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engines/gob/expression.h

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+/* 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 3 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, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * This file is dual-licensed.
+ * In addition to the GPLv3 license mentioned above, this code is also
+ * licensed under LGPL 2.1. See LICENSES/COPYING.LGPL file for the
+ * full text of the license.
+ *
+ */
+
+#ifndef GOB_EXPRESSION_H
+#define GOB_EXPRESSION_H
+
+#include "common/scummsys.h"
+
+namespace Gob {
+
+class GobEngine;
+
+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_INT8              = 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_INT32          = 23,
+	OP_LOAD_VAR_INT32_AS_INT16 = 24,
+	OP_LOAD_VAR_STR            = 25,
+	OP_ARRAY_INT32             = 26,
+	OP_ARRAY_INT16             = 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 {
+	TYPE_IMM_INT8           = OP_LOAD_IMM_INT8,          // 21
+	TYPE_IMM_INT32          = OP_LOAD_IMM_INT32,         // 19
+	TYPE_IMM_INT16          = OP_LOAD_IMM_INT16,         // 20
+	TYPE_IMM_STR            = OP_LOAD_IMM_STR,           // 22
+	TYPE_VAR_INT8           = OP_LOAD_VAR_INT8,          // 18
+	TYPE_VAR_INT16          = OP_LOAD_VAR_INT16,         // 17
+	TYPE_VAR_INT32          = OP_LOAD_VAR_INT32,         // 23
+	TYPE_VAR_STR            = OP_LOAD_VAR_STR,           // 25
+	TYPE_ARRAY_INT8         = OP_ARRAY_INT8,             // 16
+	TYPE_ARRAY_INT16        = OP_ARRAY_INT16,            // 27
+	TYPE_ARRAY_INT32        = OP_ARRAY_INT32,            // 26
+	TYPE_ARRAY_STR          = OP_ARRAY_STR,              // 28
+	TYPE_VAR_INT32_AS_INT16 = OP_LOAD_VAR_INT32_AS_INT16 // 24
+};
+
+enum {
+	// FIXME: The following two 'truth values' are stored inside the list
+	// of "operators". So they somehow coincide with OP_LOAD_VAR_INT32
+	// and OP_LOAD_VAR_INT32_AS_INT16. I haven't yet quite understood
+	// how, resp. what that means. You have been warned.
+	GOB_TRUE  = 24,
+	GOB_FALSE = 23
+};
+
+class Expression {
+public:
+	Expression(GobEngine *vm);
+	virtual ~Expression() {}
+
+	void skipExpr(char stopToken);
+	void printExpr(char stopToken);
+	void printVarIndex();
+
+	uint16 parseVarIndex(uint16 *size = 0, uint16 *type = 0);
+	int16 parseValExpr(byte stopToken = 99);
+	int16 parseExpr(byte stopToken, byte *type);
+
+	int32 getResultInt();
+	char *getResultStr();
+
+private:
+	class Stack {
+	public:
+		byte *opers;
+		int32 *values;
+
+		Stack(size_t size = 20);
+		~Stack();
+	};
+	class StackFrame {
+	public:
+		byte *opers;
+		int32 *values;
+		int16 pos;
+
+		StackFrame(const Stack &stack);
+
+		void push(int count = 1);
+		void pop(int count = 1);
+	};
+
+	enum PointerType {
+		kExecPtr  = 0,
+		kInterVar = 1,
+		kResStr   = 2
+	};
+
+	GobEngine *_vm;
+
+	int32 _resultInt;
+	char _resultStr[200];
+
+	int32 encodePtr(byte *ptr, int type);
+	byte *decodePtr(int32 n);
+
+	void printExpr_internal(char stopToken);
+
+	bool getVarBase(uint32 &varBase, bool mindStop = false,
+			uint16 *size = 0, uint16 *type = 0);
+	int cmpHelper(const StackFrame &stackFrame);
+	void loadValue(byte operation, uint32 varBase, const StackFrame &stackFrame);
+
+	void simpleArithmetic1(StackFrame &stackFrame);
+	void simpleArithmetic2(StackFrame &stackFrame);
+	bool complexArithmetic(Stack &stack, StackFrame &stackFrame, int16 brackStart);
+	void getResult(byte operation, int32 value, byte *type);
+};
+
+} // End of namespace Gob
+
+#endif // GOB_EXPRESSION_H