/* 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/>.
 */

/** @file
 * @brief Parsing (build an AST from a SExp)
 */

#include "tuplr.hpp"

using namespace std;


/***************************************************************************
 * Macro Functions                                                         *
 ***************************************************************************/

inline SExp
macDef(PEnv& penv, const SExp& exp)
{
	SExp::const_iterator i = exp.begin();
	THROW_IF(i == exp.end(), exp.loc, "Unexpected end of `def' macro call");
	const SExp& name = *(++i);
	THROW_IF(i == exp.end(), name.loc, "Unexpected end of `def' macro call");
	if (name.type == SExp::ATOM) {
		return exp;
	} else {
		// (def (f x) y) => (def f (fn (x) y))
		SExp argsExp(exp.loc);
		SExp::const_iterator j = name.begin();
		for (++j; j != name.end(); ++j)
			argsExp.push_back(*j);
		const SExp& body = *(++i);
		SExp fnExp(body.loc);
		fnExp.push_back(SExp(body.loc, "fn"));
		fnExp.push_back(argsExp);
		for (; i != exp.end(); ++i)
			fnExp.push_back(*i);
		SExp ret(exp.loc);
		ret.push_back(exp.front());
		ret.push_back(name.front());
		ret.push_back(fnExp);
		return ret;
	}
}


/***************************************************************************
 * Parser Functions                                                        *
 ***************************************************************************/

template<typename C>
inline AST*
parseCall(PEnv& penv, const SExp& exp, void* arg)
{
	return new C(exp, penv.parseTuple(exp));
}

template<typename T>
inline AST*
parseLiteral(PEnv& penv, const SExp& exp, void* arg)
{
	return new ALiteral<T>(*reinterpret_cast<T*>(arg), exp.loc);
}

inline AST*
parseFn(PEnv& penv, const SExp& exp, void* arg)
{
	SExp::const_iterator a = exp.begin();
	THROW_IF(++a == exp.end(), exp.loc, "Unexpected end of `fn' form");
	AFn* ret = tup<AFn>(exp.loc, penv.sym("fn"), new ATuple(penv.parseTuple(*a++)), 0);
	while (a != exp.end())
		ret->push_back(penv.parse(*a++));
	return ret;
}


/***************************************************************************
 * Language Definition                                                     *
 ***************************************************************************/

/// Set up language
void
initLang(PEnv& penv, TEnv& tenv)
{
	// Types
	tenv.def(penv.sym("Nothing"), make_pair((AST*)0, new AType(penv.sym("Nothing"))));
	tenv.def(penv.sym("Bool"),    make_pair((AST*)0, new AType(penv.sym("Bool"))));
	tenv.def(penv.sym("Int"),     make_pair((AST*)0, new AType(penv.sym("Int"))));
	tenv.def(penv.sym("Float"),   make_pair((AST*)0, new AType(penv.sym("Float"))));

	// Literals
	static bool trueVal  = true;
	static bool falseVal = false;
	penv.reg(false, "#t", PEnv::Handler(parseLiteral<bool>, &trueVal));
	penv.reg(false, "#f", PEnv::Handler(parseLiteral<bool>, &falseVal));

	// Macros
	penv.defmac("def",  macDef);

	// Special forms
	penv.reg(true, "fn",   PEnv::Handler(parseFn));
	penv.reg(true, "if",   PEnv::Handler(parseCall<AIf>));
	penv.reg(true, "def",  PEnv::Handler(parseCall<ADef>));

	// Numeric primitives
	penv.reg(true, "+",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "-",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "*",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "/",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "%",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "and", PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "or",  PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "xor", PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "=",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "!=",  PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, ">",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, ">=",  PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "<",   PEnv::Handler(parseCall<APrimitive>));
	penv.reg(true, "<=",  PEnv::Handler(parseCall<APrimitive>));
}