597 lines
20 KiB
Rust
597 lines
20 KiB
Rust
//! Trait implementations for `str`.
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use crate::cmp::Ordering;
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use crate::ops;
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use crate::ptr;
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use crate::slice::SliceIndex;
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use super::ParseBoolError;
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/// Implements ordering of strings.
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///
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/// Strings are ordered lexicographically by their byte values. This orders Unicode code
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/// points based on their positions in the code charts. This is not necessarily the same as
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/// "alphabetical" order, which varies by language and locale. Sorting strings according to
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/// culturally-accepted standards requires locale-specific data that is outside the scope of
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/// the `str` type.
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Ord for str {
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#[inline]
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fn cmp(&self, other: &str) -> Ordering {
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self.as_bytes().cmp(other.as_bytes())
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl PartialEq for str {
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#[inline]
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fn eq(&self, other: &str) -> bool {
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self.as_bytes() == other.as_bytes()
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}
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#[inline]
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fn ne(&self, other: &str) -> bool {
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!(*self).eq(other)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Eq for str {}
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/// Implements comparison operations on strings.
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///
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/// Strings are compared lexicographically by their byte values. This compares Unicode code
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/// points based on their positions in the code charts. This is not necessarily the same as
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/// "alphabetical" order, which varies by language and locale. Comparing strings according to
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/// culturally-accepted standards requires locale-specific data that is outside the scope of
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/// the `str` type.
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#[stable(feature = "rust1", since = "1.0.0")]
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impl PartialOrd for str {
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#[inline]
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fn partial_cmp(&self, other: &str) -> Option<Ordering> {
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Some(self.cmp(other))
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<I> ops::Index<I> for str
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where
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I: SliceIndex<str>,
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{
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type Output = I::Output;
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#[inline]
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fn index(&self, index: I) -> &I::Output {
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index.index(self)
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}
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl<I> ops::IndexMut<I> for str
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where
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I: SliceIndex<str>,
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{
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#[inline]
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fn index_mut(&mut self, index: I) -> &mut I::Output {
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index.index_mut(self)
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}
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}
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#[inline(never)]
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#[cold]
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#[track_caller]
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fn str_index_overflow_fail() -> ! {
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panic!("attempted to index str up to maximum usize");
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}
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/// Implements substring slicing with syntax `&self[..]` or `&mut self[..]`.
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///
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/// Returns a slice of the whole string, i.e., returns `&self` or `&mut
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/// self`. Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`. Unlike
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/// other indexing operations, this can never panic.
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///
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/// This operation is `O(1)`.
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///
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/// Prior to 1.20.0, these indexing operations were still supported by
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/// direct implementation of `Index` and `IndexMut`.
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///
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/// Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`.
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#[stable(feature = "str_checked_slicing", since = "1.20.0")]
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unsafe impl SliceIndex<str> for ops::RangeFull {
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type Output = str;
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#[inline]
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fn get(self, slice: &str) -> Option<&Self::Output> {
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Some(slice)
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}
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#[inline]
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fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
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Some(slice)
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}
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#[inline]
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unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output {
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slice
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}
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#[inline]
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unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output {
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slice
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}
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#[inline]
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fn index(self, slice: &str) -> &Self::Output {
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slice
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}
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#[inline]
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fn index_mut(self, slice: &mut str) -> &mut Self::Output {
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slice
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}
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}
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/// Implements substring slicing with syntax `&self[begin .. end]` or `&mut
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/// self[begin .. end]`.
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///
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/// Returns a slice of the given string from the byte range
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/// [`begin`, `end`).
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///
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/// This operation is `O(1)`.
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///
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/// Prior to 1.20.0, these indexing operations were still supported by
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/// direct implementation of `Index` and `IndexMut`.
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///
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/// # Panics
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///
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/// Panics if `begin` or `end` does not point to the starting byte offset of
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/// a character (as defined by `is_char_boundary`), if `begin > end`, or if
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/// `end > len`.
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///
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/// # Examples
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///
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/// ```
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/// let s = "Löwe 老虎 Léopard";
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/// assert_eq!(&s[0 .. 1], "L");
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///
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/// assert_eq!(&s[1 .. 9], "öwe 老");
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///
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/// // these will panic:
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/// // byte 2 lies within `ö`:
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/// // &s[2 ..3];
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///
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/// // byte 8 lies within `老`
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/// // &s[1 .. 8];
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///
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/// // byte 100 is outside the string
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/// // &s[3 .. 100];
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/// ```
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#[stable(feature = "str_checked_slicing", since = "1.20.0")]
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unsafe impl SliceIndex<str> for ops::Range<usize> {
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type Output = str;
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#[inline]
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fn get(self, slice: &str) -> Option<&Self::Output> {
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if self.start <= self.end
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&& slice.is_char_boundary(self.start)
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&& slice.is_char_boundary(self.end)
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{
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// SAFETY: just checked that `start` and `end` are on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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// We also checked char boundaries, so this is valid UTF-8.
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Some(unsafe { &*self.get_unchecked(slice) })
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} else {
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None
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}
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}
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#[inline]
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fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
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if self.start <= self.end
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&& slice.is_char_boundary(self.start)
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&& slice.is_char_boundary(self.end)
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{
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// SAFETY: just checked that `start` and `end` are on a char boundary.
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// We know the pointer is unique because we got it from `slice`.
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Some(unsafe { &mut *self.get_unchecked_mut(slice) })
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} else {
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None
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}
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}
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#[inline]
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unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output {
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let slice = slice as *const [u8];
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// SAFETY: the caller guarantees that `self` is in bounds of `slice`
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// which satisfies all the conditions for `add`.
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let ptr = unsafe { slice.as_ptr().add(self.start) };
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let len = self.end - self.start;
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ptr::slice_from_raw_parts(ptr, len) as *const str
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}
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#[inline]
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unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output {
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let slice = slice as *mut [u8];
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// SAFETY: see comments for `get_unchecked`.
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let ptr = unsafe { slice.as_mut_ptr().add(self.start) };
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let len = self.end - self.start;
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ptr::slice_from_raw_parts_mut(ptr, len) as *mut str
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}
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#[inline]
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fn index(self, slice: &str) -> &Self::Output {
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let (start, end) = (self.start, self.end);
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match self.get(slice) {
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Some(s) => s,
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None => super::slice_error_fail(slice, start, end),
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}
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}
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#[inline]
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fn index_mut(self, slice: &mut str) -> &mut Self::Output {
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// is_char_boundary checks that the index is in [0, .len()]
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// cannot reuse `get` as above, because of NLL trouble
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if self.start <= self.end
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&& slice.is_char_boundary(self.start)
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&& slice.is_char_boundary(self.end)
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{
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// SAFETY: just checked that `start` and `end` are on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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unsafe { &mut *self.get_unchecked_mut(slice) }
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} else {
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super::slice_error_fail(slice, self.start, self.end)
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}
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}
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}
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/// Implements substring slicing with syntax `&self[.. end]` or `&mut
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/// self[.. end]`.
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///
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/// Returns a slice of the given string from the byte range [`0`, `end`).
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/// Equivalent to `&self[0 .. end]` or `&mut self[0 .. end]`.
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///
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/// This operation is `O(1)`.
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///
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/// Prior to 1.20.0, these indexing operations were still supported by
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/// direct implementation of `Index` and `IndexMut`.
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///
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/// # Panics
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///
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/// Panics if `end` does not point to the starting byte offset of a
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/// character (as defined by `is_char_boundary`), or if `end > len`.
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#[stable(feature = "str_checked_slicing", since = "1.20.0")]
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unsafe impl SliceIndex<str> for ops::RangeTo<usize> {
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type Output = str;
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#[inline]
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fn get(self, slice: &str) -> Option<&Self::Output> {
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if slice.is_char_boundary(self.end) {
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// SAFETY: just checked that `end` is on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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Some(unsafe { &*self.get_unchecked(slice) })
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} else {
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None
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}
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}
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#[inline]
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fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
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if slice.is_char_boundary(self.end) {
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// SAFETY: just checked that `end` is on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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Some(unsafe { &mut *self.get_unchecked_mut(slice) })
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} else {
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None
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}
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}
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#[inline]
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unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output {
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let slice = slice as *const [u8];
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let ptr = slice.as_ptr();
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ptr::slice_from_raw_parts(ptr, self.end) as *const str
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}
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#[inline]
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unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output {
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let slice = slice as *mut [u8];
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let ptr = slice.as_mut_ptr();
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ptr::slice_from_raw_parts_mut(ptr, self.end) as *mut str
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}
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#[inline]
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fn index(self, slice: &str) -> &Self::Output {
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let end = self.end;
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match self.get(slice) {
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Some(s) => s,
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None => super::slice_error_fail(slice, 0, end),
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}
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}
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#[inline]
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fn index_mut(self, slice: &mut str) -> &mut Self::Output {
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if slice.is_char_boundary(self.end) {
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// SAFETY: just checked that `end` is on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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unsafe { &mut *self.get_unchecked_mut(slice) }
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} else {
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super::slice_error_fail(slice, 0, self.end)
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}
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}
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}
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/// Implements substring slicing with syntax `&self[begin ..]` or `&mut
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/// self[begin ..]`.
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///
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/// Returns a slice of the given string from the byte range [`begin`,
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/// `len`). Equivalent to `&self[begin .. len]` or `&mut self[begin ..
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/// len]`.
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///
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/// This operation is `O(1)`.
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///
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/// Prior to 1.20.0, these indexing operations were still supported by
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/// direct implementation of `Index` and `IndexMut`.
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///
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/// # Panics
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///
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/// Panics if `begin` does not point to the starting byte offset of
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/// a character (as defined by `is_char_boundary`), or if `begin > len`.
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#[stable(feature = "str_checked_slicing", since = "1.20.0")]
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unsafe impl SliceIndex<str> for ops::RangeFrom<usize> {
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type Output = str;
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#[inline]
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fn get(self, slice: &str) -> Option<&Self::Output> {
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if slice.is_char_boundary(self.start) {
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// SAFETY: just checked that `start` is on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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Some(unsafe { &*self.get_unchecked(slice) })
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} else {
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None
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}
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}
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#[inline]
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fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
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if slice.is_char_boundary(self.start) {
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// SAFETY: just checked that `start` is on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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Some(unsafe { &mut *self.get_unchecked_mut(slice) })
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} else {
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None
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}
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}
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#[inline]
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unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output {
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let slice = slice as *const [u8];
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// SAFETY: the caller guarantees that `self` is in bounds of `slice`
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// which satisfies all the conditions for `add`.
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let ptr = unsafe { slice.as_ptr().add(self.start) };
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let len = slice.len() - self.start;
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ptr::slice_from_raw_parts(ptr, len) as *const str
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}
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#[inline]
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unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output {
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let slice = slice as *mut [u8];
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// SAFETY: identical to `get_unchecked`.
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let ptr = unsafe { slice.as_mut_ptr().add(self.start) };
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let len = slice.len() - self.start;
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ptr::slice_from_raw_parts_mut(ptr, len) as *mut str
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}
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#[inline]
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fn index(self, slice: &str) -> &Self::Output {
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let (start, end) = (self.start, slice.len());
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match self.get(slice) {
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Some(s) => s,
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None => super::slice_error_fail(slice, start, end),
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}
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}
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#[inline]
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fn index_mut(self, slice: &mut str) -> &mut Self::Output {
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if slice.is_char_boundary(self.start) {
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// SAFETY: just checked that `start` is on a char boundary,
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// and we are passing in a safe reference, so the return value will also be one.
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unsafe { &mut *self.get_unchecked_mut(slice) }
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} else {
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super::slice_error_fail(slice, self.start, slice.len())
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}
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}
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}
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/// Implements substring slicing with syntax `&self[begin ..= end]` or `&mut
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/// self[begin ..= end]`.
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///
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/// Returns a slice of the given string from the byte range
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/// [`begin`, `end`]. Equivalent to `&self [begin .. end + 1]` or `&mut
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/// self[begin .. end + 1]`, except if `end` has the maximum value for
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/// `usize`.
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///
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/// This operation is `O(1)`.
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///
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/// # Panics
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///
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/// Panics if `begin` does not point to the starting byte offset of
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/// a character (as defined by `is_char_boundary`), if `end` does not point
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/// to the ending byte offset of a character (`end + 1` is either a starting
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/// byte offset or equal to `len`), if `begin > end`, or if `end >= len`.
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#[stable(feature = "inclusive_range", since = "1.26.0")]
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unsafe impl SliceIndex<str> for ops::RangeInclusive<usize> {
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type Output = str;
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#[inline]
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fn get(self, slice: &str) -> Option<&Self::Output> {
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if *self.end() == usize::MAX { None } else { (*self.start()..self.end() + 1).get(slice) }
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}
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#[inline]
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fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
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if *self.end() == usize::MAX {
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None
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} else {
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(*self.start()..self.end() + 1).get_mut(slice)
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}
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}
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#[inline]
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unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output {
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// SAFETY: the caller must uphold the safety contract for `get_unchecked`.
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unsafe { (*self.start()..self.end() + 1).get_unchecked(slice) }
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}
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#[inline]
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unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output {
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// SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`.
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unsafe { (*self.start()..self.end() + 1).get_unchecked_mut(slice) }
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}
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#[inline]
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fn index(self, slice: &str) -> &Self::Output {
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if *self.end() == usize::MAX {
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str_index_overflow_fail();
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}
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(*self.start()..self.end() + 1).index(slice)
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}
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#[inline]
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fn index_mut(self, slice: &mut str) -> &mut Self::Output {
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if *self.end() == usize::MAX {
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str_index_overflow_fail();
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}
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(*self.start()..self.end() + 1).index_mut(slice)
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}
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}
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/// Implements substring slicing with syntax `&self[..= end]` or `&mut
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/// self[..= end]`.
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///
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/// Returns a slice of the given string from the byte range [0, `end`].
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/// Equivalent to `&self [0 .. end + 1]`, except if `end` has the maximum
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/// value for `usize`.
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///
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/// This operation is `O(1)`.
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///
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/// # Panics
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///
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/// Panics if `end` does not point to the ending byte offset of a character
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/// (`end + 1` is either a starting byte offset as defined by
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/// `is_char_boundary`, or equal to `len`), or if `end >= len`.
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#[stable(feature = "inclusive_range", since = "1.26.0")]
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unsafe impl SliceIndex<str> for ops::RangeToInclusive<usize> {
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type Output = str;
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#[inline]
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fn get(self, slice: &str) -> Option<&Self::Output> {
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if self.end == usize::MAX { None } else { (..self.end + 1).get(slice) }
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}
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#[inline]
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fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
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if self.end == usize::MAX { None } else { (..self.end + 1).get_mut(slice) }
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}
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#[inline]
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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 {
|
|
// SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`.
|
|
unsafe { (..self.end + 1).get_unchecked_mut(slice) }
|
|
}
|
|
#[inline]
|
|
fn index(self, slice: &str) -> &Self::Output {
|
|
if self.end == usize::MAX {
|
|
str_index_overflow_fail();
|
|
}
|
|
(..self.end + 1).index(slice)
|
|
}
|
|
#[inline]
|
|
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
|
|
if self.end == usize::MAX {
|
|
str_index_overflow_fail();
|
|
}
|
|
(..self.end + 1).index_mut(slice)
|
|
}
|
|
}
|
|
|
|
/// Parse a value from a string
|
|
///
|
|
/// `FromStr`'s [`from_str`] method is often used implicitly, through
|
|
/// [`str`]'s [`parse`] method. See [`parse`]'s documentation for examples.
|
|
///
|
|
/// [`from_str`]: FromStr::from_str
|
|
/// [`parse`]: str::parse
|
|
///
|
|
/// `FromStr` does not have a lifetime parameter, and so you can only parse types
|
|
/// that do not contain a lifetime parameter themselves. In other words, you can
|
|
/// parse an `i32` with `FromStr`, but not a `&i32`. You can parse a struct that
|
|
/// contains an `i32`, but not one that contains an `&i32`.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// Basic implementation of `FromStr` on an example `Point` type:
|
|
///
|
|
/// ```
|
|
/// use std::str::FromStr;
|
|
/// use std::num::ParseIntError;
|
|
///
|
|
/// #[derive(Debug, PartialEq)]
|
|
/// struct Point {
|
|
/// x: i32,
|
|
/// y: i32
|
|
/// }
|
|
///
|
|
/// impl FromStr for Point {
|
|
/// type Err = ParseIntError;
|
|
///
|
|
/// fn from_str(s: &str) -> Result<Self, Self::Err> {
|
|
/// let coords: Vec<&str> = s.trim_matches(|p| p == '(' || p == ')' )
|
|
/// .split(',')
|
|
/// .collect();
|
|
///
|
|
/// let x_fromstr = coords[0].parse::<i32>()?;
|
|
/// let y_fromstr = coords[1].parse::<i32>()?;
|
|
///
|
|
/// Ok(Point { x: x_fromstr, y: y_fromstr })
|
|
/// }
|
|
/// }
|
|
///
|
|
/// let p = Point::from_str("(1,2)");
|
|
/// assert_eq!(p.unwrap(), Point{ x: 1, y: 2} )
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
pub trait FromStr: Sized {
|
|
/// The associated error which can be returned from parsing.
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
type Err;
|
|
|
|
/// Parses a string `s` to return a value of this type.
|
|
///
|
|
/// If parsing succeeds, return the value inside [`Ok`], otherwise
|
|
/// when the string is ill-formatted return an error specific to the
|
|
/// inside [`Err`]. The error type is specific to implementation of the trait.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// Basic usage with [`i32`][ithirtytwo], a type that implements `FromStr`:
|
|
///
|
|
/// [ithirtytwo]: ../../std/primitive.i32.html
|
|
///
|
|
/// ```
|
|
/// use std::str::FromStr;
|
|
///
|
|
/// let s = "5";
|
|
/// let x = i32::from_str(s).unwrap();
|
|
///
|
|
/// assert_eq!(5, x);
|
|
/// ```
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
fn from_str(s: &str) -> Result<Self, Self::Err>;
|
|
}
|
|
|
|
#[stable(feature = "rust1", since = "1.0.0")]
|
|
impl FromStr for bool {
|
|
type Err = ParseBoolError;
|
|
|
|
/// Parse a `bool` from a string.
|
|
///
|
|
/// Yields a `Result<bool, ParseBoolError>`, because `s` may or may not
|
|
/// actually be parseable.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use std::str::FromStr;
|
|
///
|
|
/// assert_eq!(FromStr::from_str("true"), Ok(true));
|
|
/// assert_eq!(FromStr::from_str("false"), Ok(false));
|
|
/// assert!(<bool as FromStr>::from_str("not even a boolean").is_err());
|
|
/// ```
|
|
///
|
|
/// Note, in many cases, the `.parse()` method on `str` is more proper.
|
|
///
|
|
/// ```
|
|
/// assert_eq!("true".parse(), Ok(true));
|
|
/// assert_eq!("false".parse(), Ok(false));
|
|
/// assert!("not even a boolean".parse::<bool>().is_err());
|
|
/// ```
|
|
#[inline]
|
|
fn from_str(s: &str) -> Result<bool, ParseBoolError> {
|
|
match s {
|
|
"true" => Ok(true),
|
|
"false" => Ok(false),
|
|
_ => Err(ParseBoolError { _priv: () }),
|
|
}
|
|
}
|
|
}
|