/*
 *	aegis - project change supervisor
 *	Copyright (C) 1996 Peter Miller;
 *	All rights reserved.
 *
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; either version 2 of the License, or
 *	(at your option) any later version.
 *
 *	This program is distributed in the hope that it will be useful,
 *	but WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *	GNU General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License
 *	along with this program; if not, write to the Free Software
 *	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 * MANIFEST: functions to manipulate exprs
 */

#include <sub.h>
#include <sub/expr.h>
#include <sub/expr_gram.h>
#include <str.h>
#include <trace.h>
#include <wstr_list.h>


wstring_ty *
sub_expression(scp, arg)
	sub_context_ty	*scp;
	wstring_list_ty	*arg;
{
	wstring_ty	*ws;
	string_ty	*s1;
	string_ty	*s2;
	wstring_ty	*result;

	/*
	 * Check the number of arguments
	 */
	trace(("sub_expression()\n{\n"/*}*/));
	if (arg->nitems < 2)
	{
		sub_context_error_set(scp, i18n("requires at least one argument"));
		trace(("return NULL;\n"));
		trace((/*{*/"}\n"));
		return 0;
	}

	/*
	 * Fold all of the arguments into a single string,
	 * and parse that string for an expression.
	 */
	ws = wstring_list_to_wstring(arg, 1, arg->nitems, " ");
	s1 = wstr_to_str(ws);
	trace(("s1 = \"%s\";\n", s1->str_text));
	wstr_free(ws);
	s2 = sub_expr_gram(scp, s1);
	str_free(s1);
	if (!s2)
	{
		trace(("return NULL;\n"));
		trace((/*{*/"}\n"));
		return 0;
	}

	/*
	 * Turns the result of the parse into a wide string.
	 */
	trace(("result = \"%s\";\n", s2->str_text));
	result = str_to_wstr(s2);
	str_free(s2);
	trace(("return %8.8lX;\n", (long)result));
	trace((/*{*/"}\n"));
	return result;
}