A calculator write by rust
Allow operator: + - * / ( ).
Result can be i128 or f64. A warning will
occur while result is i128 and division cast
happened, such as 3/2=1.
This calculator has three steps:
* Use logos to parse the expression to tokens.
* Use a parser to parse tokens to a AST.
* Calculate the result from the AST.
The following parser is available: * Top-down parser (default)
```rust use wcal::{calculator, parser};
fn main() { let res: f64 = calculator!("1+2").unwrap(); assert_eq!(res, 3f64);
let res: i128 = calculator("1+2", wcal::parser::top_down_parser::parse).unwrap();
assert_eq!(res, 3);
let res: f64 = calculator("1+2", wcal::parser::top_down_parser::parse).unwrap();
assert_eq!(res, 3f64);
} ``` For more usage of this crate, please see the document.
Requirement: rust cargo
shell
$ cargo run build --release
shell
$ wcal "2*6+(1/2)" -f "2*6+(1/2)"
i> 2*6+(1/2)
Warning: division will cause a cast
12
f> 2*6+(1/2)
12.5
Default mod is i128, use -f to change to
f64, use -i to change back.
shell
$ wcal
i> help
i Enter i128 mod
f Enter f64 mod
quit
q Quit
i> f
Enter f64 mod
f> 1/2
0.5
f> quit
Bye!