33 lines
715 B
Markdown
33 lines
715 B
Markdown
|
# LRU cache
|
||
|
|
|
||
|
|
The standard implemenation of LRU cache (hash table + doubly-linked list).
|
||
|
|
All operations are in time complexity of O(1).
|
||
|
|
This implementation is *not* thread-safe.
|
||
|
|
|
||
|
|
## Usage
|
||
|
|
|
||
|
|
```
|
||
|
|
# create a new LRU cache with initial capacity of 1 items
|
||
|
|
let cache = newLRUCache[int, string](1)
|
||
|
|
|
||
|
|
cache[1] = "a"
|
||
|
|
cache[2] = "b"
|
||
|
|
|
||
|
|
# key 1 is not in cache, because key 1 is eldest and capacity is only 1
|
||
|
|
assert: 1 notin cache
|
||
|
|
assert: 2 in cache
|
||
|
|
|
||
|
|
# increase capacity and add key 1
|
||
|
|
cache.capacity = 2
|
||
|
|
cache[1] = "a"
|
||
|
|
assert: 1 in cache
|
||
|
|
assert: 2 in cache
|
||
|
|
|
||
|
|
# update recentness of key 2 and add key 3, then key 1 will be discarded.
|
||
|
|
echo cache[2]
|
||
|
|
cache[3] = "c"
|
||
|
|
assert: 1 notin cache
|
||
|
|
assert: 2 in cache
|
||
|
|
assert: 3 in cache
|
||
|
|
```
|