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#![cfg_attr(feature = "nightly", feature(external_doc) )] #![cfg_attr(feature = "nightly", doc(include = "../README.md") )] #" )] #![cfg_attr(not(feature = "nightly"), doc = "for more info about this crate." )] /// Reexport a trait that [**should be in the prelude**]( /// https://internals.rust-lang.org/t/pre-rfc-add-fromiterator-to-the-prelude/4324) #[doc(hidden)] pub use core::iter::FromIterator; /// Write the most pervasive iterator adapters /// ([filter]ing and [map]ping) as [Python generator expressions]. /// /// # Examples /// /// ### Squaring even numbers /// /// ```edition2018 /// # use ::iter_python::iter; /// let mut all_evens_squared = iter!( /// x * x, /// for x in (0 ..), /// if x % 2 == 0, // trailing comma is optional /// ); /// assert_eq!(all_evens_squared.next(), Some(0)); /// assert_eq!(all_evens_squared.next(), Some(4)); /// assert_eq!(all_evens_squared.next(), Some(16)); /// ``` /// /// ### `filter`ing is optional, such as in Python: /// /// ```edition2018 /// # use ::iter_python::iter; /// let mut numbers_binary = iter!(format!("{:02b}", x), for x in 1 ..= 3); /// /// assert_eq!(numbers_binary.next(), Some("01".into())); /// assert_eq!(numbers_binary.next(), Some("10".into())); /// assert_eq!(numbers_binary.next(), Some("11".into())); /// assert_eq!(numbers_binary.next(), None); /// ``` /// /// ### You may also `filter` with `if let`: /// /// ```edition2018 /// # use ::iter_python::iter; /// let strings = ["42", "0", "zero", "27"]; /// /// let parsed_as_i32s = iter!(s.parse::<i32>(), for &s in &strings); /// /// let total: i32 = Iterator::sum(iter!( /// x, /// for res in parsed_as_i32s, /// if let Ok(x) = res, /// )); /// /// assert_eq!(total, 42 + 0 + 27); /// ``` /// /// ```edition2018 /// # use ::iter_python::iter; /// enum Fruit { Banana, Peach, RottenApple } /// use Fruit::*; /// /// impl Fruit { /// fn is_fresh (&self) -> bool /// { /// if let RottenApple = self { /// false /// } else { /// true /// } /// } /// } /// /// static BASKET: &[Fruit] = &[Banana, RottenApple, Peach, Banana]; /// /// let no_rotten_apple = iter!( /// fruit, /// for fruit in BASKET, /// if let Banana | Peach = fruit, /// ); /// /// assert!({no_rotten_apple}.all(Fruit::is_fresh)); /// ``` /// /// [filter]: https://doc.rust-lang.org/core/iter/trait.Iterator.html#method.filter /// [map]: https://doc.rust-lang.org/core/iter/trait.Iterator.html#method.map /// [Python generator expressions]: https://www.python.org/dev/peps/pep-0289 /// [`if let`]: https://doc.rust-lang.org/book/if-let.html #[macro_export] macro_rules! iter { ( $mapped_expr:expr , for $var:pat in $iterable:expr , if $cond:expr $(,)? ) => ( $iterable .into_iter() .filter_map(|$var| { if $cond { Some($mapped_expr) } else { None } }) ); ( $mapped_expr:expr , for $var:pat in $iterable:expr , if let $( $pat:pat )|+ = $value:expr $(,)? ) => ( $iterable .into_iter() .filter_map(|$var| { if let $( $pat )|+ = $value { Some($mapped_expr) } else { None } }) ); ( $mapped_expr:expr , for $var:pat in $iterable:expr $(,)? ) => ( $iterable .into_iter() .map(|$var| $mapped_expr) ); } /// [Python "list" comprehensions]: same as [`iter!`], /// but [`collect`]ed into a [`Vec`] instead. /// /// # `vec_it!` or `vec!`? /// /// **[`vec_it!`] fallbacks to [`::std::vec!`] functionality**, /// thus allowing maximum compatiblity! /// /// ### Example /// ```edition2018 /// use ::iter_python::vec_it as vec; /// /// let v1 = vec![i, for i in 1 ..= 4]; /// let v2 = vec![1, 2, 3, 4]; /// assert_eq!(v1, v2); /// ``` /// /// It has not been named `vec` to prevent lints against ambiguous glob imports. /// /// [`iter!`]: `iter` /// [`collect`]: https://doc.rust-lang.org/core/iter/trait.Iterator.html#method.collect /// [`Vec`]: https://doc.rust-lang.org/std/vec/struct.Vec.html /// [Python "list" comprehensions]: https://www.python.org/dev/peps/pep-0202 /// [`vec_it!`]: `vec_it` /// [`::std::vec!`]: https://doc.rust-lang.org/std/macro.vec.html #[macro_export] macro_rules! vec_it { ( $expr:expr , for $var:pat in $iterable:expr $( , $($if_cond:tt)* )? ) => ( $crate::iter!( $expr, for $var in $iterable $( , $($if_cond)* )? ).collect::<::std::vec::Vec<_>>() ); ( $($fallback_to_std_vec:tt)* ) => ( ::std::vec![$($fallback_to_std_vec)*] ); }