Refactoring caching systems for the Compose layer.

commons/src/main/java/com/vitorpamplona/amethyst/commons/compose/CachedState.kt

@@ -0,0 +1,62 @@
+/**
+ * Copyright (c) 2024 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.amethyst.commons.compose
+
+import android.util.LruCache
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.State
+import androidx.compose.runtime.produceState
+
+@Composable
+fun <K, V> produceCachedState(
+    cache: CachedState<K, V>,
+    key: K,
+): State<V?> {
+    return produceState(initialValue = cache.cached(key), key1 = key) {
+        value = cache.update(key)
+    }
+}
+
+interface CachedState<K, V> {
+    fun cached(k: K): V?
+
+    suspend fun update(k: K): V?
+}
+
+abstract class GenericBaseCache<K, V>(capacity: Int) : CachedState<K, V> {
+    private val cache = LruCache<K, V>(capacity)
+
+    override fun cached(k: K): V? {
+        return cache[k]
+    }
+
+    override suspend fun update(k: K): V? {
+        cache[k]?.let { return it }
+
+        val v = compute(k)
+
+        cache.put(k, v)
+
+        return v
+    }
+
+    abstract suspend fun compute(key: K): V?
+}