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https://github.com/mz2/weightedlrucache
An LRU cache in Swift, with optional support for weighted values such that values are evicted from the tail until a total weight parameter is satisfied.
https://github.com/mz2/weightedlrucache
Last synced: 25 days ago
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An LRU cache in Swift, with optional support for weighted values such that values are evicted from the tail until a total weight parameter is satisfied.
- Host: GitHub
- URL: https://github.com/mz2/weightedlrucache
- Owner: mz2
- License: mit
- Created: 2020-05-10T09:01:00.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2021-10-28T15:14:34.000Z (about 3 years ago)
- Last Synced: 2024-10-19T23:23:48.460Z (28 days ago)
- Language: Swift
- Homepage:
- Size: 57.6 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# WeightedLRUCache [](https://github.com/apple/swift-package-manager) [](https://github.com/mz2/WeightedLRUCache/actions/workflows/build.yml) 
An LRU cache in Swift, with optional support for weighted values such that values are evicted from the tail until a total weight parameter is satisfied.
## Installation
Add WeightedLRUCache to your Swift package as a dependency by adding the following to your Package.swift file in the dependencies array:
```swift
.package(url: "https://github.com/mz2/WeightedLRUCache.git", from: "")
```
If you are using Xcode 11 or newer, you can add WeightedLRUCache by entering the URL to the repository via the File menu:
```
File > Swift Packages > Add Package Dependency...
```
## Usage
Values inserted into a `WeightedLRUCache` must conform to the protocol `Weighted` (which simply requires a readonly property `weight: UInt` on the conforming type).
An example implementation `WeightedValue` is provided with the library.
To create a cache with no constrained item count, and a max weight constraint of `10`, do the following:
```swift
var cache = WeightedLRUCache>(maxCount: .max, maxWeight: 10)
cache.didEvict = { key, value in
print("Dropped \(key) : \(value)")
}
```
Note above the use of `Int.max` as the max count -- here only a weight constraint was given (both item count and total weight can be constrained). Let's add two more items in there:
```swift
cache["a"] = WeightedValue(weight: 5, value: "foo")
cache["b"] = WeightedValue(weight: 5, value: "bar")
// Upon this being inserted, value with key "a" above is dropped,
// and the callback passed to the cache initializer is called for the first inserted value.
cache["c"] = WeightedValue(weight: 1, value: "baz")
```
A cache created as above behaves such that...
- the first inserted value (with key `"a"`) will be dropped after the next two have been inserted (since the 3rd insertion brings the total weight to `11`, i.e. above the maximum of `10`).
- the callback passed into the initializer is called (synchronously, in the call stack that results from the cache insertion of key `"c"` below).
Beside a subscript based interface for key-based access, `keys` and `values` arrays available on `WeightedLRUCache` to return values in the order in which they were accessed by their key.
Given the example above, `keys` for example returns the array `["c", "b", "a"]`.
For more usage examples, see the project's test suite.
## License
WeightedLRUCache is available under the MIT license.