Simplify element decoding logic and ensuring all element indexes are accounted for

Author: rozza

bson-kotlinx/src/main/kotlin/org/bson/codecs/kotlinx/BsonDecoder.kt

@@ -63,7 +63,6 @@ internal open class DefaultBsonDecoder(
     private data class ElementMetadata(val name: String, val nullable: Boolean, var processed: Boolean = false)
     private var elementsMetadata: Array<ElementMetadata>? = null
     private var currentIndex: Int = UNKNOWN_INDEX
-    private var level = 0
 
     companion object {
         val validKeyKinds = setOf(PrimitiveKind.STRING, PrimitiveKind.CHAR, SerialKind.ENUM)
@@ -85,35 +84,24 @@ internal open class DefaultBsonDecoder(
     override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
         initElementMetadata(descriptor)
         currentIndex = decodeElementIndexImpl(descriptor)
+        elementsMetadata?.getOrNull(currentIndex)?.processed = true
         return currentIndex
     }
 
     @Suppress("ReturnCount", "ComplexMethod")
     private fun decodeElementIndexImpl(descriptor: SerialDescriptor): Int {
+        val elementMetadata = elementsMetadata ?: error("elementsMetadata may not be null.")
         val name: String? =
             when (reader.state ?: error("State of reader may not be null.")) {
                 AbstractBsonReader.State.NAME -> reader.readName()
                 AbstractBsonReader.State.VALUE -> reader.currentName
                 AbstractBsonReader.State.TYPE -> {
-                    val type = reader.readBsonType()
-                    if (type.isContainer) {
-                        level++
-                    }
+                    reader.readBsonType()
                     return decodeElementIndexImpl(descriptor)
                 }
                 AbstractBsonReader.State.END_OF_DOCUMENT,
-                AbstractBsonReader.State.END_OF_ARRAY -> {
-                    level--
-                    val elementMetadata = elementsMetadata ?: error("elementsMetadata may not be null.")
-
-                    return if (level == 0) {
-                        DECODE_DONE
-                    } else {
-                        currentIndex = elementMetadata.indexOfFirst { it.nullable && !it.processed }
-                        if (currentIndex >= 0) elementMetadata[currentIndex].processed = true
-                        return currentIndex
-                    }
-                }
+                AbstractBsonReader.State.END_OF_ARRAY ->
+                    return elementMetadata.indexOfFirst { it.nullable && !it.processed }
                 else -> null
             }
 
@@ -194,7 +182,6 @@ internal open class DefaultBsonDecoder(
 
     private inline fun <T> readOrThrow(action: () -> T, bsonType: BsonType): T {
         return try {
-            elementsMetadata?.get(currentIndex)?.processed = true
             action()
         } catch (e: BsonInvalidOperationException) {
             throw BsonInvalidOperationException(

bson-kotlinx/src/test/kotlin/org/bson/codecs/kotlinx/KotlinSerializerCodecTest.kt

@@ -29,7 +29,6 @@ import org.bson.BsonDocumentWriter
 import org.bson.BsonInvalidOperationException
 import org.bson.BsonMaxKey
 import org.bson.BsonMinKey
-import org.bson.BsonNull
 import org.bson.BsonUndefined
 import org.bson.codecs.DecoderContext
 import org.bson.codecs.EncoderContext
@@ -119,7 +118,6 @@ class KotlinSerializerCodecTest {
     | "int64": {"${'$'}numberLong": "52"},
     | "maxKey": {"${'$'}maxKey": 1},
     | "minKey": {"${'$'}minKey": 1},
-    | "null": null,
     | "objectId": {"${'$'}oid": "211111111111111111111112"},
     | "regex": {"${'$'}regularExpression": {"pattern": "^test.*regex.*xyz$", "options": "i"}},
     | "string": "the fox ...",
@@ -494,7 +492,6 @@ class KotlinSerializerCodecTest {
                 allBsonTypesDocument["int64"]!!.asInt64(),
                 allBsonTypesDocument["maxKey"]!! as BsonMaxKey,
                 allBsonTypesDocument["minKey"]!! as BsonMinKey,
-                allBsonTypesDocument["null"]!! as BsonNull,
                 allBsonTypesDocument["objectId"]!!.asObjectId(),
                 allBsonTypesDocument["regex"]!!.asRegularExpression(),
                 allBsonTypesDocument["string"]!!.asString(),
@@ -507,7 +504,6 @@ class KotlinSerializerCodecTest {
 
     @Test
     fun testDataClassOptionalBsonValues() {
-
         val dataClass =
             DataClassOptionalBsonValues(
                 allBsonTypesDocument["id"]!!.asObjectId().value,
@@ -529,7 +525,6 @@ class KotlinSerializerCodecTest {
                 allBsonTypesDocument["int64"]!!.asInt64(),
                 allBsonTypesDocument["maxKey"]!! as BsonMaxKey,
                 allBsonTypesDocument["minKey"]!! as BsonMinKey,
-                allBsonTypesDocument["null"]!! as BsonNull,
                 allBsonTypesDocument["objectId"]!!.asObjectId(),
                 allBsonTypesDocument["regex"]!!.asRegularExpression(),
                 allBsonTypesDocument["string"]!!.asString(),
@@ -565,11 +560,18 @@ class KotlinSerializerCodecTest {
                 null,
                 null,
                 null,
-                null,
-                null,
-            )
+                null)
 
         assertRoundTrips("{}", emptyDataClass)
+        assertRoundTrips(
+            """{ "id": null,  "arrayEmpty": null, "arraySimple": null, "arrayComplex": null, "arrayMixedTypes": null,
+                | "arrayComplexMixedTypes": null, "binary": null, "boolean": null, "code": null, "codeWithScope": null,
+                | "dateTime": null, "decimal128": null, "documentEmpty": null, "document": null, "double": null,
+                | "int32": null, "int64": null, "maxKey": null, "minKey": null, "objectId": null, "regex": null,
+                | "string": null, "symbol": null, "timestamp": null, "undefined": null }"""
+                .trimMargin(),
+            emptyDataClass,
+            BsonConfiguration(explicitNulls = true))
     }
 
     @Test

bson-kotlinx/src/test/kotlin/org/bson/codecs/kotlinx/samples/DataClasses.kt

@@ -34,7 +34,6 @@ import org.bson.BsonJavaScript
 import org.bson.BsonJavaScriptWithScope
 import org.bson.BsonMaxKey
 import org.bson.BsonMinKey
-import org.bson.BsonNull
 import org.bson.BsonObjectId
 import org.bson.BsonRegularExpression
 import org.bson.BsonString
@@ -201,7 +200,6 @@ data class DataClassBsonValues(
     @Contextual val int64: BsonInt64,
     @Contextual val maxKey: BsonMaxKey,
     @Contextual val minKey: BsonMinKey,
-    @Contextual val `null`: BsonNull,
     @Contextual val objectId: BsonObjectId,
     @Contextual val regex: BsonRegularExpression,
     @Contextual val string: BsonString,
@@ -231,7 +229,6 @@ data class DataClassOptionalBsonValues(
     @Contextual val int64: BsonInt64?,
     @Contextual val maxKey: BsonMaxKey?,
     @Contextual val minKey: BsonMinKey?,
-    @Contextual val `null`: BsonNull?,
     @Contextual val objectId: BsonObjectId?,
     @Contextual val regex: BsonRegularExpression?,
     @Contextual val string: BsonString?,

config/detekt/baseline.xml

@@ -6,6 +6,7 @@
     <ID>LargeClass:MongoCollectionTest.kt$MongoCollectionTest</ID>
     <ID>LongMethod:FindFlowTest.kt$FindFlowTest$@Suppress("DEPRECATION") @Test fun shouldCallTheUnderlyingMethods()</ID>
     <ID>LongMethod:FindIterableTest.kt$FindIterableTest$@Suppress("DEPRECATION") @Test fun shouldCallTheUnderlyingMethods()</ID>
+    <ID>LongMethod:KotlinSerializerCodecTest.kt$KotlinSerializerCodecTest$@Test fun testDataClassOptionalBsonValues()</ID>
     <ID>MaxLineLength:MapReduceFlow.kt$MapReduceFlow$*</ID>
     <ID>MaxLineLength:MapReduceIterable.kt$MapReduceIterable$*</ID>
     <ID>SwallowedException:MockitoHelper.kt$MockitoHelper.DeepReflectionEqMatcher$e: Throwable</ID>