feat: with & for in render tag, closes #195

src/cache/cache.ts

@@ -0,0 +1,5 @@
+export interface Cache<T> {
+  write (key: string, value: T): void;
+  read (key: string): T | undefined;
+  has (key: string): boolean;
+}

src/cache/lru.ts

@@ -0,0 +1,67 @@
+import { Cache } from './cache'
+
+class Node<T> {
+  constructor (
+    public key: string,
+    public value: T,
+    public next: Node<T>,
+    public prev: Node<T>
+  ) {}
+}
+
+export class LRU<T> implements Cache<T> {
+  private cache: { [key: string]: Node<T> } = {}
+  private head: Node<T>
+  private tail: Node<T>
+
+  constructor (
+    public limit: number,
+    public size = 0
+  ) {
+    this.head = new Node<T>('HEAD', null as any, null as any, null as any)
+    this.tail = new Node<T>('TAIL', null as any, null as any, null as any)
+    this.head.next = this.tail
+    this.tail.prev = this.head
+  }
+
+  write (key: string, value: T) {
+    const node = new Node(key, value, this.head.next, this.head)
+    this.head.next.prev = node
+    this.head.next = node
+
+    this.cache[key] = node
+    this.size++
+    this.ensureLimit()
+  }
+
+  read (key: string): T | undefined {
+    if (!this.cache[key]) return
+    const { value } = this.cache[key]
+    this.remove(key)
+    this.write(key, value)
+    return value
+  }
+
+  has (key: string): boolean {
+    return !!this.cache[key]
+  }
+
+  remove (key: string) {
+    const node = this.cache[key]
+    node.prev.next = node.next
+    node.next.prev = node.prev
+    delete this.cache[key]
+    this.size--
+  }
+
+  clear () {
+    this.head.next = this.tail
+    this.tail.prev = this.head
+    this.size = 0
+    this.cache = {}
+  }
+
+  private ensureLimit () {
+    if (this.size > this.limit) this.remove(this.tail.prev.key)
+  }
+}