KotlinX Serialization support

bson-multiplatform/src/commonMain/kotlin/BsonContext.kt

@@ -23,6 +23,7 @@ import opensavvy.ktmongo.bson.Bson
 import opensavvy.ktmongo.bson.BsonArray
 import opensavvy.ktmongo.bson.BsonContext
 import opensavvy.ktmongo.bson.types.ObjectIdGenerator
+import opensavvy.ktmongo.dsl.DangerousMongoApi
 import opensavvy.ktmongo.dsl.LowLevelApi
 import kotlin.concurrent.atomics.ExperimentalAtomicApi
 import kotlin.time.ExperimentalTime
@@ -77,4 +78,57 @@ class BsonContext @OptIn(ExperimentalAtomicApi::class) constructor(
 	override fun readArray(bytes: ByteArray): BsonArray =
 		BsonArray(Bytes(bytes.copyOf()))
 
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(): CompletableBsonFieldWriter<Bson> {
+		val buffer = Buffer()
+		val bsonWriter = RawBsonWriter(buffer)
+		val fieldWriter = MultiplatformBsonFieldWriter(bsonWriter)
+
+		bsonWriter.writeInt32(0) // Document size. 0 for now, will be overwritten later.
+		return object: CompletableBsonFieldWriter<Bson>, BsonFieldWriter by fieldWriter {
+			override fun complete(): Bson {
+				bsonWriter.writeUnsignedByte(0u)
+
+				check(buffer.size <= Int.MAX_VALUE) { "A BSON document cannot be larger than 16MiB. Found ${buffer.size} bytes." }
+				val size = buffer.size.toInt()
+				val bytes = ByteArray(size)
+				buffer.readTo(bytes)
+				// 'buffer' is now empty
+
+				// Overwrite the size at the very start of the document
+				bsonWriter.writeInt32(size)
+				buffer.readTo(bytes, 0, 4)
+
+				return Bson(Bytes(bytes))
+			}
+		}
+	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(): CompletableBsonValueWriter<BsonArray> {
+		val buffer = Buffer()
+		val bsonWriter = RawBsonWriter(buffer)
+		val fieldWriter = MultiplatformBsonArrayFieldWriter(MultiplatformBsonFieldWriter(bsonWriter))
+
+		bsonWriter.writeInt32(0) // Document size. 0 for now, will be overwritten later.
+		return object: CompletableBsonValueWriter<BsonArray>, BsonValueWriter by fieldWriter {
+			override fun complete(): BsonArray {
+				bsonWriter.writeUnsignedByte(0u)
+
+				check(buffer.size <= Int.MAX_VALUE) { "A BSON document cannot be larger than 16MiB. Found ${buffer.size} bytes." }
+				val size = buffer.size.toInt()
+				val bytes = ByteArray(size)
+				buffer.readTo(bytes)
+				// 'buffer' is now empty
+
+				// Overwrite the size at the very start of the document
+				bsonWriter.writeInt32(size)
+				buffer.readTo(bytes, 0, 4)
+
+				return BsonArray(Bytes(bytes))
+			}
+		}
+	}
 }

bson-multiplatform/src/commonMain/kotlin/MultiplatformBsonArrayFieldWriter.kt

@@ -18,8 +18,11 @@ package opensavvy.ktmongo.bson.multiplatform
 
 import opensavvy.ktmongo.bson.BsonFieldWriter
 import opensavvy.ktmongo.bson.BsonValueWriter
+import opensavvy.ktmongo.bson.CompletableBsonFieldWriter
+import opensavvy.ktmongo.bson.CompletableBsonValueWriter
 import opensavvy.ktmongo.bson.DEPRECATED_IN_BSON_SPEC
 import opensavvy.ktmongo.bson.types.Timestamp
+import opensavvy.ktmongo.dsl.DangerousMongoApi
 import opensavvy.ktmongo.dsl.LowLevelApi
 
 @LowLevelApi
@@ -143,6 +146,18 @@ internal class MultiplatformBsonArrayFieldWriter(
 		writer.writeArray(nextIndex(), block)
 	}
 
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(): CompletableBsonFieldWriter<Unit> {
+		return writer.openDocument(nextIndex())
+	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(): CompletableBsonValueWriter<Unit> {
+		return writer.openArray(nextIndex())
+	}
+
 	@LowLevelApi
 	override fun <T> writeObjectSafe(obj: T) {
 		writer.writeObjectSafe(nextIndex(), obj)

bson-multiplatform/src/commonMain/kotlin/MultiplatformBsonFieldWriter.kt

@@ -20,6 +20,8 @@ import kotlinx.io.Buffer
 import opensavvy.ktmongo.bson.BsonFieldWriter
 import opensavvy.ktmongo.bson.BsonType
 import opensavvy.ktmongo.bson.BsonValueWriter
+import opensavvy.ktmongo.bson.CompletableBsonFieldWriter
+import opensavvy.ktmongo.bson.CompletableBsonValueWriter
 import opensavvy.ktmongo.bson.DEPRECATED_IN_BSON_SPEC
 import opensavvy.ktmongo.bson.types.ObjectId
 import opensavvy.ktmongo.bson.types.Timestamp
@@ -42,6 +44,13 @@ internal class MultiplatformBsonFieldWriter(
 		writer.writeCString(name)
 	}
 
+	@DangerousMongoApi
+	override fun open(name: String): CompletableBsonValueWriter<Unit> {
+		return object: CompletableBsonValueWriter<Unit>, BsonValueWriter by MultiplatformBsonSingleFieldWriter(this, name) {
+			override fun complete() {}
+		}
+	}
+
 	@LowLevelApi
 	override fun write(name: String, block: BsonValueWriter.() -> Unit) {
 		MultiplatformBsonSingleFieldWriter(this, name).block()
@@ -228,6 +237,54 @@ internal class MultiplatformBsonFieldWriter(
 		}
 	}
 
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(name: String): CompletableBsonFieldWriter<Unit> {
+		writeType(BsonType.Document)
+		writeName(name)
+
+		// We create the entire document in a child buffer so we can measure the size.
+		// Once we know the size, we can write it entirely to the real buffer.
+		val childBuffer = Buffer()
+		val childWriter = RawBsonWriter(childBuffer)
+		val childFieldWriter = MultiplatformBsonFieldWriter(childWriter)
+
+		return object: CompletableBsonFieldWriter<Unit>, BsonFieldWriter by childFieldWriter {
+			override fun complete() {
+				childWriter.writeUnsignedByte(0u)
+
+				// We now have an intermediate buffer, we can measure the size then transfer it the real writer
+				check(childBuffer.size <= Int.MAX_VALUE) { "A BSON document cannot be larger than 16MiB. Found ${childBuffer.size} bytes." }
+				this@MultiplatformBsonFieldWriter.writer.writeInt32(childBuffer.size.toInt() + 4)
+				this@MultiplatformBsonFieldWriter.writer.sink.write(childBuffer, childBuffer.size)
+			}
+		}
+	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(name: String): CompletableBsonValueWriter<Unit> {
+		writeType(BsonType.Array)
+		writeName(name)
+
+		// We create the entire document in a child buffer so we can measure the size.
+		// Once we know the size, we can write it entirely to the real buffer.
+		val childBuffer = Buffer()
+		val childWriter = RawBsonWriter(childBuffer)
+		val childFieldWriter = MultiplatformBsonArrayFieldWriter(MultiplatformBsonFieldWriter(childWriter))
+
+		return object: CompletableBsonValueWriter<Unit>, BsonValueWriter by childFieldWriter {
+			override fun complete() {
+				childWriter.writeUnsignedByte(0u)
+
+				// We now have an intermediate buffer, we can measure the size then transfer it the real writer
+				check(childBuffer.size <= Int.MAX_VALUE) { "A BSON document cannot be larger than 16MiB. Found ${childBuffer.size} bytes." }
+				this@MultiplatformBsonFieldWriter.writer.writeInt32(childBuffer.size.toInt() + 4)
+				this@MultiplatformBsonFieldWriter.writer.sink.write(childBuffer, childBuffer.size)
+			}
+		}
+	}
+
 	@LowLevelApi
 	override fun <T> writeObjectSafe(name: String, obj: T) {
 		TODO()

bson-multiplatform/src/commonMain/kotlin/MultiplatformBsonSingleFieldWriter.kt

@@ -19,6 +19,8 @@ package opensavvy.ktmongo.bson.multiplatform
 import opensavvy.ktmongo.bson.BsonFieldWriter
 import opensavvy.ktmongo.bson.BsonValueReader
 import opensavvy.ktmongo.bson.BsonValueWriter
+import opensavvy.ktmongo.bson.CompletableBsonFieldWriter
+import opensavvy.ktmongo.bson.CompletableBsonValueWriter
 import opensavvy.ktmongo.dsl.DangerousMongoApi
 import opensavvy.ktmongo.bson.types.Timestamp
 import opensavvy.ktmongo.dsl.LowLevelApi
@@ -124,6 +126,18 @@ internal class MultiplatformBsonSingleFieldWriter(
 		writer.writeArray(name, block)
 	}
 
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(): CompletableBsonFieldWriter<Unit> {
+		return writer.openDocument(name)
+	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(): CompletableBsonValueWriter<Unit> {
+		return writer.openArray(name)
+	}
+
 	@LowLevelApi
 	override fun writeMinKey() {
 		writer.writeMinKey(name)

bson-official/src/commonMain/kotlin/BsonContext.kt

@@ -18,6 +18,7 @@ package opensavvy.ktmongo.bson.official
 
 import opensavvy.ktmongo.bson.*
 import opensavvy.ktmongo.bson.BsonContext
+import opensavvy.ktmongo.dsl.DangerousMongoApi
 import opensavvy.ktmongo.dsl.LowLevelApi
 
 /**
@@ -38,4 +39,13 @@ interface BsonContext : BsonContext {
 	@LowLevelApi
 	override fun buildArray(instance: BsonValueWriteable): BsonArray =
 		buildArray { instance.writeTo(this) }
+
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(): CompletableBsonFieldWriter<Bson>
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(): CompletableBsonValueWriter<BsonArray>
 }

bson-official/src/jvmMain/kotlin/BsonContext.jvm.kt

@@ -18,12 +18,15 @@ package opensavvy.ktmongo.bson.official
 
 import opensavvy.ktmongo.bson.BsonFieldWriter
 import opensavvy.ktmongo.bson.BsonValueWriter
+import opensavvy.ktmongo.bson.CompletableBsonFieldWriter
+import opensavvy.ktmongo.bson.CompletableBsonValueWriter
 import opensavvy.ktmongo.bson.DEPRECATED_IN_BSON_SPEC
 import opensavvy.ktmongo.bson.official.types.Jvm
 import opensavvy.ktmongo.bson.official.types.KotlinObjectIdCodec
 import opensavvy.ktmongo.bson.official.types.toOfficial
 import opensavvy.ktmongo.bson.types.ObjectIdGenerator
 import opensavvy.ktmongo.bson.types.Timestamp
+import opensavvy.ktmongo.dsl.DangerousMongoApi
 import opensavvy.ktmongo.dsl.LowLevelApi
 import org.bson.*
 import org.bson.BsonArray
@@ -98,13 +101,49 @@ class JvmBsonContext(
 		)
 		return BsonArray(document, this)
 	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(): CompletableBsonValueWriter<opensavvy.ktmongo.bson.official.BsonArray> {
+		val nativeArray = BsonArray()
+		val writer = JavaRootArrayWriter(this, nativeArray)
+		return object: CompletableBsonValueWriter<opensavvy.ktmongo.bson.official.BsonArray>, BsonValueWriter by writer {
+			override fun complete(): opensavvy.ktmongo.bson.official.BsonArray {
+				return BsonArray(nativeArray, this@JvmBsonContext)
+			}
+		}
+	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(): CompletableBsonFieldWriter<opensavvy.ktmongo.bson.official.Bson>  {
+		val document = BsonDocument()
+		val officialWriter = BsonDocumentWriter(document)
+		val writer = JavaBsonWriter(this, officialWriter)
+
+		return object: CompletableBsonFieldWriter<opensavvy.ktmongo.bson.official.Bson>, BsonFieldWriter by writer {
+			override fun complete(): opensavvy.ktmongo.bson.official.Bson {
+				officialWriter.close()
+				return Bson(document, this@JvmBsonContext)
+			}
+		}
+	}
 }
 
 @OptIn(LowLevelApi::class)
 private class JavaBsonWriter(
 	private val context: JvmBsonContext,
 	private val writer: BsonWriter
 ) : BsonFieldWriter, BsonValueWriter {
+
+	@DangerousMongoApi
+	override fun open(name: String): CompletableBsonValueWriter<Unit> {
+		writer.writeName(name)
+		return object: CompletableBsonValueWriter<Unit>, BsonValueWriter by this {
+			override fun complete() {}
+		}
+	}
+
 	override fun write(name: String, block: BsonValueWriter.() -> Unit) {
 		writer.writeName(name)
 		block()
@@ -181,6 +220,26 @@ private class JavaBsonWriter(
 		writer.writeEndArray()
 	}
 
+	@DangerousMongoApi
+	override fun openDocument(name: String): CompletableBsonFieldWriter<Unit> {
+		writer.writeStartDocument(name)
+		return object: CompletableBsonFieldWriter<Unit>, BsonFieldWriter by this {
+			override fun complete() {
+				this@JavaBsonWriter.writer.writeEndDocument()
+			}
+		}
+	}
+
+	@DangerousMongoApi
+	override fun openArray(name: String): CompletableBsonValueWriter<Unit> {
+		writer.writeStartArray(name)
+		return object: CompletableBsonValueWriter<Unit>, BsonValueWriter by this {
+			override fun complete() {
+				this@JavaBsonWriter.writer.writeEndArray()
+			}
+		}
+	}
+
 	override fun <T> writeObjectSafe(name: String, obj: T) {
 		writer.writeName(name)
 		writeObjectSafe(obj)
@@ -283,6 +342,28 @@ private class JavaBsonWriter(
 		writer.writeEndArray()
 	}
 
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(): CompletableBsonFieldWriter<Unit> {
+		writer.writeStartDocument()
+		return object: CompletableBsonFieldWriter<Unit>, BsonFieldWriter by this {
+			override fun complete() {
+				this@JavaBsonWriter.writer.writeEndDocument()
+			}
+		}
+	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(): CompletableBsonValueWriter<Unit> {
+		writer.writeStartArray()
+		return object: CompletableBsonValueWriter<Unit>, BsonValueWriter by this {
+			override fun complete() {
+				this@JavaBsonWriter.writer.writeEndArray()
+			}
+		}
+	}
+
 	override fun <T> writeObjectSafe(obj: T) {
 		if (obj == null) {
 			writer.writeNull()
@@ -425,6 +506,28 @@ private class JavaRootArrayWriter(
 		array.add(context.buildArray(block).raw)
 	}
 
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openArray(): CompletableBsonValueWriter<Unit> {
+		val root = context.openArray()
+		return object: CompletableBsonValueWriter<Unit>, BsonValueWriter by root {
+			override fun complete(): Unit {
+				this@JavaRootArrayWriter.array.add(root.complete().raw)
+			}
+		}
+	}
+
+	@LowLevelApi
+	@DangerousMongoApi
+	override fun openDocument(): CompletableBsonFieldWriter<Unit>  {
+		val root = context.openDocument()
+		return object: CompletableBsonFieldWriter<Unit>, BsonFieldWriter by root {
+			override fun complete(): Unit {
+				this@JavaRootArrayWriter.array.add(root.complete().raw)
+			}
+		}
+	}
+
 	@LowLevelApi
 	override fun <T> writeObjectSafe(obj: T) {
 		val document = BsonDocument()