macros.rs

/// A simple macro to create a HashMap with minimal fuss.
///
/// Example:
///
/// ```
/// let letters = map!{"a" => "b", "c" => "d"};
/// ```
///
/// Trailing commas are allowed.
macro_rules! map {
    ($( $key: expr => $val: expr ),* $(,)*) => {{
         let mut map = ::std::collections::HashMap::new();
         $( map.insert($key, $val); )*
         map
    }}
}

/// A simple macro to create a VecDeque from a list of initial elements.
///
/// Very similar to `vec![]` from the standard library.
/// Example:
/// ```rust
/// use saltwater_parser::vec_deque;
/// let queue = vec_deque![1, 2, 3];
/// ```
///
/// Trailing commas are allowed.
#[macro_export]
macro_rules! vec_deque {
    ($elem:expr; $n:expr) => ({
        use std::collections::VecDeque;
        VecDeque::from(vec![$elem; $n])
    });
    ($($x: expr),*) => ({
        use std::collections::VecDeque;
        VecDeque::from(vec![$($x),*])
    });
    ($($x:expr,)*) => ($crate::vec_deque![$($x),*])
}

/// ensure that a condition is true at compile time
/// thanks to https://nikolaivazquez.com/posts/programming/rust-static-assertions/
#[macro_export]
macro_rules! const_assert {
    ($condition:expr) => {
        #[deny(const_err)]
        #[allow(dead_code)]
        const ASSERT: usize = 0 - !$condition as usize;
    };
}