collect_with

Trait TryCollectWith

Source 
pub trait TryCollectWith: Iterator {
    // Provided methods
    fn try_collect_with<'a, T, OK, ERR>(
        self,
        capacity: impl FnOnce(usize) -> usize,
    ) -> Result<T, ERR>
       where T: ExtendWithCapacity<OK>,
             Self: Sized,
             Self::Item: TryExtract<'a, Ok = OK, Err = ERR> { ... }
    fn try_collect_vec_with<'a, OK, ERR>(
        self,
        capacity: impl FnOnce(usize) -> usize,
    ) -> Result<Vec<OK>, ERR>
       where Self: Sized,
             Self::Item: TryExtract<'a, Ok = OK, Err = ERR> { ... }
}
Available on crate feature try only.

Provided Methods§

Source

fn try_collect_with<'a, T, OK, ERR>( self, capacity: impl FnOnce(usize) -> usize, ) -> Result<T, ERR>
where T: ExtendWithCapacity<OK>, Self: Sized, Self::Item: TryExtract<'a, Ok = OK, Err = ERR>,

Attempt to collect iterator elements into a collection with error handling

§Closure
  • capacity - Closure that calculates initial capacity based on iterator size hint
§Type Parameters
  • T - Target collection type implementing ExtendWithCapacity
  • OK - Type of successfully extracted values
  • ERR - Error type returned from failed extraction
§Behavior
  • Uses size hints to pre-allocate capacity
  • Short-circuits on first extraction error
  • Returns collected values or first encountered error
§Example
use collect_with::TryCollectWith;

let result = ["42", "76", "abc"]
  .into_iter()
  .map(|x| x.parse::<i32>()) // &str -> Result<i32>
  .try_collect_with::<Vec<_>, _, _>(|u| u + 3); // -> Result<Vec<i32>, ParseIntError>

assert!(result.is_err());
Source

fn try_collect_vec_with<'a, OK, ERR>( self, capacity: impl FnOnce(usize) -> usize, ) -> Result<Vec<OK>, ERR>
where Self: Sized, Self::Item: TryExtract<'a, Ok = OK, Err = ERR>,

Available on crate feature collect_vec only.

Convenience method for collecting into Result<Vec<OK>, Err>

§Closure
  • capacity
    • Closure that calculates initial vector capacity
§Example
use collect_with::TryCollectWith;

let result = ["42", "73"]
  .into_iter()
  .map(|x| x.parse::<i32>()) // &str -> Result<i32>
  .try_collect_vec_with(|u| u+2); // -> Result<Vec<i32>, ParseIntError>

assert_eq!(result.as_deref(), Ok(&[42, 73][..]));

Implementors§