| // Protocol Buffers - Google's data interchange format |
| // Copyright 2024 Google LLC. All rights reserved. |
| // |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file or at |
| // https://developers.google.com/open-source/licenses/bsd |
| |
| /// ABI compatible struct with upb_StringView. |
| /// |
| /// Note that this has semantics similar to `std::string_view` in C++ and |
| /// `&[u8]` in Rust, but is not ABI-compatible with either. |
| /// |
| /// If `len` is 0, then `ptr` is allowed to be either null or dangling. C++ |
| /// considers a dangling 0-len `std::string_view` to be invalid, and Rust |
| /// considers a `&[u8]` with a null data pointer to be invalid. |
| #[repr(C)] |
| #[derive(Copy, Clone)] |
| pub struct StringView { |
| /// Pointer to the first byte. |
| /// Borrows the memory. |
| pub ptr: *const u8, |
| |
| /// Length of the `[u8]` pointed to by `ptr`. |
| pub len: usize, |
| } |
| |
| impl StringView { |
| /// Unsafely dereference this slice. |
| /// |
| /// # Safety |
| /// - `self.ptr` must be dereferencable and immutable for `self.len` bytes |
| /// for the lifetime `'a`. It can be null or dangling if `self.len == 0`. |
| pub unsafe fn as_ref<'a>(self) -> &'a [u8] { |
| if self.ptr.is_null() { |
| assert_eq!(self.len, 0, "Non-empty slice with null data pointer"); |
| &[] |
| } else { |
| // SAFETY: |
| // - `ptr` is non-null |
| // - `ptr` is valid for `len` bytes as promised by the caller. |
| unsafe { std::slice::from_raw_parts(self.ptr, self.len) } |
| } |
| } |
| } |
| |
| impl From<&[u8]> for StringView { |
| fn from(slice: &[u8]) -> Self { |
| Self { ptr: slice.as_ptr(), len: slice.len() } |
| } |
| } |
| |
| impl<const N: usize> From<&[u8; N]> for StringView { |
| fn from(slice: &[u8; N]) -> Self { |
| Self { ptr: slice.as_ptr(), len: N } |
| } |
| } |