diff --git a/src/array_string.rs b/src/array_string.rs index a044cb5..fa00938 100644 --- a/src/array_string.rs +++ b/src/array_string.rs @@ -129,6 +129,28 @@ impl ArrayString Ok(vec) } + /// Creates a new `ArrayString` instance fully filled with ASCII NULL characters (`\0`). Useful + /// to be used as buffer to collect external data or as an buffer for intermediate processing. + /// + /// ``` + /// use arrayvec::ArrayString; + /// + /// let string = ArrayString::<16>::zero_filled(); + /// assert_eq!(string.len(), 16); + /// ``` + #[inline] + pub fn zero_filled() -> Self { + let mut vec = Self::new(); + let data = [b'\0'; CAP]; + // SAFETY: The array is fully filled with valid UTF-8 + unsafe { + let ptr = data.as_ptr() as *const [MaybeUninit; CAP]; + ptr.copy_to_nonoverlapping(&mut vec.xs as *mut _, 1); + vec.set_len(CAP); + } + vec + } + /// Return the capacity of the `ArrayString`. /// /// ``` diff --git a/tests/tests.rs b/tests/tests.rs index 26d09ae..3c08de1 100644 --- a/tests/tests.rs +++ b/tests/tests.rs @@ -773,7 +773,6 @@ fn test_arrayvec_const_constructible() { assert_eq!(var[..], [vec![3, 5, 8]]); } - #[test] fn test_arraystring_const_constructible() { const AS: ArrayString<10> = ArrayString::new_const(); @@ -786,3 +785,9 @@ fn test_arraystring_const_constructible() { } +#[test] +fn test_array_string_has_some_sanity_checks() { + let string = ArrayString::<4>::zero_filled(); + assert_eq!(string.as_str(), "\0\0\0\0"); + assert_eq!(string.len(), 4); +} \ No newline at end of file