replace_or_append

Replaces the first element that matches with item, or appends item when none does: the “upsert into a list” gesture.

Import

use helpers4::array::replace_or_append;

Cargo feature array (enabled by default). To compile only this module:

cargo add helpers4 --no-default-features --features array

or in Cargo.toml:

[dependencies]
helpers4 = { version = "0.0.9", default-features = false, features = ["array"] }

Signature

pub fn replace_or_append<T: Clone>(
    items: &[T],
    item: T,
    matches: impl FnMut(&T) -> bool,
) -> Vec<T>

Parameters

Parameter	Type	Description
items	&[T]	The current elements.
item	T	The replacement, or the new element.
matches	impl FnMut(&T) -> bool	Tells which existing element item replaces.

Returns

Vec<T> — A new Vec; items is not changed.

Examples

use helpers4::array::replace_or_append;

let users = [(1, "ana"), (2, "bo")];
assert_eq!(
    replace_or_append(&users, (1, "Ana"), |u| u.0 == 1),
    vec![(1, "Ana"), (2, "bo")]
);
assert_eq!(
    replace_or_append(&users, (3, "cy"), |u| u.0 == 3),
    vec![(1, "ana"), (2, "bo"), (3, "cy")]
);

Source

src/array/replace_or_append.rs