FormulaParser.h

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/*****************************************************************************
 * Copyright (C) 2011 by Benjamin Hadorn (b_hadorn@bluewin.ch)
 *****************************************************************************
 * Project    : Zeus Math Library
 * Module     : FormulaParser
 * Package    : Zeus.ZeusMath.System
 * Author     : Benjamin Hadorn
 * Date       : 27.12.2011
 * System     : Zeus-Framework
 *****************************************************************************
 * Licence:                                                                  *
 *   This library is free software; you can redistribute it and/or modify    *
 *   it under the terms of the GNU Lesser General Public License as          *
 *   published by the Free Software Foundation; either version               *
 *   2.1 of the License, or (at your option) any later version.              *
 *                                                                           *
 *   This library 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 Lesser General Public License for more details.                     *
 *                                                                           *
 *   You should have received a copy of the GNU Lesser General Public        *
 *   License along with this library; if not, write to the Free Software     *
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA    *
 *****************************************************************************/

/*****************************************************************************
 * Changes:
 *  27.12.2011 bha: created zeus 2.0
 *****************************************************************************/

#ifndef FormulaParserH
#define FormulaParserH

#include <zeusmath/System/Interfaces/IAngle.hpp>
#include <zeusmath/System/Interfaces/IFormulaParserObserver.hpp>
#include <zeusbase/System/ZObject.h>
#include <zeusbase/System/SingleLinkedList.hpp>
#include <zeusbase/System/Interfaces/ISubject.hpp>

BEGIN_NAMESPACE_Zeus

class IFormulaParserObserver;

/****************************************************************************/
/* Accepted sytanx of formula parser in BNF

  expr :== expr '+' term  |
           expr '-' term  |
           term

  term :== term '*' fact  |
           term '/' fact  |
           fact

  fact :== fact '^' expo  |
           expo

  expo :== <NUMBER>       |
           <CONSTANT>     |
           '(' expr ')'   |
           '-' expo       |
           '+' expo       |
           funct

  funct :== identifier '(' exprlist ')'

  exprlist :== expr ',' exprlist |
               expr
*/
/****************************************************************************/

/*************************************************************************/
/*************************************************************************/
enum ETokenType
{
  etUnknownToken = 0,
  etOpenBracket = 1,      // '('
  etCloseBracket = 2,     // ')'
  etMul = 3,              // '*'
  etDiff = 4,             // '/'
  etAdd = 5,              // '+'
  etSub = 6,              // '-'
  etExponent = 7,         // '^'
  etListSeperator = 8,    // ','
  etName = 20,            // name starting with a alpha char
  etNumber = 21           // number
};

/*****************************************************************************/
/*****************************************************************************/
zeusmath_class TFormulaParser : public TZObject, public ISubject
{
  public:
    TFormulaParser(const TString& rFormula = L"");

    Retval evalFloatValue(Float& rfValue);

    void setFormula(const TString& rValue);
    void setAngleSystemProperty(IAngle::ESystem eSystem);

    //methods of ISubject
    virtual Retval MQUALIFIER attach(IObserver& rObserver);
    virtual Retval MQUALIFIER detach(IObserver& rObserver);

    //Methods of IZUnknown
    MEMORY_MANAGER_DECL

  protected:
    virtual ~TFormulaParser();

  private:
    TString m_strFormula;
    IAngle::ESystem m_eSystem;

    //-----------------------------------------------------------------------
    // Lexer

    /*************************************************************************/
    /*************************************************************************/
    struct TypeToken
    {
      ETokenType eType;
      TString strData;

      TypeToken()
      {
        eType = etUnknownToken;
      }

      bool operator==(const TypeToken& rInPar) const
      {
        return (rInPar.eType == eType &&
                rInPar.strData == strData);
      }

    };

    TSingleLinkedList<IFormulaParserObserver*> m_lstObservers;
    TSingleLinkedList<TypeToken> m_lstTokenList;
    Int m_iTokenIndex;
    Retval m_retErrorCode;

    void notifyObserver(IFormulaParserObserver::EFormulaErrorType eErrorType, const TString& rMessage);
    Float parsePrimitive(bool bAllowUnaryOperator,
                         bool& bError);
    Float parseExpression(const Float& rLeftSide,
                          Int iPrecedence,
                          bool& bError);
    Float parseFunction(const TString& rName, bool& bError);
    Float callPow(const Float& rfBasis, const Float& rfExponent, bool& bError);
    Int getNextOperatorPrecedence(bool& bError);
    bool isExpressionEndReached();
    
    void startScanner();
    static bool getNameToken(TypeToken& rToken, const char* pcBuffer, Int& rCounter);
    static bool getNumberToken(TypeToken& rToken, const char* pcBuffer, Int& rCounter);


};

/*****************************************************************************/
/*****************************************************************************/
inline void TFormulaParser::setAngleSystemProperty(IAngle::ESystem eSystem)
{
  m_eSystem = eSystem;
}

/**************************************************************************/
/**************************************************************************/
inline void TFormulaParser::notifyObserver(IFormulaParserObserver::EFormulaErrorType eErrorType, const TString& rMessage)
{
  TIterator<IFormulaParserObserver*> It = m_lstObservers.getIterator();
  while(It.hasNextItem())
  {
    It.getNextItem()->onErrorOccured(eErrorType, rMessage);
  }
}

END_NAMESPACE_Zeus

#endif