Files
a0_basic_app
a1_vehicle
a2_async_sim
ab_glyph
ab_glyph_rasterizer
adler
adler32
agents
aho_corasick
anyhow
approx
aquamarine
ash
atty
bitflags
bytemuck
byteorder
cache_padded
cfg_if
chrono
color_quant
crc32fast
crossbeam_channel
crossbeam_deque
crossbeam_epoch
crossbeam_utils
deflate
draw2d
either
flexi_logger
generic_array
gif
glfw
glfw_sys
glob
image
indoc
itertools
jpeg_decoder
lazy_static
libc
libloading
log
matrixmultiply
memchr
memoffset
miniz_oxide
nalgebra
base
geometry
linalg
third_party
num_complex
num_cpus
num_integer
num_iter
num_rational
num_traits
owned_ttf_parser
paste
png
proc_macro2
proc_macro_error
proc_macro_error_attr
quote
raw_window_handle
rawpointer
rayon
rayon_core
regex
regex_syntax
scoped_threadpool
scopeguard
semver
semver_parser
serde
serde_derive
simba
smawk
spin_sleep
syn
terminal_size
textwrap
thiserror
thiserror_impl
tiff
time
triple_buffer
ttf_parser
typenum
unicode_width
unicode_xid
unindent
vk_sys
weezl
yansi
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
use crate::size_hint;

/// An iterator adaptor that allows putting multiple
/// items in front of the iterator.
///
/// Iterator element type is `I::Item`.
#[derive(Debug, Clone)]
pub struct PutBackN<I: Iterator> {
    top: Vec<I::Item>,
    iter: I,
}

/// Create an iterator where you can put back multiple values to the front
/// of the iteration.
///
/// Iterator element type is `I::Item`.
pub fn put_back_n<I>(iterable: I) -> PutBackN<I::IntoIter>
    where I: IntoIterator
{
    PutBackN {
        top: Vec::new(),
        iter: iterable.into_iter(),
    }
}

impl<I: Iterator> PutBackN<I> {
    /// Puts x in front of the iterator.
    /// The values are yielded in order of the most recently put back
    /// values first.
    ///
    /// ```rust
    /// use itertools::put_back_n;
    ///
    /// let mut it = put_back_n(1..5);
    /// it.next();
    /// it.put_back(1);
    /// it.put_back(0);
    ///
    /// assert!(itertools::equal(it, 0..5));
    /// ```
    #[inline]
    pub fn put_back(&mut self, x: I::Item) {
        self.top.push(x);
    }
}

impl<I: Iterator> Iterator for PutBackN<I> {
    type Item = I::Item;
    #[inline]
    fn next(&mut self) -> Option<I::Item> {
        if self.top.is_empty() {
            self.iter.next()
        } else {
            self.top.pop()
        }
    }

    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        size_hint::add_scalar(self.iter.size_hint(), self.top.len())
    }
}