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/// From itertools /// Create an iterator running multiple iterators in lockstep. /// /// The `izip!` iterator yields elements until any subiterator /// returns `None`. /// /// This is a version of the standard ``.zip()`` that's supporting more than /// two iterators. The iterator element type is a tuple with one element /// from each of the input iterators. Just like ``.zip()``, the iteration stops /// when the shortest of the inputs reaches its end. /// /// **Note:** The result of this macro is in the general case an iterator /// composed of repeated `.zip()` and a `.map()`; it has an anonymous type. /// The special cases of one and two arguments produce the equivalent of /// `$a.into_iter()` and `$a.into_iter().zip($b)` respectively. /// /// Prefer this macro `izip!()` over [`multizip`] for the performance benefits /// of using the standard library `.zip()`. /// /// [`multizip`]: fn.multizip.html /// /// ``` /// # use itertools::izip; /// # /// # fn main() { /// /// // iterate over three sequences side-by-side /// let mut results = [0, 0, 0, 0]; /// let inputs = [3, 7, 9, 6]; /// /// for (r, index, input) in izip!(&mut results, 0..10, &inputs) { /// *r = index * 10 + input; /// } /// /// assert_eq!(results, [0 + 3, 10 + 7, 29, 36]); /// # } /// ``` macro_rules! izip { // @closure creates a tuple-flattening closure for .map() call. usage: // @closure partial_pattern => partial_tuple , rest , of , iterators // eg. izip!( @closure ((a, b), c) => (a, b, c) , dd , ee ) ( @closure $p:pat => $tup:expr ) => { |$p| $tup }; // The "b" identifier is a different identifier on each recursion level thanks to hygiene. ( @closure $p:pat => ( $($tup:tt)* ) , $_iter:expr $( , $tail:expr )* ) => { izip!(@closure ($p, b) => ( $($tup)*, b ) $( , $tail )*) }; // unary ($first:expr $(,)*) => { std::iter::IntoIterator::into_iter($first) }; // binary ($first:expr, $second:expr $(,)*) => { izip!($first) .zip($second) }; // n-ary where n > 2 ( $first:expr $( , $rest:expr )* $(,)* ) => { izip!($first) $( .zip($rest) )* .map( izip!(@closure a => (a) $( , $rest )*) ) }; } mod file; pub use file::*; mod verify; pub use verify::*;