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filter_map

Function filter_map 

Source
pub fn filter_map<'a, Brand: Kind_cdc7cd43dac7585f, A: 'a, B: 'a, FA, Marker>(
    f: impl FilterMapDispatch<'a, Brand, A, B, FA, Marker>,
    fa: FA,
) -> <Brand as Kind_cdc7cd43dac7585f>::Of<'a, B>
Expand description

Filters and maps the values in a filterable context.

Dispatches to either Filterable::filter_map or RefFilterable::ref_filter_map based on the closure’s argument type:

  • If the closure takes owned values (Fn(A) -> Option<B>) and the container is owned, dispatches to Filterable::filter_map.
  • If the closure takes references (Fn(&A) -> Option<B>) and the container is borrowed (&fa), dispatches to RefFilterable::ref_filter_map.

The Marker and FA type parameters are inferred automatically by the compiler from the closure’s argument type and the container argument. Callers write filter_map::<Brand, _, _, _, _>(...) and never need to specify Marker or FA explicitly.

The dispatch is resolved at compile time with no runtime cost.

§Type Signature

forall Brand A B. Filterable Brand => (A -> Option B, Brand A) -> Brand B

§Type Parameters

  • 'a: The lifetime of the values.
  • Brand: The brand of the filterable.
  • A: The type of the value(s) inside the filterable.
  • B: The type of the result(s) of applying the function.
  • FA: The container type (owned or borrowed), inferred from the argument.
  • Marker: Dispatch marker type, inferred automatically.

§Parameters

  • f: The function to apply to each value. Returns Some(b) to keep the value or None to discard it.
  • fa: The filterable instance (owned for Val, borrowed for Ref).

§Returns

A new filterable instance containing only the values for which the function returned Some.

§Examples

use fp_library::{
	brands::*,
	functions::explicit::*,
};

// Owned: dispatches to Filterable::filter_map
let y =
	filter_map::<OptionBrand, _, _, _, _>(|x: i32| if x > 3 { Some(x) } else { None }, Some(5));
assert_eq!(y, Some(5));

// By-ref: dispatches to RefFilterable::ref_filter_map
let y = filter_map::<OptionBrand, _, _, _, _>(
	|x: &i32| if *x > 3 { Some(*x) } else { None },
	&Some(5),
);
assert_eq!(y, Some(5));