Add more Box conversions

Author: tormol

src/ascii_str.rs

@@ -87,6 +87,20 @@ impl AsciiStr {
         AsciiString::from(self.slice.to_vec())
     }
 
+    /// for compatibility with `str`
+    #[cfg(feature = "alloc")]
+    #[must_use]
+    pub fn into_boxed_bytes(self: Box<Self>) -> Box<[u8]> {
+        self.into()
+    }
+
+    /// Convert a `Box<[u8]>` to `Box<AsciiStr>` without allocating.
+    #[cfg(feature = "alloc")]
+    #[must_use]
+    pub unsafe fn from_boxed_ascii_bytes_unchecked(box_not_checked: Box<[u8]>) -> Box<Self> {
+        Box::from_raw(Box::into_raw(box_not_checked) as *mut AsciiStr)
+    }
+
     /// Converts anything that can represent a byte slice into an `AsciiStr`.
     ///
     /// # Errors
@@ -1414,6 +1428,19 @@ mod tests {
         assert_eq!(AsRef::<[u8]>::as_ref(v), b"( ;");
     }
 
+    #[test]
+    #[cfg(feature = "alloc")]
+    fn to_and_from_byte_box() {
+        let s = "abc".as_ascii_str().unwrap().to_ascii_string();
+        let boxed = s.clone().into_boxed_ascii_str();
+        unsafe {
+            let converted = boxed.into_boxed_bytes();
+            assert_eq!(&converted[..], &b"abc"[..]);
+            let converted_back = AsciiStr::from_boxed_ascii_bytes_unchecked(converted);
+            assert_eq!(&converted_back[..], &s[..]);
+        }
+    }
+
     #[test]
     fn make_ascii_case() {
         let mut bytes = ([b'a', b'@', b'A'], [b'A', b'@', b'a']);