feat: async cache.read()/write(), remove .has()

src/cache/cache.ts

@@ -1,5 +1,4 @@
 export interface Cache<T> {
-  write (key: string, value: T): void;
-  read (key: string): T | undefined;
-  has (key: string): boolean;
+  write (key: string, value: T): void | Promise<void>;
+  read (key: string): T | undefined | Promise<T | undefined>;
 }

src/cache/lru.ts

@@ -42,10 +42,6 @@ export class LRU<T> implements Cache<T> {
     return value
   }
 
-  has (key: string): boolean {
-    return !!this.cache[key]
-  }
-
   remove (key: string) {
     const node = this.cache[key]
     node.prev.next = node.next

src/liquid.ts

@@ -76,10 +76,13 @@ export class Liquid {
 
     for (const filepath of paths) {
       const { cache } = this.options
-      if (cache && cache.has(filepath)) return cache.read(filepath)
+      if (cache) {
+        const tpls = yield cache.read(filepath)
+        if (tpls) return tpls
+      }
       if (!(sync ? this.fs.existsSync(filepath) : yield this.fs.exists(filepath))) continue
       const tpl = this.parse(sync ? this.fs.readFileSync(filepath) : yield this.fs.readFile(filepath), filepath)
-      cache && cache.write(filepath, tpl)
+      if (cache) cache.write(filepath, tpl)
       return tpl
     }
     throw this.lookupError(file, options.root)