| use core::ops; |
| #[cfg(feature = "std")] |
| use std::borrow::Cow; |
| |
| /// A specialized copy-on-write byte string. |
| /// |
| /// The purpose of this type is to permit usage of a "borrowed or owned |
| /// byte string" in a way that keeps std/no-std compatibility. That is, in |
| /// no-std mode, this type devolves into a simple &[u8] with no owned variant |
| /// availble. |
| #[derive(Clone, Debug)] |
| pub struct CowBytes<'a>(Imp<'a>); |
| |
| #[cfg(feature = "std")] |
| #[derive(Clone, Debug)] |
| struct Imp<'a>(Cow<'a, [u8]>); |
| |
| #[cfg(not(feature = "std"))] |
| #[derive(Clone, Debug)] |
| struct Imp<'a>(&'a [u8]); |
| |
| impl<'a> ops::Deref for CowBytes<'a> { |
| type Target = [u8]; |
| |
| fn deref(&self) -> &[u8] { |
| self.as_slice() |
| } |
| } |
| |
| impl<'a> CowBytes<'a> { |
| /// Create a new borrowed CowBytes. |
| pub fn new<B: ?Sized + AsRef<[u8]>>(bytes: &'a B) -> CowBytes<'a> { |
| CowBytes(Imp::new(bytes.as_ref())) |
| } |
| |
| /// Create a new owned CowBytes. |
| #[cfg(feature = "std")] |
| pub fn new_owned(bytes: Vec<u8>) -> CowBytes<'static> { |
| CowBytes(Imp(Cow::Owned(bytes))) |
| } |
| |
| /// Return a borrowed byte string, regardless of whether this is an owned |
| /// or borrowed byte string internally. |
| pub fn as_slice(&self) -> &[u8] { |
| self.0.as_slice() |
| } |
| |
| /// Return an owned version of this copy-on-write byte string. |
| /// |
| /// If this is already an owned byte string internally, then this is a |
| /// no-op. Otherwise, the internal byte string is copied. |
| #[cfg(feature = "std")] |
| pub fn into_owned(self) -> CowBytes<'static> { |
| match (self.0).0 { |
| Cow::Borrowed(b) => CowBytes::new_owned(b.to_vec()), |
| Cow::Owned(b) => CowBytes::new_owned(b), |
| } |
| } |
| } |
| |
| impl<'a> Imp<'a> { |
| #[cfg(feature = "std")] |
| pub fn new(bytes: &'a [u8]) -> Imp<'a> { |
| Imp(Cow::Borrowed(bytes)) |
| } |
| |
| #[cfg(not(feature = "std"))] |
| pub fn new(bytes: &'a [u8]) -> Imp<'a> { |
| Imp(bytes) |
| } |
| |
| #[cfg(feature = "std")] |
| pub fn as_slice(&self) -> &[u8] { |
| match self.0 { |
| Cow::Owned(ref x) => x, |
| Cow::Borrowed(x) => x, |
| } |
| } |
| |
| #[cfg(not(feature = "std"))] |
| pub fn as_slice(&self) -> &[u8] { |
| self.0 |
| } |
| } |