maplit.rs

// License
//
// Dual-licensed to be compatible with the Rust project.
//
// Licensed under the Apache License, Version 2.0
// http://www.apache.org/licenses/LICENSE-2.0 or the MIT license
// http://opensource.org/licenses/MIT, at your option. This file may not
// be copied, modified, or distributed except according to those terms.
//
// From: https://github.com/bluss/maplit
macro_rules! hashmap {
    (@single $($x:tt)*) => (());
    (@count $($rest:expr),*) => (<[()]>::len(&[$(hashmap!(@single $rest)),*]));
    
    ($($key:expr => $value:expr,)+) => { hashmap!($($key => $value),+) };
    ($($key:expr => $value:expr),*) => {
        {
            let _cap = hashmap!(@count $($key),*);
            let mut _map = ::std::collections::HashMap::with_capacity(_cap);
            $(
                _map.insert($key, $value);
            )*
            _map
        }
    };
}