function.h

#ifndef FUNCTION_H
#define FUNCTION_H

#include <vector>
#include <string>
#include "variable.h"

using namespace std;

/*
An abstract subclass of node class and represents the functions.
Due to the different functionality, we have variable and function classes.
*/
class Function : public Node{
    
public:

    // represents the list of variables that are inputs of this function
    vector<Variable *> inputs;

    // represents the output variable of the function.
    Variable * output = nullptr;

    Function(); //default constructor

    Function(int _id, string _name=""); // custom constructor

    ~Function(); // destructor
    
    // adds given variable as an input of this function
    void addInput(Variable *input);

    // sets the output variable of the function
    void setOutput(Variable *_output);

    // following two functions are inherited features from node class
    vector<Node *> getIncomings();
    vector<Node *> getOutgoings();
    
    // following two functions will be implemented by the subclasses of Function class

    // performs forward pass and sets the value of output variable
    virtual void doForward() = 0;

    // performs backward pass and sets the derivative values of the input variables
    virtual void doBackward() = 0; 

};

/*
Subclass of function class that provides forward and backward pass functionalities 
for multiplication
*/
class Multiplication : public Function{
public:
    Multiplication(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for addition
*/
class Addition : public Function{
public:
    Addition(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for subtraction
*/
class Subtraction : public Function{
public:
    Subtraction(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for division
*/
class Division : public Function{
public:
    Division(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for sine
*/
class Sine : public Function{
public:
    Sine(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for cosine
*/
class Cosine : public Function{
public:
    Cosine(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for identity
*/
class Identity : public Function{
public:
    Identity(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for tangent
*/
class Tangent : public Function{
public:
    Tangent(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for arccosine
*/
class ArcCosine : public Function{
public:
    ArcCosine(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for arcsine
*/
class ArcSine : public Function{
public:
    ArcSine(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for arctangent
*/
class ArcTangent : public Function{
public:
    ArcTangent(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for exponential
*/
class Exponential : public Function{
public:
    Exponential(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for log
*/
class Log : public Function{
public:
    Log(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for log10
*/
class Log10 : public Function{
public:
    Log10(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for power
*/
class Power : public Function{
public:
    Power(int _id, string _name="");
    void doForward();
    void doBackward();
};

/*
Subclass of function class that provides forward and backward pass functionalities 
for square root
*/
class Sqrt : public Function{
public:
    Sqrt(int _id, string _name="");
    void doForward();
    void doBackward();
};



#endif // VARIABLE