Expand description
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§
- Parser
RpnResolver
- Session
- Token