/rust/registry/src/index.crates.io-6f17d22bba15001f/itertools-0.11.0/src/flatten_ok.rs

Source (jump to first uncovered line)
use crate::size_hint;
use std::{
    fmt,
    iter::{DoubleEndedIterator, FusedIterator},
};

pub fn flatten_ok<I, T, E>(iter: I) -> FlattenOk<I, T, E>
where
    I: Iterator<Item = Result<T, E>>,
    T: IntoIterator,
{
    FlattenOk {
        iter,
        inner_front: None,
        inner_back: None,
    }
}

/// An iterator adaptor that flattens `Result::Ok` values and
/// allows `Result::Err` values through unchanged.
///
/// See [`.flatten_ok()`](crate::Itertools::flatten_ok) for more information.
#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
pub struct FlattenOk<I, T, E>
where
    I: Iterator<Item = Result<T, E>>,
    T: IntoIterator,
{
    iter: I,
    inner_front: Option<T::IntoIter>,
    inner_back: Option<T::IntoIter>,
}

impl<I, T, E> Iterator for FlattenOk<I, T, E>
where
    I: Iterator<Item = Result<T, E>>,
    T: IntoIterator,
{
    type Item = Result<T::Item, E>;

    fn next(&mut self) -> Option<Self::Item> {
        loop {
            // Handle the front inner iterator.
            if let Some(inner) = &mut self.inner_front {
                if let Some(item) = inner.next() {
                    return Some(Ok(item));
                }

                // This is necessary for the iterator to implement `FusedIterator`
                // with only the original iterator being fused.
                self.inner_front = None;
            }

            match self.iter.next() {
                Some(Ok(ok)) => self.inner_front = Some(ok.into_iter()),
                Some(Err(e)) => return Some(Err(e)),
                None => {
                    // Handle the back inner iterator.
                    if let Some(inner) = &mut self.inner_back {
                        if let Some(item) = inner.next() {
                            return Some(Ok(item));
                        }

                        // This is necessary for the iterator to implement `FusedIterator`
                        // with only the original iterator being fused.
                        self.inner_back = None;
                    } else {
                        return None;
                    }
                }
            }
        }
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        let inner_hint = |inner: &Option<T::IntoIter>| {
            inner
                .as_ref()
                .map(Iterator::size_hint)
                .unwrap_or((0, Some(0)))
        };
        let inner_front = inner_hint(&self.inner_front);
        let inner_back = inner_hint(&self.inner_back);
        // The outer iterator `Ok` case could be (0, None) as we don't know its size_hint yet.
        let outer = match self.iter.size_hint() {
            (0, Some(0)) => (0, Some(0)),
            _ => (0, None),
        };

        size_hint::add(size_hint::add(inner_front, inner_back), outer)
    }
}

impl<I, T, E> DoubleEndedIterator for FlattenOk<I, T, E>
where
    I: DoubleEndedIterator<Item = Result<T, E>>,
    T: IntoIterator,
    T::IntoIter: DoubleEndedIterator,
{
    fn next_back(&mut self) -> Option<Self::Item> {
        loop {
            // Handle the back inner iterator.
            if let Some(inner) = &mut self.inner_back {
                if let Some(item) = inner.next_back() {
                    return Some(Ok(item));
                }

                // This is necessary for the iterator to implement `FusedIterator`
                // with only the original iterator being fused.
                self.inner_back = None;
            }

            match self.iter.next_back() {
                Some(Ok(ok)) => self.inner_back = Some(ok.into_iter()),
                Some(Err(e)) => return Some(Err(e)),
                None => {
                    // Handle the front inner iterator.
                    if let Some(inner) = &mut self.inner_front {
                        if let Some(item) = inner.next_back() {
                            return Some(Ok(item));
                        }

                        // This is necessary for the iterator to implement `FusedIterator`
                        // with only the original iterator being fused.
                        self.inner_front = None;
                    } else {
                        return None;
                    }
                }
            }
        }
    }
}

impl<I, T, E> Clone for FlattenOk<I, T, E>
where
    I: Iterator<Item = Result<T, E>> + Clone,
    T: IntoIterator,
    T::IntoIter: Clone,
{
    clone_fields!(iter, inner_front, inner_back);
}

impl<I, T, E> fmt::Debug for FlattenOk<I, T, E>
where
    I: Iterator<Item = Result<T, E>> + fmt::Debug,
    T: IntoIterator,
    T::IntoIter: fmt::Debug,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("FlattenOk")
            .field("iter", &self.iter)
            .field("inner_front", &self.inner_front)
            .field("inner_back", &self.inner_back)
            .finish()
    }
}

/// Only the iterator being flattened needs to implement [`FusedIterator`].
impl<I, T, E> FusedIterator for FlattenOk<I, T, E>
where
    I: FusedIterator<Item = Result<T, E>>,
    T: IntoIterator,
{
}

Line	Count	Source (jump to first uncovered line)
1		use crate::size_hint;
2		use std::{
3		fmt,
4		iter::{DoubleEndedIterator, FusedIterator},
5		};
6
7	0	pub fn flatten_ok<I, T, E>(iter: I) -> FlattenOk<I, T, E>
8	0	where
9	0	I: Iterator<Item = Result<T, E>>,
10	0	T: IntoIterator,
11	0	{
12	0	FlattenOk {
13	0	iter,
14	0	inner_front: None,
15	0	inner_back: None,
16	0	}
17	0	}
18
19		/// An iterator adaptor that flattens `Result::Ok` values and
20		/// allows `Result::Err` values through unchanged.
21		///
22		/// See [`.flatten_ok()`](crate::Itertools::flatten_ok) for more information.
23		#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
24		pub struct FlattenOk<I, T, E>
25		where
26		I: Iterator<Item = Result<T, E>>,
27		T: IntoIterator,
28		{
29		iter: I,
30		inner_front: Option<T::IntoIter>,
31		inner_back: Option<T::IntoIter>,
32		}
33
34		impl<I, T, E> Iterator for FlattenOk<I, T, E>
35		where
36		I: Iterator<Item = Result<T, E>>,
37		T: IntoIterator,
38		{
39		type Item = Result<T::Item, E>;
40
41	0	fn next(&mut self) -> Option<Self::Item> {
42		loop {
43		// Handle the front inner iterator.
44	0	if let Some(inner) = &mut self.inner_front {
45	0	if let Some(item) = inner.next() {
46	0	return Some(Ok(item));
47	0	}
48	0
49	0	// This is necessary for the iterator to implement `FusedIterator`
50	0	// with only the original iterator being fused.
51	0	self.inner_front = None;
52	0	}
53
54	0	match self.iter.next() {
55	0	Some(Ok(ok)) => self.inner_front = Some(ok.into_iter()),
56	0	Some(Err(e)) => return Some(Err(e)),
57		None => {
58		// Handle the back inner iterator.
59	0	if let Some(inner) = &mut self.inner_back {
60	0	if let Some(item) = inner.next() {
61	0	return Some(Ok(item));
62	0	}
63	0
64	0	// This is necessary for the iterator to implement `FusedIterator`
65	0	// with only the original iterator being fused.
66	0	self.inner_back = None;
67		} else {
68	0	return None;
69		}
70		}
71		}
72		}
73	0	}
74
75	0	fn size_hint(&self) -> (usize, Option<usize>) {
76	0	let inner_hint = \|inner: &Option<T::IntoIter>\| {
77	0	inner
78	0	.as_ref()
79	0	.map(Iterator::size_hint)
80	0	.unwrap_or((0, Some(0)))
81	0	};
82	0	let inner_front = inner_hint(&self.inner_front);
83	0	let inner_back = inner_hint(&self.inner_back);
84		// The outer iterator `Ok` case could be (0, None) as we don't know its size_hint yet.
85	0	let outer = match self.iter.size_hint() {
86	0	(0, Some(0)) => (0, Some(0)),
87	0	_ => (0, None),
88		};
89
90	0	size_hint::add(size_hint::add(inner_front, inner_back), outer)
91	0	}
92		}
93
94		impl<I, T, E> DoubleEndedIterator for FlattenOk<I, T, E>
95		where
96		I: DoubleEndedIterator<Item = Result<T, E>>,
97		T: IntoIterator,
98		T::IntoIter: DoubleEndedIterator,
99		{
100	0	fn next_back(&mut self) -> Option<Self::Item> {
101		loop {
102		// Handle the back inner iterator.
103	0	if let Some(inner) = &mut self.inner_back {
104	0	if let Some(item) = inner.next_back() {
105	0	return Some(Ok(item));
106	0	}
107	0
108	0	// This is necessary for the iterator to implement `FusedIterator`
109	0	// with only the original iterator being fused.
110	0	self.inner_back = None;
111	0	}
112
113	0	match self.iter.next_back() {
114	0	Some(Ok(ok)) => self.inner_back = Some(ok.into_iter()),
115	0	Some(Err(e)) => return Some(Err(e)),
116		None => {
117		// Handle the front inner iterator.
118	0	if let Some(inner) = &mut self.inner_front {
119	0	if let Some(item) = inner.next_back() {
120	0	return Some(Ok(item));
121	0	}
122	0
123	0	// This is necessary for the iterator to implement `FusedIterator`
124	0	// with only the original iterator being fused.
125	0	self.inner_front = None;
126		} else {
127	0	return None;
128		}
129		}
130		}
131		}
132	0	}
133		}
134
135		impl<I, T, E> Clone for FlattenOk<I, T, E>
136		where
137		I: Iterator<Item = Result<T, E>> + Clone,
138		T: IntoIterator,
139		T::IntoIter: Clone,
140		{
141		clone_fields!(iter, inner_front, inner_back);
142		}
143
144		impl<I, T, E> fmt::Debug for FlattenOk<I, T, E>
145		where
146		I: Iterator<Item = Result<T, E>> + fmt::Debug,
147		T: IntoIterator,
148		T::IntoIter: fmt::Debug,
149		{
150	0	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
151	0	f.debug_struct("FlattenOk")
152	0	.field("iter", &self.iter)
153	0	.field("inner_front", &self.inner_front)
154	0	.field("inner_back", &self.inner_back)
155	0	.finish()
156	0	}
157		}
158
159		/// Only the iterator being flattened needs to implement [`FusedIterator`].
160		impl<I, T, E> FusedIterator for FlattenOk<I, T, E>
161		where
162		I: FusedIterator<Item = Result<T, E>>,
163		T: IntoIterator,
164		{
165		}

Coverage Report

Created: 2024-05-20 06:38