/
TreeJsonDecoder.kt
330 lines (272 loc) · 12.8 KB
/
TreeJsonDecoder.kt
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/*
* Copyright 2017-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
@file:Suppress("LeakingThis")
@file:OptIn(ExperimentalSerializationApi::class)
package kotlinx.serialization.json.internal
import kotlinx.serialization.*
import kotlinx.serialization.descriptors.*
import kotlinx.serialization.encoding.*
import kotlinx.serialization.internal.*
import kotlinx.serialization.json.*
import kotlinx.serialization.modules.*
import kotlin.jvm.*
@JsonFriendModuleApi
public fun <T> readJson(json: Json, element: JsonElement, deserializer: DeserializationStrategy<T>): T {
val input = when (element) {
is JsonObject -> JsonTreeDecoder(json, element)
is JsonArray -> JsonTreeListDecoder(json, element)
is JsonLiteral, JsonNull -> JsonPrimitiveDecoder(json, element as JsonPrimitive)
}
return input.decodeSerializableValue(deserializer)
}
internal fun <T> Json.readPolymorphicJson(
discriminator: String,
element: JsonObject,
deserializer: DeserializationStrategy<T>
): T {
return JsonTreeDecoder(this, element, discriminator, deserializer.descriptor).decodeSerializableValue(deserializer)
}
private sealed class AbstractJsonTreeDecoder(
override val json: Json,
open val value: JsonElement,
protected val polyDiscriminator: String? = null
) : NamedValueDecoder(), JsonDecoder {
override val serializersModule: SerializersModule
get() = json.serializersModule
@JvmField
protected val configuration = json.configuration
protected fun currentObject() = currentTagOrNull?.let { currentElement(it) } ?: value
override fun decodeJsonElement(): JsonElement = currentObject()
override fun <T> decodeSerializableValue(deserializer: DeserializationStrategy<T>): T {
return decodeSerializableValuePolymorphic(deserializer)
}
override fun composeName(parentName: String, childName: String): String = childName
override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder {
val currentObject = currentObject()
return when (descriptor.kind) {
StructureKind.LIST, is PolymorphicKind -> JsonTreeListDecoder(json, cast(currentObject, descriptor))
StructureKind.MAP -> json.selectMapMode(
descriptor,
{ JsonTreeMapDecoder(json, cast(currentObject, descriptor)) },
{ JsonTreeListDecoder(json, cast(currentObject, descriptor)) }
)
else -> JsonTreeDecoder(json, cast(currentObject, descriptor), polyDiscriminator)
}
}
override fun endStructure(descriptor: SerialDescriptor) {
// Nothing
}
override fun decodeNotNullMark(): Boolean = currentObject() !is JsonNull
protected fun getPrimitiveValue(tag: String): JsonPrimitive {
val currentElement = currentElement(tag)
return currentElement as? JsonPrimitive ?: throw JsonDecodingException(
-1,
"Expected JsonPrimitive at $tag, found $currentElement", currentObject().toString()
)
}
protected abstract fun currentElement(tag: String): JsonElement
override fun decodeTaggedEnum(tag: String, enumDescriptor: SerialDescriptor): Int =
enumDescriptor.getJsonNameIndexOrThrow(json, getPrimitiveValue(tag).content)
override fun decodeTaggedNull(tag: String): Nothing? = null
override fun decodeTaggedNotNullMark(tag: String): Boolean = currentElement(tag) !== JsonNull
override fun decodeTaggedBoolean(tag: String): Boolean {
return getPrimitiveValue(tag).primitive("boolean", JsonPrimitive::booleanOrNull)
}
override fun decodeTaggedByte(tag: String) = getPrimitiveValue(tag).primitive("byte") {
val result = int
if (result in Byte.MIN_VALUE..Byte.MAX_VALUE) result.toByte()
else null
}
override fun decodeTaggedShort(tag: String) = getPrimitiveValue(tag).primitive("short") {
val result = int
if (result in Short.MIN_VALUE..Short.MAX_VALUE) result.toShort()
else null
}
override fun decodeTaggedInt(tag: String) = getPrimitiveValue(tag).primitive("int") { int }
override fun decodeTaggedLong(tag: String) = getPrimitiveValue(tag).primitive("long") { long }
override fun decodeTaggedFloat(tag: String): Float {
val result = getPrimitiveValue(tag).primitive("float") { float }
val specialFp = json.configuration.allowSpecialFloatingPointValues
if (specialFp || result.isFinite()) return result
throw InvalidFloatingPointDecoded(result, tag, currentObject().toString())
}
override fun decodeTaggedDouble(tag: String): Double {
val result = getPrimitiveValue(tag).primitive("double") { double }
val specialFp = json.configuration.allowSpecialFloatingPointValues
if (specialFp || result.isFinite()) return result
throw InvalidFloatingPointDecoded(result, tag, currentObject().toString())
}
override fun decodeTaggedChar(tag: String): Char = getPrimitiveValue(tag).primitive("char") { content.single() }
private inline fun <T : Any> JsonPrimitive.primitive(primitive: String, block: JsonPrimitive.() -> T?): T {
try {
return block() ?: unparsedPrimitive(primitive)
} catch (e: IllegalArgumentException) {
unparsedPrimitive(primitive)
}
}
private fun unparsedPrimitive(primitive: String): Nothing {
throw JsonDecodingException(-1, "Failed to parse literal as '$primitive' value", currentObject().toString())
}
override fun decodeTaggedString(tag: String): String {
val value = getPrimitiveValue(tag)
if (!json.configuration.isLenient) {
val literal = value.asLiteral("string")
if (!literal.isString) throw JsonDecodingException(
-1, "String literal for key '$tag' should be quoted.\n$lenientHint", currentObject().toString()
)
}
if (value is JsonNull) throw JsonDecodingException(-1, "Unexpected 'null' value instead of string literal", currentObject().toString())
return value.content
}
private fun JsonPrimitive.asLiteral(type: String): JsonLiteral {
return this as? JsonLiteral ?: throw JsonDecodingException(-1, "Unexpected 'null' literal when non-nullable $type was expected")
}
override fun decodeTaggedInline(tag: String, inlineDescriptor: SerialDescriptor): Decoder =
if (inlineDescriptor.isUnsignedNumber) JsonDecoderForUnsignedTypes(StringJsonLexer(getPrimitiveValue(tag).content), json)
else super.decodeTaggedInline(tag, inlineDescriptor)
override fun decodeInline(descriptor: SerialDescriptor): Decoder {
return if (currentTagOrNull != null) super.decodeInline(descriptor)
else JsonPrimitiveDecoder(json, value, polyDiscriminator).decodeInline(descriptor)
}
}
private class JsonPrimitiveDecoder(
json: Json,
override val value: JsonElement,
polyDiscriminator: String? = null
) : AbstractJsonTreeDecoder(json, value, polyDiscriminator) {
init {
pushTag(PRIMITIVE_TAG)
}
override fun decodeElementIndex(descriptor: SerialDescriptor): Int = 0
override fun currentElement(tag: String): JsonElement {
require(tag === PRIMITIVE_TAG) { "This input can only handle primitives with '$PRIMITIVE_TAG' tag" }
return value
}
}
private open class JsonTreeDecoder(
json: Json,
override val value: JsonObject,
polyDiscriminator: String? = null,
private val polyDescriptor: SerialDescriptor? = null
) : AbstractJsonTreeDecoder(json, value, polyDiscriminator) {
private var position = 0
private var forceNull: Boolean = false
/*
* Checks whether JSON has `null` value for non-null property or unknown enum value for enum property
*/
private fun coerceInputValue(descriptor: SerialDescriptor, index: Int, tag: String): Boolean =
json.tryCoerceValue(
descriptor, index,
{ currentElement(tag) is JsonNull },
{ (currentElement(tag) as? JsonPrimitive)?.contentOrNull }
)
@Suppress("INVISIBLE_MEMBER")
override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
while (position < descriptor.elementsCount) {
val name = descriptor.getTag(position++)
val index = position - 1
forceNull = false
if ((name in value || absenceIsNull(descriptor, index))
&& (!configuration.coerceInputValues || !coerceInputValue(descriptor, index, name))
) {
return index
}
}
return CompositeDecoder.DECODE_DONE
}
private fun absenceIsNull(descriptor: SerialDescriptor, index: Int): Boolean {
forceNull = !json.configuration.explicitNulls
&& !descriptor.isElementOptional(index) && descriptor.getElementDescriptor(index).isNullable
return forceNull
}
override fun decodeNotNullMark(): Boolean {
return !forceNull && super.decodeNotNullMark()
}
override fun elementName(descriptor: SerialDescriptor, index: Int): String {
val strategy = descriptor.namingStrategy(json)
val baseName = descriptor.getElementName(index)
if (strategy == null) {
if (!configuration.useAlternativeNames) return baseName
// Fast path, do not go through ConcurrentHashMap.get
// Note, it blocks ability to detect collisions between the primary name and alternate,
// but it eliminates a significant performance penalty (about -15% without this optimization)
if (baseName in value.keys) return baseName
}
// Slow path
val deserializationNamesMap = json.deserializationNamesMap(descriptor)
value.keys.find { deserializationNamesMap[it] == index }?.let {
return it
}
val fallbackName = strategy?.serialNameForJson(
descriptor,
index,
baseName
) // Key not found exception should be thrown with transformed name, not original
return fallbackName ?: baseName
}
override fun currentElement(tag: String): JsonElement = value.getValue(tag)
override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder {
// polyDiscriminator needs to be preserved so the check for unknown keys
// in endStructure can filter polyDiscriminator out.
if (descriptor === polyDescriptor) {
return JsonTreeDecoder(
json, cast(currentObject(), polyDescriptor), polyDiscriminator, polyDescriptor
)
}
return super.beginStructure(descriptor)
}
override fun endStructure(descriptor: SerialDescriptor) {
if (configuration.ignoreUnknownKeys || descriptor.kind is PolymorphicKind) return
// Validate keys
val strategy = descriptor.namingStrategy(json)
@Suppress("DEPRECATION_ERROR")
val names: Set<String> = when {
strategy == null && !configuration.useAlternativeNames -> descriptor.jsonCachedSerialNames()
strategy != null -> json.deserializationNamesMap(descriptor).keys
else -> descriptor.jsonCachedSerialNames() + json.schemaCache[descriptor, JsonDeserializationNamesKey]?.keys.orEmpty()
}
for (key in value.keys) {
if (key !in names && key != polyDiscriminator) {
throw UnknownKeyException(key, value.toString())
}
}
}
}
private class JsonTreeMapDecoder(json: Json, override val value: JsonObject) : JsonTreeDecoder(json, value) {
private val keys = value.keys.toList()
private val size: Int = keys.size * 2
private var position = -1
override fun elementName(descriptor: SerialDescriptor, index: Int): String {
val i = index / 2
return keys[i]
}
override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
while (position < size - 1) {
position++
return position
}
return CompositeDecoder.DECODE_DONE
}
override fun currentElement(tag: String): JsonElement {
return if (position % 2 == 0) JsonPrimitive(tag) else value.getValue(tag)
}
override fun endStructure(descriptor: SerialDescriptor) {
// do nothing, maps do not have strict keys, so strict mode check is omitted
}
}
private class JsonTreeListDecoder(json: Json, override val value: JsonArray) : AbstractJsonTreeDecoder(json, value) {
private val size = value.size
private var currentIndex = -1
override fun elementName(descriptor: SerialDescriptor, index: Int): String = index.toString()
override fun currentElement(tag: String): JsonElement {
return value[tag.toInt()]
}
override fun decodeElementIndex(descriptor: SerialDescriptor): Int {
while (currentIndex < size - 1) {
currentIndex++
return currentIndex
}
return CompositeDecoder.DECODE_DONE
}
}