Merge "Fix decoding logic for fields with default values" into androidx-main
diff --git a/savedstate/savedstate/src/commonMain/kotlin/androidx/savedstate/serialization/SavedStateDecoder.kt b/savedstate/savedstate/src/commonMain/kotlin/androidx/savedstate/serialization/SavedStateDecoder.kt
index 65ccd1f..3f06dff 100644
--- a/savedstate/savedstate/src/commonMain/kotlin/androidx/savedstate/serialization/SavedStateDecoder.kt
+++ b/savedstate/savedstate/src/commonMain/kotlin/androidx/savedstate/serialization/SavedStateDecoder.kt
@@ -22,6 +22,7 @@
import kotlinx.serialization.ExperimentalSerializationApi
import kotlinx.serialization.SerializationException
import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.descriptors.StructureKind
import kotlinx.serialization.encoding.AbstractDecoder
import kotlinx.serialization.encoding.CompositeDecoder
import kotlinx.serialization.modules.EmptySerializersModule
@@ -73,9 +74,31 @@
private var index = 0
override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
- if (index == savedState.read { size() }) return CompositeDecoder.DECODE_DONE
- key = descriptor.getElementName(index)
- return index++
+ val size =
+ if (descriptor.kind == StructureKind.LIST || descriptor.kind == StructureKind.MAP) {
+ // Use the number of elements encoded for collections.
+ savedState.read { size() }
+ } else {
+ // We may skip elements when encoding so if we used `size()`
+ // here we may miss some fields.
+ descriptor.elementsCount
+ }
+ fun hasDefaultValueDefined(index: Int) = descriptor.isElementOptional(index)
+ fun presentInEncoding(index: Int) =
+ savedState.read {
+ val key = descriptor.getElementName(index)
+ contains(key)
+ }
+ // Skip elements omitted from encoding (those assigned with its default values).
+ while (index < size && hasDefaultValueDefined(index) && !presentInEncoding(index)) {
+ index++
+ }
+ if (index < size) {
+ key = descriptor.getElementName(index)
+ return index++
+ } else {
+ return CompositeDecoder.DECODE_DONE
+ }
}
override fun decodeBoolean(): Boolean = savedState.read { getBoolean(key) }
diff --git a/savedstate/savedstate/src/commonTest/kotlin/androidx/savedstate/SavedStateCodecTest.kt b/savedstate/savedstate/src/commonTest/kotlin/androidx/savedstate/SavedStateCodecTest.kt
index 89d6548..88c33e4 100644
--- a/savedstate/savedstate/src/commonTest/kotlin/androidx/savedstate/SavedStateCodecTest.kt
+++ b/savedstate/savedstate/src/commonTest/kotlin/androidx/savedstate/SavedStateCodecTest.kt
@@ -401,15 +401,19 @@
@Test
fun sealedClasses() {
- Node.Add(Node.Operand(3), Node.Operand(5)).encodeDecode {
+ // Should use base type for encoding/decoding.
+ Node.Add(Node.Operand(3), Node.Operand(5)).encodeDecode<Node> {
assertThat(size()).isEqualTo(2)
- getSavedState("lhs").read {
- assertThat(size()).isEqualTo(1)
- assertThat(getInt("value")).isEqualTo(3)
- }
- getSavedState("rhs").read {
- assertThat(size()).isEqualTo(1)
- assertThat(getInt("value")).isEqualTo(5)
+ assertThat(getString("type")).isEqualTo("androidx.savedstate.Node.Add")
+ getSavedState("value").read {
+ getSavedState("lhs").read {
+ assertThat(size()).isEqualTo(1)
+ assertThat(getInt("value")).isEqualTo(3)
+ }
+ getSavedState("rhs").read {
+ assertThat(size()).isEqualTo(1)
+ assertThat(getInt("value")).isEqualTo(5)
+ }
}
}
}
@@ -425,12 +429,24 @@
}
// Nullable with default value.
- @Serializable data class B(val s: String? = "foo")
- B().encodeDecode()
- B(s = "bar").encodeDecode {
+ @Serializable data class B(val s: String? = "foo", val i: Int)
+ B(i = 3).encodeDecode {
assertThat(size()).isEqualTo(1)
+ assertThat(getInt("i")).isEqualTo(3)
+ }
+ B(s = null, i = 3).encodeDecode {
+ assertThat(size()).isEqualTo(2)
+ assertThat(isNull("s")).isTrue()
+ }
+ B(s = "bar", i = 3).encodeDecode {
+ assertThat(size()).isEqualTo(2)
assertThat(getString("s")).isEqualTo("bar")
}
+ // The value of `s` is the same as its default value so it's omitted from encoding.
+ B(s = "foo", i = 3).encodeDecode {
+ assertThat(size()).isEqualTo(1)
+ assertThat(getInt("i")).isEqualTo(3)
+ }
// Nullable without default value
@Serializable data class C(val s: String?)
@@ -450,6 +466,22 @@
assertThat(getInt("i")).isEqualTo(5)
assertThat(getString("s")).isEqualTo("foo")
}
+
+ // Nullable with null as default value.
+ @Serializable data class E(val s: String? = null)
+ // Even though we encode `null`s in general as we don't encode default values
+ // nothing is encoded.
+ E().encodeDecode()
+
+ // Nullable in parent
+ G(i = 3).encodeDecode<F> {
+ assertThat(size()).isEqualTo(2)
+ assertThat(getString("type")).isEqualTo("androidx.savedstate.G")
+ getSavedState("value").read {
+ assertThat(size()).isEqualTo(1)
+ assertThat(getInt("i")).isEqualTo(3)
+ }
+ }
}
@Test
@@ -568,6 +600,7 @@
private typealias MyNestedTypeAlias = MyTypeAliasToInt
+@Serializable
private sealed class Node {
@Serializable data class Add(val lhs: Operand, val rhs: Operand) : Node()
@@ -610,3 +643,10 @@
return MyColor(array[0], array[1], array[2])
}
}
+
+@Serializable
+private sealed class F {
+ val s: String? = null
+}
+
+@Serializable private data class G(val i: Int) : F()
