org.bson.codecs.kotlinx.BsonDecoder.kt Maven / Gradle / Ivy
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/*
* Copyright 2008-present MongoDB, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.bson.codecs.kotlinx
import kotlinx.serialization.DeserializationStrategy
import kotlinx.serialization.ExperimentalSerializationApi
import kotlinx.serialization.SerializationException
import kotlinx.serialization.descriptors.PolymorphicKind
import kotlinx.serialization.descriptors.PrimitiveKind
import kotlinx.serialization.descriptors.SerialDescriptor
import kotlinx.serialization.descriptors.SerialKind
import kotlinx.serialization.descriptors.StructureKind
import kotlinx.serialization.encoding.AbstractDecoder
import kotlinx.serialization.encoding.CompositeDecoder
import kotlinx.serialization.encoding.CompositeDecoder.Companion.DECODE_DONE
import kotlinx.serialization.encoding.CompositeDecoder.Companion.UNKNOWN_NAME
import kotlinx.serialization.modules.SerializersModule
import org.bson.AbstractBsonReader
import org.bson.BsonInvalidOperationException
import org.bson.BsonReader
import org.bson.BsonReaderMark
import org.bson.BsonType
import org.bson.BsonValue
import org.bson.codecs.BsonValueCodec
import org.bson.codecs.DecoderContext
import org.bson.internal.NumberCodecHelper
import org.bson.internal.StringCodecHelper
import org.bson.types.ObjectId
/**
* The BsonDecoder interface
*
* For custom serialization handlers
*/
public sealed interface BsonDecoder {
/** @return the decoded ObjectId */
public fun decodeObjectId(): ObjectId
/** @return the decoded BsonValue */
public fun decodeBsonValue(): BsonValue
/** @return the BsonReader */
public fun reader(): BsonReader
}
@ExperimentalSerializationApi
internal open class DefaultBsonDecoder(
internal val reader: AbstractBsonReader,
override val serializersModule: SerializersModule,
internal val configuration: BsonConfiguration
) : BsonDecoder, AbstractDecoder() {
private data class ElementMetadata(val name: String, val nullable: Boolean, var processed: Boolean = false)
private var elementsMetadata: Array? = null
private var currentIndex: Int = UNKNOWN_INDEX
companion object {
val validKeyKinds = setOf(PrimitiveKind.STRING, PrimitiveKind.CHAR, SerialKind.ENUM)
val bsonValueCodec = BsonValueCodec()
const val UNKNOWN_INDEX = -10
fun validateCurrentBsonType(
reader: AbstractBsonReader,
expectedType: BsonType,
descriptor: SerialDescriptor,
actualType: (descriptor: SerialDescriptor) -> String = { it.kind.toString() }
) {
reader.currentBsonType?.let {
if (it != expectedType) {
throw SerializationException(
"Invalid data for `${actualType(descriptor)}` expected a bson " +
"${expectedType.name.lowercase()} found: ${reader.currentBsonType}")
}
}
}
}
private fun initElementMetadata(descriptor: SerialDescriptor) {
if (this.elementsMetadata != null) return
val elementsMetadata =
Array(descriptor.elementsCount) {
val elementDescriptor = descriptor.getElementDescriptor(it)
ElementMetadata(
elementDescriptor.serialName, elementDescriptor.isNullable && !descriptor.isElementOptional(it))
}
this.elementsMetadata = elementsMetadata
}
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 -> {
reader.readBsonType()
return decodeElementIndexImpl(descriptor)
}
AbstractBsonReader.State.END_OF_DOCUMENT,
AbstractBsonReader.State.END_OF_ARRAY ->
return elementMetadata.indexOfFirst { it.nullable && !it.processed }
else -> null
}
return name?.let {
val index = descriptor.getElementIndex(it)
return if (index == UNKNOWN_NAME) {
reader.skipValue()
decodeElementIndexImpl(descriptor)
} else {
index
}
}
?: UNKNOWN_NAME
}
@Suppress("ReturnCount")
override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder {
return when (descriptor.kind) {
is StructureKind.LIST -> BsonArrayDecoder(descriptor, reader, serializersModule, configuration)
is PolymorphicKind -> PolymorphicDecoder(descriptor, reader, serializersModule, configuration)
is StructureKind.CLASS,
StructureKind.OBJECT -> BsonDocumentDecoder(descriptor, reader, serializersModule, configuration)
is StructureKind.MAP -> MapDecoder(descriptor, reader, serializersModule, configuration)
else -> throw SerializationException("Primitives are not supported at top-level")
}
}
override fun endStructure(descriptor: SerialDescriptor) {
when (descriptor.kind) {
is StructureKind.LIST -> reader.readEndArray()
is StructureKind.MAP,
StructureKind.CLASS,
StructureKind.OBJECT -> reader.readEndDocument()
else -> super.endStructure(descriptor)
}
}
override fun decodeByte(): Byte = NumberCodecHelper.decodeByte(reader)
override fun decodeChar(): Char = StringCodecHelper.decodeChar(reader)
override fun decodeFloat(): Float = NumberCodecHelper.decodeFloat(reader)
override fun decodeShort(): Short = NumberCodecHelper.decodeShort(reader)
override fun decodeBoolean(): Boolean = reader.readBoolean()
override fun decodeDouble(): Double = NumberCodecHelper.decodeDouble(reader)
override fun decodeInt(): Int = NumberCodecHelper.decodeInt(reader)
override fun decodeLong(): Long = NumberCodecHelper.decodeLong(reader)
override fun decodeString(): String = readOrThrow({ reader.readString() }, BsonType.STRING)
override fun decodeNull(): Nothing? {
if (reader.state == AbstractBsonReader.State.VALUE) {
readOrThrow({ reader.readNull() }, BsonType.NULL)
}
return null
}
override fun decodeEnum(enumDescriptor: SerialDescriptor): Int = enumDescriptor.getElementIndex(decodeString())
override fun decodeNotNullMark(): Boolean {
return reader.state != AbstractBsonReader.State.END_OF_DOCUMENT && reader.currentBsonType != BsonType.NULL
}
override fun decodeObjectId(): ObjectId = readOrThrow({ reader.readObjectId() }, BsonType.OBJECT_ID)
override fun decodeBsonValue(): BsonValue = bsonValueCodec.decode(reader, DecoderContext.builder().build())
override fun reader(): BsonReader = reader
private inline fun readOrThrow(action: () -> T, bsonType: BsonType): T {
return try {
action()
} catch (e: BsonInvalidOperationException) {
throw BsonInvalidOperationException(
"Reading field '${reader.currentName}' failed expected $bsonType type but found:" +
" ${reader.currentBsonType}.",
e)
}
}
}
@OptIn(ExperimentalSerializationApi::class)
private class BsonArrayDecoder(
descriptor: SerialDescriptor,
reader: AbstractBsonReader,
serializersModule: SerializersModule,
configuration: BsonConfiguration
) : DefaultBsonDecoder(reader, serializersModule, configuration) {
init {
validateCurrentBsonType(reader, BsonType.ARRAY, descriptor)
reader.readStartArray()
}
private var index = 0
override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
val nextType = reader.readBsonType()
if (nextType == BsonType.END_OF_DOCUMENT) return DECODE_DONE
return index++
}
}
@OptIn(ExperimentalSerializationApi::class)
private class PolymorphicDecoder(
descriptor: SerialDescriptor,
reader: AbstractBsonReader,
serializersModule: SerializersModule,
configuration: BsonConfiguration
) : DefaultBsonDecoder(reader, serializersModule, configuration) {
private var index = 0
private var mark: BsonReaderMark?
init {
mark = reader.mark
validateCurrentBsonType(reader, BsonType.DOCUMENT, descriptor) { it.serialName }
reader.readStartDocument()
}
override fun decodeSerializableValue(deserializer: DeserializationStrategy): T {
mark?.let {
it.reset()
mark = null
}
return deserializer.deserialize(DefaultBsonDecoder(reader, serializersModule, configuration))
}
override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
var found = false
return when (index) {
0 -> {
while (reader.readBsonType() != BsonType.END_OF_DOCUMENT) {
if (reader.readName() == configuration.classDiscriminator) {
found = true
break
}
reader.skipValue()
}
if (!found) {
throw SerializationException(
"Missing required discriminator field `${configuration.classDiscriminator}` " +
"for polymorphic class: `${descriptor.serialName}`.")
}
index++
}
1 -> index++
else -> DECODE_DONE
}
}
}
@OptIn(ExperimentalSerializationApi::class)
private class BsonDocumentDecoder(
descriptor: SerialDescriptor,
reader: AbstractBsonReader,
serializersModule: SerializersModule,
configuration: BsonConfiguration
) : DefaultBsonDecoder(reader, serializersModule, configuration) {
init {
validateCurrentBsonType(reader, BsonType.DOCUMENT, descriptor) { it.serialName }
reader.readStartDocument()
}
}
@OptIn(ExperimentalSerializationApi::class)
private class MapDecoder(
descriptor: SerialDescriptor,
reader: AbstractBsonReader,
serializersModule: SerializersModule,
configuration: BsonConfiguration
) : DefaultBsonDecoder(reader, serializersModule, configuration) {
private var index = 0
private var isKey = false
init {
validateCurrentBsonType(reader, BsonType.DOCUMENT, descriptor)
reader.readStartDocument()
}
override fun decodeString(): String {
return if (isKey) {
reader.readName()
} else {
super.decodeString()
}
}
override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
val keyKind = descriptor.getElementDescriptor(0).kind
if (!validKeyKinds.contains(keyKind)) {
throw SerializationException(
"Invalid key type for ${descriptor.serialName}. Expected STRING or ENUM but found: `${keyKind}`")
}
if (!isKey) {
isKey = true
val nextType = reader.readBsonType()
if (nextType == BsonType.END_OF_DOCUMENT) return DECODE_DONE
} else {
isKey = false
}
return index++
}
}