1 files changed, 185 insertions, 0 deletions
diff --git a/runtime/commonMain/src/kotlinx/serialization/Coders.kt b/runtime/commonMain/src/kotlinx/serialization/Coders.kt
new file mode 100644
index 00000000..3aeaf5c9
--- /dev/null
+++ b/runtime/commonMain/src/kotlinx/serialization/Coders.kt
@@ -0,0 +1,185 @@
+/*
+ * Copyright 2018 JetBrains s.r.o.
+ *
+ * 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 kotlinx.serialization
+
+import kotlinx.serialization.modules.SerialModule
+import kotlinx.serialization.internal.EnumDescriptor
+
+interface Encoder {
+    val context: SerialModule
+
+    fun encodeNotNullMark()
+    fun encodeNull()
+
+    fun encodeUnit()
+    fun encodeBoolean(value: Boolean)
+    fun encodeByte(value: Byte)
+    fun encodeShort(value: Short)
+    fun encodeInt(value: Int)
+    fun encodeLong(value: Long)
+    fun encodeFloat(value: Float)
+    fun encodeDouble(value: Double)
+    fun encodeChar(value: Char)
+    fun encodeString(value: String)
+
+    fun encodeEnum(enumDescription: EnumDescriptor, ordinal: Int)
+
+    fun <T : Any?> encodeSerializableValue(serializer: SerializationStrategy<T>, value: T) {
+        serializer.serialize(this, value)
+    }
+
+    fun <T : Any> encodeNullableSerializableValue(serializer: SerializationStrategy<T>, value: T?) {
+        if (value == null) {
+            encodeNull()
+        } else {
+            encodeNotNullMark()
+            encodeSerializableValue(serializer, value)
+        }
+    }
+
+    fun beginStructure(desc: SerialDescriptor, vararg typeParams: KSerializer<*>): CompositeEncoder
+
+    fun beginCollection(desc: SerialDescriptor, collectionSize: Int, vararg typeParams: KSerializer<*>) =
+        beginStructure(desc, *typeParams)
+}
+
+interface CompositeEncoder {
+    val context: SerialModule
+
+    fun endStructure(desc: SerialDescriptor) {}
+
+    fun shouldEncodeElementDefault(desc: SerialDescriptor, index: Int): Boolean = true
+
+    fun encodeUnitElement(desc: SerialDescriptor, index: Int)
+    fun encodeBooleanElement(desc: SerialDescriptor, index: Int, value: Boolean)
+    fun encodeByteElement(desc: SerialDescriptor, index: Int, value: Byte)
+    fun encodeShortElement(desc: SerialDescriptor, index: Int, value: Short)
+    fun encodeIntElement(desc: SerialDescriptor, index: Int, value: Int)
+    fun encodeLongElement(desc: SerialDescriptor, index: Int, value: Long)
+    fun encodeFloatElement(desc: SerialDescriptor, index: Int, value: Float)
+    fun encodeDoubleElement(desc: SerialDescriptor, index: Int, value: Double)
+    fun encodeCharElement(desc: SerialDescriptor, index: Int, value: Char)
+    fun encodeStringElement(desc: SerialDescriptor, index: Int, value: String)
+
+    fun <T : Any?> encodeSerializableElement(desc: SerialDescriptor, index: Int, serializer: SerializationStrategy<T>, value: T)
+
+    fun encodeNonSerializableElement(desc: SerialDescriptor, index: Int, value: Any)
+
+    fun <T : Any> encodeNullableSerializableElement(desc: SerialDescriptor, index: Int, serializer: SerializationStrategy<T>, value: T?)
+}
+
+
+interface Decoder {
+    val context: SerialModule
+
+    /**
+     * Returns true if the current value in decoder is not null, false otherwise
+     */
+    fun decodeNotNullMark(): Boolean
+
+    /**
+     * Consumes null, returns null, will be called when [decodeNotNullMark] is false
+     */
+    fun decodeNull(): Nothing?
+
+    fun decodeUnit()
+    fun decodeBoolean(): Boolean
+    fun decodeByte(): Byte
+    fun decodeShort(): Short
+    fun decodeInt(): Int
+    fun decodeLong(): Long
+    fun decodeFloat(): Float
+    fun decodeDouble(): Double
+    fun decodeChar(): Char
+    fun decodeString(): String
+
+    fun decodeEnum(enumDescription: EnumDescriptor): Int
+
+
+    fun <T : Any?> decodeSerializableValue(deserializer: DeserializationStrategy<T>): T = deserializer.deserialize(this)
+
+    fun <T : Any> decodeNullableSerializableValue(deserializer: DeserializationStrategy<T?>): T? =
+        if (decodeNotNullMark()) decodeSerializableValue(deserializer) else decodeNull()
+
+    fun beginStructure(desc: SerialDescriptor, vararg typeParams: KSerializer<*>): CompositeDecoder
+
+    val updateMode: UpdateMode
+
+    fun <T> updateSerializableValue(deserializer: DeserializationStrategy<T>, old: T): T {
+        return when(updateMode) {
+            UpdateMode.BANNED -> throw UpdateNotSupportedException(deserializer.descriptor.name)
+            UpdateMode.OVERWRITE -> decodeSerializableValue(deserializer)
+            UpdateMode.UPDATE -> deserializer.patch(this, old)
+        }
+    }
+
+    fun <T: Any> updateNullableSerializableValue(deserializer: DeserializationStrategy<T?>, old: T?): T? {
+        return when {
+            updateMode == UpdateMode.BANNED -> throw UpdateNotSupportedException(deserializer.descriptor.name)
+            updateMode == UpdateMode.OVERWRITE || old == null -> decodeNullableSerializableValue(deserializer)
+            decodeNotNullMark() -> deserializer.patch(this, old)
+            else -> decodeNull().let { old }
+        }
+    }
+}
+
+interface CompositeDecoder {
+    val context: SerialModule
+    fun endStructure(desc: SerialDescriptor) {}
+
+    /**
+     * Results of [decodeElementIndex]
+     */
+    companion object {
+        const val READ_DONE = -1
+        const val READ_ALL = -2
+        const val UNKNOWN_NAME = -3
+    }
+
+    /**
+     *  Returns either index or one of READ_XXX constants
+     */
+    fun decodeElementIndex(desc: SerialDescriptor): Int
+
+    /**
+     * Optional method to specify collection size to pre-allocate memory.
+     * If decoder specifies stream reading ([READ_ALL] is returned from [decodeElementIndex], then
+     * correct implementation of this method is mandatory.
+     *
+     * @return Collection size or -1 if not available.
+     */
+    fun decodeCollectionSize(desc: SerialDescriptor): Int = -1
+
+    fun decodeUnitElement(desc: SerialDescriptor, index: Int)
+    fun decodeBooleanElement(desc: SerialDescriptor, index: Int): Boolean
+    fun decodeByteElement(desc: SerialDescriptor, index: Int): Byte
+    fun decodeShortElement(desc: SerialDescriptor, index: Int): Short
+    fun decodeIntElement(desc: SerialDescriptor, index: Int): Int
+    fun decodeLongElement(desc: SerialDescriptor, index: Int): Long
+    fun decodeFloatElement(desc: SerialDescriptor, index: Int): Float
+    fun decodeDoubleElement(desc: SerialDescriptor, index: Int): Double
+    fun decodeCharElement(desc: SerialDescriptor, index: Int): Char
+    fun decodeStringElement(desc: SerialDescriptor, index: Int): String
+
+    fun <T : Any?> decodeSerializableElement(desc: SerialDescriptor, index: Int, deserializer: DeserializationStrategy<T>): T
+    fun <T : Any> decodeNullableSerializableElement(desc: SerialDescriptor, index: Int, deserializer: DeserializationStrategy<T?>): T?
+
+    val updateMode: UpdateMode
+
+    fun <T> updateSerializableElement(desc: SerialDescriptor, index: Int, deserializer: DeserializationStrategy<T>, old: T): T
+    fun <T: Any> updateNullableSerializableElement(desc: SerialDescriptor, index: Int, deserializer: DeserializationStrategy<T?>, old: T?): T?
+}