/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

#ifndef GOB_PARSE_H
#define GOB_PARSE_H

namespace Gob {

enum {
	OP_NEG = 1,
	OP_ADD = 2,
	OP_SUB = 3,
	OP_BITOR = 4,
	OP_MUL = 5,
	OP_DIV = 6,
	OP_MOD = 7,
	OP_BITAND = 8,
	OP_BEGIN_EXPR = 9,
	OP_END_EXPR = 10,
	OP_NOT = 11,

	OP_END_MARKER = 12,	// Marks end of an array or string


	OP_ARRAY_UINT8 = 16,

	OP_LOAD_VAR_INT16 = 17,
	OP_LOAD_VAR_INT8 = 18,
	OP_LOAD_IMM_INT32 = 19,
	OP_LOAD_IMM_INT16 = 20,
	OP_LOAD_IMM_INT8 = 21,
	OP_LOAD_IMM_STR = 22,

	OP_LOAD_VAR_UINT32 = 23,		// ???
	OP_LOAD_VAR_UINT32_AS_UINT16 = 24,		// ???
	OP_LOAD_VAR_STR = 25,

	OP_ARRAY_UINT32 = 26,
	OP_ARRAY_UINT16 = 27,
	OP_ARRAY_STR = 28,

	OP_FUNC = 29,

	OP_OR = 30,	// Logical OR
	OP_AND = 31,	// Logical AND
	OP_LESS = 32,
	OP_LEQ = 33,
	OP_GREATER = 34,
	OP_GEQ = 35,
	OP_EQ = 36,
	OP_NEQ = 37
};

enum {
	FUNC_SQRT1 = 0,
	FUNC_SQRT2 = 1,
	FUNC_SQRT3 = 6,

	FUNC_SQR = 5,
	FUNC_ABS = 7,
	FUNC_RAND = 10
};

enum {
	// FIXME: The following two 'truth values' are stored inside the list
	// of "operators". So they somehow coincide with OP_LOAD_VAR_UINT32
	// and OP_LOAD_VAR_UINT32_AS_UINT16. I haven't yet quite understood 
	// how, resp. what that means. You have been warned.
	GOB_TRUE = 24,
	GOB_FALSE = 23
};

class Parse {
public:
	void skipExpr(char stopToken);
	void printExpr(char stopToken);
	void printVarIndex(void);
	virtual int16 parseVarIndex(uint16 *arg_0 = 0, uint16 *arg_4 = 0) = 0;
	virtual int16 parseValExpr(byte stopToken = 99) = 0;
	virtual int16 parseExpr(byte stopToken, byte *resultPtr) = 0;

	Parse(GobEngine *vm);
	virtual ~Parse() {}

protected:
	enum PointerType {
		kExecPtr = 0,
		kInterVar = 1,
		kResStr = 2
	};

	GobEngine *_vm;

	int32 encodePtr(byte *ptr, int type);
	byte *decodePtr(int32 n);

	void printExpr_internal(char stopToken);

	int cmpHelper(byte *operPtr, int32 *valPtr);
};

class Parse_v1 : public Parse {
public:
	Parse_v1(GobEngine *vm);
	virtual ~Parse_v1() {}

	virtual int16 parseVarIndex(uint16 *arg_0 = 0, uint16 *arg_4 = 0);
	virtual int16 parseValExpr(byte stopToken = 99);
	virtual int16 parseExpr(byte stopToken, byte *resultPtr);
};

class Parse_v2 : public Parse_v1 {
public:
	Parse_v2(GobEngine *vm);
	virtual ~Parse_v2() {}

	virtual int16 getOffset(int16 arg_0, byte arg_2, uint32 arg_3, uint16 arg_7, uint16 arg_9);

	virtual int16 parseVarIndex(uint16 *arg_0 = 0, uint16 *arg_4 = 0);
	virtual int16 parseValExpr(byte stopToken = 99);
	virtual int16 parseExpr(byte stopToken, byte *resultPtr);
};

} // End of namespace Gob

#endif // GOB_PARSE_H