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#ifndef FORMULA_H
#define FORMULA_H
#include <stdint.h>
#include <math.h>
#include <stack>
#include "sbuffer.h"
#include "exceptionbase.h"
#include "hash.h"
subExceptionDecl( ParseException );
/**
* Implements a very simple formula parser that allows use of variables and
* custom functions. This is based on a simple calculator-type parser that
* executes as it processes, accounting for operator precedence and grouping.
*/
class Formula
{
public:
Formula();
virtual ~Formula();
double run( char *sFormula );
typedef Hash<std::string, double> varHash;
varHash hVars;
typedef struct Func
{
double operator()( double x )
{
return 0.0;
}
} Func;
typedef Hash<std::string, Func> funcHash;
funcHash hFunc;
typedef struct FuncSin : Func
{
double operator()( double x )
{
return sin( x );
}
} FuncSin;
private:
enum
{
symEOS,
symAdd,
symSubtract,
symMultiply,
symDivide,
symOpenParen,
symCloseParen,
symNumber,
symVariable,
symExponent,
symModulus
};
typedef uint8_t symType;
std::stack<symType> sOper;
std::stack<double> sValue;
private:
symType getPrec( symType nOper );
symType nextToken( char **sBuf );
void reduce( bool bCloseParen = false );
};
#endif
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