diff options
| -rw-r--r-- | users/tazjin/german-string/src/lib.rs | 52 |
1 files changed, 40 insertions, 12 deletions
diff --git a/users/tazjin/german-string/src/lib.rs b/users/tazjin/german-string/src/lib.rs index 09ac3384d916..b6e6a6057e78 100644 --- a/users/tazjin/german-string/src/lib.rs +++ b/users/tazjin/german-string/src/lib.rs @@ -36,10 +36,9 @@ const _ASSERT_GSTRING_SIZE: () = assert!( ); impl GermanString { - // Creates a new transient German String from the given bytes. Transient - // strings are destroyed when the object is destroyed. Persistent strings - // are not supported yet. - pub fn new_transient(bytes: &[u8]) -> GermanString { + /// Creates a new transient German String from the given slice, copying the + /// data in the process. + pub fn transient(bytes: &[u8]) -> GermanString { if bytes.len() > u32::MAX as usize { panic!("GermanString maximum length is {} bytes", u32::MAX); } @@ -72,6 +71,35 @@ impl GermanString { } } + /// Creates a new transient German String from the given owned bytes. Short + /// strings will be copied into the string representation, long strings will + /// be moved out of the given vector without additional allocations. + pub fn transient_from_owned(bytes: Vec<u8>) -> GermanString { + if bytes.len() > u32::MAX as usize { + panic!("GermanString maximum length is {} bytes", u32::MAX); + } + + if bytes.len() <= 12 { + let mut s = GSSmall { + len: bytes.len() as u32, + data: [0u8; 12], + }; + + s.data[..bytes.len()].copy_from_slice(&bytes); + GermanString(GSRepr { small: s }) + } else { + let mut md = std::mem::ManuallyDrop::new(bytes); + let mut large = GSLarge { + len: md.len() as u32, + prefix: [0u8; 4], + data: md.as_mut_ptr(), + }; + + large.prefix.copy_from_slice(&md[..4]); + GermanString(GSRepr { large }) + } + } + pub fn len(&self) -> usize { // SAFETY: The length field is located in the same location for both // variants, reading it from either is safe. @@ -186,14 +214,14 @@ mod tests { fn arbitrary_with(args: Self::Parameters) -> Self::Strategy { any_with::<String>(args) - .prop_map(|s| GermanString::new_transient(s.as_bytes())) + .prop_map(|s| GermanString::transient(s.as_bytes())) .boxed() } } #[test] fn test_empty_string() { - let empty = GermanString::new_transient(b""); + let empty = GermanString::transient(b""); assert_eq!(empty.len(), 0, "empty string should be empty"); assert_eq!(empty.as_bytes(), b"", "empty string should contain nothing"); @@ -206,7 +234,7 @@ mod tests { #[test] fn test_short_string() { - let short = GermanString::new_transient(b"meow"); + let short = GermanString::transient(b"meow"); assert_eq!(short.len(), 4, "'meow' is four characters"); assert_eq!( @@ -224,7 +252,7 @@ mod tests { #[test] fn test_long_string() { let input: &str = "This code was written at https://signal.live"; - let long = GermanString::new_transient(input.as_bytes()); + let long = GermanString::transient(input.as_bytes()); assert_eq!(long.len(), 44, "long string has correct length"); assert_eq!( @@ -243,7 +271,7 @@ mod tests { proptest! { #[test] fn test_roundtrip_vec(input: Vec<u8>) { - let gs = GermanString::new_transient(input.as_slice()); + let gs = GermanString::transient_from_owned(input.clone()); assert_eq!(input.len(), gs.len(), "length should match"); let out = gs.as_bytes().to_owned(); @@ -252,7 +280,7 @@ mod tests { #[test] fn test_roundtrip_string(input: String) { - let gs = GermanString::new_transient(input.as_bytes()); + let gs = GermanString::transient_from_owned(input.clone().into_bytes()); assert_eq!(input.len(), gs.len(), "length should match"); let out = String::from_utf8(gs.as_bytes().to_owned()) @@ -264,8 +292,8 @@ mod tests { // Test [`Eq`] implementation. #[test] fn test_eq(lhs: Vec<u8>, rhs: Vec<u8>) { - let lhs_gs = GermanString::new_transient(lhs.as_slice()); - let rhs_gs = GermanString::new_transient(rhs.as_slice()); + let lhs_gs = GermanString::transient(lhs.as_slice()); + let rhs_gs = GermanString::transient(rhs.as_slice()); assert_eq!( (lhs == rhs), |