# wcal
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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)

## Library Usage
### Example
```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](https://docs.rs/wcal).

## Executable Usage
### Build
Requirement: `rust` `cargo`
```shell
$ cargo run build --release
```
### Command line mode
```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.

### Interactive mode
```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!
```