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
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
//! Free functions that create iterator adaptors or call iterator methods.
//!
//! The benefit of free functions is that they accept any [`IntoIterator`] as
//! argument, so the resulting code may be easier to read.

#[cfg(feature = "use_alloc")]
use std::fmt::Display;
use std::iter::{self, Zip};
#[cfg(feature = "use_alloc")]
type VecIntoIter<T> = alloc::vec::IntoIter<T>;

#[cfg(feature = "use_alloc")]
use alloc::string::String;

use crate::intersperse::{Intersperse, IntersperseWith};
use crate::Itertools;

pub use crate::adaptors::{interleave, put_back};
#[cfg(feature = "use_alloc")]
pub use crate::kmerge_impl::kmerge;
pub use crate::merge_join::{merge, merge_join_by};
#[cfg(feature = "use_alloc")]
pub use crate::multipeek_impl::multipeek;
#[cfg(feature = "use_alloc")]
pub use crate::peek_nth::peek_nth;
#[cfg(feature = "use_alloc")]
pub use crate::put_back_n_impl::put_back_n;
#[cfg(feature = "use_alloc")]
pub use crate::rciter_impl::rciter;
pub use crate::zip_eq_impl::zip_eq;

/// Iterate `iterable` with a particular value inserted between each element.
///
/// [`IntoIterator`] enabled version of [`Iterator::intersperse`].
///
/// ```
/// use itertools::intersperse;
///
/// itertools::assert_equal(intersperse((0..3), 8), vec![0, 8, 1, 8, 2]);
/// ```
pub fn intersperse<I>(iterable: I, element: I::Item) -> Intersperse<I::IntoIter>
where
    I: IntoIterator,
    <I as IntoIterator>::Item: Clone,
{
    Itertools::intersperse(iterable.into_iter(), element)
}

/// Iterate `iterable` with a particular value created by a function inserted
/// between each element.
///
/// [`IntoIterator`] enabled version of [`Iterator::intersperse_with`].
///
/// ```
/// use itertools::intersperse_with;
///
/// let mut i = 10;
/// itertools::assert_equal(intersperse_with((0..3), || { i -= 1; i }), vec![0, 9, 1, 8, 2]);
/// assert_eq!(i, 8);
/// ```
pub fn intersperse_with<I, F>(iterable: I, element: F) -> IntersperseWith<I::IntoIter, F>
where
    I: IntoIterator,
    F: FnMut() -> I::Item,
{
    Itertools::intersperse_with(iterable.into_iter(), element)
}

/// Iterate `iterable` with a running index.
///
/// [`IntoIterator`] enabled version of [`Iterator::enumerate`].
///
/// ```
/// use itertools::enumerate;
///
/// for (i, elt) in enumerate(&[1, 2, 3]) {
///     /* loop body */
/// }
/// ```
pub fn enumerate<I>(iterable: I) -> iter::Enumerate<I::IntoIter>
where
    I: IntoIterator,
{
    iterable.into_iter().enumerate()
}

/// Iterate `iterable` in reverse.
///
/// [`IntoIterator`] enabled version of [`Iterator::rev`].
///
/// ```
/// use itertools::rev;
///
/// for elt in rev(&[1, 2, 3]) {
///     /* loop body */
/// }
/// ```
pub fn rev<I>(iterable: I) -> iter::Rev<I::IntoIter>
where
    I: IntoIterator,
    I::IntoIter: DoubleEndedIterator,
{
    iterable.into_iter().rev()
}

/// Converts the arguments to iterators and zips them.
///
/// [`IntoIterator`] enabled version of [`Iterator::zip`].
///
/// ## Example
///
/// ```
/// use itertools::zip;
///
/// let mut result: Vec<(i32, char)> = Vec::new();
///
/// for (a, b) in zip(&[1, 2, 3, 4, 5], &['a', 'b', 'c']) {
///     result.push((*a, *b));
/// }
/// assert_eq!(result, vec![(1, 'a'),(2, 'b'),(3, 'c')]);
/// ```
#[deprecated(
    note = "Use [std::iter::zip](https://doc.rust-lang.org/std/iter/fn.zip.html) instead",
    since = "0.10.4"
)]
pub fn zip<I, J>(i: I, j: J) -> Zip<I::IntoIter, J::IntoIter>
where
    I: IntoIterator,
    J: IntoIterator,
{
    i.into_iter().zip(j)
}

/// Takes two iterables and creates a new iterator over both in sequence.
///
/// [`IntoIterator`] enabled version of [`Iterator::chain`].
///
/// ## Example
/// ```
/// use itertools::chain;
///
/// let mut result:Vec<i32> = Vec::new();
///
/// for element in chain(&[1, 2, 3], &[4]) {
///     result.push(*element);
/// }
/// assert_eq!(result, vec![1, 2, 3, 4]);
/// ```
pub fn chain<I, J>(
    i: I,
    j: J,
) -> iter::Chain<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter>
where
    I: IntoIterator,
    J: IntoIterator<Item = I::Item>,
{
    i.into_iter().chain(j)
}

/// Create an iterator that clones each element from &T to T
///
/// [`IntoIterator`] enabled version of [`Iterator::cloned`].
///
/// ```
/// use itertools::cloned;
///
/// assert_eq!(cloned(b"abc").next(), Some(b'a'));
/// ```
pub fn cloned<'a, I, T: 'a>(iterable: I) -> iter::Cloned<I::IntoIter>
where
    I: IntoIterator<Item = &'a T>,
    T: Clone,
{
    iterable.into_iter().cloned()
}

/// Perform a fold operation over the iterable.
///
/// [`IntoIterator`] enabled version of [`Iterator::fold`].
///
/// ```
/// use itertools::fold;
///
/// assert_eq!(fold(&[1., 2., 3.], 0., |a, &b| f32::max(a, b)), 3.);
/// ```
pub fn fold<I, B, F>(iterable: I, init: B, f: F) -> B
where
    I: IntoIterator,
    F: FnMut(B, I::Item) -> B,
{
    iterable.into_iter().fold(init, f)
}

/// Test whether the predicate holds for all elements in the iterable.
///
/// [`IntoIterator`] enabled version of [`Iterator::all`].
///
/// ```
/// use itertools::all;
///
/// assert!(all(&[1, 2, 3], |elt| *elt > 0));
/// ```
pub fn all<I, F>(iterable: I, f: F) -> bool
where
    I: IntoIterator,
    F: FnMut(I::Item) -> bool,
{
    iterable.into_iter().all(f)
}

/// Test whether the predicate holds for any elements in the iterable.
///
/// [`IntoIterator`] enabled version of [`Iterator::any`].
///
/// ```
/// use itertools::any;
///
/// assert!(any(&[0, -1, 2], |elt| *elt > 0));
/// ```
pub fn any<I, F>(iterable: I, f: F) -> bool
where
    I: IntoIterator,
    F: FnMut(I::Item) -> bool,
{
    iterable.into_iter().any(f)
}

/// Return the maximum value of the iterable.
///
/// [`IntoIterator`] enabled version of [`Iterator::max`].
///
/// ```
/// use itertools::max;
///
/// assert_eq!(max(0..10), Some(9));
/// ```
pub fn max<I>(iterable: I) -> Option<I::Item>
where
    I: IntoIterator,
    I::Item: Ord,
{
    iterable.into_iter().max()
}

/// Return the minimum value of the iterable.
///
/// [`IntoIterator`] enabled version of [`Iterator::min`].
///
/// ```
/// use itertools::min;
///
/// assert_eq!(min(0..10), Some(0));
/// ```
pub fn min<I>(iterable: I) -> Option<I::Item>
where
    I: IntoIterator,
    I::Item: Ord,
{
    iterable.into_iter().min()
}

/// Combine all iterator elements into one String, separated by `sep`.
///
/// [`IntoIterator`] enabled version of [`Itertools::join`].
///
/// ```
/// use itertools::join;
///
/// assert_eq!(join(&[1, 2, 3], ", "), "1, 2, 3");
/// ```
#[cfg(feature = "use_alloc")]
pub fn join<I>(iterable: I, sep: &str) -> String
where
    I: IntoIterator,
    I::Item: Display,
{
    iterable.into_iter().join(sep)
}

/// Sort all iterator elements into a new iterator in ascending order.
///
/// [`IntoIterator`] enabled version of [`Itertools::sorted`].
///
/// ```
/// use itertools::sorted;
/// use itertools::assert_equal;
///
/// assert_equal(sorted("rust".chars()), "rstu".chars());
/// ```
#[cfg(feature = "use_alloc")]
pub fn sorted<I>(iterable: I) -> VecIntoIter<I::Item>
where
    I: IntoIterator,
    I::Item: Ord,
{
    iterable.into_iter().sorted()
}

/// Sort all iterator elements into a new iterator in ascending order.
/// This sort is unstable (i.e., may reorder equal elements).
/// [`IntoIterator`] enabled version of [`Itertools::sorted_unstable`].
///
/// ```
/// use itertools::sorted_unstable;
/// use itertools::assert_equal;
///
/// assert_equal(sorted_unstable("rust".chars()), "rstu".chars());
/// ```
#[cfg(feature = "use_alloc")]
pub fn sorted_unstable<I>(iterable: I) -> VecIntoIter<I::Item>
where
    I: IntoIterator,
    I::Item: Ord,
{
    iterable.into_iter().sorted_unstable()
}