From 4d950b7618829d61df64687626420ba3800149c3 Mon Sep 17 00:00:00 2001
From: pengzhanbo <volodymyr@foxmail.com>
Date: Sun, 25 Feb 2024 00:44:20 +0800
Subject: [PATCH] =?UTF-8?q?perf(plugin-shikiji):=20=E4=BC=98=E5=8C=96?=
 =?UTF-8?q?=E5=BC=80=E5=8F=91=E6=97=B6=E7=BC=96=E8=AF=91=E9=80=9F=E5=BA=A6?=
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---
 plugins/plugin-shikiji/src/node/lru.ts | 39 ++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 plugins/plugin-shikiji/src/node/lru.ts

diff --git a/plugins/plugin-shikiji/src/node/lru.ts b/plugins/plugin-shikiji/src/node/lru.ts
new file mode 100644
index 000000000..191a6f0c2
--- /dev/null
+++ b/plugins/plugin-shikiji/src/node/lru.ts
@@ -0,0 +1,39 @@
+// adapted from https://stackoverflow.com/a/46432113/11613622
+
+export class LRUCache<K, V> {
+  private max: number
+  private cache: Map<K, V>
+
+  constructor(max: number = 10) {
+    this.max = max
+    this.cache = new Map<K, V>()
+  }
+
+  get(key: K): V | undefined {
+    const item = this.cache.get(key)
+    if (item !== undefined) {
+      // refresh key
+      this.cache.delete(key)
+      this.cache.set(key, item)
+    }
+    return item
+  }
+
+  set(key: K, val: V): void {
+    // refresh key
+    if (this.cache.has(key))
+      this.cache.delete(key)
+    // evict oldest
+    else if (this.cache.size === this.max)
+      this.cache.delete(this.first()!)
+    this.cache.set(key, val)
+  }
+
+  first(): K | undefined {
+    return this.cache.keys().next().value
+  }
+
+  clear(): void {
+    this.cache.clear()
+  }
+}