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// license:GPL-2.0+
// copyright-holders:Couriersud
/*
* pfunction.h
*
*/
#ifndef PFUNCTION_H_
#define PFUNCTION_H_
#include "pstring.h"
#include "pstate.h"
#include <vector>
namespace plib {
//============================================================
// function evaluation
//============================================================
/*! Class providing support for evaluating expressions
*
*/
class pfunction
{
enum rpn_cmd
{
ADD,
MULT,
SUB,
DIV,
POW,
SIN,
COS,
RAND, /* random number between 0 and 1 */
PUSH_CONST,
PUSH_INPUT
};
struct rpn_inst
{
rpn_inst() : m_cmd(ADD), m_param(0.0) { }
rpn_cmd m_cmd;
double m_param;
};
public:
/*! Constructor with state saving support
*
* @param name Name of this object
* @param owner Owner of this object
* @param state_manager State manager to handle saving object state
*
*/
pfunction(const pstring &name, const void *owner, state_manager_t &state_manager)
: m_lfsr(0xACE1u)
{
state_manager.save_item(owner, m_lfsr, name + ".lfsr");
}
/*! Constructor without state saving support
*
*/
pfunction()
: m_lfsr(0xACE1u)
{
}
/*! Compile an expression
*
* @param inputs Vector of input variables, e.g. {"A","B"}
* @param expr infix or postfix expression. default is infix, postrix
* to be prefixed with rpn, e.g. "rpn:A B + 1.3 /"
*/
void compile(const std::vector<pstring> &inputs, const pstring &expr);
/*! Compile a rpn expression
*
* @param inputs Vector of input variables, e.g. {"A","B"}
* @param expr Reverse polish notation expression, e.g. "A B + 1.3 /"
*/
void compile_postfix(const std::vector<pstring> &inputs, const pstring &expr);
/*! Compile an infix expression
*
* @param inputs Vector of input variables, e.g. {"A","B"}
* @param expr Infix expression, e.g. "(A+B)/1.3"
*/
void compile_infix(const std::vector<pstring> &inputs, const pstring &expr);
/*! Evaluate the expression
*
* @param values for input variables, e.g. {1.1, 2.2}
* @return value of expression
*/
double evaluate(const std::vector<double> &values);
private:
void compile_postfix(const std::vector<pstring> &inputs,
const std::vector<pstring> &cmds, const pstring &expr);
double lfsr_random()
{
std::uint16_t lsb = m_lfsr & 1;
m_lfsr >>= 1;
if (lsb)
m_lfsr ^= 0xB400u; // taps 15, 13, 12, 10
return static_cast<double>(m_lfsr) / static_cast<double>(0xffffu);
}
std::vector<rpn_inst> m_precompiled; //!< precompiled expression
std::uint16_t m_lfsr; //!< lfsr used for generating random numbers
};
}
#endif /* PEXCEPTION_H_ */
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