1 use crate::EitherOrBoth::*;
2 
3 use either::Either;
4 
5 /// Value that either holds a single A or B, or both.
6 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
7 pub enum EitherOrBoth<A, B> {
8     /// Both values are present.
9     Both(A, B),
10     /// Only the left value of type `A` is present.
11     Left(A),
12     /// Only the right value of type `B` is present.
13     Right(B),
14 }
15 
16 impl<A, B> EitherOrBoth<A, B> {
17     /// If `Left`, or `Both`, return true, otherwise, return false.
has_left(&self) -> bool18     pub fn has_left(&self) -> bool {
19         self.as_ref().left().is_some()
20     }
21 
22     /// If `Right`, or `Both`, return true, otherwise, return false.
has_right(&self) -> bool23     pub fn has_right(&self) -> bool {
24         self.as_ref().right().is_some()
25     }
26 
27     /// If Left, return true otherwise, return false.
28     /// Exclusive version of [`has_left`](EitherOrBoth::has_left).
is_left(&self) -> bool29     pub fn is_left(&self) -> bool {
30         match *self {
31             Left(_) => true,
32             _ => false,
33         }
34     }
35 
36     /// If Right, return true otherwise, return false.
37     /// Exclusive version of [`has_right`](EitherOrBoth::has_right).
is_right(&self) -> bool38     pub fn is_right(&self) -> bool {
39         match *self {
40             Right(_) => true,
41             _ => false,
42         }
43     }
44 
45     /// If Right, return true otherwise, return false.
46     /// Equivalent to `self.as_ref().both().is_some()`.
is_both(&self) -> bool47     pub fn is_both(&self) -> bool {
48         self.as_ref().both().is_some()
49     }
50 
51     /// If `Left`, or `Both`, return `Some` with the left value, otherwise, return `None`.
left(self) -> Option<A>52     pub fn left(self) -> Option<A> {
53         match self {
54             Left(left) | Both(left, _) => Some(left),
55             _ => None,
56         }
57     }
58 
59     /// If `Right`, or `Both`, return `Some` with the right value, otherwise, return `None`.
right(self) -> Option<B>60     pub fn right(self) -> Option<B> {
61         match self {
62             Right(right) | Both(_, right) => Some(right),
63             _ => None,
64         }
65     }
66 
67     /// If Both, return `Some` tuple containing left and right.
both(self) -> Option<(A, B)>68     pub fn both(self) -> Option<(A, B)> {
69         match self {
70             Both(a, b) => Some((a, b)),
71             _ => None,
72         }
73     }
74 
75     /// Converts from `&EitherOrBoth<A, B>` to `EitherOrBoth<&A, &B>`.
as_ref(&self) -> EitherOrBoth<&A, &B>76     pub fn as_ref(&self) -> EitherOrBoth<&A, &B> {
77         match *self {
78             Left(ref left) => Left(left),
79             Right(ref right) => Right(right),
80             Both(ref left, ref right) => Both(left, right),
81         }
82     }
83 
84     /// Converts from `&mut EitherOrBoth<A, B>` to `EitherOrBoth<&mut A, &mut B>`.
as_mut(&mut self) -> EitherOrBoth<&mut A, &mut B>85     pub fn as_mut(&mut self) -> EitherOrBoth<&mut A, &mut B> {
86         match *self {
87             Left(ref mut left) => Left(left),
88             Right(ref mut right) => Right(right),
89             Both(ref mut left, ref mut right) => Both(left, right),
90         }
91     }
92 
93     /// Convert `EitherOrBoth<A, B>` to `EitherOrBoth<B, A>`.
flip(self) -> EitherOrBoth<B, A>94     pub fn flip(self) -> EitherOrBoth<B, A> {
95         match self {
96             Left(a) => Right(a),
97             Right(b) => Left(b),
98             Both(a, b) => Both(b, a),
99         }
100     }
101 
102     /// Apply the function `f` on the value `a` in `Left(a)` or `Both(a, b)` variants. If it is
103     /// present rewrapping the result in `self`'s original variant.
map_left<F, M>(self, f: F) -> EitherOrBoth<M, B> where F: FnOnce(A) -> M,104     pub fn map_left<F, M>(self, f: F) -> EitherOrBoth<M, B>
105     where
106         F: FnOnce(A) -> M,
107     {
108         match self {
109             Both(a, b) => Both(f(a), b),
110             Left(a) => Left(f(a)),
111             Right(b) => Right(b),
112         }
113     }
114 
115     /// Apply the function `f` on the value `b` in `Right(b)` or `Both(a, b)` variants.
116     /// If it is present rewrapping the result in `self`'s original variant.
map_right<F, M>(self, f: F) -> EitherOrBoth<A, M> where F: FnOnce(B) -> M,117     pub fn map_right<F, M>(self, f: F) -> EitherOrBoth<A, M>
118     where
119         F: FnOnce(B) -> M,
120     {
121         match self {
122             Left(a) => Left(a),
123             Right(b) => Right(f(b)),
124             Both(a, b) => Both(a, f(b)),
125         }
126     }
127 
128     /// Apply the functions `f` and `g` on the value `a` and `b` respectively;
129     /// found in `Left(a)`, `Right(b)`, or `Both(a, b)` variants.
130     /// The Result is rewrapped `self`'s original variant.
map_any<F, L, G, R>(self, f: F, g: G) -> EitherOrBoth<L, R> where F: FnOnce(A) -> L, G: FnOnce(B) -> R,131     pub fn map_any<F, L, G, R>(self, f: F, g: G) -> EitherOrBoth<L, R>
132     where
133         F: FnOnce(A) -> L,
134         G: FnOnce(B) -> R,
135     {
136         match self {
137             Left(a) => Left(f(a)),
138             Right(b) => Right(g(b)),
139             Both(a, b) => Both(f(a), g(b)),
140         }
141     }
142 
143     /// Apply the function `f` on the value `a` in `Left(a)` or `Both(a, _)` variants if it is
144     /// present.
left_and_then<F, L>(self, f: F) -> EitherOrBoth<L, B> where F: FnOnce(A) -> EitherOrBoth<L, B>,145     pub fn left_and_then<F, L>(self, f: F) -> EitherOrBoth<L, B>
146     where
147         F: FnOnce(A) -> EitherOrBoth<L, B>,
148     {
149         match self {
150             Left(a) | Both(a, _) => f(a),
151             Right(b) => Right(b),
152         }
153     }
154 
155     /// Apply the function `f` on the value `b`
156     /// in `Right(b)` or `Both(_, b)` variants if it is present.
right_and_then<F, R>(self, f: F) -> EitherOrBoth<A, R> where F: FnOnce(B) -> EitherOrBoth<A, R>,157     pub fn right_and_then<F, R>(self, f: F) -> EitherOrBoth<A, R>
158     where
159         F: FnOnce(B) -> EitherOrBoth<A, R>,
160     {
161         match self {
162             Left(a) => Left(a),
163             Right(b) | Both(_, b) => f(b),
164         }
165     }
166 
167     /// Returns a tuple consisting of the `l` and `r` in `Both(l, r)`, if present.
168     /// Otherwise, returns the wrapped value for the present element, and the [`default`](Default::default)
169     /// for the other.
or_default(self) -> (A, B) where A: Default, B: Default,170     pub fn or_default(self) -> (A, B)
171     where
172         A: Default,
173         B: Default,
174     {
175         match self {
176             EitherOrBoth::Left(l) => (l, B::default()),
177             EitherOrBoth::Right(r) => (A::default(), r),
178             EitherOrBoth::Both(l, r) => (l, r),
179         }
180     }
181 }
182 
183 impl<T> EitherOrBoth<T, T> {
184     /// Return either value of left, right, or the product of `f` applied where `Both` are present.
reduce<F>(self, f: F) -> T where F: FnOnce(T, T) -> T,185     pub fn reduce<F>(self, f: F) -> T
186     where
187         F: FnOnce(T, T) -> T,
188     {
189         match self {
190             Left(a) => a,
191             Right(b) => b,
192             Both(a, b) => f(a, b),
193         }
194     }
195 }
196 
197 impl<A, B> Into<Option<Either<A, B>>> for EitherOrBoth<A, B> {
into(self) -> Option<Either<A, B>>198     fn into(self) -> Option<Either<A, B>> {
199         match self {
200             EitherOrBoth::Left(l) => Some(Either::Left(l)),
201             EitherOrBoth::Right(r) => Some(Either::Right(r)),
202             _ => None,
203         }
204     }
205 }
206