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Diffstat (limited to 'src/free.rs')
| -rw-r--r-- | src/free.rs | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/src/free.rs b/src/free.rs new file mode 100644 index 0000000..a6bc1bd --- /dev/null +++ b/src/free.rs @@ -0,0 +1,236 @@ +//! 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_std")] +use std::fmt::Display; +use std::iter::{self, Zip}; +#[cfg(feature = "use_std")] +type VecIntoIter<T> = ::std::vec::IntoIter<T>; + +#[cfg(feature = "use_std")] +use crate::Itertools; + +pub use crate::adaptors::{ + interleave, + merge, + put_back, +}; +#[cfg(feature = "use_std")] +pub use crate::put_back_n_impl::put_back_n; +#[cfg(feature = "use_std")] +pub use crate::multipeek_impl::multipeek; +#[cfg(feature = "use_std")] +pub use crate::kmerge_impl::kmerge; +pub use crate::zip_eq_impl::zip_eq; +pub use crate::merge_join::merge_join_by; +#[cfg(feature = "use_std")] +pub use crate::rciter_impl::rciter; + +/// Iterate `iterable` with a running index. +/// +/// `IntoIterator` enabled version of `.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 `.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() +} + +/// Iterate `i` and `j` in lock step. +/// +/// `IntoIterator` enabled version of `i.zip(j)`. +/// +/// ``` +/// use itertools::zip; +/// +/// let data = [1, 2, 3, 4, 5]; +/// for (a, b) in zip(&data, &data[1..]) { +/// /* loop body */ +/// } +/// ``` +pub fn zip<I, J>(i: I, j: J) -> Zip<I::IntoIter, J::IntoIter> + where I: IntoIterator, + J: IntoIterator +{ + i.into_iter().zip(j) +} + +/// Create an iterator that first iterates `i` and then `j`. +/// +/// `IntoIterator` enabled version of `i.chain(j)`. +/// +/// ``` +/// use itertools::chain; +/// +/// for elt in chain(&[1, 2, 3], &[4]) { +/// /* loop body */ +/// } +/// ``` +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 `i.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 `i.fold(init, f)` +/// +/// ``` +/// 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 `i.all(f)` +/// +/// ``` +/// 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 `i.any(f)` +/// +/// ``` +/// 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 `i.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 `i.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, seperated by `sep`. +/// +/// `IntoIterator` enabled version of `iterable.join(sep)`. +/// +/// ``` +/// use itertools::join; +/// +/// assert_eq!(join(&[1, 2, 3], ", "), "1, 2, 3"); +/// ``` +#[cfg(feature = "use_std")] +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 [`iterable.sorted()`][1]. +/// +/// [1]: trait.Itertools.html#method.sorted +/// +/// ``` +/// use itertools::sorted; +/// use itertools::assert_equal; +/// +/// assert_equal(sorted("rust".chars()), "rstu".chars()); +/// ``` +#[cfg(feature = "use_std")] +pub fn sorted<I>(iterable: I) -> VecIntoIter<I::Item> + where I: IntoIterator, + I::Item: Ord +{ + iterable.into_iter().sorted() +} + |