Jakub Kotur | a425e55 | 2020-12-21 17:28:15 +0100 | [diff] [blame] | 1 | //! Free functions that create iterator adaptors or call iterator methods. |
| 2 | //! |
| 3 | //! The benefit of free functions is that they accept any `IntoIterator` as |
| 4 | //! argument, so the resulting code may be easier to read. |
| 5 | |
| 6 | #[cfg(feature = "use_std")] |
| 7 | use std::fmt::Display; |
| 8 | use std::iter::{self, Zip}; |
| 9 | #[cfg(feature = "use_std")] |
| 10 | type VecIntoIter<T> = ::std::vec::IntoIter<T>; |
| 11 | |
| 12 | #[cfg(feature = "use_std")] |
| 13 | use crate::Itertools; |
| 14 | |
| 15 | pub use crate::adaptors::{ |
| 16 | interleave, |
| 17 | merge, |
| 18 | put_back, |
| 19 | }; |
| 20 | #[cfg(feature = "use_std")] |
| 21 | pub use crate::put_back_n_impl::put_back_n; |
| 22 | #[cfg(feature = "use_std")] |
| 23 | pub use crate::multipeek_impl::multipeek; |
| 24 | #[cfg(feature = "use_std")] |
| 25 | pub use crate::kmerge_impl::kmerge; |
| 26 | pub use crate::zip_eq_impl::zip_eq; |
| 27 | pub use crate::merge_join::merge_join_by; |
| 28 | #[cfg(feature = "use_std")] |
| 29 | pub use crate::rciter_impl::rciter; |
| 30 | |
| 31 | /// Iterate `iterable` with a running index. |
| 32 | /// |
| 33 | /// `IntoIterator` enabled version of `.enumerate()`. |
| 34 | /// |
| 35 | /// ``` |
| 36 | /// use itertools::enumerate; |
| 37 | /// |
| 38 | /// for (i, elt) in enumerate(&[1, 2, 3]) { |
| 39 | /// /* loop body */ |
| 40 | /// } |
| 41 | /// ``` |
| 42 | pub fn enumerate<I>(iterable: I) -> iter::Enumerate<I::IntoIter> |
| 43 | where I: IntoIterator |
| 44 | { |
| 45 | iterable.into_iter().enumerate() |
| 46 | } |
| 47 | |
| 48 | /// Iterate `iterable` in reverse. |
| 49 | /// |
| 50 | /// `IntoIterator` enabled version of `.rev()`. |
| 51 | /// |
| 52 | /// ``` |
| 53 | /// use itertools::rev; |
| 54 | /// |
| 55 | /// for elt in rev(&[1, 2, 3]) { |
| 56 | /// /* loop body */ |
| 57 | /// } |
| 58 | /// ``` |
| 59 | pub fn rev<I>(iterable: I) -> iter::Rev<I::IntoIter> |
| 60 | where I: IntoIterator, |
| 61 | I::IntoIter: DoubleEndedIterator |
| 62 | { |
| 63 | iterable.into_iter().rev() |
| 64 | } |
| 65 | |
| 66 | /// Iterate `i` and `j` in lock step. |
| 67 | /// |
| 68 | /// `IntoIterator` enabled version of `i.zip(j)`. |
| 69 | /// |
| 70 | /// ``` |
| 71 | /// use itertools::zip; |
| 72 | /// |
| 73 | /// let data = [1, 2, 3, 4, 5]; |
| 74 | /// for (a, b) in zip(&data, &data[1..]) { |
| 75 | /// /* loop body */ |
| 76 | /// } |
| 77 | /// ``` |
| 78 | pub fn zip<I, J>(i: I, j: J) -> Zip<I::IntoIter, J::IntoIter> |
| 79 | where I: IntoIterator, |
| 80 | J: IntoIterator |
| 81 | { |
| 82 | i.into_iter().zip(j) |
| 83 | } |
| 84 | |
| 85 | /// Create an iterator that first iterates `i` and then `j`. |
| 86 | /// |
| 87 | /// `IntoIterator` enabled version of `i.chain(j)`. |
| 88 | /// |
| 89 | /// ``` |
| 90 | /// use itertools::chain; |
| 91 | /// |
| 92 | /// for elt in chain(&[1, 2, 3], &[4]) { |
| 93 | /// /* loop body */ |
| 94 | /// } |
| 95 | /// ``` |
| 96 | pub fn chain<I, J>(i: I, j: J) -> iter::Chain<<I as IntoIterator>::IntoIter, <J as IntoIterator>::IntoIter> |
| 97 | where I: IntoIterator, |
| 98 | J: IntoIterator<Item = I::Item> |
| 99 | { |
| 100 | i.into_iter().chain(j) |
| 101 | } |
| 102 | |
| 103 | /// Create an iterator that clones each element from &T to T |
| 104 | /// |
| 105 | /// `IntoIterator` enabled version of `i.cloned()`. |
| 106 | /// |
| 107 | /// ``` |
| 108 | /// use itertools::cloned; |
| 109 | /// |
| 110 | /// assert_eq!(cloned(b"abc").next(), Some(b'a')); |
| 111 | /// ``` |
| 112 | pub fn cloned<'a, I, T: 'a>(iterable: I) -> iter::Cloned<I::IntoIter> |
| 113 | where I: IntoIterator<Item=&'a T>, |
| 114 | T: Clone, |
| 115 | { |
| 116 | iterable.into_iter().cloned() |
| 117 | } |
| 118 | |
| 119 | /// Perform a fold operation over the iterable. |
| 120 | /// |
| 121 | /// `IntoIterator` enabled version of `i.fold(init, f)` |
| 122 | /// |
| 123 | /// ``` |
| 124 | /// use itertools::fold; |
| 125 | /// |
| 126 | /// assert_eq!(fold(&[1., 2., 3.], 0., |a, &b| f32::max(a, b)), 3.); |
| 127 | /// ``` |
| 128 | pub fn fold<I, B, F>(iterable: I, init: B, f: F) -> B |
| 129 | where I: IntoIterator, |
| 130 | F: FnMut(B, I::Item) -> B |
| 131 | { |
| 132 | iterable.into_iter().fold(init, f) |
| 133 | } |
| 134 | |
| 135 | /// Test whether the predicate holds for all elements in the iterable. |
| 136 | /// |
| 137 | /// `IntoIterator` enabled version of `i.all(f)` |
| 138 | /// |
| 139 | /// ``` |
| 140 | /// use itertools::all; |
| 141 | /// |
| 142 | /// assert!(all(&[1, 2, 3], |elt| *elt > 0)); |
| 143 | /// ``` |
| 144 | pub fn all<I, F>(iterable: I, f: F) -> bool |
| 145 | where I: IntoIterator, |
| 146 | F: FnMut(I::Item) -> bool |
| 147 | { |
| 148 | iterable.into_iter().all(f) |
| 149 | } |
| 150 | |
| 151 | /// Test whether the predicate holds for any elements in the iterable. |
| 152 | /// |
| 153 | /// `IntoIterator` enabled version of `i.any(f)` |
| 154 | /// |
| 155 | /// ``` |
| 156 | /// use itertools::any; |
| 157 | /// |
| 158 | /// assert!(any(&[0, -1, 2], |elt| *elt > 0)); |
| 159 | /// ``` |
| 160 | pub fn any<I, F>(iterable: I, f: F) -> bool |
| 161 | where I: IntoIterator, |
| 162 | F: FnMut(I::Item) -> bool |
| 163 | { |
| 164 | iterable.into_iter().any(f) |
| 165 | } |
| 166 | |
| 167 | /// Return the maximum value of the iterable. |
| 168 | /// |
| 169 | /// `IntoIterator` enabled version of `i.max()`. |
| 170 | /// |
| 171 | /// ``` |
| 172 | /// use itertools::max; |
| 173 | /// |
| 174 | /// assert_eq!(max(0..10), Some(9)); |
| 175 | /// ``` |
| 176 | pub fn max<I>(iterable: I) -> Option<I::Item> |
| 177 | where I: IntoIterator, |
| 178 | I::Item: Ord |
| 179 | { |
| 180 | iterable.into_iter().max() |
| 181 | } |
| 182 | |
| 183 | /// Return the minimum value of the iterable. |
| 184 | /// |
| 185 | /// `IntoIterator` enabled version of `i.min()`. |
| 186 | /// |
| 187 | /// ``` |
| 188 | /// use itertools::min; |
| 189 | /// |
| 190 | /// assert_eq!(min(0..10), Some(0)); |
| 191 | /// ``` |
| 192 | pub fn min<I>(iterable: I) -> Option<I::Item> |
| 193 | where I: IntoIterator, |
| 194 | I::Item: Ord |
| 195 | { |
| 196 | iterable.into_iter().min() |
| 197 | } |
| 198 | |
| 199 | |
| 200 | /// Combine all iterator elements into one String, seperated by `sep`. |
| 201 | /// |
| 202 | /// `IntoIterator` enabled version of `iterable.join(sep)`. |
| 203 | /// |
| 204 | /// ``` |
| 205 | /// use itertools::join; |
| 206 | /// |
| 207 | /// assert_eq!(join(&[1, 2, 3], ", "), "1, 2, 3"); |
| 208 | /// ``` |
| 209 | #[cfg(feature = "use_std")] |
| 210 | pub fn join<I>(iterable: I, sep: &str) -> String |
| 211 | where I: IntoIterator, |
| 212 | I::Item: Display |
| 213 | { |
| 214 | iterable.into_iter().join(sep) |
| 215 | } |
| 216 | |
| 217 | /// Sort all iterator elements into a new iterator in ascending order. |
| 218 | /// |
| 219 | /// `IntoIterator` enabled version of [`iterable.sorted()`][1]. |
| 220 | /// |
| 221 | /// [1]: trait.Itertools.html#method.sorted |
| 222 | /// |
| 223 | /// ``` |
| 224 | /// use itertools::sorted; |
| 225 | /// use itertools::assert_equal; |
| 226 | /// |
| 227 | /// assert_equal(sorted("rust".chars()), "rstu".chars()); |
| 228 | /// ``` |
| 229 | #[cfg(feature = "use_std")] |
| 230 | pub fn sorted<I>(iterable: I) -> VecIntoIter<I::Item> |
| 231 | where I: IntoIterator, |
| 232 | I::Item: Ord |
| 233 | { |
| 234 | iterable.into_iter().sorted() |
| 235 | } |
| 236 | |