1 files changed, 58 insertions, 0 deletions
diff --git a/src/js/mrucache.js b/src/js/mrucache.js
new file mode 100644
index 0000000..9a16047
--- /dev/null
+++ b/src/js/mrucache.js
@@ -0,0 +1,58 @@
+/*******************************************************************************
+
+    uBlock Origin - a comprehensive, efficient content blocker
+    Copyright (C) 2014-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+*/
+
+'use strict';
+
+export class MRUCache {
+    constructor(maxSize) {
+        this.maxSize = maxSize;
+        this.array = [];
+        this.map = new Map();
+        this.resetTime = Date.now();
+    }
+    add(key, value) {
+        const found = this.map.has(key);
+        this.map.set(key, value);
+        if ( found ) { return; }
+        if ( this.array.length === this.maxSize ) {
+            this.map.delete(this.array.pop());
+        }
+        this.array.unshift(key);
+    }
+    remove(key) {
+        if ( this.map.delete(key) === false ) { return; }
+        this.array.splice(this.array.indexOf(key), 1);
+    }
+    lookup(key) {
+        const value = this.map.get(key);
+        if ( value === undefined ) { return; }
+        if ( this.array[0] === key ) { return value; }
+        const i = this.array.indexOf(key);
+        this.array.copyWithin(1, 0, i);
+        this.array[0] = key;
+        return value;
+    }
+    reset() {
+        this.array = [];
+        this.map.clear();
+        this.resetTime = Date.now();
+    }
+}