reformation's Introduction

reformation

Parsing via regular expressions using format syntax

Deriving trait Reformation will also implement trait FromStr, with Err=Box<Error>

Derive will require attribute reformation to specify format string, which will be treated as format string -> regular expression string

Types implementing Reformation by default:

signed integers: i8 i16 i32 i64 i128 isize
unsigned integers: u8 u16 u32 u64 u128 usize
floats: f32 f64
String

use reformation::Reformation;

#[derive(Reformation)]
#[reformation(r"{year}-{month}-{day} {hour}:{minute}")]
struct Date{
    year: u16,
    month: u8,
    day: u8,
    hour: u8,
    minute: u8,
}

fn main(){
    let date: Date = "2018-12-22 20:23".parse().unwrap();

    assert_eq!(date.year, 2018);
    assert_eq!(date.month, 12);
    assert_eq!(date.day, 22);
    assert_eq!(date.hour, 20);
    assert_eq!(date.minute, 23);
}

Format string behaves as regular expression, so special symbols needs to be escaped. Also they can be used for more flexible format strings. AVOID capture groups, since they would mess up with indexing of capture group generated by macro. use non-capturing groups r"(?:)" instead.

use reformation::Reformation;

// '{' is special symbol in both format and regex syntax, so it must be escaped twice.
// Say hello to good old escape hell.
#[derive(Reformation)]
#[reformation(r"Vec\{{{x},\s*{y},\s*{z}\}}")]
struct Vec{
    x: f64,
    y: f64,
    z: f64,
}

fn main(){
    // spaces between coordinates does not matter, since any amount of spaces
    // matches to r"\s*"
    let v: Vec = "Vec{-0.4,1e-3,   2e-3}".parse().unwrap();

    assert_eq!(v.x, -0.4);
    assert_eq!(v.y, 0.001);
    assert_eq!(v.z, 0.002);
}

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