# eyes

Parse and convert strings using human-readable templates.

The crate's primary purpose is parsing challenge inputs for [Advent of Code](https://adventofcode.com) challenges. It currently provides limited functionality, but more options may be added provided they are useful additions for parsing slightly more complicated formats.

This crate does not have any dependencies, as I wanted to keep it simple to and lightweight in design.

## Syntax

The only special characters in templates are curly brackets ('{}'). These act as stand-ins for where the extracted values are in the input strings.

## Examples:

```rust
use eyes::parse;

let input = "#lol @ 338,7643: 20.2x24.5";
let template = "#{} @ {},{}: {}x{}";
let (id, x, y, w, h) = parse!(input, template, String, isize, isize, f64, f64);

assert_eq!((id.as_str(), x, y, w, h), ("lol", 338, 7643, 20.2, 24.5));
```

**eyes** will match capture groups greedily and expand them as far as possible, so that the following example also works as expected:

```rust
use eyes::parse;

let input = "turn off 660,55 through 986,197";
let template = "{} {},{} through {},{}";
let (op, x1, y1, x2, y2) = parse!(input, template, String, usize, usize, usize, usize);

assert_eq!(
    (op.as_str(), x1, y1, x2, y2),
    ("turn off", 660, 55, 986, 197)
);
```

Notice that "turn off" is captured correctly, even though it contains a space.

For error handling, the [`try_parse`] macro is provided which can be very useful in parsing potentially malformed input:

```rust
use eyes::try_parse;

let input = "1 2\n3,4\n5 6";
let result = input
    .lines()
    .filter_map(|line| try_parse!(line, "{} {}", i64, i64))
    .collect::<Vec<_>>();

assert_eq!(vec![(1, 2), (5, 6)], result);
```