vendor/itertools-0.9.0/src/either_or_both.rs

   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.
  18     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.
  23     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`].
  29     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`].
  38     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()`.
  47     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`.
  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`.
  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.
  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>`.
  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>`.
  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>`.
  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.
 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.
 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.
 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 `b` in `Right(b)` or `Both(a, _)` variants if it is
 144     /// present.
 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 `a`
 156     /// in `Left(a)` or `Both(a, _)` variants if it is present.
 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
 168 impl<T> EitherOrBoth<T, T> {
 169     /// Return either value of left, right, or the product of `f` applied where `Both` are present.
 170     pub fn reduce<F>(self, f: F) -> T
 171     where
 172         F: FnOnce(T, T) -> T,
 173     {
 174         match self {
 175             Left(a) => a,
 176             Right(b) => b,
 177             Both(a, b) => f(a, b),
 178         }
 179     }
 180 }
 181
 182 impl<A, B> Into<Option<Either<A, B>>> for EitherOrBoth<A, B> {
 183     fn into(self) -> Option<Either<A, B>> {
 184         match self {
 185             EitherOrBoth::Left(l) => Some(Either::Left(l)),
 186             EitherOrBoth::Right(r) => Some(Either::Right(r)),
 187             _ => None,
 188         }
 189     }
 190 }