to_vec()in rust

2023-04-18

to_vec is a crate that provides specialized implementations of collect for common use cases when collecting into Vec, HashSet, or HashMap containers. The main functionality can be broken down into:

• ToVec: Collects an iterator's items into a Vec. For example:

  #![allow(unused)]
  fn main() {
  use to_vec::ToVec;
  let v = "one two three".split_whitespace().to_vec();
  assert_eq!(v, &["one", "two", "three"]);
  }

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• ToVecResult: Collects an iterator of Result<T, E> into a Result<Vec<T>, E>, where the error is the first error encountered.

  #![allow(unused)]
  fn main() {
  use to_vec::ToVecResult;
  let numbers = "23E 5F5 FF00".split_whitespace()
      .map(|s| u32::from_str_radix(s, 16)).to_vec_result().unwrap();
  assert_eq!(numbers, &[0x23E, 0x5F5, 0xFF00]);
  }

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Some other similar crates

• ToSet: Collects an iterator of references into a HashSet, implicitly cloning the items.

  #![allow(unused)]
  fn main() {
  use to_vec::ToSet;
  let colours = ["green", "orange", "blue"].iter().to_set();
  let fruit = ["apple", "banana", "orange"].iter().to_set();
  let common = colours.intersection(&fruit).to_set();
  assert_eq!(common, ["orange"].iter().to_set());
  }

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• ToMap: Collects an iterator of references to key-value pairs into a HashMap, implicitly cloning the keys and values.

  #![allow(unused)]
  fn main() {
  use to_vec::ToMap;
  const VALUES: &[(&str, i32)] = &[("hello", 10), ("dolly", 20)];
  let map = VALUES.iter().to_map();
  assert_eq!(map.get("hello"), Some(&10));
  assert_eq!(map.get("dolly"), Some(&20));
  }

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These specialized forms provide a more ergonomic and efficient way to collect iterators into commonly used containers.