Merge pull request #17 from gmerinojimenez/state-flow

State flow instead of flow

app/src/main/java/com/gmerinojimenez/tweaks/demo/TweakDemoApplication.kt

@@ -4,33 +4,40 @@ import android.app.Application
 import android.widget.Toast
 import com.gmerinojimenez.tweaks.Tweaks
 import com.gmerinojimenez.tweaks.domain.*
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.launch
 
 class TweakDemoApplication : Application() {
     override fun onCreate() {
         super.onCreate()
         Tweaks.init(this@TweakDemoApplication, demoTweakGraph())
     }
 
-    var counter = 0
+    var timestampState = MutableStateFlow("0")
+
+    init {
+        CoroutineScope(Dispatchers.Default).launch {
+            while (true) {
+                timestampState.value = "${System.currentTimeMillis() / 1000}"
+                delay(1000)
+            }
+        }
+    }
 
     private fun demoTweakGraph() = tweaksGraph {
         cover("Tweaks Demo") {
-            label("cover-key", "Current user ID:") { flow { emit("1")} }
+            label("cover-key", "Current user ID:") { MutableStateFlow("1") }
         }
         category("Screen 1") {
             group("Group 1") {
                 label(
                     key = "timestamp",
                     name = "Current timestamp",
                 ) {
-                    flow {
-                        while (true) {
-                            emit("${System.currentTimeMillis() / 1000}")
-                            delay(1000)
-                        }
-                    }
+                    timestampState
                 }
                 editableString(
                     key = "value1",
@@ -40,17 +47,6 @@ class TweakDemoApplication : Application() {
                     key = "value2",
                     name = "Value 2",
                 )
-                editableInt(
-                    key = "value3",
-                    name = "Value 3",
-                    defaultValue = flow {
-                        while (true) {
-                            counter += 1
-                            emit(counter)
-                            delay(1000)
-                        }
-                    }
-                )
                 editableLong(
                     key = "value4",
                     name = "Value 4",

library/src/enabled/java/com/gmerinojimenez/tweaks/Tweaks.kt

@@ -30,7 +30,7 @@ import com.gmerinojimenez.tweaks.domain.TweaksGraph
 import com.gmerinojimenez.tweaks.ui.TweaksCategoryScreen
 import com.gmerinojimenez.tweaks.ui.TweaksScreen
 import com.squareup.seismic.ShakeDetector
-import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.StateFlow
 import javax.inject.Inject
 
 
@@ -39,9 +39,9 @@ class Tweaks {
     @Inject
     internal lateinit var tweaksBusinessLogic: TweaksBusinessLogic
 
-    fun <T>getTweakValue(key: String): Flow<T?> = tweaksBusinessLogic.getValue(key)
+    fun <T>getTweakValue(key: String): StateFlow<T?> = tweaksBusinessLogic.getValue(key)
 
-    fun <T> getTweakValue(entry: TweakEntry<T>): Flow<T?> = tweaksBusinessLogic.getValue(entry)
+    fun <T> getTweakValue(entry: TweakEntry<T>): StateFlow<T?> = tweaksBusinessLogic.getValue(entry)
 
     private fun initializeGraph(tweaksGraph: TweaksGraph) {
         tweaksBusinessLogic.initialize(tweaksGraph)

library/src/enabled/java/com/gmerinojimenez/tweaks/domain/TweaksBusinessLogic.kt

@@ -2,6 +2,8 @@ package com.gmerinojimenez.tweaks.domain
 
 import androidx.datastore.preferences.core.*
 import com.gmerinojimenez.tweaks.data.TweaksDataStore
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.*
 import javax.inject.Inject
@@ -48,24 +50,29 @@ class TweaksBusinessLogic @Inject constructor(
     }
 
     @Suppress("UNCHECKED_CAST")
-    fun <T> getValue(key: String): Flow<T?> {
+    fun <T> getValue(key: String): StateFlow<T?> {
         val tweakEntry = keyToEntryValueMap[key] as TweakEntry<T>
         return getValue(tweakEntry)
     }
 
-    fun <T> getValue(entry: TweakEntry<T>): Flow<T?> = when (entry as Modifiable) {
+    fun <T> getValue(entry: TweakEntry<T>): StateFlow<T?> = when (entry as Modifiable) {
         is ReadOnly<*> -> (entry as ReadOnly<T>).value
         is Editable<*> -> getEditableValue(entry)
     }
 
     @OptIn(ExperimentalCoroutinesApi::class)
-    private fun <T> getEditableValue(entry: TweakEntry<T>): Flow<T?> {
+    private fun <T> getEditableValue(entry: TweakEntry<T>): StateFlow<T?> {
         val editableCasted = entry as Editable<T>
-        val defaultValue = editableCasted.defaultValue
-        return defaultValue?.combine(getFromStorage(entry)) { default, storage ->
-            storage ?: default
-        }
-            ?: getFromStorage(entry)
+        val defaultValueFlow: StateFlow<T>? = editableCasted.defaultValue
+        val initialValue = defaultValueFlow?.value
+
+        val mergedFlow: Flow<T?> = if (defaultValueFlow != null) merge(getFromStorage(entry), defaultValueFlow) else getFromStorage(entry)
+
+        return mergedFlow.stateIn(
+            scope = CoroutineScope(Dispatchers.Default),
+            started = SharingStarted.Lazily,
+            initialValue = initialValue
+        )
     }
 
     private fun <T> getFromStorage(entry: TweakEntry<T>) =

library/src/main/java/com/gmerinojimenez/tweaks/domain/tweakModels.kt

@@ -1,6 +1,8 @@
 package com.gmerinojimenez.tweaks.domain
 
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.flow
 
 fun tweaksGraph(block: TweaksGraph.Builder.() -> Unit): TweaksGraph {
@@ -76,15 +78,15 @@ data class TweakGroup(val title: String, val entries: List<TweakEntry<*>>) {
         fun label(
             key: String,
             name: String,
-            value: () -> Flow<String>,
+            value: () -> StateFlow<String>,
         ) {
             tweak(ReadOnlyStringTweakEntry(key, name, value()))
         }
 
         fun editableString(
             key: String,
             name: String,
-            defaultValue: Flow<String>? = null,
+            defaultValue: StateFlow<String>? = null,
         ) {
             tweak(EditableStringTweakEntry(key, name, defaultValue))
         }
@@ -100,7 +102,7 @@ data class TweakGroup(val title: String, val entries: List<TweakEntry<*>>) {
         fun editableBoolean(
             key: String,
             name: String,
-            defaultValue: Flow<Boolean>? = null,
+            defaultValue: StateFlow<Boolean>? = null,
         ) {
             tweak(EditableBooleanTweakEntry(key, name, defaultValue))
         }
@@ -116,7 +118,7 @@ data class TweakGroup(val title: String, val entries: List<TweakEntry<*>>) {
         fun editableInt(
             key: String,
             name: String,
-            defaultValue: Flow<Int>? = null,
+            defaultValue: StateFlow<Int>? = null,
         ) {
             tweak(EditableIntTweakEntry(key, name, defaultValue))
         }
@@ -132,7 +134,7 @@ data class TweakGroup(val title: String, val entries: List<TweakEntry<*>>) {
         fun editableLong(
             key: String,
             name: String,
-            defaultValue: Flow<Long>? = null,
+            defaultValue: StateFlow<Long>? = null,
         ) {
             tweak(EditableLongTweakEntry(key, name, defaultValue))
         }
@@ -160,68 +162,68 @@ class RouteButtonTweakEntry(key: String, name: String, val route: String) :
     TweakEntry<Unit>(key, name)
 
 /** A non editable entry */
-class ReadOnlyStringTweakEntry(key: String, name: String, override val value: Flow<String>) :
+class ReadOnlyStringTweakEntry(key: String, name: String, override val value: StateFlow<String>) :
     TweakEntry<String>(key, name), ReadOnly<String>
 
 /** An editable entry. It can be modified by using long-press*/
 class EditableStringTweakEntry(
     key: String,
     name: String,
-    override val defaultValue: Flow<String>? = null,
+    override val defaultValue: StateFlow<String>? = null,
 ) : TweakEntry<String>(key, name), Editable<String> {
     constructor(
         key: String,
         name: String,
         defaultUniqueValue: String,
-    ) : this(key, name, flow { emit(defaultUniqueValue) })
+    ) : this(key, name, MutableStateFlow(defaultUniqueValue))
 }
 
 /** An editable entry. It can be modified by using long-press*/
 class EditableBooleanTweakEntry(
     key: String,
     name: String,
-    override val defaultValue: Flow<Boolean>? = null,
+    override val defaultValue: StateFlow<Boolean>? = null,
 ) : TweakEntry<Boolean>(key, name), Editable<Boolean> {
     constructor(
         key: String,
         name: String,
         defaultUniqueValue: Boolean,
-    ) : this(key, name, flow { emit(defaultUniqueValue) })
+    ) : this(key, name, MutableStateFlow(defaultUniqueValue))
 }
 
 /** An editable entry. It can be modified by using long-press*/
 class EditableIntTweakEntry(
     key: String,
     name: String,
-    override val defaultValue: Flow<Int>? = null,
+    override val defaultValue: StateFlow<Int>? = null,
 ) : TweakEntry<Int>(key, name), Editable<Int> {
     constructor(
         key: String,
         name: String,
         defaultUniqueValue: Int,
-    ) : this(key, name, flow { emit(defaultUniqueValue) })
+    ) : this(key, name, MutableStateFlow(defaultUniqueValue))
 }
 
 /** An editable entry. It can be modified by using long-press*/
 class EditableLongTweakEntry(
     key: String,
     name: String,
-    override val defaultValue: Flow<Long>? = null,
+    override val defaultValue: StateFlow<Long>? = null,
 ) : TweakEntry<Long>(key, name), Editable<Long> {
     constructor(
         key: String,
         name: String,
         defaultUniqueValue: Long,
-    ) : this(key, name, flow { emit(defaultUniqueValue) })
+    ) : this(key, name, MutableStateFlow(defaultUniqueValue))
 }
 
 sealed interface Modifiable
 interface Editable<T> : Modifiable {
-    val defaultValue: Flow<T>?
+    val defaultValue: StateFlow<T>?
 }
 
 interface ReadOnly<T> : Modifiable {
-    val value: Flow<T>
+    val value: StateFlow<T>
 }
 
 internal object Constants {