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</pre><div class="example-wrap"><pre class="rust ">
<span class="doccomment">//! A module for working with borrowed data.</span>
<span class="attribute">#![<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">cmp</span>::<span class="ident">Ordering</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">hash</span>::{<span class="ident">Hash</span>, <span class="ident">Hasher</span>};
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">ops</span>::{<span class="ident">Add</span>, <span class="ident">AddAssign</span>, <span class="ident">Deref</span>};
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="ident">core</span>::<span class="ident">borrow</span>::{<span class="ident">Borrow</span>, <span class="ident">BorrowMut</span>};
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">fmt</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">string</span>::<span class="ident">String</span>;
<span class="kw">use</span> <span class="ident">Cow</span>::<span class="kw-2">*</span>;
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Borrow</span><span class="op"><</span><span class="ident">B</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">ToOwned</span>,
<span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span>: <span class="lifetime">'a</span>
{
<span class="kw">fn</span> <span class="ident">borrow</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">B</span> {
<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>
}
}
<span class="doccomment">/// A generalization of `Clone` to borrowed data.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Some types make it possible to go from borrowed to owned, usually by</span>
<span class="doccomment">/// implementing the `Clone` trait. But `Clone` works only for going from `&T`</span>
<span class="doccomment">/// to `T`. The `ToOwned` trait generalizes `Clone` to construct owned data</span>
<span class="doccomment">/// from any borrow of a given type.</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">trait</span> <span class="ident">ToOwned</span> {
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">type</span> <span class="ident">Owned</span>: <span class="ident">Borrow</span><span class="op"><</span><span class="self">Self</span><span class="op">></span>;
<span class="doccomment">/// Creates owned data from borrowed data, usually by cloning.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Basic usage:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// let s: &str = "a";</span>
<span class="doccomment">/// let ss: String = s.to_owned();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let v: &[i32] = &[1, 2];</span>
<span class="doccomment">/// let vv: Vec<i32> = v.to_owned();</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"cloning is often expensive and is not expected to have side effects"</span>]</span>
<span class="kw">fn</span> <span class="ident">to_owned</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="self">Self</span>::<span class="ident">Owned</span>;
<span class="doccomment">/// Uses borrowed data to replace owned data, usually by cloning.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is borrow-generalized version of `Clone::clone_from`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Basic usage:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// # #![feature(toowned_clone_into)]</span>
<span class="doccomment">/// let mut s: String = String::new();</span>
<span class="doccomment">/// "hello".clone_into(&mut s);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut v: Vec<i32> = Vec::new();</span>
<span class="doccomment">/// [1, 2][..].clone_into(&mut v);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"toowned_clone_into"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"recently added"</span>,
<span class="ident">issue</span> <span class="op">=</span> <span class="string">"41263"</span>)]</span>
<span class="kw">fn</span> <span class="ident">clone_into</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">target</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">Self</span>::<span class="ident">Owned</span>) {
<span class="kw-2">*</span><span class="ident">target</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">to_owned</span>();
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">ToOwned</span> <span class="kw">for</span> <span class="ident">T</span>
<span class="kw">where</span> <span class="ident">T</span>: <span class="ident">Clone</span>
{
<span class="kw">type</span> <span class="ident">Owned</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">fn</span> <span class="ident">to_owned</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">T</span> {
<span class="self">self</span>.<span class="ident">clone</span>()
}
<span class="kw">fn</span> <span class="ident">clone_into</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">target</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">T</span>) {
<span class="ident">target</span>.<span class="ident">clone_from</span>(<span class="self">self</span>);
}
}
<span class="doccomment">/// A clone-on-write smart pointer.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The type `Cow` is a smart pointer providing clone-on-write functionality: it</span>
<span class="doccomment">/// can enclose and provide immutable access to borrowed data, and clone the</span>
<span class="doccomment">/// data lazily when mutation or ownership is required. The type is designed to</span>
<span class="doccomment">/// work with general borrowed data via the `Borrow` trait.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// `Cow` implements `Deref`, which means that you can call</span>
<span class="doccomment">/// non-mutating methods directly on the data it encloses. If mutation</span>
<span class="doccomment">/// is desired, `to_mut` will obtain a mutable reference to an owned</span>
<span class="doccomment">/// value, cloning if necessary.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::borrow::Cow;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// fn abs_all(input: &mut Cow<[i32]>) {</span>
<span class="doccomment">/// for i in 0..input.len() {</span>
<span class="doccomment">/// let v = input[i];</span>
<span class="doccomment">/// if v < 0 {</span>
<span class="doccomment">/// // Clones into a vector if not already owned.</span>
<span class="doccomment">/// input.to_mut()[i] = -v;</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // No clone occurs because `input` doesn't need to be mutated.</span>
<span class="doccomment">/// let slice = [0, 1, 2];</span>
<span class="doccomment">/// let mut input = Cow::from(&slice[..]);</span>
<span class="doccomment">/// abs_all(&mut input);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Clone occurs because `input` needs to be mutated.</span>
<span class="doccomment">/// let slice = [-1, 0, 1];</span>
<span class="doccomment">/// let mut input = Cow::from(&slice[..]);</span>
<span class="doccomment">/// abs_all(&mut input);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // No clone occurs because `input` is already owned.</span>
<span class="doccomment">/// let mut input = Cow::from(vec![-1, 0, 1]);</span>
<span class="doccomment">/// abs_all(&mut input);</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Another example showing how to keep `Cow` in a struct:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::borrow::Cow;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// struct Items<'a, X: 'a> where [X]: ToOwned<Owned = Vec<X>> {</span>
<span class="doccomment">/// values: Cow<'a, [X]>,</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// impl<'a, X: Clone + 'a> Items<'a, X> where [X]: ToOwned<Owned = Vec<X>> {</span>
<span class="doccomment">/// fn new(v: Cow<'a, [X]>) -> Self {</span>
<span class="doccomment">/// Items { values: v }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Creates a container from borrowed values of a slice</span>
<span class="doccomment">/// let readonly = [1, 2];</span>
<span class="doccomment">/// let borrowed = Items::new((&readonly[..]).into());</span>
<span class="doccomment">/// match borrowed {</span>
<span class="doccomment">/// Items { values: Cow::Borrowed(b) } => println!("borrowed {:?}", b),</span>
<span class="doccomment">/// _ => panic!("expect borrowed value"),</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut clone_on_write = borrowed;</span>
<span class="doccomment">/// // Mutates the data from slice into owned vec and pushes a new value on top</span>
<span class="doccomment">/// clone_on_write.values.to_mut().push(3);</span>
<span class="doccomment">/// println!("clone_on_write = {:?}", clone_on_write.values);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // The data was mutated. Let check it out.</span>
<span class="doccomment">/// match clone_on_write {</span>
<span class="doccomment">/// Items { values: Cow::Owned(_) } => println!("clone_on_write contains owned data"),</span>
<span class="doccomment">/// _ => panic!("expect owned data"),</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="lifetime">'a</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">ToOwned</span>
{
<span class="doccomment">/// Borrowed data.</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="ident">Borrowed</span>(<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">B</span>),
<span class="doccomment">/// Owned data.</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="ident">Owned</span>(<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span>),
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">ToOwned</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">Borrowed</span>(<span class="ident">b</span>) <span class="op">=></span> <span class="ident">Borrowed</span>(<span class="ident">b</span>),
<span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="ident">o</span>) <span class="op">=></span> {
<span class="kw">let</span> <span class="ident">b</span>: <span class="kw-2">&</span><span class="ident">B</span> <span class="op">=</span> <span class="ident">o</span>.<span class="ident">borrow</span>();
<span class="ident">Owned</span>(<span class="ident">b</span>.<span class="ident">to_owned</span>())
}
}
}
<span class="kw">fn</span> <span class="ident">clone_from</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">source</span>: <span class="kw-2">&</span><span class="self">Self</span>) {
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">dest</span>) <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="ident">o</span>) <span class="op">=</span> <span class="kw-2">*</span><span class="ident">source</span> {
<span class="ident">o</span>.<span class="ident">borrow</span>().<span class="ident">clone_into</span>(<span class="ident">dest</span>);
<span class="kw">return</span>;
}
}
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">source</span>.<span class="ident">clone</span>();
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">ToOwned</span><span class="op">></span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span> {
<span class="doccomment">/// Acquires a mutable reference to the owned form of the data.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Clones the data if it is not already owned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::borrow::Cow;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut cow = Cow::Borrowed("foo");</span>
<span class="doccomment">/// cow.to_mut().make_ascii_uppercase();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(</span>
<span class="doccomment">/// cow,</span>
<span class="doccomment">/// Cow::Owned(String::from("FOO")) as Cow<str></span>
<span class="doccomment">/// );</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">to_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">Borrowed</span>(<span class="ident">borrowed</span>) <span class="op">=></span> {
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">Owned</span>(<span class="ident">borrowed</span>.<span class="ident">to_owned</span>());
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">Borrowed</span>(..) <span class="op">=></span> <span class="macro">unreachable</span><span class="macro">!</span>(),
<span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">owned</span>) <span class="op">=></span> <span class="ident">owned</span>,
}
}
<span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">owned</span>) <span class="op">=></span> <span class="ident">owned</span>,
}
}
<span class="doccomment">/// Extracts the owned data.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Clones the data if it is not already owned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Calling `into_owned` on a `Cow::Borrowed` clones the underlying data</span>
<span class="doccomment">/// and becomes a `Cow::Owned`:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::borrow::Cow;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let s = "Hello world!";</span>
<span class="doccomment">/// let cow = Cow::Borrowed(s);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(</span>
<span class="doccomment">/// cow.into_owned(),</span>
<span class="doccomment">/// String::from(s)</span>
<span class="doccomment">/// );</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Calling `into_owned` on a `Cow::Owned` is a no-op:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::borrow::Cow;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let s = "Hello world!";</span>
<span class="doccomment">/// let cow: Cow<str> = Cow::Owned(String::from(s));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(</span>
<span class="doccomment">/// cow.into_owned(),</span>
<span class="doccomment">/// String::from(s)</span>
<span class="doccomment">/// );</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">into_owned</span>(<span class="self">self</span>) <span class="op">-></span> <span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span> {
<span class="kw">match</span> <span class="self">self</span> {
<span class="ident">Borrowed</span>(<span class="ident">borrowed</span>) <span class="op">=></span> <span class="ident">borrowed</span>.<span class="ident">to_owned</span>(),
<span class="ident">Owned</span>(<span class="ident">owned</span>) <span class="op">=></span> <span class="ident">owned</span>,
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">ToOwned</span><span class="op">></span> <span class="ident">Deref</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Target</span> <span class="op">=</span> <span class="ident">B</span>;
<span class="kw">fn</span> <span class="ident">deref</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">B</span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">Borrowed</span>(<span class="ident">borrowed</span>) <span class="op">=></span> <span class="ident">borrowed</span>,
<span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="ident">owned</span>) <span class="op">=></span> <span class="ident">owned</span>.<span class="ident">borrow</span>(),
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Eq</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span> <span class="kw">where</span> <span class="ident">B</span>: <span class="ident">Eq</span> <span class="op">+</span> <span class="ident">ToOwned</span> {}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Ord</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">Ord</span> <span class="op">+</span> <span class="ident">ToOwned</span>
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">cmp</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="self">Self</span>) <span class="op">-></span> <span class="ident">Ordering</span> {
<span class="ident">Ord</span>::<span class="ident">cmp</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>, <span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="lifetime">'b</span>, <span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span>, <span class="ident">C</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">PartialEq</span><span class="op"><</span><span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'b</span>, <span class="ident">C</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">PartialEq</span><span class="op"><</span><span class="ident">C</span><span class="op">></span> <span class="op">+</span> <span class="ident">ToOwned</span>,
<span class="ident">C</span>: <span class="ident">ToOwned</span>
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">eq</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'b</span>, <span class="ident">C</span><span class="op">></span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="ident">PartialEq</span>::<span class="ident">eq</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>, <span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">PartialOrd</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">PartialOrd</span> <span class="op">+</span> <span class="ident">ToOwned</span>
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">partial_cmp</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">B</span><span class="op">></span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Ordering</span><span class="op">></span> {
<span class="ident">PartialOrd</span>::<span class="ident">partial_cmp</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>, <span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">other</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="op">+</span> <span class="ident">ToOwned</span>,
<span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span>: <span class="ident">fmt</span>::<span class="ident">Debug</span>
{
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">Borrowed</span>(<span class="kw-2">ref</span> <span class="ident">b</span>) <span class="op">=></span> <span class="ident">fmt</span>::<span class="ident">Debug</span>::<span class="ident">fmt</span>(<span class="ident">b</span>, <span class="ident">f</span>),
<span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="ident">o</span>) <span class="op">=></span> <span class="ident">fmt</span>::<span class="ident">Debug</span>::<span class="ident">fmt</span>(<span class="ident">o</span>, <span class="ident">f</span>),
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="op">+</span> <span class="ident">ToOwned</span>,
<span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span>: <span class="ident">fmt</span>::<span class="ident">Display</span>
{
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">Borrowed</span>(<span class="kw-2">ref</span> <span class="ident">b</span>) <span class="op">=></span> <span class="ident">fmt</span>::<span class="ident">Display</span>::<span class="ident">fmt</span>(<span class="ident">b</span>, <span class="ident">f</span>),
<span class="ident">Owned</span>(<span class="kw-2">ref</span> <span class="ident">o</span>) <span class="op">=></span> <span class="ident">fmt</span>::<span class="ident">Display</span>::<span class="ident">fmt</span>(<span class="ident">o</span>, <span class="ident">f</span>),
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"default"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.11.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Default</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">ToOwned</span>,
<span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span>: <span class="ident">Default</span>
{
<span class="doccomment">/// Creates an owned Cow<'a, B> with the default value for the contained owned value.</span>
<span class="kw">fn</span> <span class="ident">default</span>() <span class="op">-></span> <span class="self">Self</span> {
<span class="ident">Owned</span>(<span class="op"><</span><span class="ident">B</span> <span class="kw">as</span> <span class="ident">ToOwned</span><span class="op">></span>::<span class="ident">Owned</span>::<span class="ident">default</span>())
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">B</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Hash</span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">B</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">B</span>: <span class="ident">Hash</span> <span class="op">+</span> <span class="ident">ToOwned</span>
{
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">hash</span><span class="op"><</span><span class="ident">H</span>: <span class="ident">Hasher</span><span class="op">></span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">state</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">H</span>) {
<span class="ident">Hash</span>::<span class="ident">hash</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>, <span class="ident">state</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">ToOwned</span><span class="op">></span> <span class="ident">AsRef</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">as_ref</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">T</span> {
<span class="self">self</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"cow_add"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.14.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">Add</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">str</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Output</span> <span class="op">=</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">add</span>(<span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">rhs</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">str</span>) <span class="op">-></span> <span class="self">Self</span>::<span class="ident">Output</span> {
<span class="self">self</span> <span class="op">+=</span> <span class="ident">rhs</span>;
<span class="self">self</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"cow_add"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.14.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">Add</span><span class="op"><</span><span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Output</span> <span class="op">=</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span>;
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">add</span>(<span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">rhs</span>: <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span>) <span class="op">-></span> <span class="self">Self</span>::<span class="ident">Output</span> {
<span class="self">self</span> <span class="op">+=</span> <span class="ident">rhs</span>;
<span class="self">self</span>
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"cow_add"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.14.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">AddAssign</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">str</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">add_assign</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">rhs</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">str</span>) {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_empty</span>() {
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">Cow</span>::<span class="ident">Borrowed</span>(<span class="ident">rhs</span>)
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">rhs</span>.<span class="ident">is_empty</span>() {
<span class="kw">return</span>;
} <span class="kw">else</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">Cow</span>::<span class="ident">Borrowed</span>(<span class="ident">lhs</span>) <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">with_capacity</span>(<span class="ident">lhs</span>.<span class="ident">len</span>() <span class="op">+</span> <span class="ident">rhs</span>.<span class="ident">len</span>());
<span class="ident">s</span>.<span class="ident">push_str</span>(<span class="ident">lhs</span>);
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">Cow</span>::<span class="ident">Owned</span>(<span class="ident">s</span>);
}
<span class="self">self</span>.<span class="ident">to_mut</span>().<span class="ident">push_str</span>(<span class="ident">rhs</span>);
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"cow_add"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.14.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">AddAssign</span><span class="op"><</span><span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">add_assign</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">rhs</span>: <span class="ident">Cow</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">str</span><span class="op">></span>) {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_empty</span>() {
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">rhs</span>
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">rhs</span>.<span class="ident">is_empty</span>() {
<span class="kw">return</span>;
} <span class="kw">else</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">Cow</span>::<span class="ident">Borrowed</span>(<span class="ident">lhs</span>) <span class="op">=</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">with_capacity</span>(<span class="ident">lhs</span>.<span class="ident">len</span>() <span class="op">+</span> <span class="ident">rhs</span>.<span class="ident">len</span>());
<span class="ident">s</span>.<span class="ident">push_str</span>(<span class="ident">lhs</span>);
<span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">Cow</span>::<span class="ident">Owned</span>(<span class="ident">s</span>);
}
<span class="self">self</span>.<span class="ident">to_mut</span>().<span class="ident">push_str</span>(<span class="kw-2">&</span><span class="ident">rhs</span>);
}
}
}
</pre></div>
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