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flatten an array (of i32) in rust
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| #![allow(non_snake_case)] | |
| /// This rust lib contains one function that will flatten an array of arbitrarily nested arrays of integers into a flat array of integers. | |
| /// e.g. [[1,2,[3]],4] -> [1,2,3,4]. | |
| /// | |
| /// # Example usage | |
| /// | |
| /// ``` | |
| /// use rsflatten::{ | |
| /// flatten, | |
| /// Node::{Array as a, I32 as i}, | |
| /// }; | |
| /// | |
| /// let input = a(vec![ | |
| /// i(1), | |
| /// a(vec![i(2), i(3), i(4), i(5)]), | |
| /// i(6), | |
| /// a(vec![i(7), i(8), i(9), i(10)]), | |
| /// ]); | |
| /// flatten(&input); | |
| /// ``` | |
| /// | |
| #[derive(Clone, Debug)] | |
| // Node models the input: an array of {integers OR arbitrarily nested arrays of integers} | |
| pub enum Node { | |
| I32(i32), | |
| Array(Vec<Node>), | |
| } | |
| // flatten flattens a Node. e.g. [[1,2,[3]],4] -> [1,2,3,4]. | |
| pub fn flatten(node: &Node) -> Vec<i32> { | |
| match node { | |
| Node::I32(i) => ([*i].to_vec()), | |
| Node::Array(a) => a.iter().fold(vec![], |mut acc, aSubNode| { | |
| for e in flatten(aSubNode) { | |
| acc.push(e) | |
| } | |
| return acc; | |
| }), | |
| } | |
| } | |
| #[cfg(test)] | |
| mod tests { | |
| use super::{ | |
| flatten, | |
| Node::{Array as a, I32 as i}, | |
| }; | |
| #[test] | |
| fn already_flat_array() { | |
| let input = a(vec![i(1), i(2), i(3), i(4)]); | |
| assert_eq!(flatten(&input), vec!(1, 2, 3, 4)); | |
| } | |
| #[test] | |
| fn nested_one_level() { | |
| let input = a(vec![ | |
| i(1), | |
| a(vec![i(2), i(3), i(4), i(5)]), | |
| i(6), | |
| a(vec![i(7), i(8), i(9), i(10)]), | |
| ]); | |
| assert_eq!(flatten(&input), vec!(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)); | |
| } | |
| #[test] | |
| fn nested_three_levels() { | |
| let input = a(vec![ | |
| i(1), | |
| a(vec![i(2), i(3), i(4), i(5)]), | |
| i(6), | |
| a(vec![ | |
| i(7), | |
| i(8), | |
| i(9), | |
| a(vec![i(1), i(2), i(3), a(vec![i(4), i(5), i(6), i(7)])]), | |
| ]), | |
| ]); | |
| assert_eq!( | |
| flatten(&input), | |
| vec!(1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7) | |
| ); | |
| } | |
| #[test] | |
| fn empty_array() { | |
| let input = a(vec![]); | |
| assert!(flatten(&input).is_empty()); | |
| } | |
| } |
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