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#ifndef __LIBUTIL_CALCULATOR_H__
#define __LIBUTIL_CALCULATOR_H__
#include <sstream>
#include "String.h"
#include "Map.h"
#include "Assert.h"
namespace LibUtil
{
using std::istringstream;
/*
* program:
* END // END is end-of-input
* expr_list END
*
* expr_list:
* expression SEP expr_list // SEP is semicolon
* expression
* print expression
* print STRING
* print STRING expression
* print STRING expression SEP expr_list
*
*
* expression:
* expression + term
* expression - term
* term
*
* term:
* term / primary
* term * primary
* primary
*
* primary:
* NUMBER
* NAME
* NAME = expression
* NAME string expression // NAME is print
* - primary
* ( expression )
*
* string:
*
**/
class Calculator
{
protected:
enum Token
{
NAME, NAME2, NUMBER, STRING, END,
PLUS = '+', MINUS = '-', MUL = '*', DIV = '/',
SEP = ';', ASSIGN = '=', LP = '(', RP = ')'
};
public:
Calculator();
virtual ~Calculator();
public:
void reset();
void evaluateString(const String& str_);
protected:
Token getToken(istringstream& ist_);
double prim(istringstream& ist_, bool is_get_);
double term(istringstream& ist_, bool is_get_);
double expr(istringstream& ist_, bool is_get_);
virtual double getEnvVar(const String& var_name_) const;
protected:
String m_reserved_chars_;
Map<double> m_var_;
Token m_curr_token_;
double m_value_number_;
String m_value_string_;
}; // class Calculator
} // namespace LibUtil
#endif // __LIBUTIL_CALCULATOR_H__
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