forked from Orchid/orchid
37 lines
971 B
Rust
37 lines
971 B
Rust
/// Utility functions to get rid of explicit casts to BoxedIter which are tedious
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use std::{iter, mem};
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pub type BoxedIter<'a, T> = Box<dyn Iterator<Item = T> + 'a>;
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pub type BoxedIterIter<'a, T> = BoxedIter<'a, BoxedIter<'a, T>>;
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/// BoxedIter of a single element
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pub fn box_once<'a, T: 'a>(t: T) -> BoxedIter<'a, T> {
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Box::new(iter::once(t))
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}
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/// BoxedIter of no elements
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pub fn box_empty<'a, T: 'a>() -> BoxedIter<'a, T> {
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Box::new(iter::empty())
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}
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#[macro_export]
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macro_rules! box_chain {
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($curr:expr) => {
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Box::new($curr) as BoxedIter<_>
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};
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($curr:expr, $($rest:expr),*) => {
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Box::new($curr$(.chain($rest))*) as $crate::utils::iter::BoxedIter<_>
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};
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}
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pub fn box_flatten<'a, T: 'a, I: 'a, J: 'a>(i: I) -> BoxedIter<'a, T>
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where
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J: Iterator<Item = T>,
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I: Iterator<Item = J>,
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{
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Box::new(i.flatten())
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}
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pub fn into_boxed_iter<'a, T: 'a>(t: T) -> BoxedIter<'a, <T as IntoIterator>::Item>
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where T: IntoIterator {
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Box::new(t.into_iter())
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} |