/* Tuplr: A programming language
 * Copyright (C) 2008-2009 David Robillard <dave@drobilla.net>
 *
 * Tuplr is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * Tuplr 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 Affero General
 * Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Tuplr.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stack>
#include "tuplr.hpp"

#define FOREACH(IT, i, c) for (IT i = (c).begin(); i != (c).end(); ++i)

using namespace std;
using boost::format;

Funcs ASTConsCall::funcs;

std::ostream& err = std::cerr;
std::ostream& out = std::cout;

/***************************************************************************
 * S-Expression Lexer :: text -> S-Expressions (SExp)                      *
 ***************************************************************************/

SExp
readExpression(Cursor& cur, std::istream& in)
{
#define PUSH(s, t)  { if (t != "") { s.top().list.push_back(SExp(loc, t)); t = ""; } }
#define YIELD(s, t) { if (s.empty()) { return SExp(loc, t); } else PUSH(s, t) }
	stack<SExp> stk;
	string      tok;
	Cursor      loc; // start of tok
	while (char ch = in.get()) {
		++cur.col;
		switch (ch) {
		case EOF:
			if (!stk.empty()) throw Error("unexpected end of file", cur);
			return SExp(cur);
		case ';':
			while ((ch = in.get()) != '\n') {}
		case '\n':
			++cur.line; cur.col = 0;
		case ' ': case '\t':
			if (tok != "") YIELD(stk, tok);
			break;
		case '"':
			loc = cur;
			do { tok.push_back(ch); ++cur.col; } while ((ch = in.get()) != '"');
			YIELD(stk, tok + '"');
			break;
		case '(':
			stk.push(SExp(cur));
			break;
		case ')':
			switch (stk.size()) {
			case 0:
				throw Error("unexpected `)'", cur);
			case 1:
				PUSH(stk, tok);
				return stk.top();
			default:
				PUSH(stk, tok);
				SExp l = stk.top();
				stk.pop();
				stk.top().list.push_back(l);
			}
			break;
		default:
			if (tok == "") loc = cur;
			tok += ch;
		}
	}
	switch (stk.size()) {
	case 0:  return SExp(loc, tok);
	case 1:  return stk.top();
	default: throw  Error("missing `)'", cur);
	}
	return SExp(cur);
}