Crate yarer

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Yarer (Yet another (Rusty || Rpn) expression resolver) is a flexible library, written in Rust, for the processing, compilation and evaluation of mathematical expressions using Reverse Polish Notation.

§Example of usage of the library:

   use yarer::{rpn_resolver::RpnResolver, session::Session, token::Number};

   let exp = "((10 + 5) - 3 * ( 9 / 3 )) + 2";
   let session = Session::init();
   let mut resolver: RpnResolver = session.process(&exp);

   let result: Number = resolver.resolve().unwrap();
   println!("The result of {} is {}", exp, result);

All that’s needed is to create a new instance of the [RpnResolver] and hand over the expression to be analysed. The library just returns a variant natural number, or a decimal number if one exists in the expression (i.e ‘2.1+1’) or there’s a trigonometric function (i.e. 1/cos(x+1)).

Yarer can handle also variables and functions. Here an example:


let session: Session = Session::init();
let mut resolver: RpnResolver = session.process("1/cos(x^2)");
session.set("x",1);

println!("The result is {}", resolver.resolve().unwrap());

and of course, the expression can be re-evaluated if the variable changes.


session.set("x",-1);
println!("The result is {}", resolver.resolve().unwrap());

session.setf("x",0.001);
println!("The result is {}", resolver.resolve().unwrap());

The result can be simply converted into a i32 or a f64 (if decimal) simply with


let result: Number = resolver.resolve().unwrap();

let int : i32 = result.clone().into();
// or
let float : f64 = result.into();

Yarer can be used also from command line, and behaves in a very similar manner to GNU bc

ⓘ
$ yarer
Yarer v.0.1.1 - Yet Another (Rusty||Rpn) Expression Resolver.
License MIT OR Apache-2.0
> (1+9)*(8+2)
100
> (1./2)+atan(10)
1.1483608274590869
> x=10
> 3/sin(5*x^2)
-6.41338354698791
> ln(1)
0
> log(10)
1
> -2^-2
0.25
> 1/(log(10)+cos(0))^-2
4
> 4.5+7.9*2.2
21.88
> 9801/(2206*sqrt(2)) // approx of PI
3.1415927300133055

§Built-in Defined Functions

There are several math functions defined that you can use in your expression. More to come! There are many examples of processed expressions in the integration test file

ⓘ
Sin
Cos
Tan
ASin
ACos
ATan
Ln
Log
Abs
Sqrt

Modules§