParserData[$token+0],'ALF_REVISION') 
	&& (	$ALF_ParserData[$token+1] =~ /$ALF_string_value/
	||	&ALF_SyntaxError('ALF_REVISION',$token+1)
	) &&	($AutoFirstLine = "ALF_REVISION ".$ALF_ParserData[$token+1]."\n// ")
	&&	&ALF_SyntaxItems('ALF_statement',$token+2,$parent,1,1)
	||	&ALF_SyntaxItems('ALF_statement',$token+0,$parent,1,1);
	print("# System Message:\tfinished adding contents to ALF database \47$parent\47 ",&DateTime,"\n");
	1;
}

sub ALF_SyntaxItems {	local($rule,$token,$object,$openstart,$openend) = @_;	### evaluates syntax $rule related to children{$object} from '{' to '}'. Does not check for '{' if $openstart. Does not check for '}' if $openend. Returns token at end of evaluation.
	local $continue = 1;
	local $nexttoken = $token;
### check for ';' or for '{'
	unless ($openstart) {
		if (&StringMatch($ALF_ParserData[$token],';')) {
	### object is atomic
			print("# ALF Data Info:\tobject $object is atomic\n") if ($ALF_Debug > 1);
			$token = 0;
		} else {
	### object is compound
			print("# ALF Data Info:\tobject $object is compound\n") if ($ALF_Debug > 1);
			$nexttoken = $token + 1;
			$ALF_Children{$object} = &CreateArray();
			&ALF_SyntaxError($rule,$token) unless &StringMatch($ALF_ParserData[$token],'{');
		}
		$continue = $token;
	}
### evaluate until '}'
	while ($continue) {
		if (&StringMatch($ALF_ParserData[$nexttoken],'}')) {
			$token = 0;
		} else {
			print("# ALF Syntax Info:\tevaluating rule $rule\tdata[",$nexttoken,"]=\47",$ALF_ParserData[$nexttoken],"\47\n") if ($ALF_Debug > 1);
			$token = &Eval('ALF_'.$rule,$nexttoken,$object);
			$token = &ALF_SyntaxError($rule,$nexttoken) unless ($token || $openend);
			$nexttoken = $token + 1 if $token;
		}
		if ($token) {
			print("# ALF Syntax Info:\tsatisfying rule $rule \tdata[$token]=\47",$ALF_ParserData[$token],"\47\n") if ($ALF_Debug > 1);
		}
		$continue = $token;
	}
	$nexttoken;
}

sub ALF_AssertExpressionRule {	local($rule,$token,$list) = @_;
	print("# ALF Syntax Info:\tparsed rule \47$rule\47 at $token\n") if ($ALF_Debug > 1);
	if (defined($list) && ! &FindAssocKey('ALF_ExpressionToken',$token)) {
		local $next = &AutoName;
		$ALF_ExpressionRule{$next} = $rule;
		$ALF_ExpressionToken{$next} = $token;
		&AppendArray($list,$next);
#print("\tparser rule = (",join(' ',&Array($list)),")\n");
	} 1;
}

sub ALF_ExpressionData {	local ($item) = @_;
	local $rule  = $ALF_ExpressionRule{$item};
	local $token = $ALF_ExpressionToken{$item};
	($ALF_ParserData[$token],$rule,$token);
}

1;