2844 lines
96 KiB
Rust
2844 lines
96 KiB
Rust
//! String manipulation.
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//!
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//! For more details, see the [`std::str`] module.
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//!
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//! [`std::str`]: ../../std/str/index.html
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#![stable(feature = "rust1", since = "1.0.0")]
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mod converts;
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mod count;
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mod error;
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mod iter;
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mod traits;
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mod validations;
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use self::pattern::{DoubleEndedSearcher, Pattern, ReverseSearcher, Searcher};
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use crate::char::{self, EscapeDebugExtArgs};
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use crate::ops::Range;
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use crate::slice::{self, SliceIndex};
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use crate::{ascii, mem};
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pub mod pattern;
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mod lossy;
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#[unstable(feature = "str_from_raw_parts", issue = "119206")]
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pub use converts::{from_raw_parts, from_raw_parts_mut};
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use converts::{from_utf8, from_utf8_unchecked};
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#[stable(feature = "str_mut_extras", since = "1.20.0")]
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pub use converts::{from_utf8_mut, from_utf8_unchecked_mut};
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use error::{ParseBoolError, Utf8Error};
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#[stable(feature = "encode_utf16", since = "1.8.0")]
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pub use iter::EncodeUtf16;
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#[stable(feature = "rust1", since = "1.0.0")]
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#[allow(deprecated)]
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pub use iter::LinesAny;
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#[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
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pub use iter::SplitAsciiWhitespace;
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#[stable(feature = "split_inclusive", since = "1.51.0")]
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pub use iter::SplitInclusive;
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use iter::{Bytes, CharIndices, Chars, Lines, SplitWhitespace};
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#[stable(feature = "str_escape", since = "1.34.0")]
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pub use iter::{EscapeDebug, EscapeDefault, EscapeUnicode};
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#[stable(feature = "str_match_indices", since = "1.5.0")]
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pub use iter::{MatchIndices, RMatchIndices};
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use iter::{MatchIndicesInternal, MatchesInternal, SplitInternal, SplitNInternal};
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#[stable(feature = "str_matches", since = "1.2.0")]
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pub use iter::{Matches, RMatches};
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use iter::{RSplit, RSplitTerminator, Split, SplitTerminator};
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use iter::{RSplitN, SplitN};
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#[stable(feature = "utf8_chunks", since = "1.79.0")]
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pub use lossy::{Utf8Chunk, Utf8Chunks};
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use traits::FromStr;
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#[unstable(feature = "str_internals", issue = "none")]
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pub use validations::{next_code_point, utf8_char_width};
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#[inline(never)]
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#[cold]
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#[track_caller]
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#[rustc_allow_const_fn_unstable(const_eval_select)]
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#[cfg(not(feature = "panic_immediate_abort"))]
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const fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
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crate::intrinsics::const_eval_select((s, begin, end), slice_error_fail_ct, slice_error_fail_rt)
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}
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#[cfg(feature = "panic_immediate_abort")]
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const fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
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slice_error_fail_ct(s, begin, end)
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}
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#[track_caller]
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const fn slice_error_fail_ct(_: &str, _: usize, _: usize) -> ! {
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panic!("failed to slice string");
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}
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#[track_caller]
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fn slice_error_fail_rt(s: &str, begin: usize, end: usize) -> ! {
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const MAX_DISPLAY_LENGTH: usize = 256;
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let trunc_len = s.floor_char_boundary(MAX_DISPLAY_LENGTH);
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let s_trunc = &s[..trunc_len];
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let ellipsis = if trunc_len < s.len() { "[...]" } else { "" };
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// 1. out of bounds
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if begin > s.len() || end > s.len() {
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let oob_index = if begin > s.len() { begin } else { end };
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panic!("byte index {oob_index} is out of bounds of `{s_trunc}`{ellipsis}");
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}
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// 2. begin <= end
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assert!(
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begin <= end,
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"begin <= end ({} <= {}) when slicing `{}`{}",
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begin,
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end,
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s_trunc,
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ellipsis
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);
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// 3. character boundary
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let index = if !s.is_char_boundary(begin) { begin } else { end };
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// find the character
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let char_start = s.floor_char_boundary(index);
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// `char_start` must be less than len and a char boundary
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let ch = s[char_start..].chars().next().unwrap();
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let char_range = char_start..char_start + ch.len_utf8();
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panic!(
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"byte index {} is not a char boundary; it is inside {:?} (bytes {:?}) of `{}`{}",
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index, ch, char_range, s_trunc, ellipsis
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);
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}
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#[cfg(not(test))]
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impl str {
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/// Returns the length of `self`.
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///
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/// This length is in bytes, not [`char`]s or graphemes. In other words,
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/// it might not be what a human considers the length of the string.
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///
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/// [`char`]: prim@char
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///
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/// # Examples
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///
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/// ```
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/// let len = "foo".len();
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/// assert_eq!(3, len);
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///
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/// assert_eq!("ƒoo".len(), 4); // fancy f!
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/// assert_eq!("ƒoo".chars().count(), 3);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[rustc_const_stable(feature = "const_str_len", since = "1.39.0")]
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#[cfg_attr(not(test), rustc_diagnostic_item = "str_len")]
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#[must_use]
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#[inline]
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pub const fn len(&self) -> usize {
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self.as_bytes().len()
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}
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/// Returns `true` if `self` has a length of zero bytes.
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///
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/// # Examples
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///
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/// ```
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/// let s = "";
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/// assert!(s.is_empty());
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///
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/// let s = "not empty";
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/// assert!(!s.is_empty());
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[rustc_const_stable(feature = "const_str_is_empty", since = "1.39.0")]
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#[must_use]
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#[inline]
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pub const fn is_empty(&self) -> bool {
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self.len() == 0
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}
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/// Checks that `index`-th byte is the first byte in a UTF-8 code point
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/// sequence or the end of the string.
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///
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/// The start and end of the string (when `index == self.len()`) are
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/// considered to be boundaries.
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///
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/// Returns `false` if `index` is greater than `self.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!(s.is_char_boundary(0));
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/// // start of `老`
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/// assert!(s.is_char_boundary(6));
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/// assert!(s.is_char_boundary(s.len()));
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///
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/// // second byte of `ö`
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/// assert!(!s.is_char_boundary(2));
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///
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/// // third byte of `老`
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/// assert!(!s.is_char_boundary(8));
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/// ```
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#[must_use]
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#[stable(feature = "is_char_boundary", since = "1.9.0")]
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#[inline]
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pub fn is_char_boundary(&self, index: usize) -> bool {
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// 0 is always ok.
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// Test for 0 explicitly so that it can optimize out the check
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// easily and skip reading string data for that case.
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// Note that optimizing `self.get(..index)` relies on this.
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if index == 0 {
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return true;
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}
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match self.as_bytes().get(index) {
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// For `None` we have two options:
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//
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// - index == self.len()
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// Empty strings are valid, so return true
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// - index > self.len()
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// In this case return false
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//
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// The check is placed exactly here, because it improves generated
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// code on higher opt-levels. See PR #84751 for more details.
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None => index == self.len(),
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Some(&b) => b.is_utf8_char_boundary(),
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}
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}
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/// Finds the closest `x` not exceeding `index` where `is_char_boundary(x)` is `true`.
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///
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/// This method can help you truncate a string so that it's still valid UTF-8, but doesn't
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/// exceed a given number of bytes. Note that this is done purely at the character level
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/// and can still visually split graphemes, even though the underlying characters aren't
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/// split. For example, the emoji 🧑🔬 (scientist) could be split so that the string only
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/// includes 🧑 (person) instead.
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///
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/// # Examples
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///
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/// ```
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/// #![feature(round_char_boundary)]
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/// let s = "❤️🧡💛💚💙💜";
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/// assert_eq!(s.len(), 26);
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/// assert!(!s.is_char_boundary(13));
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///
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/// let closest = s.floor_char_boundary(13);
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/// assert_eq!(closest, 10);
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/// assert_eq!(&s[..closest], "❤️🧡");
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/// ```
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#[unstable(feature = "round_char_boundary", issue = "93743")]
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#[inline]
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pub fn floor_char_boundary(&self, index: usize) -> usize {
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if index >= self.len() {
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self.len()
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} else {
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let lower_bound = index.saturating_sub(3);
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let new_index = self.as_bytes()[lower_bound..=index]
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.iter()
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.rposition(|b| b.is_utf8_char_boundary());
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// SAFETY: we know that the character boundary will be within four bytes
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unsafe { lower_bound + new_index.unwrap_unchecked() }
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}
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}
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/// Finds the closest `x` not below `index` where `is_char_boundary(x)` is `true`.
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///
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/// If `index` is greater than the length of the string, this returns the length of the string.
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///
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/// This method is the natural complement to [`floor_char_boundary`]. See that method
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/// for more details.
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///
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/// [`floor_char_boundary`]: str::floor_char_boundary
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///
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///
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/// # Examples
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///
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/// ```
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/// #![feature(round_char_boundary)]
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/// let s = "❤️🧡💛💚💙💜";
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/// assert_eq!(s.len(), 26);
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/// assert!(!s.is_char_boundary(13));
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///
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/// let closest = s.ceil_char_boundary(13);
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/// assert_eq!(closest, 14);
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/// assert_eq!(&s[..closest], "❤️🧡💛");
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/// ```
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#[unstable(feature = "round_char_boundary", issue = "93743")]
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#[inline]
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pub fn ceil_char_boundary(&self, index: usize) -> usize {
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if index > self.len() {
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self.len()
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} else {
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let upper_bound = Ord::min(index + 4, self.len());
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self.as_bytes()[index..upper_bound]
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.iter()
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.position(|b| b.is_utf8_char_boundary())
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.map_or(upper_bound, |pos| pos + index)
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}
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}
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/// Converts a string slice to a byte slice. To convert the byte slice back
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/// into a string slice, use the [`from_utf8`] function.
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///
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/// # Examples
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///
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/// ```
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/// let bytes = "bors".as_bytes();
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/// assert_eq!(b"bors", bytes);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[rustc_const_stable(feature = "str_as_bytes", since = "1.39.0")]
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#[must_use]
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#[inline(always)]
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#[allow(unused_attributes)]
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pub const fn as_bytes(&self) -> &[u8] {
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// SAFETY: const sound because we transmute two types with the same layout
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unsafe { mem::transmute(self) }
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}
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/// Converts a mutable string slice to a mutable byte slice.
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///
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/// # Safety
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///
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/// The caller must ensure that the content of the slice is valid UTF-8
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/// before the borrow ends and the underlying `str` is used.
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///
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/// Use of a `str` whose contents are not valid UTF-8 is undefined behavior.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// let mut s = String::from("Hello");
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/// let bytes = unsafe { s.as_bytes_mut() };
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///
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/// assert_eq!(b"Hello", bytes);
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/// ```
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///
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/// Mutability:
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///
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/// ```
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/// let mut s = String::from("🗻∈🌏");
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///
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/// unsafe {
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/// let bytes = s.as_bytes_mut();
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///
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/// bytes[0] = 0xF0;
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/// bytes[1] = 0x9F;
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/// bytes[2] = 0x8D;
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/// bytes[3] = 0x94;
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/// }
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///
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/// assert_eq!("🍔∈🌏", s);
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/// ```
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#[stable(feature = "str_mut_extras", since = "1.20.0")]
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#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
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#[rustc_const_stable(feature = "const_str_as_mut", since = "CURRENT_RUSTC_VERSION")]
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#[must_use]
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#[inline(always)]
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pub const unsafe fn as_bytes_mut(&mut self) -> &mut [u8] {
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// SAFETY: the cast from `&str` to `&[u8]` is safe since `str`
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// has the same layout as `&[u8]` (only std can make this guarantee).
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// The pointer dereference is safe since it comes from a mutable reference which
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// is guaranteed to be valid for writes.
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unsafe { &mut *(self as *mut str as *mut [u8]) }
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}
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/// Converts a string slice to a raw pointer.
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///
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/// As string slices are a slice of bytes, the raw pointer points to a
|
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/// [`u8`]. This pointer will be pointing to the first byte of the string
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/// slice.
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///
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/// The caller must ensure that the returned pointer is never written to.
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/// If you need to mutate the contents of the string slice, use [`as_mut_ptr`].
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///
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/// [`as_mut_ptr`]: str::as_mut_ptr
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///
|
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/// # Examples
|
||
///
|
||
/// ```
|
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/// let s = "Hello";
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/// let ptr = s.as_ptr();
|
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/// ```
|
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#[stable(feature = "rust1", since = "1.0.0")]
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#[rustc_const_stable(feature = "rustc_str_as_ptr", since = "1.32.0")]
|
||
#[rustc_never_returns_null_ptr]
|
||
#[must_use]
|
||
#[inline(always)]
|
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pub const fn as_ptr(&self) -> *const u8 {
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self as *const str as *const u8
|
||
}
|
||
|
||
/// Converts a mutable string slice to a raw pointer.
|
||
///
|
||
/// As string slices are a slice of bytes, the raw pointer points to a
|
||
/// [`u8`]. This pointer will be pointing to the first byte of the string
|
||
/// slice.
|
||
///
|
||
/// It is your responsibility to make sure that the string slice only gets
|
||
/// modified in a way that it remains valid UTF-8.
|
||
#[stable(feature = "str_as_mut_ptr", since = "1.36.0")]
|
||
#[cfg_attr(bootstrap, rustc_allow_const_fn_unstable(const_mut_refs))]
|
||
#[rustc_const_stable(feature = "const_str_as_mut", since = "CURRENT_RUSTC_VERSION")]
|
||
#[rustc_never_returns_null_ptr]
|
||
#[must_use]
|
||
#[inline(always)]
|
||
pub const fn as_mut_ptr(&mut self) -> *mut u8 {
|
||
self as *mut str as *mut u8
|
||
}
|
||
|
||
/// Returns a subslice of `str`.
|
||
///
|
||
/// This is the non-panicking alternative to indexing the `str`. Returns
|
||
/// [`None`] whenever equivalent indexing operation would panic.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v = String::from("🗻∈🌏");
|
||
///
|
||
/// assert_eq!(Some("🗻"), v.get(0..4));
|
||
///
|
||
/// // indices not on UTF-8 sequence boundaries
|
||
/// assert!(v.get(1..).is_none());
|
||
/// assert!(v.get(..8).is_none());
|
||
///
|
||
/// // out of bounds
|
||
/// assert!(v.get(..42).is_none());
|
||
/// ```
|
||
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
|
||
#[inline]
|
||
pub fn get<I: SliceIndex<str>>(&self, i: I) -> Option<&I::Output> {
|
||
i.get(self)
|
||
}
|
||
|
||
/// Returns a mutable subslice of `str`.
|
||
///
|
||
/// This is the non-panicking alternative to indexing the `str`. Returns
|
||
/// [`None`] whenever equivalent indexing operation would panic.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = String::from("hello");
|
||
/// // correct length
|
||
/// assert!(v.get_mut(0..5).is_some());
|
||
/// // out of bounds
|
||
/// assert!(v.get_mut(..42).is_none());
|
||
/// assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));
|
||
///
|
||
/// assert_eq!("hello", v);
|
||
/// {
|
||
/// let s = v.get_mut(0..2);
|
||
/// let s = s.map(|s| {
|
||
/// s.make_ascii_uppercase();
|
||
/// &*s
|
||
/// });
|
||
/// assert_eq!(Some("HE"), s);
|
||
/// }
|
||
/// assert_eq!("HEllo", v);
|
||
/// ```
|
||
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
|
||
#[inline]
|
||
pub fn get_mut<I: SliceIndex<str>>(&mut self, i: I) -> Option<&mut I::Output> {
|
||
i.get_mut(self)
|
||
}
|
||
|
||
/// Returns an unchecked subslice of `str`.
|
||
///
|
||
/// This is the unchecked alternative to indexing the `str`.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Callers of this function are responsible that these preconditions are
|
||
/// satisfied:
|
||
///
|
||
/// * The starting index must not exceed the ending index;
|
||
/// * Indexes must be within bounds of the original slice;
|
||
/// * Indexes must lie on UTF-8 sequence boundaries.
|
||
///
|
||
/// Failing that, the returned string slice may reference invalid memory or
|
||
/// violate the invariants communicated by the `str` type.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v = "🗻∈🌏";
|
||
/// unsafe {
|
||
/// assert_eq!("🗻", v.get_unchecked(0..4));
|
||
/// assert_eq!("∈", v.get_unchecked(4..7));
|
||
/// assert_eq!("🌏", v.get_unchecked(7..11));
|
||
/// }
|
||
/// ```
|
||
#[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`;
|
||
// the slice is dereferenceable 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`.
|
||
///
|
||
/// This is the unchecked alternative to indexing the `str`.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Callers of this function are responsible that these preconditions are
|
||
/// satisfied:
|
||
///
|
||
/// * The starting index must not exceed the ending index;
|
||
/// * Indexes must be within bounds of the original slice;
|
||
/// * Indexes must lie on UTF-8 sequence boundaries.
|
||
///
|
||
/// Failing that, the returned string slice may reference invalid memory or
|
||
/// violate the invariants communicated by the `str` type.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut v = String::from("🗻∈🌏");
|
||
/// unsafe {
|
||
/// assert_eq!("🗻", v.get_unchecked_mut(0..4));
|
||
/// assert_eq!("∈", v.get_unchecked_mut(4..7));
|
||
/// assert_eq!("🌏", v.get_unchecked_mut(7..11));
|
||
/// }
|
||
/// ```
|
||
#[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`;
|
||
// the slice is dereferenceable 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
|
||
/// checks.
|
||
///
|
||
/// This is generally not recommended, use with caution! For a safe
|
||
/// alternative see [`str`] and [`Index`].
|
||
///
|
||
/// [`Index`]: crate::ops::Index
|
||
///
|
||
/// This new slice goes from `begin` to `end`, including `begin` but
|
||
/// excluding `end`.
|
||
///
|
||
/// To get a mutable string slice instead, see the
|
||
/// [`slice_mut_unchecked`] method.
|
||
///
|
||
/// [`slice_mut_unchecked`]: str::slice_mut_unchecked
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Callers of this function are responsible that three preconditions are
|
||
/// satisfied:
|
||
///
|
||
/// * `begin` must not exceed `end`.
|
||
/// * `begin` and `end` must be byte positions within the string slice.
|
||
/// * `begin` and `end` must lie on UTF-8 sequence boundaries.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let s = "Löwe 老虎 Léopard";
|
||
///
|
||
/// unsafe {
|
||
/// assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21));
|
||
/// }
|
||
///
|
||
/// let s = "Hello, world!";
|
||
///
|
||
/// unsafe {
|
||
/// assert_eq!("world", s.slice_unchecked(7, 12));
|
||
/// }
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[deprecated(since = "1.29.0", note = "use `get_unchecked(begin..end)` instead")]
|
||
#[must_use]
|
||
#[inline]
|
||
pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str {
|
||
// SAFETY: the caller must uphold the safety contract for `get_unchecked`;
|
||
// the slice is dereferenceable 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
|
||
/// checks.
|
||
///
|
||
/// This is generally not recommended, use with caution! For a safe
|
||
/// alternative see [`str`] and [`IndexMut`].
|
||
///
|
||
/// [`IndexMut`]: crate::ops::IndexMut
|
||
///
|
||
/// This new slice goes from `begin` to `end`, including `begin` but
|
||
/// excluding `end`.
|
||
///
|
||
/// To get an immutable string slice instead, see the
|
||
/// [`slice_unchecked`] method.
|
||
///
|
||
/// [`slice_unchecked`]: str::slice_unchecked
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Callers of this function are responsible that three preconditions are
|
||
/// satisfied:
|
||
///
|
||
/// * `begin` must not exceed `end`.
|
||
/// * `begin` and `end` must be byte positions within the string slice.
|
||
/// * `begin` and `end` must lie on UTF-8 sequence boundaries.
|
||
#[stable(feature = "str_slice_mut", since = "1.5.0")]
|
||
#[deprecated(since = "1.29.0", note = "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`;
|
||
// the slice is dereferenceable 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) }
|
||
}
|
||
|
||
/// Divides one string slice into two at an index.
|
||
///
|
||
/// The argument, `mid`, should be a byte offset from the start of the
|
||
/// string. It must also be on the boundary of a UTF-8 code point.
|
||
///
|
||
/// The two slices returned go from the start of the string slice to `mid`,
|
||
/// and from `mid` to the end of the string slice.
|
||
///
|
||
/// To get mutable string slices instead, see the [`split_at_mut`]
|
||
/// method.
|
||
///
|
||
/// [`split_at_mut`]: str::split_at_mut
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `mid` is not on a UTF-8 code point boundary, or if it is past
|
||
/// the end of the last code point of the string slice. For a non-panicking
|
||
/// alternative see [`split_at_checked`](str::split_at_checked).
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let s = "Per Martin-Löf";
|
||
///
|
||
/// let (first, last) = s.split_at(3);
|
||
///
|
||
/// assert_eq!("Per", first);
|
||
/// assert_eq!(" Martin-Löf", last);
|
||
/// ```
|
||
#[inline]
|
||
#[must_use]
|
||
#[stable(feature = "str_split_at", since = "1.4.0")]
|
||
pub fn split_at(&self, mid: usize) -> (&str, &str) {
|
||
match self.split_at_checked(mid) {
|
||
None => slice_error_fail(self, 0, mid),
|
||
Some(pair) => pair,
|
||
}
|
||
}
|
||
|
||
/// Divides one mutable string slice into two at an index.
|
||
///
|
||
/// The argument, `mid`, should be a byte offset from the start of the
|
||
/// string. It must also be on the boundary of a UTF-8 code point.
|
||
///
|
||
/// The two slices returned go from the start of the string slice to `mid`,
|
||
/// and from `mid` to the end of the string slice.
|
||
///
|
||
/// To get immutable string slices instead, see the [`split_at`] method.
|
||
///
|
||
/// [`split_at`]: str::split_at
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if `mid` is not on a UTF-8 code point boundary, or if it is past
|
||
/// the end of the last code point of the string slice. For a non-panicking
|
||
/// alternative see [`split_at_mut_checked`](str::split_at_mut_checked).
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut s = "Per Martin-Löf".to_string();
|
||
/// {
|
||
/// let (first, last) = s.split_at_mut(3);
|
||
/// first.make_ascii_uppercase();
|
||
/// assert_eq!("PER", first);
|
||
/// assert_eq!(" Martin-Löf", last);
|
||
/// }
|
||
/// assert_eq!("PER Martin-Löf", s);
|
||
/// ```
|
||
#[inline]
|
||
#[must_use]
|
||
#[stable(feature = "str_split_at", since = "1.4.0")]
|
||
pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str) {
|
||
// is_char_boundary checks that the index is in [0, .len()]
|
||
if self.is_char_boundary(mid) {
|
||
// SAFETY: just checked that `mid` is on a char boundary.
|
||
unsafe { self.split_at_mut_unchecked(mid) }
|
||
} else {
|
||
slice_error_fail(self, 0, mid)
|
||
}
|
||
}
|
||
|
||
/// Divides one string slice into two at an index.
|
||
///
|
||
/// The argument, `mid`, should be a valid byte offset from the start of the
|
||
/// string. It must also be on the boundary of a UTF-8 code point. The
|
||
/// method returns `None` if that’s not the case.
|
||
///
|
||
/// The two slices returned go from the start of the string slice to `mid`,
|
||
/// and from `mid` to the end of the string slice.
|
||
///
|
||
/// To get mutable string slices instead, see the [`split_at_mut_checked`]
|
||
/// method.
|
||
///
|
||
/// [`split_at_mut_checked`]: str::split_at_mut_checked
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let s = "Per Martin-Löf";
|
||
///
|
||
/// let (first, last) = s.split_at_checked(3).unwrap();
|
||
/// assert_eq!("Per", first);
|
||
/// assert_eq!(" Martin-Löf", last);
|
||
///
|
||
/// assert_eq!(None, s.split_at_checked(13)); // Inside “ö”
|
||
/// assert_eq!(None, s.split_at_checked(16)); // Beyond the string length
|
||
/// ```
|
||
#[inline]
|
||
#[must_use]
|
||
#[stable(feature = "split_at_checked", since = "1.80.0")]
|
||
pub fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)> {
|
||
// is_char_boundary checks that the index is in [0, .len()]
|
||
if self.is_char_boundary(mid) {
|
||
// SAFETY: just checked that `mid` is on a char boundary.
|
||
Some(unsafe { (self.get_unchecked(0..mid), self.get_unchecked(mid..self.len())) })
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
/// Divides one mutable string slice into two at an index.
|
||
///
|
||
/// The argument, `mid`, should be a valid byte offset from the start of the
|
||
/// string. It must also be on the boundary of a UTF-8 code point. The
|
||
/// method returns `None` if that’s not the case.
|
||
///
|
||
/// The two slices returned go from the start of the string slice to `mid`,
|
||
/// and from `mid` to the end of the string slice.
|
||
///
|
||
/// To get immutable string slices instead, see the [`split_at_checked`] method.
|
||
///
|
||
/// [`split_at_checked`]: str::split_at_checked
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut s = "Per Martin-Löf".to_string();
|
||
/// if let Some((first, last)) = s.split_at_mut_checked(3) {
|
||
/// first.make_ascii_uppercase();
|
||
/// assert_eq!("PER", first);
|
||
/// assert_eq!(" Martin-Löf", last);
|
||
/// }
|
||
/// assert_eq!("PER Martin-Löf", s);
|
||
///
|
||
/// assert_eq!(None, s.split_at_mut_checked(13)); // Inside “ö”
|
||
/// assert_eq!(None, s.split_at_mut_checked(16)); // Beyond the string length
|
||
/// ```
|
||
#[inline]
|
||
#[must_use]
|
||
#[stable(feature = "split_at_checked", since = "1.80.0")]
|
||
pub fn split_at_mut_checked(&mut self, mid: usize) -> Option<(&mut str, &mut str)> {
|
||
// is_char_boundary checks that the index is in [0, .len()]
|
||
if self.is_char_boundary(mid) {
|
||
// SAFETY: just checked that `mid` is on a char boundary.
|
||
Some(unsafe { self.split_at_mut_unchecked(mid) })
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
/// Divides one string slice into two at an index.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// The caller must ensure that `mid` is a valid byte offset from the start
|
||
/// of the string and falls on the boundary of a UTF-8 code point.
|
||
unsafe fn split_at_mut_unchecked(&mut self, mid: usize) -> (&mut str, &mut str) {
|
||
let len = self.len();
|
||
let ptr = self.as_mut_ptr();
|
||
// SAFETY: caller guarantees `mid` is on a char boundary.
|
||
unsafe {
|
||
(
|
||
from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, mid)),
|
||
from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr.add(mid), len - mid)),
|
||
)
|
||
}
|
||
}
|
||
|
||
/// Returns an iterator over the [`char`]s of a string slice.
|
||
///
|
||
/// As a string slice consists of valid UTF-8, we can iterate through a
|
||
/// string slice by [`char`]. This method returns such an iterator.
|
||
///
|
||
/// It's important to remember that [`char`] represents a Unicode Scalar
|
||
/// Value, and might not match your idea of what a 'character' is. Iteration
|
||
/// over grapheme clusters may be what you actually want. This functionality
|
||
/// is not provided by Rust's standard library, check crates.io instead.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let word = "goodbye";
|
||
///
|
||
/// let count = word.chars().count();
|
||
/// assert_eq!(7, count);
|
||
///
|
||
/// let mut chars = word.chars();
|
||
///
|
||
/// assert_eq!(Some('g'), chars.next());
|
||
/// assert_eq!(Some('o'), chars.next());
|
||
/// assert_eq!(Some('o'), chars.next());
|
||
/// assert_eq!(Some('d'), chars.next());
|
||
/// assert_eq!(Some('b'), chars.next());
|
||
/// assert_eq!(Some('y'), chars.next());
|
||
/// assert_eq!(Some('e'), chars.next());
|
||
///
|
||
/// assert_eq!(None, chars.next());
|
||
/// ```
|
||
///
|
||
/// Remember, [`char`]s might not match your intuition about characters:
|
||
///
|
||
/// [`char`]: prim@char
|
||
///
|
||
/// ```
|
||
/// let y = "y̆";
|
||
///
|
||
/// let mut chars = y.chars();
|
||
///
|
||
/// assert_eq!(Some('y'), chars.next()); // not 'y̆'
|
||
/// assert_eq!(Some('\u{0306}'), chars.next());
|
||
///
|
||
/// assert_eq!(None, chars.next());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "str_chars")]
|
||
pub fn chars(&self) -> Chars<'_> {
|
||
Chars { iter: self.as_bytes().iter() }
|
||
}
|
||
|
||
/// Returns an iterator over the [`char`]s of a string slice, and their
|
||
/// positions.
|
||
///
|
||
/// As a string slice consists of valid UTF-8, we can iterate through a
|
||
/// string slice by [`char`]. This method returns an iterator of both
|
||
/// these [`char`]s, as well as their byte positions.
|
||
///
|
||
/// The iterator yields tuples. The position is first, the [`char`] is
|
||
/// second.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let word = "goodbye";
|
||
///
|
||
/// let count = word.char_indices().count();
|
||
/// assert_eq!(7, count);
|
||
///
|
||
/// let mut char_indices = word.char_indices();
|
||
///
|
||
/// assert_eq!(Some((0, 'g')), char_indices.next());
|
||
/// assert_eq!(Some((1, 'o')), char_indices.next());
|
||
/// assert_eq!(Some((2, 'o')), char_indices.next());
|
||
/// assert_eq!(Some((3, 'd')), char_indices.next());
|
||
/// assert_eq!(Some((4, 'b')), char_indices.next());
|
||
/// assert_eq!(Some((5, 'y')), char_indices.next());
|
||
/// assert_eq!(Some((6, 'e')), char_indices.next());
|
||
///
|
||
/// assert_eq!(None, char_indices.next());
|
||
/// ```
|
||
///
|
||
/// Remember, [`char`]s might not match your intuition about characters:
|
||
///
|
||
/// [`char`]: prim@char
|
||
///
|
||
/// ```
|
||
/// let yes = "y̆es";
|
||
///
|
||
/// let mut char_indices = yes.char_indices();
|
||
///
|
||
/// assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
|
||
/// assert_eq!(Some((1, '\u{0306}')), char_indices.next());
|
||
///
|
||
/// // note the 3 here - the previous character took up two bytes
|
||
/// assert_eq!(Some((3, 'e')), char_indices.next());
|
||
/// assert_eq!(Some((4, 's')), char_indices.next());
|
||
///
|
||
/// assert_eq!(None, char_indices.next());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn char_indices(&self) -> CharIndices<'_> {
|
||
CharIndices { front_offset: 0, iter: self.chars() }
|
||
}
|
||
|
||
/// Returns an iterator over the bytes of a string slice.
|
||
///
|
||
/// As a string slice consists of a sequence of bytes, we can iterate
|
||
/// through a string slice by byte. This method returns such an iterator.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut bytes = "bors".bytes();
|
||
///
|
||
/// assert_eq!(Some(b'b'), bytes.next());
|
||
/// assert_eq!(Some(b'o'), bytes.next());
|
||
/// assert_eq!(Some(b'r'), bytes.next());
|
||
/// assert_eq!(Some(b's'), bytes.next());
|
||
///
|
||
/// assert_eq!(None, bytes.next());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn bytes(&self) -> Bytes<'_> {
|
||
Bytes(self.as_bytes().iter().copied())
|
||
}
|
||
|
||
/// Splits a string slice by whitespace.
|
||
///
|
||
/// The iterator returned will return string slices that are sub-slices of
|
||
/// the original string slice, separated by any amount of whitespace.
|
||
///
|
||
/// 'Whitespace' is defined according to the terms of the Unicode Derived
|
||
/// Core Property `White_Space`. If you only want to split on ASCII whitespace
|
||
/// instead, use [`split_ascii_whitespace`].
|
||
///
|
||
/// [`split_ascii_whitespace`]: str::split_ascii_whitespace
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut iter = "A few words".split_whitespace();
|
||
///
|
||
/// assert_eq!(Some("A"), iter.next());
|
||
/// assert_eq!(Some("few"), iter.next());
|
||
/// assert_eq!(Some("words"), iter.next());
|
||
///
|
||
/// assert_eq!(None, iter.next());
|
||
/// ```
|
||
///
|
||
/// All kinds of whitespace are considered:
|
||
///
|
||
/// ```
|
||
/// let mut iter = " Mary had\ta\u{2009}little \n\t lamb".split_whitespace();
|
||
/// assert_eq!(Some("Mary"), iter.next());
|
||
/// assert_eq!(Some("had"), iter.next());
|
||
/// assert_eq!(Some("a"), iter.next());
|
||
/// assert_eq!(Some("little"), iter.next());
|
||
/// assert_eq!(Some("lamb"), iter.next());
|
||
///
|
||
/// assert_eq!(None, iter.next());
|
||
/// ```
|
||
///
|
||
/// If the string is empty or all whitespace, the iterator yields no string slices:
|
||
/// ```
|
||
/// assert_eq!("".split_whitespace().next(), None);
|
||
/// assert_eq!(" ".split_whitespace().next(), None);
|
||
/// ```
|
||
#[must_use = "this returns the split string as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "split_whitespace", since = "1.1.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "str_split_whitespace")]
|
||
#[inline]
|
||
pub fn split_whitespace(&self) -> SplitWhitespace<'_> {
|
||
SplitWhitespace { inner: self.split(IsWhitespace).filter(IsNotEmpty) }
|
||
}
|
||
|
||
/// Splits a string slice by ASCII whitespace.
|
||
///
|
||
/// The iterator returned will return string slices that are sub-slices of
|
||
/// the original string slice, separated by any amount of ASCII whitespace.
|
||
///
|
||
/// To split by Unicode `Whitespace` instead, use [`split_whitespace`].
|
||
///
|
||
/// [`split_whitespace`]: str::split_whitespace
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut iter = "A few words".split_ascii_whitespace();
|
||
///
|
||
/// assert_eq!(Some("A"), iter.next());
|
||
/// assert_eq!(Some("few"), iter.next());
|
||
/// assert_eq!(Some("words"), iter.next());
|
||
///
|
||
/// assert_eq!(None, iter.next());
|
||
/// ```
|
||
///
|
||
/// All kinds of ASCII whitespace are considered:
|
||
///
|
||
/// ```
|
||
/// let mut iter = " Mary had\ta little \n\t lamb".split_ascii_whitespace();
|
||
/// assert_eq!(Some("Mary"), iter.next());
|
||
/// assert_eq!(Some("had"), iter.next());
|
||
/// assert_eq!(Some("a"), iter.next());
|
||
/// assert_eq!(Some("little"), iter.next());
|
||
/// assert_eq!(Some("lamb"), iter.next());
|
||
///
|
||
/// assert_eq!(None, iter.next());
|
||
/// ```
|
||
///
|
||
/// If the string is empty or all ASCII whitespace, the iterator yields no string slices:
|
||
/// ```
|
||
/// assert_eq!("".split_ascii_whitespace().next(), None);
|
||
/// assert_eq!(" ".split_ascii_whitespace().next(), None);
|
||
/// ```
|
||
#[must_use = "this returns the split string as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
|
||
#[inline]
|
||
pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_> {
|
||
let inner =
|
||
self.as_bytes().split(IsAsciiWhitespace).filter(BytesIsNotEmpty).map(UnsafeBytesToStr);
|
||
SplitAsciiWhitespace { inner }
|
||
}
|
||
|
||
/// Returns an iterator over the lines of a string, as string slices.
|
||
///
|
||
/// Lines are split at line endings that are either newlines (`\n`) or
|
||
/// sequences of a carriage return followed by a line feed (`\r\n`).
|
||
///
|
||
/// Line terminators are not included in the lines returned by the iterator.
|
||
///
|
||
/// Note that any carriage return (`\r`) not immediately followed by a
|
||
/// line feed (`\n`) does not split a line. These carriage returns are
|
||
/// thereby included in the produced lines.
|
||
///
|
||
/// The final line ending is optional. A string that ends with a final line
|
||
/// ending will return the same lines as an otherwise identical string
|
||
/// without a final line ending.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let text = "foo\r\nbar\n\nbaz\r";
|
||
/// let mut lines = text.lines();
|
||
///
|
||
/// assert_eq!(Some("foo"), lines.next());
|
||
/// assert_eq!(Some("bar"), lines.next());
|
||
/// assert_eq!(Some(""), lines.next());
|
||
/// // Trailing carriage return is included in the last line
|
||
/// assert_eq!(Some("baz\r"), lines.next());
|
||
///
|
||
/// assert_eq!(None, lines.next());
|
||
/// ```
|
||
///
|
||
/// The final line does not require any ending:
|
||
///
|
||
/// ```
|
||
/// let text = "foo\nbar\n\r\nbaz";
|
||
/// let mut lines = text.lines();
|
||
///
|
||
/// assert_eq!(Some("foo"), lines.next());
|
||
/// assert_eq!(Some("bar"), lines.next());
|
||
/// assert_eq!(Some(""), lines.next());
|
||
/// assert_eq!(Some("baz"), lines.next());
|
||
///
|
||
/// assert_eq!(None, lines.next());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn lines(&self) -> Lines<'_> {
|
||
Lines(self.split_inclusive('\n').map(LinesMap))
|
||
}
|
||
|
||
/// Returns an iterator over the lines of a string.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[deprecated(since = "1.4.0", note = "use lines() instead now", suggestion = "lines")]
|
||
#[inline]
|
||
#[allow(deprecated)]
|
||
pub fn lines_any(&self) -> LinesAny<'_> {
|
||
LinesAny(self.lines())
|
||
}
|
||
|
||
/// Returns an iterator of `u16` over the string encoded as UTF-16.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let text = "Zażółć gęślą jaźń";
|
||
///
|
||
/// let utf8_len = text.len();
|
||
/// let utf16_len = text.encode_utf16().count();
|
||
///
|
||
/// assert!(utf16_len <= utf8_len);
|
||
/// ```
|
||
#[must_use = "this returns the encoded string as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "encode_utf16", since = "1.8.0")]
|
||
pub fn encode_utf16(&self) -> EncodeUtf16<'_> {
|
||
EncodeUtf16 { chars: self.chars(), extra: 0 }
|
||
}
|
||
|
||
/// Returns `true` if the given pattern matches a sub-slice of
|
||
/// this string slice.
|
||
///
|
||
/// Returns `false` if it does not.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let bananas = "bananas";
|
||
///
|
||
/// assert!(bananas.contains("nana"));
|
||
/// assert!(!bananas.contains("apples"));
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn contains<P: Pattern>(&self, pat: P) -> bool {
|
||
pat.is_contained_in(self)
|
||
}
|
||
|
||
/// Returns `true` if the given pattern matches a prefix of this
|
||
/// string slice.
|
||
///
|
||
/// Returns `false` if it does not.
|
||
///
|
||
/// The [pattern] can be a `&str`, in which case this function will return true if
|
||
/// the `&str` is a prefix of this string slice.
|
||
///
|
||
/// The [pattern] can also be a [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
/// These will only be checked against the first character of this string slice.
|
||
/// Look at the second example below regarding behavior for slices of [`char`]s.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let bananas = "bananas";
|
||
///
|
||
/// assert!(bananas.starts_with("bana"));
|
||
/// assert!(!bananas.starts_with("nana"));
|
||
/// ```
|
||
///
|
||
/// ```
|
||
/// let bananas = "bananas";
|
||
///
|
||
/// // Note that both of these assert successfully.
|
||
/// assert!(bananas.starts_with(&['b', 'a', 'n', 'a']));
|
||
/// assert!(bananas.starts_with(&['a', 'b', 'c', 'd']));
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "str_starts_with")]
|
||
pub fn starts_with<P: Pattern>(&self, pat: P) -> bool {
|
||
pat.is_prefix_of(self)
|
||
}
|
||
|
||
/// Returns `true` if the given pattern matches a suffix of this
|
||
/// string slice.
|
||
///
|
||
/// Returns `false` if it does not.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let bananas = "bananas";
|
||
///
|
||
/// assert!(bananas.ends_with("anas"));
|
||
/// assert!(!bananas.ends_with("nana"));
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "str_ends_with")]
|
||
pub fn ends_with<P: Pattern>(&self, pat: P) -> bool
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
pat.is_suffix_of(self)
|
||
}
|
||
|
||
/// Returns the byte index of the first character of this string slice that
|
||
/// matches the pattern.
|
||
///
|
||
/// Returns [`None`] if the pattern doesn't match.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// let s = "Löwe 老虎 Léopard Gepardi";
|
||
///
|
||
/// assert_eq!(s.find('L'), Some(0));
|
||
/// assert_eq!(s.find('é'), Some(14));
|
||
/// assert_eq!(s.find("pard"), Some(17));
|
||
/// ```
|
||
///
|
||
/// More complex patterns using point-free style and closures:
|
||
///
|
||
/// ```
|
||
/// let s = "Löwe 老虎 Léopard";
|
||
///
|
||
/// assert_eq!(s.find(char::is_whitespace), Some(5));
|
||
/// assert_eq!(s.find(char::is_lowercase), Some(1));
|
||
/// assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1));
|
||
/// assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));
|
||
/// ```
|
||
///
|
||
/// Not finding the pattern:
|
||
///
|
||
/// ```
|
||
/// let s = "Löwe 老虎 Léopard";
|
||
/// let x: &[_] = &['1', '2'];
|
||
///
|
||
/// assert_eq!(s.find(x), None);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn find<P: Pattern>(&self, pat: P) -> Option<usize> {
|
||
pat.into_searcher(self).next_match().map(|(i, _)| i)
|
||
}
|
||
|
||
/// Returns the byte index for the first character of the last match of the pattern in
|
||
/// this string slice.
|
||
///
|
||
/// Returns [`None`] if the pattern doesn't match.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// let s = "Löwe 老虎 Léopard Gepardi";
|
||
///
|
||
/// assert_eq!(s.rfind('L'), Some(13));
|
||
/// assert_eq!(s.rfind('é'), Some(14));
|
||
/// assert_eq!(s.rfind("pard"), Some(24));
|
||
/// ```
|
||
///
|
||
/// More complex patterns with closures:
|
||
///
|
||
/// ```
|
||
/// let s = "Löwe 老虎 Léopard";
|
||
///
|
||
/// assert_eq!(s.rfind(char::is_whitespace), Some(12));
|
||
/// assert_eq!(s.rfind(char::is_lowercase), Some(20));
|
||
/// ```
|
||
///
|
||
/// Not finding the pattern:
|
||
///
|
||
/// ```
|
||
/// let s = "Löwe 老虎 Léopard";
|
||
/// let x: &[_] = &['1', '2'];
|
||
///
|
||
/// assert_eq!(s.rfind(x), None);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn rfind<P: Pattern>(&self, pat: P) -> Option<usize>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
pat.into_searcher(self).next_match_back().map(|(i, _)| i)
|
||
}
|
||
|
||
/// Returns an iterator over substrings of this string slice, separated by
|
||
/// characters matched by a pattern.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
|
||
/// allows a reverse search and forward/reverse search yields the same
|
||
/// elements. This is true for, e.g., [`char`], but not for `&str`.
|
||
///
|
||
/// If the pattern allows a reverse search but its results might differ
|
||
/// from a forward search, the [`rsplit`] method can be used.
|
||
///
|
||
/// [`rsplit`]: str::rsplit
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
|
||
/// assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);
|
||
///
|
||
/// let v: Vec<&str> = "".split('X').collect();
|
||
/// assert_eq!(v, [""]);
|
||
///
|
||
/// let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
|
||
/// assert_eq!(v, ["lion", "", "tiger", "leopard"]);
|
||
///
|
||
/// let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
|
||
/// assert_eq!(v, ["lion", "tiger", "leopard"]);
|
||
///
|
||
/// let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect();
|
||
/// assert_eq!(v, ["abc", "def", "ghi"]);
|
||
///
|
||
/// let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
|
||
/// assert_eq!(v, ["lion", "tiger", "leopard"]);
|
||
/// ```
|
||
///
|
||
/// If the pattern is a slice of chars, split on each occurrence of any of the characters:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "2020-11-03 23:59".split(&['-', ' ', ':', '@'][..]).collect();
|
||
/// assert_eq!(v, ["2020", "11", "03", "23", "59"]);
|
||
/// ```
|
||
///
|
||
/// A more complex pattern, using a closure:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect();
|
||
/// assert_eq!(v, ["abc", "def", "ghi"]);
|
||
/// ```
|
||
///
|
||
/// If a string contains multiple contiguous separators, you will end up
|
||
/// with empty strings in the output:
|
||
///
|
||
/// ```
|
||
/// let x = "||||a||b|c".to_string();
|
||
/// let d: Vec<_> = x.split('|').collect();
|
||
///
|
||
/// assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
|
||
/// ```
|
||
///
|
||
/// Contiguous separators are separated by the empty string.
|
||
///
|
||
/// ```
|
||
/// let x = "(///)".to_string();
|
||
/// let d: Vec<_> = x.split('/').collect();
|
||
///
|
||
/// assert_eq!(d, &["(", "", "", ")"]);
|
||
/// ```
|
||
///
|
||
/// Separators at the start or end of a string are neighbored
|
||
/// by empty strings.
|
||
///
|
||
/// ```
|
||
/// let d: Vec<_> = "010".split("0").collect();
|
||
/// assert_eq!(d, &["", "1", ""]);
|
||
/// ```
|
||
///
|
||
/// When the empty string is used as a separator, it separates
|
||
/// every character in the string, along with the beginning
|
||
/// and end of the string.
|
||
///
|
||
/// ```
|
||
/// let f: Vec<_> = "rust".split("").collect();
|
||
/// assert_eq!(f, &["", "r", "u", "s", "t", ""]);
|
||
/// ```
|
||
///
|
||
/// Contiguous separators can lead to possibly surprising behavior
|
||
/// when whitespace is used as the separator. This code is correct:
|
||
///
|
||
/// ```
|
||
/// let x = " a b c".to_string();
|
||
/// let d: Vec<_> = x.split(' ').collect();
|
||
///
|
||
/// assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
|
||
/// ```
|
||
///
|
||
/// It does _not_ give you:
|
||
///
|
||
/// ```,ignore
|
||
/// assert_eq!(d, &["a", "b", "c"]);
|
||
/// ```
|
||
///
|
||
/// Use [`split_whitespace`] for this behavior.
|
||
///
|
||
/// [`split_whitespace`]: str::split_whitespace
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn split<P: Pattern>(&self, pat: P) -> Split<'_, P> {
|
||
Split(SplitInternal {
|
||
start: 0,
|
||
end: self.len(),
|
||
matcher: pat.into_searcher(self),
|
||
allow_trailing_empty: true,
|
||
finished: false,
|
||
})
|
||
}
|
||
|
||
/// Returns an iterator over substrings of this string slice, separated by
|
||
/// characters matched by a pattern.
|
||
///
|
||
/// Differs from the iterator produced by `split` in that `split_inclusive`
|
||
/// leaves the matched part as the terminator of the substring.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
|
||
/// .split_inclusive('\n').collect();
|
||
/// assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);
|
||
/// ```
|
||
///
|
||
/// If the last element of the string is matched,
|
||
/// that element will be considered the terminator of the preceding substring.
|
||
/// That substring will be the last item returned by the iterator.
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n"
|
||
/// .split_inclusive('\n').collect();
|
||
/// assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);
|
||
/// ```
|
||
#[stable(feature = "split_inclusive", since = "1.51.0")]
|
||
#[inline]
|
||
pub fn split_inclusive<P: Pattern>(&self, pat: P) -> SplitInclusive<'_, P> {
|
||
SplitInclusive(SplitInternal {
|
||
start: 0,
|
||
end: self.len(),
|
||
matcher: pat.into_searcher(self),
|
||
allow_trailing_empty: false,
|
||
finished: false,
|
||
})
|
||
}
|
||
|
||
/// Returns an iterator over substrings of the given string slice, separated
|
||
/// by characters matched by a pattern and yielded in reverse order.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator requires that the pattern supports a reverse
|
||
/// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse
|
||
/// search yields the same elements.
|
||
///
|
||
/// For iterating from the front, the [`split`] method can be used.
|
||
///
|
||
/// [`split`]: str::split
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
|
||
/// assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);
|
||
///
|
||
/// let v: Vec<&str> = "".rsplit('X').collect();
|
||
/// assert_eq!(v, [""]);
|
||
///
|
||
/// let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
|
||
/// assert_eq!(v, ["leopard", "tiger", "", "lion"]);
|
||
///
|
||
/// let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
|
||
/// assert_eq!(v, ["leopard", "tiger", "lion"]);
|
||
/// ```
|
||
///
|
||
/// A more complex pattern, using a closure:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect();
|
||
/// assert_eq!(v, ["ghi", "def", "abc"]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn rsplit<P: Pattern>(&self, pat: P) -> RSplit<'_, P>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
RSplit(self.split(pat).0)
|
||
}
|
||
|
||
/// Returns an iterator over substrings of the given string slice, separated
|
||
/// by characters matched by a pattern.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// Equivalent to [`split`], except that the trailing substring
|
||
/// is skipped if empty.
|
||
///
|
||
/// [`split`]: str::split
|
||
///
|
||
/// This method can be used for string data that is _terminated_,
|
||
/// rather than _separated_ by a pattern.
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
|
||
/// allows a reverse search and forward/reverse search yields the same
|
||
/// elements. This is true for, e.g., [`char`], but not for `&str`.
|
||
///
|
||
/// If the pattern allows a reverse search but its results might differ
|
||
/// from a forward search, the [`rsplit_terminator`] method can be used.
|
||
///
|
||
/// [`rsplit_terminator`]: str::rsplit_terminator
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "A.B.".split_terminator('.').collect();
|
||
/// assert_eq!(v, ["A", "B"]);
|
||
///
|
||
/// let v: Vec<&str> = "A..B..".split_terminator(".").collect();
|
||
/// assert_eq!(v, ["A", "", "B", ""]);
|
||
///
|
||
/// let v: Vec<&str> = "A.B:C.D".split_terminator(&['.', ':'][..]).collect();
|
||
/// assert_eq!(v, ["A", "B", "C", "D"]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn split_terminator<P: Pattern>(&self, pat: P) -> SplitTerminator<'_, P> {
|
||
SplitTerminator(SplitInternal { allow_trailing_empty: false, ..self.split(pat).0 })
|
||
}
|
||
|
||
/// Returns an iterator over substrings of `self`, separated by characters
|
||
/// matched by a pattern and yielded in reverse order.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// Equivalent to [`split`], except that the trailing substring is
|
||
/// skipped if empty.
|
||
///
|
||
/// [`split`]: str::split
|
||
///
|
||
/// This method can be used for string data that is _terminated_,
|
||
/// rather than _separated_ by a pattern.
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator requires that the pattern supports a
|
||
/// reverse search, and it will be double ended if a forward/reverse
|
||
/// search yields the same elements.
|
||
///
|
||
/// For iterating from the front, the [`split_terminator`] method can be
|
||
/// used.
|
||
///
|
||
/// [`split_terminator`]: str::split_terminator
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
|
||
/// assert_eq!(v, ["B", "A"]);
|
||
///
|
||
/// let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
|
||
/// assert_eq!(v, ["", "B", "", "A"]);
|
||
///
|
||
/// let v: Vec<&str> = "A.B:C.D".rsplit_terminator(&['.', ':'][..]).collect();
|
||
/// assert_eq!(v, ["D", "C", "B", "A"]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn rsplit_terminator<P: Pattern>(&self, pat: P) -> RSplitTerminator<'_, P>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
RSplitTerminator(self.split_terminator(pat).0)
|
||
}
|
||
|
||
/// Returns an iterator over substrings of the given string slice, separated
|
||
/// by a pattern, restricted to returning at most `n` items.
|
||
///
|
||
/// If `n` substrings are returned, the last substring (the `n`th substring)
|
||
/// will contain the remainder of the string.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator will not be double ended, because it is
|
||
/// not efficient to support.
|
||
///
|
||
/// If the pattern allows a reverse search, the [`rsplitn`] method can be
|
||
/// used.
|
||
///
|
||
/// [`rsplitn`]: str::rsplitn
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
|
||
/// assert_eq!(v, ["Mary", "had", "a little lambda"]);
|
||
///
|
||
/// let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
|
||
/// assert_eq!(v, ["lion", "", "tigerXleopard"]);
|
||
///
|
||
/// let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
|
||
/// assert_eq!(v, ["abcXdef"]);
|
||
///
|
||
/// let v: Vec<&str> = "".splitn(1, 'X').collect();
|
||
/// assert_eq!(v, [""]);
|
||
/// ```
|
||
///
|
||
/// A more complex pattern, using a closure:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect();
|
||
/// assert_eq!(v, ["abc", "defXghi"]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn splitn<P: Pattern>(&self, n: usize, pat: P) -> SplitN<'_, P> {
|
||
SplitN(SplitNInternal { iter: self.split(pat).0, count: n })
|
||
}
|
||
|
||
/// Returns an iterator over substrings of this string slice, separated by a
|
||
/// pattern, starting from the end of the string, restricted to returning at
|
||
/// most `n` items.
|
||
///
|
||
/// If `n` substrings are returned, the last substring (the `n`th substring)
|
||
/// will contain the remainder of the string.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator will not be double ended, because it is not
|
||
/// efficient to support.
|
||
///
|
||
/// For splitting from the front, the [`splitn`] method can be used.
|
||
///
|
||
/// [`splitn`]: str::splitn
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
|
||
/// assert_eq!(v, ["lamb", "little", "Mary had a"]);
|
||
///
|
||
/// let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
|
||
/// assert_eq!(v, ["leopard", "tiger", "lionX"]);
|
||
///
|
||
/// let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
|
||
/// assert_eq!(v, ["leopard", "lion::tiger"]);
|
||
/// ```
|
||
///
|
||
/// A more complex pattern, using a closure:
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect();
|
||
/// assert_eq!(v, ["ghi", "abc1def"]);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn rsplitn<P: Pattern>(&self, n: usize, pat: P) -> RSplitN<'_, P>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
RSplitN(self.splitn(n, pat).0)
|
||
}
|
||
|
||
/// Splits the string on the first occurrence of the specified delimiter and
|
||
/// returns prefix before delimiter and suffix after delimiter.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("cfg".split_once('='), None);
|
||
/// assert_eq!("cfg=".split_once('='), Some(("cfg", "")));
|
||
/// assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));
|
||
/// assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));
|
||
/// ```
|
||
#[stable(feature = "str_split_once", since = "1.52.0")]
|
||
#[inline]
|
||
pub fn split_once<P: Pattern>(&self, delimiter: P) -> Option<(&'_ str, &'_ str)> {
|
||
let (start, end) = delimiter.into_searcher(self).next_match()?;
|
||
// SAFETY: `Searcher` is known to return valid indices.
|
||
unsafe { Some((self.get_unchecked(..start), self.get_unchecked(end..))) }
|
||
}
|
||
|
||
/// Splits the string on the last occurrence of the specified delimiter and
|
||
/// returns prefix before delimiter and suffix after delimiter.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("cfg".rsplit_once('='), None);
|
||
/// assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
|
||
/// assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));
|
||
/// ```
|
||
#[stable(feature = "str_split_once", since = "1.52.0")]
|
||
#[inline]
|
||
pub fn rsplit_once<P: Pattern>(&self, delimiter: P) -> Option<(&'_ str, &'_ str)>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
let (start, end) = delimiter.into_searcher(self).next_match_back()?;
|
||
// SAFETY: `Searcher` is known to return valid indices.
|
||
unsafe { Some((self.get_unchecked(..start), self.get_unchecked(end..))) }
|
||
}
|
||
|
||
/// Returns an iterator over the disjoint matches of a pattern within the
|
||
/// given string slice.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
|
||
/// allows a reverse search and forward/reverse search yields the same
|
||
/// elements. This is true for, e.g., [`char`], but not for `&str`.
|
||
///
|
||
/// If the pattern allows a reverse search but its results might differ
|
||
/// from a forward search, the [`rmatches`] method can be used.
|
||
///
|
||
/// [`rmatches`]: str::rmatches
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
|
||
/// assert_eq!(v, ["abc", "abc", "abc"]);
|
||
///
|
||
/// let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect();
|
||
/// assert_eq!(v, ["1", "2", "3"]);
|
||
/// ```
|
||
#[stable(feature = "str_matches", since = "1.2.0")]
|
||
#[inline]
|
||
pub fn matches<P: Pattern>(&self, pat: P) -> Matches<'_, P> {
|
||
Matches(MatchesInternal(pat.into_searcher(self)))
|
||
}
|
||
|
||
/// Returns an iterator over the disjoint matches of a pattern within this
|
||
/// string slice, yielded in reverse order.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator requires that the pattern supports a reverse
|
||
/// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse
|
||
/// search yields the same elements.
|
||
///
|
||
/// For iterating from the front, the [`matches`] method can be used.
|
||
///
|
||
/// [`matches`]: str::matches
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
|
||
/// assert_eq!(v, ["abc", "abc", "abc"]);
|
||
///
|
||
/// let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect();
|
||
/// assert_eq!(v, ["3", "2", "1"]);
|
||
/// ```
|
||
#[stable(feature = "str_matches", since = "1.2.0")]
|
||
#[inline]
|
||
pub fn rmatches<P: Pattern>(&self, pat: P) -> RMatches<'_, P>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
RMatches(self.matches(pat).0)
|
||
}
|
||
|
||
/// Returns an iterator over the disjoint matches of a pattern within this string
|
||
/// slice as well as the index that the match starts at.
|
||
///
|
||
/// For matches of `pat` within `self` that overlap, only the indices
|
||
/// corresponding to the first match are returned.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
|
||
/// allows a reverse search and forward/reverse search yields the same
|
||
/// elements. This is true for, e.g., [`char`], but not for `&str`.
|
||
///
|
||
/// If the pattern allows a reverse search but its results might differ
|
||
/// from a forward search, the [`rmatch_indices`] method can be used.
|
||
///
|
||
/// [`rmatch_indices`]: str::rmatch_indices
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect();
|
||
/// assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]);
|
||
///
|
||
/// let v: Vec<_> = "1abcabc2".match_indices("abc").collect();
|
||
/// assert_eq!(v, [(1, "abc"), (4, "abc")]);
|
||
///
|
||
/// let v: Vec<_> = "ababa".match_indices("aba").collect();
|
||
/// assert_eq!(v, [(0, "aba")]); // only the first `aba`
|
||
/// ```
|
||
#[stable(feature = "str_match_indices", since = "1.5.0")]
|
||
#[inline]
|
||
pub fn match_indices<P: Pattern>(&self, pat: P) -> MatchIndices<'_, P> {
|
||
MatchIndices(MatchIndicesInternal(pat.into_searcher(self)))
|
||
}
|
||
|
||
/// Returns an iterator over the disjoint matches of a pattern within `self`,
|
||
/// yielded in reverse order along with the index of the match.
|
||
///
|
||
/// For matches of `pat` within `self` that overlap, only the indices
|
||
/// corresponding to the last match are returned.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Iterator behavior
|
||
///
|
||
/// The returned iterator requires that the pattern supports a reverse
|
||
/// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse
|
||
/// search yields the same elements.
|
||
///
|
||
/// For iterating from the front, the [`match_indices`] method can be used.
|
||
///
|
||
/// [`match_indices`]: str::match_indices
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect();
|
||
/// assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]);
|
||
///
|
||
/// let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect();
|
||
/// assert_eq!(v, [(4, "abc"), (1, "abc")]);
|
||
///
|
||
/// let v: Vec<_> = "ababa".rmatch_indices("aba").collect();
|
||
/// assert_eq!(v, [(2, "aba")]); // only the last `aba`
|
||
/// ```
|
||
#[stable(feature = "str_match_indices", since = "1.5.0")]
|
||
#[inline]
|
||
pub fn rmatch_indices<P: Pattern>(&self, pat: P) -> RMatchIndices<'_, P>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
RMatchIndices(self.match_indices(pat).0)
|
||
}
|
||
|
||
/// Returns a string slice with leading and trailing whitespace removed.
|
||
///
|
||
/// 'Whitespace' is defined according to the terms of the Unicode Derived
|
||
/// Core Property `White_Space`, which includes newlines.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let s = "\n Hello\tworld\t\n";
|
||
///
|
||
/// assert_eq!("Hello\tworld", s.trim());
|
||
/// ```
|
||
#[inline]
|
||
#[must_use = "this returns the trimmed string as a slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "str_trim")]
|
||
pub fn trim(&self) -> &str {
|
||
self.trim_matches(|c: char| c.is_whitespace())
|
||
}
|
||
|
||
/// Returns a string slice with leading whitespace removed.
|
||
///
|
||
/// 'Whitespace' is defined according to the terms of the Unicode Derived
|
||
/// Core Property `White_Space`, which includes newlines.
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. `start` in this context means the first
|
||
/// position of that byte string; for a left-to-right language like English or
|
||
/// Russian, this will be left side, and for right-to-left languages like
|
||
/// Arabic or Hebrew, this will be the right side.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = "\n Hello\tworld\t\n";
|
||
/// assert_eq!("Hello\tworld\t\n", s.trim_start());
|
||
/// ```
|
||
///
|
||
/// Directionality:
|
||
///
|
||
/// ```
|
||
/// let s = " English ";
|
||
/// assert!(Some('E') == s.trim_start().chars().next());
|
||
///
|
||
/// let s = " עברית ";
|
||
/// assert!(Some('ע') == s.trim_start().chars().next());
|
||
/// ```
|
||
#[inline]
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "trim_direction", since = "1.30.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "str_trim_start")]
|
||
pub fn trim_start(&self) -> &str {
|
||
self.trim_start_matches(|c: char| c.is_whitespace())
|
||
}
|
||
|
||
/// Returns a string slice with trailing whitespace removed.
|
||
///
|
||
/// 'Whitespace' is defined according to the terms of the Unicode Derived
|
||
/// Core Property `White_Space`, which includes newlines.
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. `end` in this context means the last
|
||
/// position of that byte string; for a left-to-right language like English or
|
||
/// Russian, this will be right side, and for right-to-left languages like
|
||
/// Arabic or Hebrew, this will be the left side.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = "\n Hello\tworld\t\n";
|
||
/// assert_eq!("\n Hello\tworld", s.trim_end());
|
||
/// ```
|
||
///
|
||
/// Directionality:
|
||
///
|
||
/// ```
|
||
/// let s = " English ";
|
||
/// assert!(Some('h') == s.trim_end().chars().rev().next());
|
||
///
|
||
/// let s = " עברית ";
|
||
/// assert!(Some('ת') == s.trim_end().chars().rev().next());
|
||
/// ```
|
||
#[inline]
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "trim_direction", since = "1.30.0")]
|
||
#[cfg_attr(not(test), rustc_diagnostic_item = "str_trim_end")]
|
||
pub fn trim_end(&self) -> &str {
|
||
self.trim_end_matches(|c: char| c.is_whitespace())
|
||
}
|
||
|
||
/// Returns a string slice with leading whitespace removed.
|
||
///
|
||
/// 'Whitespace' is defined according to the terms of the Unicode Derived
|
||
/// Core Property `White_Space`.
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. 'Left' in this context means the first
|
||
/// position of that byte string; for a language like Arabic or Hebrew
|
||
/// which are 'right to left' rather than 'left to right', this will be
|
||
/// the _right_ side, not the left.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = " Hello\tworld\t";
|
||
///
|
||
/// assert_eq!("Hello\tworld\t", s.trim_left());
|
||
/// ```
|
||
///
|
||
/// Directionality:
|
||
///
|
||
/// ```
|
||
/// let s = " English";
|
||
/// assert!(Some('E') == s.trim_left().chars().next());
|
||
///
|
||
/// let s = " עברית";
|
||
/// assert!(Some('ע') == s.trim_left().chars().next());
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[deprecated(since = "1.33.0", note = "superseded by `trim_start`", suggestion = "trim_start")]
|
||
pub fn trim_left(&self) -> &str {
|
||
self.trim_start()
|
||
}
|
||
|
||
/// Returns a string slice with trailing whitespace removed.
|
||
///
|
||
/// 'Whitespace' is defined according to the terms of the Unicode Derived
|
||
/// Core Property `White_Space`.
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. 'Right' in this context means the last
|
||
/// position of that byte string; for a language like Arabic or Hebrew
|
||
/// which are 'right to left' rather than 'left to right', this will be
|
||
/// the _left_ side, not the right.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = " Hello\tworld\t";
|
||
///
|
||
/// assert_eq!(" Hello\tworld", s.trim_right());
|
||
/// ```
|
||
///
|
||
/// Directionality:
|
||
///
|
||
/// ```
|
||
/// let s = "English ";
|
||
/// assert!(Some('h') == s.trim_right().chars().rev().next());
|
||
///
|
||
/// let s = "עברית ";
|
||
/// assert!(Some('ת') == s.trim_right().chars().rev().next());
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[deprecated(since = "1.33.0", note = "superseded by `trim_end`", suggestion = "trim_end")]
|
||
pub fn trim_right(&self) -> &str {
|
||
self.trim_end()
|
||
}
|
||
|
||
/// Returns a string slice with all prefixes and suffixes that match a
|
||
/// pattern repeatedly removed.
|
||
///
|
||
/// The [pattern] can be a [`char`], a slice of [`char`]s, or a function
|
||
/// or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
|
||
/// assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar");
|
||
///
|
||
/// let x: &[_] = &['1', '2'];
|
||
/// assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");
|
||
/// ```
|
||
///
|
||
/// A more complex pattern, using a closure:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn trim_matches<P: Pattern>(&self, pat: P) -> &str
|
||
where
|
||
for<'a> P::Searcher<'a>: DoubleEndedSearcher<'a>,
|
||
{
|
||
let mut i = 0;
|
||
let mut j = 0;
|
||
let mut matcher = pat.into_searcher(self);
|
||
if let Some((a, b)) = matcher.next_reject() {
|
||
i = a;
|
||
j = b; // Remember earliest known match, correct it below if
|
||
// last match is different
|
||
}
|
||
if let Some((_, b)) = matcher.next_reject_back() {
|
||
j = b;
|
||
}
|
||
// SAFETY: `Searcher` is known to return valid indices.
|
||
unsafe { self.get_unchecked(i..j) }
|
||
}
|
||
|
||
/// Returns a string slice with all prefixes that match a pattern
|
||
/// repeatedly removed.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. `start` in this context means the first
|
||
/// position of that byte string; for a left-to-right language like English or
|
||
/// Russian, this will be left side, and for right-to-left languages like
|
||
/// Arabic or Hebrew, this will be the right side.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
|
||
/// assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");
|
||
///
|
||
/// let x: &[_] = &['1', '2'];
|
||
/// assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "trim_direction", since = "1.30.0")]
|
||
pub fn trim_start_matches<P: Pattern>(&self, pat: P) -> &str {
|
||
let mut i = self.len();
|
||
let mut matcher = pat.into_searcher(self);
|
||
if let Some((a, _)) = matcher.next_reject() {
|
||
i = a;
|
||
}
|
||
// SAFETY: `Searcher` is known to return valid indices.
|
||
unsafe { self.get_unchecked(i..self.len()) }
|
||
}
|
||
|
||
/// Returns a string slice with the prefix removed.
|
||
///
|
||
/// If the string starts with the pattern `prefix`, returns the substring after the prefix,
|
||
/// wrapped in `Some`. Unlike `trim_start_matches`, this method removes the prefix exactly once.
|
||
///
|
||
/// If the string does not start with `prefix`, returns `None`.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar"));
|
||
/// assert_eq!("foo:bar".strip_prefix("bar"), None);
|
||
/// assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));
|
||
/// ```
|
||
#[must_use = "this returns the remaining substring as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "str_strip", since = "1.45.0")]
|
||
pub fn strip_prefix<P: Pattern>(&self, prefix: P) -> Option<&str> {
|
||
prefix.strip_prefix_of(self)
|
||
}
|
||
|
||
/// Returns a string slice with the suffix removed.
|
||
///
|
||
/// If the string ends with the pattern `suffix`, returns the substring before the suffix,
|
||
/// wrapped in `Some`. Unlike `trim_end_matches`, this method removes the suffix exactly once.
|
||
///
|
||
/// If the string does not end with `suffix`, returns `None`.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar"));
|
||
/// assert_eq!("bar:foo".strip_suffix("bar"), None);
|
||
/// assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));
|
||
/// ```
|
||
#[must_use = "this returns the remaining substring as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "str_strip", since = "1.45.0")]
|
||
pub fn strip_suffix<P: Pattern>(&self, suffix: P) -> Option<&str>
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
suffix.strip_suffix_of(self)
|
||
}
|
||
|
||
/// Returns a string slice with all suffixes that match a pattern
|
||
/// repeatedly removed.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. `end` in this context means the last
|
||
/// position of that byte string; for a left-to-right language like English or
|
||
/// Russian, this will be right side, and for right-to-left languages like
|
||
/// Arabic or Hebrew, this will be the left side.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
|
||
/// assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");
|
||
///
|
||
/// let x: &[_] = &['1', '2'];
|
||
/// assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");
|
||
/// ```
|
||
///
|
||
/// A more complex pattern, using a closure:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "trim_direction", since = "1.30.0")]
|
||
pub fn trim_end_matches<P: Pattern>(&self, pat: P) -> &str
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
let mut j = 0;
|
||
let mut matcher = pat.into_searcher(self);
|
||
if let Some((_, b)) = matcher.next_reject_back() {
|
||
j = b;
|
||
}
|
||
// SAFETY: `Searcher` is known to return valid indices.
|
||
unsafe { self.get_unchecked(0..j) }
|
||
}
|
||
|
||
/// Returns a string slice with all prefixes that match a pattern
|
||
/// repeatedly removed.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. 'Left' in this context means the first
|
||
/// position of that byte string; for a language like Arabic or Hebrew
|
||
/// which are 'right to left' rather than 'left to right', this will be
|
||
/// the _right_ side, not the left.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11");
|
||
/// assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123");
|
||
///
|
||
/// let x: &[_] = &['1', '2'];
|
||
/// assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[deprecated(
|
||
since = "1.33.0",
|
||
note = "superseded by `trim_start_matches`",
|
||
suggestion = "trim_start_matches"
|
||
)]
|
||
pub fn trim_left_matches<P: Pattern>(&self, pat: P) -> &str {
|
||
self.trim_start_matches(pat)
|
||
}
|
||
|
||
/// Returns a string slice with all suffixes that match a pattern
|
||
/// repeatedly removed.
|
||
///
|
||
/// The [pattern] can be a `&str`, [`char`], a slice of [`char`]s, or a
|
||
/// function or closure that determines if a character matches.
|
||
///
|
||
/// [`char`]: prim@char
|
||
/// [pattern]: self::pattern
|
||
///
|
||
/// # Text directionality
|
||
///
|
||
/// A string is a sequence of bytes. 'Right' in this context means the last
|
||
/// position of that byte string; for a language like Arabic or Hebrew
|
||
/// which are 'right to left' rather than 'left to right', this will be
|
||
/// the _left_ side, not the right.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Simple patterns:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar");
|
||
/// assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar");
|
||
///
|
||
/// let x: &[_] = &['1', '2'];
|
||
/// assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");
|
||
/// ```
|
||
///
|
||
/// A more complex pattern, using a closure:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[deprecated(
|
||
since = "1.33.0",
|
||
note = "superseded by `trim_end_matches`",
|
||
suggestion = "trim_end_matches"
|
||
)]
|
||
pub fn trim_right_matches<P: Pattern>(&self, pat: P) -> &str
|
||
where
|
||
for<'a> P::Searcher<'a>: ReverseSearcher<'a>,
|
||
{
|
||
self.trim_end_matches(pat)
|
||
}
|
||
|
||
/// Parses this string slice into another type.
|
||
///
|
||
/// Because `parse` is so general, it can cause problems with type
|
||
/// inference. As such, `parse` is one of the few times you'll see
|
||
/// the syntax affectionately known as the 'turbofish': `::<>`. This
|
||
/// helps the inference algorithm understand specifically which type
|
||
/// you're trying to parse into.
|
||
///
|
||
/// `parse` can parse into any type that implements the [`FromStr`] trait.
|
||
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// Will return [`Err`] if it's not possible to parse this string slice into
|
||
/// the desired type.
|
||
///
|
||
/// [`Err`]: FromStr::Err
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage
|
||
///
|
||
/// ```
|
||
/// let four: u32 = "4".parse().unwrap();
|
||
///
|
||
/// assert_eq!(4, four);
|
||
/// ```
|
||
///
|
||
/// Using the 'turbofish' instead of annotating `four`:
|
||
///
|
||
/// ```
|
||
/// let four = "4".parse::<u32>();
|
||
///
|
||
/// assert_eq!(Ok(4), four);
|
||
/// ```
|
||
///
|
||
/// Failing to parse:
|
||
///
|
||
/// ```
|
||
/// let nope = "j".parse::<u32>();
|
||
///
|
||
/// assert!(nope.is_err());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn parse<F: FromStr>(&self) -> Result<F, F::Err> {
|
||
FromStr::from_str(self)
|
||
}
|
||
|
||
/// Checks if all characters in this string are within the ASCII range.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let ascii = "hello!\n";
|
||
/// let non_ascii = "Grüße, Jürgen ❤";
|
||
///
|
||
/// assert!(ascii.is_ascii());
|
||
/// assert!(!non_ascii.is_ascii());
|
||
/// ```
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[rustc_const_stable(feature = "const_slice_is_ascii", since = "1.74.0")]
|
||
#[must_use]
|
||
#[inline]
|
||
pub const fn is_ascii(&self) -> bool {
|
||
// We can treat each byte as character here: all multibyte characters
|
||
// start with a byte that is not in the ASCII range, so we will stop
|
||
// there already.
|
||
self.as_bytes().is_ascii()
|
||
}
|
||
|
||
/// If this string slice [`is_ascii`](Self::is_ascii), returns it as a slice
|
||
/// of [ASCII characters](`ascii::Char`), otherwise returns `None`.
|
||
#[unstable(feature = "ascii_char", issue = "110998")]
|
||
#[must_use]
|
||
#[inline]
|
||
pub const fn as_ascii(&self) -> Option<&[ascii::Char]> {
|
||
// Like in `is_ascii`, we can work on the bytes directly.
|
||
self.as_bytes().as_ascii()
|
||
}
|
||
|
||
/// Checks that two strings are an ASCII case-insensitive match.
|
||
///
|
||
/// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
|
||
/// but without allocating and copying temporaries.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert!("Ferris".eq_ignore_ascii_case("FERRIS"));
|
||
/// assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
|
||
/// assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));
|
||
/// ```
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[must_use]
|
||
#[inline]
|
||
pub fn eq_ignore_ascii_case(&self, other: &str) -> bool {
|
||
self.as_bytes().eq_ignore_ascii_case(other.as_bytes())
|
||
}
|
||
|
||
/// Converts this string to its ASCII upper case equivalent in-place.
|
||
///
|
||
/// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
|
||
/// but non-ASCII letters are unchanged.
|
||
///
|
||
/// To return a new uppercased value without modifying the existing one, use
|
||
/// [`to_ascii_uppercase()`].
|
||
///
|
||
/// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("Grüße, Jürgen ❤");
|
||
///
|
||
/// s.make_ascii_uppercase();
|
||
///
|
||
/// assert_eq!("GRüßE, JüRGEN ❤", s);
|
||
/// ```
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
|
||
#[inline]
|
||
pub const fn make_ascii_uppercase(&mut self) {
|
||
// SAFETY: changing ASCII letters only does not invalidate UTF-8.
|
||
let me = unsafe { self.as_bytes_mut() };
|
||
me.make_ascii_uppercase()
|
||
}
|
||
|
||
/// Converts this string to its ASCII lower case equivalent in-place.
|
||
///
|
||
/// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
|
||
/// but non-ASCII letters are unchanged.
|
||
///
|
||
/// To return a new lowercased value without modifying the existing one, use
|
||
/// [`to_ascii_lowercase()`].
|
||
///
|
||
/// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("GRÜßE, JÜRGEN ❤");
|
||
///
|
||
/// s.make_ascii_lowercase();
|
||
///
|
||
/// assert_eq!("grÜße, jÜrgen ❤", s);
|
||
/// ```
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
|
||
#[inline]
|
||
pub const fn make_ascii_lowercase(&mut self) {
|
||
// SAFETY: changing ASCII letters only does not invalidate UTF-8.
|
||
let me = unsafe { self.as_bytes_mut() };
|
||
me.make_ascii_lowercase()
|
||
}
|
||
|
||
/// Returns a string slice with leading ASCII whitespace removed.
|
||
///
|
||
/// 'Whitespace' refers to the definition used by
|
||
/// [`u8::is_ascii_whitespace`].
|
||
///
|
||
/// [`u8::is_ascii_whitespace`]: u8::is_ascii_whitespace
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!(" \t \u{3000}hello world\n".trim_ascii_start(), "\u{3000}hello world\n");
|
||
/// assert_eq!(" ".trim_ascii_start(), "");
|
||
/// assert_eq!("".trim_ascii_start(), "");
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "byte_slice_trim_ascii", since = "1.80.0")]
|
||
#[rustc_const_stable(feature = "byte_slice_trim_ascii", since = "1.80.0")]
|
||
#[inline]
|
||
pub const fn trim_ascii_start(&self) -> &str {
|
||
// SAFETY: Removing ASCII characters from a `&str` does not invalidate
|
||
// UTF-8.
|
||
unsafe { core::str::from_utf8_unchecked(self.as_bytes().trim_ascii_start()) }
|
||
}
|
||
|
||
/// Returns a string slice with trailing ASCII whitespace removed.
|
||
///
|
||
/// 'Whitespace' refers to the definition used by
|
||
/// [`u8::is_ascii_whitespace`].
|
||
///
|
||
/// [`u8::is_ascii_whitespace`]: u8::is_ascii_whitespace
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("\r hello world\u{3000}\n ".trim_ascii_end(), "\r hello world\u{3000}");
|
||
/// assert_eq!(" ".trim_ascii_end(), "");
|
||
/// assert_eq!("".trim_ascii_end(), "");
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "byte_slice_trim_ascii", since = "1.80.0")]
|
||
#[rustc_const_stable(feature = "byte_slice_trim_ascii", since = "1.80.0")]
|
||
#[inline]
|
||
pub const fn trim_ascii_end(&self) -> &str {
|
||
// SAFETY: Removing ASCII characters from a `&str` does not invalidate
|
||
// UTF-8.
|
||
unsafe { core::str::from_utf8_unchecked(self.as_bytes().trim_ascii_end()) }
|
||
}
|
||
|
||
/// Returns a string slice with leading and trailing ASCII whitespace
|
||
/// removed.
|
||
///
|
||
/// 'Whitespace' refers to the definition used by
|
||
/// [`u8::is_ascii_whitespace`].
|
||
///
|
||
/// [`u8::is_ascii_whitespace`]: u8::is_ascii_whitespace
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// assert_eq!("\r hello world\n ".trim_ascii(), "hello world");
|
||
/// assert_eq!(" ".trim_ascii(), "");
|
||
/// assert_eq!("".trim_ascii(), "");
|
||
/// ```
|
||
#[must_use = "this returns the trimmed string as a new slice, \
|
||
without modifying the original"]
|
||
#[stable(feature = "byte_slice_trim_ascii", since = "1.80.0")]
|
||
#[rustc_const_stable(feature = "byte_slice_trim_ascii", since = "1.80.0")]
|
||
#[inline]
|
||
pub const fn trim_ascii(&self) -> &str {
|
||
// SAFETY: Removing ASCII characters from a `&str` does not invalidate
|
||
// UTF-8.
|
||
unsafe { core::str::from_utf8_unchecked(self.as_bytes().trim_ascii()) }
|
||
}
|
||
|
||
/// Returns an iterator that escapes each char in `self` with [`char::escape_debug`].
|
||
///
|
||
/// Note: only extended grapheme codepoints that begin the string will be
|
||
/// escaped.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
||
/// ```
|
||
/// for c in "❤\n!".escape_debug() {
|
||
/// print!("{c}");
|
||
/// }
|
||
/// println!();
|
||
/// ```
|
||
///
|
||
/// Using `println!` directly:
|
||
///
|
||
/// ```
|
||
/// println!("{}", "❤\n!".escape_debug());
|
||
/// ```
|
||
///
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("❤\\n!");
|
||
/// ```
|
||
///
|
||
/// Using `to_string`:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");
|
||
/// ```
|
||
#[must_use = "this returns the escaped string as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "str_escape", since = "1.34.0")]
|
||
pub fn escape_debug(&self) -> EscapeDebug<'_> {
|
||
let mut chars = self.chars();
|
||
EscapeDebug {
|
||
inner: chars
|
||
.next()
|
||
.map(|first| first.escape_debug_ext(EscapeDebugExtArgs::ESCAPE_ALL))
|
||
.into_iter()
|
||
.flatten()
|
||
.chain(chars.flat_map(CharEscapeDebugContinue)),
|
||
}
|
||
}
|
||
|
||
/// Returns an iterator that escapes each char in `self` with [`char::escape_default`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
||
/// ```
|
||
/// for c in "❤\n!".escape_default() {
|
||
/// print!("{c}");
|
||
/// }
|
||
/// println!();
|
||
/// ```
|
||
///
|
||
/// Using `println!` directly:
|
||
///
|
||
/// ```
|
||
/// println!("{}", "❤\n!".escape_default());
|
||
/// ```
|
||
///
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("\\u{{2764}}\\n!");
|
||
/// ```
|
||
///
|
||
/// Using `to_string`:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");
|
||
/// ```
|
||
#[must_use = "this returns the escaped string as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "str_escape", since = "1.34.0")]
|
||
pub fn escape_default(&self) -> EscapeDefault<'_> {
|
||
EscapeDefault { inner: self.chars().flat_map(CharEscapeDefault) }
|
||
}
|
||
|
||
/// Returns an iterator that escapes each char in `self` with [`char::escape_unicode`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
||
/// ```
|
||
/// for c in "❤\n!".escape_unicode() {
|
||
/// print!("{c}");
|
||
/// }
|
||
/// println!();
|
||
/// ```
|
||
///
|
||
/// Using `println!` directly:
|
||
///
|
||
/// ```
|
||
/// println!("{}", "❤\n!".escape_unicode());
|
||
/// ```
|
||
///
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("\\u{{2764}}\\u{{a}}\\u{{21}}");
|
||
/// ```
|
||
///
|
||
/// Using `to_string`:
|
||
///
|
||
/// ```
|
||
/// assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");
|
||
/// ```
|
||
#[must_use = "this returns the escaped string as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "str_escape", since = "1.34.0")]
|
||
pub fn escape_unicode(&self) -> EscapeUnicode<'_> {
|
||
EscapeUnicode { inner: self.chars().flat_map(CharEscapeUnicode) }
|
||
}
|
||
|
||
/// Returns the range that a substring points to.
|
||
///
|
||
/// Returns `None` if `substr` does not point within `self`.
|
||
///
|
||
/// Unlike [`str::find`], **this does not search through the string**.
|
||
/// Instead, it uses pointer arithmetic to find where in the string
|
||
/// `substr` is derived from.
|
||
///
|
||
/// This is useful for extending [`str::split`] and similar methods.
|
||
///
|
||
/// Note that this method may return false positives (typically either
|
||
/// `Some(0..0)` or `Some(self.len()..self.len())`) if `substr` is a
|
||
/// zero-length `str` that points at the beginning or end of another,
|
||
/// independent, `str`.
|
||
///
|
||
/// # Examples
|
||
/// ```
|
||
/// #![feature(substr_range)]
|
||
///
|
||
/// let data = "a, b, b, a";
|
||
/// let mut iter = data.split(", ").map(|s| data.substr_range(s).unwrap());
|
||
///
|
||
/// assert_eq!(iter.next(), Some(0..1));
|
||
/// assert_eq!(iter.next(), Some(3..4));
|
||
/// assert_eq!(iter.next(), Some(6..7));
|
||
/// assert_eq!(iter.next(), Some(9..10));
|
||
/// ```
|
||
#[must_use]
|
||
#[unstable(feature = "substr_range", issue = "126769")]
|
||
pub fn substr_range(&self, substr: &str) -> Option<Range<usize>> {
|
||
self.as_bytes().subslice_range(substr.as_bytes())
|
||
}
|
||
|
||
/// Returns the same string as a string slice `&str`.
|
||
///
|
||
/// This method is redundant when used directly on `&str`, but
|
||
/// it helps dereferencing other string-like types to string slices,
|
||
/// for example references to `Box<str>` or `Arc<str>`.
|
||
#[inline]
|
||
#[unstable(feature = "str_as_str", issue = "130366")]
|
||
pub fn as_str(&self) -> &str {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl AsRef<[u8]> for str {
|
||
#[inline]
|
||
fn as_ref(&self) -> &[u8] {
|
||
self.as_bytes()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Default for &str {
|
||
/// Creates an empty str
|
||
#[inline]
|
||
fn default() -> Self {
|
||
""
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "default_mut_str", since = "1.28.0")]
|
||
impl Default for &mut str {
|
||
/// Creates an empty mutable str
|
||
#[inline]
|
||
fn default() -> Self {
|
||
// SAFETY: The empty string is valid UTF-8.
|
||
unsafe { from_utf8_unchecked_mut(&mut []) }
|
||
}
|
||
}
|
||
|
||
impl_fn_for_zst! {
|
||
/// A nameable, cloneable fn type
|
||
#[derive(Clone)]
|
||
struct LinesMap impl<'a> Fn = |line: &'a str| -> &'a str {
|
||
let Some(line) = line.strip_suffix('\n') else { return line };
|
||
let Some(line) = line.strip_suffix('\r') else { return line };
|
||
line
|
||
};
|
||
|
||
#[derive(Clone)]
|
||
struct CharEscapeDebugContinue impl Fn = |c: char| -> char::EscapeDebug {
|
||
c.escape_debug_ext(EscapeDebugExtArgs {
|
||
escape_grapheme_extended: false,
|
||
escape_single_quote: true,
|
||
escape_double_quote: true
|
||
})
|
||
};
|
||
|
||
#[derive(Clone)]
|
||
struct CharEscapeUnicode impl Fn = |c: char| -> char::EscapeUnicode {
|
||
c.escape_unicode()
|
||
};
|
||
#[derive(Clone)]
|
||
struct CharEscapeDefault impl Fn = |c: char| -> char::EscapeDefault {
|
||
c.escape_default()
|
||
};
|
||
|
||
#[derive(Clone)]
|
||
struct IsWhitespace impl Fn = |c: char| -> bool {
|
||
c.is_whitespace()
|
||
};
|
||
|
||
#[derive(Clone)]
|
||
struct IsAsciiWhitespace impl Fn = |byte: &u8| -> bool {
|
||
byte.is_ascii_whitespace()
|
||
};
|
||
|
||
#[derive(Clone)]
|
||
struct IsNotEmpty impl<'a, 'b> Fn = |s: &'a &'b str| -> bool {
|
||
!s.is_empty()
|
||
};
|
||
|
||
#[derive(Clone)]
|
||
struct BytesIsNotEmpty impl<'a, 'b> Fn = |s: &'a &'b [u8]| -> bool {
|
||
!s.is_empty()
|
||
};
|
||
|
||
#[derive(Clone)]
|
||
struct UnsafeBytesToStr impl<'a> Fn = |bytes: &'a [u8]| -> &'a str {
|
||
// SAFETY: not safe
|
||
unsafe { from_utf8_unchecked(bytes) }
|
||
};
|
||
}
|
||
|
||
// This is required to make `impl From<&str> for Box<dyn Error>` and `impl<E> From<E> for Box<dyn Error>` not overlap.
|
||
#[stable(feature = "error_in_core_neg_impl", since = "1.65.0")]
|
||
impl !crate::error::Error for &str {}
|