arrayvec-util 0.1.0

#![no_std]

use core::fmt::{Display, Write};

use arrayvec::ArrayString;

pub trait ToArrayString {
    fn to_array_string<const N: usize>(&self) -> ArrayString<N>;
}

impl<T: Display + ?Sized> ToArrayString for T {
    #[inline]
    fn to_array_string<const N: usize>(&self) -> ArrayString<N> {
        let mut buf = ArrayString::new();
        write!(buf, "{self}").expect("a Display implementation returned an error unexpectedly");
        buf
    }
}

#[macro_export]
macro_rules! array_format {
    ($($tt:tt)*) => {{
        let mut w = arrayvec::ArrayString::new();
        core::fmt::Write::write_fmt(&mut w, core::format_args!($($tt)*)).expect("a formatting trait implementation returned an error when the underlying stream did not");
        w
    }};
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn to_array_string_trait() {
        struct EndWithExclamationMark(&'static str);

        impl Display for EndWithExclamationMark {
            fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
                write!(f, "{}!", self.0)
            }
        }

        let sentence = EndWithExclamationMark("The quick brown fox jumps over the lazy dog");
        let sentence_str: ArrayString<44> = sentence.to_array_string();

        assert_eq!(
            ArrayString::from("The quick brown fox jumps over the lazy dog!"),
            Ok(sentence_str)
        );
    }

    #[test]
    fn array_format_macro() {
        let name = "John Doe";
        let format: ArrayString<22> = array_format!("Hello World, {name}!");

        assert_eq!(ArrayString::from("Hello World, John Doe!"), Ok(format));
    }
}