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documentation update to demonstrate mutability #44467

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Sep 10, 2017
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documentation update to demonstrate mutability #44467

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23 changes: 16 additions & 7 deletions src/liballoc/str.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -362,16 +362,25 @@ impl str {
/// # Examples
///
/// ```
/// let mut v = String::from("🗻∈🌏");
///
/// assert_eq!(Some("🗻"), v.get_mut(0..4).map(|v| &*v));
///
/// // indices not on UTF-8 sequence boundaries
/// assert!(v.get_mut(1..).is_none());
/// assert!(v.get_mut(..8).is_none());
/// use std::ascii::AsciiExt;
///
/// 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| {
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@frewsxcv frewsxcv Sep 9, 2017 •
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alternatively, something like this could maybe work here, but what you have is 🆒 too

if let Some(s) = v.get_mut(0..2) {
    s.make_ascii_uppercase();
}

/// s.make_ascii_uppercase();
/// &*s
/// });
/// assert_eq!(Some("HE"), s);
/// }
/// assert_eq!("HEllo", v);
/// ```
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
#[inline]
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