mateusns12/rust-sscanf

Sscanf in Rust using macros

Sscanf in RUST using macros

Rust implementation of C function sscanf. It is not entirely equal, as it receives a string and a array of separators, instead of a formatted string with types.

Not using any extern crates, but unstable feature declarative macros 2.0.

Using macro_rules! works fine and will compile on stable.

Usage

let a :u8;   
let b :i32;   
let c :String;   
let d :f32;

let buffer = "02:98;abc,39.6";
let sep = [':',';',',',' '];

scan::sscanf!(buffer,sep,[u8,i32,String,f32],a,b,e,d);

println!("{} {} {} {}",a,b,e,d);

Result

2 98 abc 39.6

Notes

• Using nightly-x86_64-unknown-linux-gnu.
• Using Macro 2.0 instead of macro_rules! , as it seems to be getting deprecated, but works in both situations.
• Using #![feature(decl_macro)]

Known Issue

So far the string variable has to be of the type String, since the macro cant receive a &str as argument, otherwise it would expand into invalid code. The problem with using String, is that is creates a copy of the parsed &str in the buffer. Using &str would be ideal performance wise. A better implementation has been discussed in this topic, adressing the problem with functions as well.