parent
bfccf7a426
commit
6a2aefc1d9
GPG Key ID:
284488987C31F630
@ -1,207 +0,0 @@
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//! Extensions
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use std::iter::{
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self,
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FusedIterator,
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};
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/// An iterator adaptor for taking two items off an iterator
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#[derive(Debug, Clone)]
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pub struct TakeTwo<I: ?Sized>(I);
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impl<I: ?Sized, T> Iterator for TakeTwo<I>
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where I: Iterator<Item=T>
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{
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type Item = (T, Option<T>);
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#[inline]
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fn next(&mut self) -> Option<Self::Item>
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{
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let first = self.0.next()?;
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Some((first, self.0.next()))
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}
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#[inline]
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fn size_hint(&self) -> (usize, Option<usize>) {
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let (low, high) = self.0.size_hint();
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(low / 2, high.map(|x| x/2))
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}
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}
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impl<I: ?Sized + ExactSizeIterator> ExactSizeIterator for TakeTwo<I>{}
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impl<I: ?Sized + FusedIterator> FusedIterator for TakeTwo<I> {}
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pub trait TakeTwoExt: Sized {
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/// Create an adaptor from `T` to `(T, Option<T>)`, taking the next available value if one exists in the iterator
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fn take_two(self) -> TakeTwo<Self>;
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}
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pub trait TakeTwoBoxedExt {
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/// Create an adaptor from `T` to `(T, Option<T>)`, taking the next available value if one exists in the iterator
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fn take_two(self: Box<Self>) -> TakeTwo<Box<Self>>;
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}
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impl<I: Iterator> TakeTwoExt for I
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{
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#[inline(always)]
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fn take_two(self) -> TakeTwo<Self> {
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TakeTwo(self)
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}
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}
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impl<I: ?Sized + Iterator> TakeTwoBoxedExt for I
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{
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#[inline(always)]
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fn take_two(self: Box<Self>) -> TakeTwo<Box<Self>> {
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TakeTwo(self)
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}
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}
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pub trait Tuple2OptExt<T, U>: Sized
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{
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/// The unwrapped type for the option in the tuple
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type OptionType;
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/// Unwrap a tuple containing an option into an option containing the full tuple if the `Option` value in the tuple is `Some`
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fn unwrap_two(self) -> Option<(T, U)>;
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/// Unwrap the option value or get the value from `f`
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fn unwrap_two_or_else<F>(self, f: F) -> (T, U)
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where F: FnOnce() -> Self::OptionType;
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}
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impl<T, U> Tuple2OptExt<T, U> for (T, Option<U>)
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{
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type OptionType = U;
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#[inline]
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fn unwrap_two(self) -> Option<(T, U)> {
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self.1.map(move |u| (self.0, u))
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}
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#[inline]
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fn unwrap_two_or_else<F>(self, f: F) -> (T, U)
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where F: FnOnce() -> Self::OptionType {
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match self.1 {
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Some(u) => (self.0, u),
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None => (self.0, f()),
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}
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}
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}
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impl<T, U> Tuple2OptExt<T, U> for (Option<T>, U)
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{
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type OptionType = T;
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#[inline]
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fn unwrap_two(self) -> Option<(T, U)> {
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self.0.map(move |u| (u, self.1))
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}
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#[inline]
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fn unwrap_two_or_else<F>(self, f: F) -> (T, U)
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where F: FnOnce() -> Self::OptionType {
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match self.0 {
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Some(u) => (u, self.1),
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None => (f(), self.1),
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}
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}
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}
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impl<T, U> Tuple2OptExt<T, U> for (Option<T>, Option<U>)
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{
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type OptionType = (T, U);
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#[inline]
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fn unwrap_two(self) -> Option<(T, U)> {
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self.0.and_then(move |u| self.1.map(move |v| (u, v)))
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}
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#[inline]
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fn unwrap_two_or_else<F>(self, f: F) -> (T, U)
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where F: FnOnce() -> Self::OptionType {
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match self {
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//XXX: This is not ideal...
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(Some(u), Some(v)) => (u, v),
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(Some(u), None) => (u, f().1),
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(None, Some(v)) => (f().0, v),
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_ => f()
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}
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}
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}
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pub trait Tuple2Ext<T,U>: Sized
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{
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/// Swap the elements in a 2-tuple
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fn swap(self) -> (U, T);
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/// Reduce the tuple elements into `V`
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fn reduce<V>(self, into: V) -> V
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where V: Extend<T> + Extend<U>;
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/// Collect the tuple elements into `O`
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fn collect<V, O>(self) -> O
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where V: From<T> + From<U> + FromIterator<V>,
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O: FromIterator<V>;
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/// Consume into `V`
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fn consume<V>(self) -> V
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where V: FromIterator<T> + Extend<U>;
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/// Consume both elements into a new single type.
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fn into<V>(self) -> (V, V)
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where V: From<T> + From<U>;
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}
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pub trait Tuple2STExt<T>: Sized
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{
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/// Consume into an array of two elements.
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fn into_array(self) -> [T; 2];
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/// Consume into an iterator of both elements
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fn into_iter(self) -> <[T; 2] as IntoIterator>::IntoIter;
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}
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impl<T, U> Tuple2Ext<T, U> for (T, U)
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{
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#[inline]
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fn swap(self) -> (U, T) {
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(self.1, self.0)
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}
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#[inline]
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fn reduce<V>(self, mut into: V) -> V
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where V: Extend<T> + Extend<U> {
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into.extend(iter::once(self.0));
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into.extend(iter::once(self.1));
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into
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}
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#[inline]
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fn collect<V, O>(self) -> O
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where V: From<T> + From<U>,
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O: FromIterator<V> {
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[self.0.into(), self.1.into()].into_iter().collect()
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}
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#[inline]
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fn consume<V>(self) -> V
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where V: FromIterator<T> + Extend<U> {
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let mut o: V = iter::once(self.0).collect();
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o.extend(iter::once(self.1));
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o
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}
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#[inline]
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fn into<V>(self) -> (V, V)
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where V: From<T> + From<U> {
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(self.0.into(), self.1.into())
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}
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}
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impl<T> Tuple2STExt<T> for (T, T)
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{
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#[inline]
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fn into_array(self) -> [T; 2] {
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[self.0, self.1]
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}
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#[inline]
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fn into_iter(self) -> <[T; 2] as IntoIterator>::IntoIter {
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self.into_array().into_iter()
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}
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}
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