diff options
Diffstat (limited to 'src/libcore/str/mod.rs')
| -rw-r--r-- | src/libcore/str/mod.rs | 152 |
1 files changed, 75 insertions, 77 deletions
diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs index 003ed7df36e..89233259a04 100644 --- a/src/libcore/str/mod.rs +++ b/src/libcore/str/mod.rs @@ -1731,7 +1731,8 @@ Section: Trait implementations mod traits { use crate::cmp::Ordering; use crate::ops; - use crate::slice::{self, SliceIndex}; + use crate::ptr; + use crate::slice::SliceIndex; /// Implements ordering of strings. /// @@ -1822,7 +1823,7 @@ mod traits { /// /// Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`. #[stable(feature = "str_checked_slicing", since = "1.20.0")] - impl SliceIndex<str> for ops::RangeFull { + unsafe impl SliceIndex<str> for ops::RangeFull { type Output = str; #[inline] fn get(self, slice: &str) -> Option<&Self::Output> { @@ -1833,11 +1834,11 @@ mod traits { Some(slice) } #[inline] - unsafe fn get_unchecked(self, slice: &str) -> &Self::Output { + unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output { slice } #[inline] - unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { + unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output { slice } #[inline] @@ -1886,7 +1887,7 @@ mod traits { /// // &s[3 .. 100]; /// ``` #[stable(feature = "str_checked_slicing", since = "1.20.0")] - impl SliceIndex<str> for ops::Range<usize> { + unsafe impl SliceIndex<str> for ops::Range<usize> { type Output = str; #[inline] fn get(self, slice: &str) -> Option<&Self::Output> { @@ -1894,8 +1895,10 @@ mod traits { && slice.is_char_boundary(self.start) && slice.is_char_boundary(self.end) { - // SAFETY: just checked that `start` and `end` are on a char boundary. - Some(unsafe { self.get_unchecked(slice) }) + // SAFETY: just checked that `start` and `end` are on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + // We also checked char boundaries, so this is valid UTF-8. + Some(unsafe { &*self.get_unchecked(slice) }) } else { None } @@ -1907,34 +1910,28 @@ mod traits { && slice.is_char_boundary(self.end) { // SAFETY: just checked that `start` and `end` are on a char boundary. - Some(unsafe { self.get_unchecked_mut(slice) }) + // We know the pointer is unique because we got it from `slice`. + Some(unsafe { &mut *self.get_unchecked_mut(slice) }) } else { None } } #[inline] - unsafe fn get_unchecked(self, slice: &str) -> &Self::Output { + unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output { + let slice = slice as *const [u8]; // SAFETY: the caller guarantees that `self` is in bounds of `slice` // which satisfies all the conditions for `add`. let ptr = unsafe { slice.as_ptr().add(self.start) }; let len = self.end - self.start; - // SAFETY: as the caller guarantees that `self` is in bounds of `slice`, - // we can safely construct a subslice with `from_raw_parts` and use it - // since we return a shared thus immutable reference. - // The call to `from_utf8_unchecked` is safe since the data comes from - // a `str` which is guaranteed to be valid utf8, since the caller - // must guarantee that `self.start` and `self.end` are char boundaries. - unsafe { super::from_utf8_unchecked(slice::from_raw_parts(ptr, len)) } + ptr::slice_from_raw_parts(ptr, len) as *const str } #[inline] - unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { + unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output { + let slice = slice as *mut [u8]; // SAFETY: see comments for `get_unchecked`. let ptr = unsafe { slice.as_mut_ptr().add(self.start) }; let len = self.end - self.start; - // SAFETY: mostly identical to the comments for `get_unchecked`, except that we - // can return a mutable reference since the caller passed a mutable reference - // and is thus guaranteed to have exclusive write access to `slice`. - unsafe { super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, len)) } + ptr::slice_from_raw_parts_mut(ptr, len) as *mut str } #[inline] fn index(self, slice: &str) -> &Self::Output { @@ -1949,8 +1946,9 @@ mod traits { && slice.is_char_boundary(self.start) && slice.is_char_boundary(self.end) { - // SAFETY: just checked that `start` and `end` are on a char boundary. - unsafe { self.get_unchecked_mut(slice) } + // SAFETY: just checked that `start` and `end` are on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + unsafe { &mut *self.get_unchecked_mut(slice) } } else { super::slice_error_fail(slice, self.start, self.end) } @@ -1973,13 +1971,14 @@ mod traits { /// Panics if `end` does not point to the starting byte offset of a /// character (as defined by `is_char_boundary`), or if `end > len`. #[stable(feature = "str_checked_slicing", since = "1.20.0")] - impl SliceIndex<str> for ops::RangeTo<usize> { + unsafe impl SliceIndex<str> for ops::RangeTo<usize> { type Output = str; #[inline] fn get(self, slice: &str) -> Option<&Self::Output> { if slice.is_char_boundary(self.end) { - // SAFETY: just checked that `end` is on a char boundary. - Some(unsafe { self.get_unchecked(slice) }) + // SAFETY: just checked that `end` is on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + Some(unsafe { &*self.get_unchecked(slice) }) } else { None } @@ -1987,30 +1986,24 @@ mod traits { #[inline] fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> { if slice.is_char_boundary(self.end) { - // SAFETY: just checked that `end` is on a char boundary. - Some(unsafe { self.get_unchecked_mut(slice) }) + // SAFETY: just checked that `end` is on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + Some(unsafe { &mut *self.get_unchecked_mut(slice) }) } else { None } } #[inline] - unsafe fn get_unchecked(self, slice: &str) -> &Self::Output { + unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output { + let slice = slice as *const [u8]; let ptr = slice.as_ptr(); - // SAFETY: as the caller guarantees that `self` is in bounds of `slice`, - // we can safely construct a subslice with `from_raw_parts` and use it - // since we return a shared thus immutable reference. - // The call to `from_utf8_unchecked` is safe since the data comes from - // a `str` which is guaranteed to be valid utf8, since the caller - // must guarantee that `self.end` is a char boundary. - unsafe { super::from_utf8_unchecked(slice::from_raw_parts(ptr, self.end)) } + ptr::slice_from_raw_parts(ptr, self.end) as *const str } #[inline] - unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { + unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output { + let slice = slice as *mut [u8]; let ptr = slice.as_mut_ptr(); - // SAFETY: mostly identical to `get_unchecked`, except that we can safely - // return a mutable reference since the caller passed a mutable reference - // and is thus guaranteed to have exclusive write access to `slice`. - unsafe { super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, self.end)) } + ptr::slice_from_raw_parts_mut(ptr, self.end) as *mut str } #[inline] fn index(self, slice: &str) -> &Self::Output { @@ -2020,8 +2013,9 @@ mod traits { #[inline] fn index_mut(self, slice: &mut str) -> &mut Self::Output { if slice.is_char_boundary(self.end) { - // SAFETY: just checked that `end` is on a char boundary. - unsafe { self.get_unchecked_mut(slice) } + // SAFETY: just checked that `end` is on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + unsafe { &mut *self.get_unchecked_mut(slice) } } else { super::slice_error_fail(slice, 0, self.end) } @@ -2045,13 +2039,14 @@ mod traits { /// Panics if `begin` does not point to the starting byte offset of /// a character (as defined by `is_char_boundary`), or if `begin >= len`. #[stable(feature = "str_checked_slicing", since = "1.20.0")] - impl SliceIndex<str> for ops::RangeFrom<usize> { + unsafe impl SliceIndex<str> for ops::RangeFrom<usize> { type Output = str; #[inline] fn get(self, slice: &str) -> Option<&Self::Output> { if slice.is_char_boundary(self.start) { - // SAFETY: just checked that `start` is on a char boundary. - Some(unsafe { self.get_unchecked(slice) }) + // SAFETY: just checked that `start` is on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + Some(unsafe { &*self.get_unchecked(slice) }) } else { None } @@ -2059,35 +2054,29 @@ mod traits { #[inline] fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> { if slice.is_char_boundary(self.start) { - // SAFETY: just checked that `start` is on a char boundary. - Some(unsafe { self.get_unchecked_mut(slice) }) + // SAFETY: just checked that `start` is on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + Some(unsafe { &mut *self.get_unchecked_mut(slice) }) } else { None } } #[inline] - unsafe fn get_unchecked(self, slice: &str) -> &Self::Output { + unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output { + let slice = slice as *const [u8]; // SAFETY: the caller guarantees that `self` is in bounds of `slice` // which satisfies all the conditions for `add`. let ptr = unsafe { slice.as_ptr().add(self.start) }; let len = slice.len() - self.start; - // SAFETY: as the caller guarantees that `self` is in bounds of `slice`, - // we can safely construct a subslice with `from_raw_parts` and use it - // since we return a shared thus immutable reference. - // The call to `from_utf8_unchecked` is safe since the data comes from - // a `str` which is guaranteed to be valid utf8, since the caller - // must guarantee that `self.start` is a char boundary. - unsafe { super::from_utf8_unchecked(slice::from_raw_parts(ptr, len)) } + ptr::slice_from_raw_parts(ptr, len) as *const str } #[inline] - unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { + unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output { + let slice = slice as *mut [u8]; // SAFETY: identical to `get_unchecked`. let ptr = unsafe { slice.as_mut_ptr().add(self.start) }; let len = slice.len() - self.start; - // SAFETY: mostly identical to `get_unchecked`, except that we can safely - // return a mutable reference since the caller passed a mutable reference - // and is thus guaranteed to have exclusive write access to `slice`. - unsafe { super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, len)) } + ptr::slice_from_raw_parts_mut(ptr, len) as *mut str } #[inline] fn index(self, slice: &str) -> &Self::Output { @@ -2097,8 +2086,9 @@ mod traits { #[inline] fn index_mut(self, slice: &mut str) -> &mut Self::Output { if slice.is_char_boundary(self.start) { - // SAFETY: just checked that `start` is on a char boundary. - unsafe { self.get_unchecked_mut(slice) } + // SAFETY: just checked that `start` is on a char boundary, + // and we are passing in a safe reference, so the return value will also be one. + unsafe { &mut *self.get_unchecked_mut(slice) } } else { super::slice_error_fail(slice, self.start, slice.len()) } @@ -2122,7 +2112,7 @@ mod traits { /// to the ending byte offset of a character (`end + 1` is either a starting /// byte offset or equal to `len`), if `begin > end`, or if `end >= len`. #[stable(feature = "inclusive_range", since = "1.26.0")] - impl SliceIndex<str> for ops::RangeInclusive<usize> { + unsafe impl SliceIndex<str> for ops::RangeInclusive<usize> { type Output = str; #[inline] fn get(self, slice: &str) -> Option<&Self::Output> { @@ -2141,12 +2131,12 @@ mod traits { } } #[inline] - unsafe fn get_unchecked(self, slice: &str) -> &Self::Output { + unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output { // SAFETY: the caller must uphold the safety contract for `get_unchecked`. unsafe { (*self.start()..self.end() + 1).get_unchecked(slice) } } #[inline] - unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { + unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output { // SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`. unsafe { (*self.start()..self.end() + 1).get_unchecked_mut(slice) } } @@ -2181,7 +2171,7 @@ mod traits { /// (`end + 1` is either a starting byte offset as defined by /// `is_char_boundary`, or equal to `len`), or if `end >= len`. #[stable(feature = "inclusive_range", since = "1.26.0")] - impl SliceIndex<str> for ops::RangeToInclusive<usize> { + unsafe impl SliceIndex<str> for ops::RangeToInclusive<usize> { type Output = str; #[inline] fn get(self, slice: &str) -> Option<&Self::Output> { @@ -2192,12 +2182,12 @@ mod traits { if self.end == usize::MAX { None } else { (..self.end + 1).get_mut(slice) } } #[inline] - unsafe fn get_unchecked(self, slice: &str) -> &Self::Output { + unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output { // SAFETY: the caller must uphold the safety contract for `get_unchecked`. unsafe { (..self.end + 1).get_unchecked(slice) } } #[inline] - unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output { + unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output { // SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`. unsafe { (..self.end + 1).get_unchecked_mut(slice) } } @@ -2560,8 +2550,10 @@ impl str { #[stable(feature = "str_checked_slicing", since = "1.20.0")] #[inline] pub unsafe fn get_unchecked<I: SliceIndex<str>>(&self, i: I) -> &I::Output { - // SAFETY: the caller must uphold the safety contract for `get_unchecked`. - unsafe { i.get_unchecked(self) } + // SAFETY: the caller must uphold the safety contract for `get_unchecked`; + // the slice is dereferencable because `self` is a safe reference. + // The returned pointer is safe because impls of `SliceIndex` have to guarantee that it is. + unsafe { &*i.get_unchecked(self) } } /// Returns a mutable, unchecked subslice of `str`. @@ -2593,8 +2585,10 @@ impl str { #[stable(feature = "str_checked_slicing", since = "1.20.0")] #[inline] pub unsafe fn get_unchecked_mut<I: SliceIndex<str>>(&mut self, i: I) -> &mut I::Output { - // SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`. - unsafe { i.get_unchecked_mut(self) } + // SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`; + // the slice is dereferencable because `self` is a safe reference. + // The returned pointer is safe because impls of `SliceIndex` have to guarantee that it is. + unsafe { &mut *i.get_unchecked_mut(self) } } /// Creates a string slice from another string slice, bypassing safety @@ -2644,8 +2638,10 @@ impl str { #[rustc_deprecated(since = "1.29.0", reason = "use `get_unchecked(begin..end)` instead")] #[inline] pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str { - // SAFETY: the caller must uphold the safety contract for `get_unchecked`. - unsafe { (begin..end).get_unchecked(self) } + // SAFETY: the caller must uphold the safety contract for `get_unchecked`; + // the slice is dereferencable because `self` is a safe reference. + // The returned pointer is safe because impls of `SliceIndex` have to guarantee that it is. + unsafe { &*(begin..end).get_unchecked(self) } } /// Creates a string slice from another string slice, bypassing safety @@ -2676,8 +2672,10 @@ impl str { #[rustc_deprecated(since = "1.29.0", reason = "use `get_unchecked_mut(begin..end)` instead")] #[inline] pub unsafe fn slice_mut_unchecked(&mut self, begin: usize, end: usize) -> &mut str { - // SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`. - unsafe { (begin..end).get_unchecked_mut(self) } + // SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`; + // the slice is dereferencable because `self` is a safe reference. + // The returned pointer is safe because impls of `SliceIndex` have to guarantee that it is. + unsafe { &mut *(begin..end).get_unchecked_mut(self) } } /// Divide one string slice into two at an index. |