parser.h

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#ifndef PARSER_H
#define PARSER_H
 
#ifdef WIN32
  
// disable warnings about long names
  #pragma warning( disable : 4786)
 
#endif
 
 
#include <string>
#include <map>
#include <stdexcept>
#include <sstream>
 
#include <cmath>
#include <ctime>
#include <cstdlib>
 
namespace hipo {
 
 
 
class Parser
  {
 
  public:
 
  enum TokenType
    {
    NONE,        
    NAME,        
    NUMBER,      
    END,         
    PLUS='+',    
    MINUS='-',   
    MULTIPLY='*',
    DIVIDE='/',  
    ASSIGN='=',  
    LHPAREN='(', 
    RHPAREN=')', 
    COMMA=',',   
    NOT='!',     
 
    LT='<',      
    GT='>',      
    LE,          
    GE,          
    EQ,          
    NE,          
    AND,         
    OR,          
 
    ASSIGN_ADD,  
    ASSIGN_SUB,  
    ASSIGN_MUL,  
    ASSIGN_DIV   
 
    };
 
  private:
    
  std::string program_;
  
  const char * pWord_;
  const char * pWordStart_;
  // last token parsed
  TokenType type_;
  std::string word_;
  double value_;
     
  public:
 
  Parser (const std::string & program) 
    : program_ (program)
      {  
      // insert pre-defined names:
      symbols_ ["pi"] = 3.1415926535897932385;
      symbols_ ["e"]  = 2.7182818284590452354;      
      }
  
  const double Evaluate ();
  const double Evaluate (const std::string & program);
 
  double & operator[] (const std::string & key) { return symbols_ [key]; }
 
  std::map<std::string, double> symbols_;
 
  private:
 
  const TokenType GetToken (const bool ignoreSign = false);  
  const double CommaList (const bool get);
  const double Expression (const bool get);
  const double Comparison (const bool get);
  const double AddSubtract (const bool get);
  const double Term (const bool get);      // multiply and divide
  const double Primary (const bool get);   // primary (base) tokens
 
  inline void CheckToken (const TokenType wanted)
    {
    if (type_ != wanted)
      {
      std::ostringstream s;
      s << "'" << static_cast <char> (wanted) << "' expected.";
      throw std::runtime_error (s.str ());    
      }
    }
  };  // end of Parser
}
 
#endif // PARSER_H