vecmac.rs

#[macro_export]
macro_rules! avec {
    ($($element:expr),*) => {{
        // check that count is const
        const C: usize = $crate::count![@COUNT; $($element),*];

        #[allow(unused_mut)]
        let mut vs = Vec::with_capacity(C);
        $(vs.push($element);)*
        vs
    }};
    ($($element:expr,)*) => {{
        $crate::avec![$($element),*]
    }};
    ($element:expr; $count:expr) => {{
        let mut vs = Vec::new();
        vs.resize($count, $element);
        vs
    }};

}

#[macro_export]
#[doc(hidden)]
macro_rules! count {
    (@COUNT; $($element:expr),*) => {
        <[()]>::len(&[$($crate::count![@SUBST; $element]),*])
    };
    (@SUBST; $_element:expr) => { () };
}

#[test]
fn empty_vec() {
    let x: Vec<u32> = avec![];
    assert!(x.is_empty());
}

#[test]
fn single() {
    let x: Vec<u32> = avec![42];
    assert!(!x.is_empty());
    assert_eq!(x.len(), 1);
    assert_eq!(x[0], 42);
}

#[test]
fn double() {
    let x: Vec<u32> = avec![42, 43];
    assert!(!x.is_empty());
    assert_eq!(x.len(), 2);
    assert_eq!(x[0], 42);
    assert_eq!(x[1], 43);
}

#[test]
fn trailing() {
    let _: Vec<&'static str> = avec![
        "lakdjwaidjiwalfjhawligfjawilfjawlifwjalwijwfalijawfiljfaew",
        "lakdjwaidjiwalfjhawligfjawilfjawlifwjalwijwfalijawfiljfaew",
        "lakdjwaidjiwalfjhawligfjawilfjawlifwjalwijwfalijawfiljfaew",
        "lakdjwaidjiwalfjhawligfjawilfjawlifwjalwijwfalijawfiljfaew",
        "lakdjwaidjiwalfjhawligfjawilfjawlifwjalwijwfalijawfiljfaew",
    ];
}

#[test]
fn clone_2() {
    let x: Vec<u32> = avec![42; 2];
    assert!(!x.is_empty());
    assert_eq!(x.len(), 2);
    assert_eq!(x[0], 42);
    assert_eq!(x[1], 42);
}

#[test]
fn clone_2_nonliteral() {
    let mut y = Some(42);
    let x: Vec<u32> = avec![y.take().unwrap(); 2];
    assert!(!x.is_empty());
    assert_eq!(x.len(), 2);
    assert_eq!(x[0], 42);
    assert_eq!(x[1], 42);
}

/// ```compile_fail
/// let x: Vec<u32> = vecmac::avec![42; "foo"];
/// ```
#[allow(dead_code)]
struct CompileFailTest;

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