0.6.0

compose/persist/.gitignore

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+/build

compose/persist/build.gradle.kts

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+plugins {
+    alias(libs.plugins.android.library)
+    alias(libs.plugins.kotlin.android)
+}
+
+android {
+    namespace = "it.hamy.compose.persist"
+    compileSdk = 34
+
+    defaultConfig {
+        minSdk = 21
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(getDefaultProguardFile("proguard-android-optimize.txt"))
+        }
+    }
+
+    sourceSets.all {
+        kotlin.srcDir("src/$name/kotlin")
+    }
+
+    buildFeatures {
+        compose = true
+    }
+
+    composeOptions {
+        kotlinCompilerExtensionVersion = libs.versions.compose.compiler.get()
+    }
+}
+
+kotlin {
+    jvmToolchain(libs.versions.jvm.get().toInt())
+}
+
+dependencies {
+    implementation(platform(libs.compose.bom))
+    implementation(libs.compose.foundation)
+
+    detektPlugins(libs.detekt.compose)
+    detektPlugins(libs.detekt.formatting)
+}

compose/persist/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest>
+
+</manifest>

compose/persist/src/main/kotlin/it/hamy/compose/persist/Persist.kt

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+package it.hamy.compose.persist
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.SnapshotMutationPolicy
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.structuralEqualityPolicy
+
+@Suppress("UNCHECKED_CAST")
+@Composable
+fun <T> persist(
+    tag: String,
+    initialValue: T,
+    policy: SnapshotMutationPolicy<T> = structuralEqualityPolicy()
+): MutableState<T> {
+    val persistMap = LocalPersistMap.current
+
+    return remember(persistMap) {
+        persistMap?.map?.getOrPut(tag) { mutableStateOf(initialValue, policy) } as? MutableState<T>
+            ?: mutableStateOf(initialValue, policy)
+    }
+}
+
+@Composable
+fun <T> persistList(tag: String): MutableState<List<T>> =
+    persist(tag = tag, initialValue = emptyList())
+
+@Composable
+fun <T : Any?> persist(tag: String): MutableState<T?> =
+    persist(tag = tag, initialValue = null)

compose/persist/src/main/kotlin/it/hamy/compose/persist/PersistMap.kt

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+package it.hamy.compose.persist
+
+import android.util.Log
+import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.compositionLocalOf
+
+@JvmInline
+value class PersistMap(val map: MutableMap<String, MutableState<*>> = hashMapOf()) {
+    fun clean(prefix: String) = map.keys.removeAll { it.startsWith(prefix) }
+}
+
+val LocalPersistMap = compositionLocalOf<PersistMap?> {
+    Log.e("PersistMap", "Tried to reference uninitialized PersistMap, stacktrace:")
+    runCatching { error("Stack:") }.exceptionOrNull()?.printStackTrace()
+    null
+}

compose/persist/src/main/kotlin/it/hamy/compose/persist/PersistMapCleanup.kt

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+package it.hamy.compose.persist
+
+import android.app.Activity
+import android.content.Context
+import android.content.ContextWrapper
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.ui.platform.LocalContext
+
+@Composable
+fun PersistMapCleanup(prefix: String) {
+    val context = LocalContext.current
+    val persistMap = LocalPersistMap.current
+
+    DisposableEffect(persistMap) {
+        onDispose {
+            if (context.findActivityNullable()?.isChangingConfigurations == false)
+                persistMap?.clean(prefix)
+        }
+    }
+}
+
+fun Context.findActivityNullable(): Activity? {
+    var current = this
+    while (current is ContextWrapper) {
+        if (current is Activity) return current
+        current = current.baseContext
+    }
+    return null
+}