segment_tree/
maybe_owned.rs

1//! This module contains a variant of [`Cow`] that doesn't require [`Clone`].
2//!
3//! [`Cow`]: https://doc.rust-lang.org/std/borrow/enum.Cow.html
4//! [`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html
5
6use std::cmp;
7use std::fmt::{self, Debug, Display, Formatter};
8use std::default::Default;
9use std::hash::{Hash, Hasher};
10use std::borrow::Cow;
11
12/// A variant of [`Cow`] that doesn't require [`Clone`].
13///
14/// [`Cow`]: https://doc.rust-lang.org/std/borrow/enum.Cow.html
15/// [`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html
16pub enum MaybeOwned<'a, T: 'a> {
17    Borrowed(&'a T),
18    Owned(T)
19}
20
21impl<'a, T: 'a> MaybeOwned<'a, T> {
22    /// Get a reference to the contained value.
23    #[inline]
24    pub fn borrow(&self) -> &T {
25        match *self {
26            MaybeOwned::Borrowed(v) => v,
27            MaybeOwned::Owned(ref v) => &v
28        }
29    }
30    /// Turn this type into a [`Cow`].
31    ///
32    /// Requires [`Clone`].
33    ///
34    /// [`Cow`]: https://doc.rust-lang.org/std/borrow/enum.Cow.html
35    /// [`Clone`]: https://doc.rust-lang.org/std/clone/trait.Clone.html
36    #[inline]
37    pub fn into_cow(self) -> Cow<'a, T> where T: Clone {
38        match self {
39            MaybeOwned::Borrowed(v) => Cow::Borrowed(v),
40            MaybeOwned::Owned(v) => Cow::Owned(v),
41        }
42    }
43}
44
45impl<'a, T: 'a + Clone> MaybeOwned<'a, T> {
46    /// Get the value, cloning if necessary.
47    #[inline]
48    pub fn unwrap_or_clone(self) -> T {
49        match self {
50            MaybeOwned::Borrowed(v) => v.clone(),
51            MaybeOwned::Owned(v) => v
52        }
53    }
54}
55
56impl<'a, T: 'a + Debug> Debug for MaybeOwned<'a, T> {
57    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
58        match *self {
59            MaybeOwned::Borrowed(v)  => write!(f, "Borrw({:?})", v),
60            MaybeOwned::Owned(ref v) => write!(f, "Owned({:?})", v),
61        }
62    }
63}
64
65impl<'a, T: 'a + Display> Display for MaybeOwned<'a, T> {
66    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
67        match *self {
68            MaybeOwned::Borrowed(v)  => v.fmt(f),
69            MaybeOwned::Owned(ref v) => v.fmt(f),
70        }
71    }
72}
73
74impl<'a, T: 'a + PartialEq> cmp::PartialEq for MaybeOwned<'a, T> {
75    #[inline]
76    fn eq(&self, other: &MaybeOwned<T>) -> bool {
77        self.borrow().eq(other.borrow())
78    }
79    #[inline]
80    fn ne(&self, other: &MaybeOwned<T>) -> bool {
81        self.borrow().ne(other.borrow())
82    }
83}
84impl<'a, T: 'a + Eq> cmp::Eq for MaybeOwned<'a, T> { }
85
86impl<'a, T: 'a + PartialOrd> cmp::PartialOrd for MaybeOwned<'a, T> {
87    #[inline]
88    fn partial_cmp(&self, other: &MaybeOwned<T>) -> Option<cmp::Ordering> {
89        self.borrow().partial_cmp(other.borrow())
90    }
91    #[inline]
92    fn lt(&self, other: &MaybeOwned<T>) -> bool {
93        self.borrow().lt(other.borrow())
94    }
95    #[inline]
96    fn le(&self, other: &MaybeOwned<T>) -> bool {
97        self.borrow().le(other.borrow())
98    }
99    #[inline]
100    fn gt(&self, other: &MaybeOwned<T>) -> bool {
101        self.borrow().gt(other.borrow())
102    }
103    #[inline]
104    fn ge(&self, other: &MaybeOwned<T>) -> bool {
105        self.borrow().ge(other.borrow())
106    }
107}
108impl<'a, T: 'a + Ord> cmp::Ord for MaybeOwned<'a, T> {
109    #[inline]
110    fn cmp(&self, other: &MaybeOwned<T>) -> cmp::Ordering {
111        self.borrow().cmp(other.borrow())
112    }
113}
114
115impl<'a, T: 'a + Default> Default for MaybeOwned<'a, T> {
116    #[inline]
117    fn default() -> MaybeOwned<'a, T> {
118        MaybeOwned::Owned(Default::default())
119    }
120}
121
122impl<'a, T: 'a + Hash> Hash for MaybeOwned<'a, T> {
123    #[inline]
124    fn hash<H: Hasher>(&self, state: &mut H) {
125        self.borrow().hash(state)
126    }
127}
segment_tree/maybe_owned.rs

segment_tree/
maybe_owned.rs
