EXP_PARSER

It is a c++ template class used to evaluate simple mathematical expression in string

Supports basic mathematical operators like

^ power

* multiplication

/ division

+ addition

- subtraction

listed in order of precedence

( ) can be used used to group expression and has the highest order of precedence

Supports implicit multiplication operator

i.e: '*' can be omitted in expressions like a*(b) or (a)*b

Support variables

Variable name should start with alphabet and can contain numbers
Variables can be declared by the statement variable=expression in the expression string
Predefined variable 'a' containes value of previously parsed expressioned

To use expression parser in your program just include the header file the header file 'exp_parser.h' in your program

create an object of EP::exp_parser<T> T can be any type that should supported atleast + , - , / , * , %, >> operators

####exp_parser contains following constructor

exp_parser() - default constructor
exp_parser(std::string) - parametrized constructor used to initialize expression string

####exp_parser contains following public member functions

bool parser() - evaluate the string initialized with exp_parser(std::string) constructor and returns true if success else false
bool parser(std::string expression) - evaluate the string and returns true if success else false
bool add_var(string var_name,T val=0,EP::type _type=EP::type::constant) - used to add variable or constant with value of type T
bool find_var(std::string var,T& val) - returns true if var is defined and stores its value in val else false
bool isconst(std::string var) - returns true if var is a constant else false

####exp_parser contains following public data member

T value - returns the result of last evaluated expression
enum class EP::error errorstatus - All the above public members set this errorstatus which takes the values { noerror, undefined_var, unexpected, predefined_const }
errorpos - Contains the position where the error is

####Eg of simple expression parser

    #include <iostream.h>
    #include <cmath> 
	#include <exp_parser.h>  /* expression parser header file */

	using namespace std;
	using namespace EP;
	
    int main()
    {
        exp_parse<double> e; /* create an  expression parser of type double */
        e.add_var("pi",3.14,type::cons);
		e.add_func("log",&log10);
		string s;
        cout << "Enter a mathematical expression : \n ";
        cin >> s;
        e.parser( s );
        cout << "Result : " << e.getValue();
        return 0;
  	}

//TODO: to add support for hex bin oct

jaiselrahman / exp_parser