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