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diff --git a/runtime/commonMain/src/kotlinx/serialization/json/JsonElement.kt b/runtime/commonMain/src/kotlinx/serialization/json/JsonElement.kt
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+++ b/runtime/commonMain/src/kotlinx/serialization/json/JsonElement.kt
@@ -0,0 +1,358 @@
+/*
+ * Copyright 2017-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+@file:Suppress("RedundantVisibilityModifier")
+
+package kotlinx.serialization.json
+
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.internal.*
+
+/**
+ * Class representing single JSON element.
+ * Can be [JsonPrimitive], [JsonArray] or [JsonObject].
+ *
+ * [JsonElement.toString] properly prints JSON tree as valid JSON, taking into account quoted values and primitives.
+ * Whole hierarchy is serializable, but only when used with [Json] as [JsonElement] is purely JSON-specific structure
+ * which has a meaningful schemaless semantics only for JSON.
+ *
+ * The whole hierarchy is [serializable][Serializable] only by [Json] format.
+ */
+@Serializable(JsonElementSerializer::class)
+public sealed class JsonElement {
+
+    /**
+     * Convenience method to get current element as [JsonPrimitive]
+     * @throws JsonElementTypeMismatchException is current element is not a [JsonPrimitive]
+     */
+    public open val primitive: JsonPrimitive
+        get() = error("JsonLiteral")
+
+    /**
+     * Convenience method to get current element as [JsonObject]
+     * @throws JsonElementTypeMismatchException is current element is not a [JsonObject]
+     */
+    public open val jsonObject: JsonObject
+        get() = error("JsonObject")
+
+    /**
+     * Convenience method to get current element as [JsonArray]
+     * @throws JsonElementTypeMismatchException is current element is not a [JsonArray]
+     */
+    public open val jsonArray: JsonArray
+        get() = error("JsonArray")
+
+    /**
+     * Convenience method to get current element as [JsonNull]
+     * @throws JsonElementTypeMismatchException is current element is not a [JsonNull]
+     */
+    public open val jsonNull: JsonNull
+        get() = error("JsonPrimitive")
+
+    /**
+     * Checks whether current element is [JsonNull]
+     */
+    public val isNull: Boolean
+        get() = this === JsonNull
+
+    private fun error(element: String): Nothing =
+        throw JsonElementTypeMismatchException(this::class.toString(), element)
+}
+
+/**
+ * Class representing JSON primitive value. Can be either [JsonLiteral] or [JsonNull].
+ */
+@Serializable(JsonPrimitiveSerializer::class)
+public sealed class JsonPrimitive : JsonElement() {
+
+    /**
+     * Content of given element without quotes. For [JsonNull] this methods returns `null`
+     */
+    public abstract val content: String
+
+    /**
+     * Content of the given element without quotes or `null` if current element is [JsonNull]
+     */
+    public abstract val contentOrNull: String?
+
+    @Suppress("LeakingThis")
+    public final override val primitive: JsonPrimitive = this
+
+    /**
+     * Returns content of current element as int
+     * @throws NumberFormatException if current element is not a valid representation of number
+     */
+    public val int: Int get() = content.toInt()
+
+    /**
+     * Returns content of current element as int or `null` if current element is not a valid representation of number
+     */
+    public val intOrNull: Int? get() = content.toIntOrNull()
+
+    /**
+     * Returns content of current element as long
+     * @throws NumberFormatException if current element is not a valid representation of number
+     */
+    public val long: Long get() = content.toLong()
+
+    /**
+     * Returns content of current element as long or `null` if current element is not a valid representation of number
+     */
+    public val longOrNull: Long? get() = content.toLongOrNull()
+
+    /**
+     * Returns content of current element as double
+     * @throws NumberFormatException if current element is not a valid representation of number
+     */
+    public val double: Double get() = content.toDouble()
+
+    /**
+     * Returns content of current element as double or `null` if current element is not a valid representation of number
+     */
+    public val doubleOrNull: Double? get() = content.toDoubleOrNull()
+
+    /**
+     * Returns content of current element as float
+     * @throws NumberFormatException if current element is not a valid representation of number
+     */
+    public val float: Float get() = content.toFloat()
+
+    /**
+     * Returns content of current element as float or `null` if current element is not a valid representation of number
+     */
+    public val floatOrNull: Float? get() = content.toFloatOrNull()
+
+    /**
+     * Returns content of current element as boolean
+     * @throws IllegalStateException if current element doesn't represent boolean
+     */
+    public val boolean: Boolean get() = content.toBooleanStrict()
+
+    /**
+     * Returns content of current element as boolean or `null` if current element is not a valid representation of boolean
+     */
+    public val booleanOrNull: Boolean? get() = content.toBooleanStrictOrNull()
+
+    public override fun toString() = content
+}
+
+/**
+ * Class representing JSON literals: numbers, booleans and string.
+ * Strings are always quoted.
+ *
+ * [isString] indicates whether literal was explicitly constructed as a [String] and
+ * whether it should be serialized as one. E.g. `JsonLiteral("42", false)`
+ * and `JsonLiteral("42", true)` will be serialized as `42` and `"42"` respectively.
+ */
+@Serializable(JsonLiteralSerializer::class) // TODO val for body is workaround for plugin bug
+public class JsonLiteral internal constructor(val body: Any, public val isString: Boolean) : JsonPrimitive() {
+    public override val content = body.toString()
+    public override val contentOrNull: String = content
+
+    /**
+     * Creates number literal
+     */
+    public constructor(number: Number) : this(number, false)
+
+    /**
+     * Creates boolean literal
+     */
+    public constructor(boolean: Boolean) : this(boolean, false)
+
+    /**
+     * Creates quoted string literal
+     */
+    public constructor(string: String) : this(string, true)
+
+    public override fun toString() =
+        if (isString) buildString { printQuoted(content) }
+        else content
+
+    // Compare by `content` and `isString`, because body can be kotlin.Long=42 or kotlin.String="42"
+    public override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as JsonLiteral
+
+        if (isString != other.isString) return false
+        if (content != other.content) return false
+
+        return true
+    }
+
+    public override fun hashCode(): Int {
+        var result = isString.hashCode()
+        result = 31 * result + content.hashCode()
+        return result
+    }
+}
+
+/**
+ * Class representing JSON `null` value
+ */
+@Serializable(JsonNullSerializer::class)
+public object JsonNull : JsonPrimitive() {
+    override val jsonNull: JsonNull = this
+    override val content: String = "null"
+    override val contentOrNull: String? = null
+}
+
+/**
+ * Class representing JSON object, consisting of name-value pairs, where value is arbitrary [JsonElement]
+ *
+ * Since this class also implements [Map] interface, you can use
+ * traditional methods like [Map.get] or [Map.getValue] to obtain Json elements.
+ */
+@Serializable(JsonObjectSerializer::class)
+public data class JsonObject(val content: Map<String, JsonElement>) : JsonElement(), Map<String, JsonElement> by content {
+
+    override val jsonObject: JsonObject = this
+
+    /**
+     * Returns [JsonPrimitive] associated with given [key]
+     *
+     * @throws NoSuchElementException if element is not present
+     * @throws JsonElementTypeMismatchException if element is present, but has invalid type
+     */
+    public fun getPrimitive(key: String): JsonPrimitive = getValue(key) as? JsonPrimitive
+            ?: unexpectedJson(key, "JsonPrimitive")
+
+    /**
+     * Returns [JsonObject] associated with given [key]
+     *
+     * @throws NoSuchElementException if element is not present
+     * @throws JsonElementTypeMismatchException if element is present, but has invalid type
+     */
+    public fun getObject(key: String): JsonObject = getValue(key) as? JsonObject
+            ?: unexpectedJson(key, "JsonObject")
+
+    /**
+     * Returns [JsonArray] associated with given [key]
+     *
+     * @throws NoSuchElementException if element is not present
+     * @throws JsonElementTypeMismatchException if element is present, but has invalid type
+     */
+    public fun getArray(key: String): JsonArray = getValue(key) as? JsonArray
+            ?: unexpectedJson(key, "JsonArray")
+
+    /**
+     * Returns [JsonPrimitive] associated with given [key] or `null` if element
+     * is not present or has different type
+     */
+    public fun getPrimitiveOrNull(key: String): JsonPrimitive? = content[key] as? JsonPrimitive
+
+    /**
+     * Returns [JsonObject] associated with given [key] or `null` if element
+     * is not present or has different type
+     */
+    public fun getObjectOrNull(key: String): JsonObject? = content[key] as? JsonObject
+
+    /**
+     * Returns [JsonArray] associated with given [key] or `null` if element
+     * is not present or has different type
+     */
+    public fun getArrayOrNull(key: String): JsonArray? = content[key] as? JsonArray
+
+    /**
+     * Returns [J] associated with given [key]
+     *
+     * @throws NoSuchElementException if element is not present
+     * @throws JsonElementTypeMismatchException if element is present, but has invalid type
+     */
+    public inline fun <reified J : JsonElement> getAs(key: String): J = get(key) as? J
+            ?: unexpectedJson(key, J::class.toString())
+
+    /**
+     * Returns [J] associated with given [key] or `null` if element
+     * is not present or has different type
+     */
+    public inline fun <reified J : JsonElement> getAsOrNull(key: String): J? = content[key] as? J
+
+    public override fun toString(): String {
+        return content.entries.joinToString(
+            separator = ",",
+            prefix = "{",
+            postfix = "}",
+            transform = {(k, v) -> """"$k":$v"""}
+        )
+    }
+
+    public override fun equals(other: Any?): Boolean = content == other
+
+    public override fun hashCode(): Int = content.hashCode()
+}
+
+/**
+ * Class representing JSON array, consisting of indexed values, where value is arbitrary [JsonElement]
+ *
+ * Since this class also implements [List] interface, you can use
+ * traditional methods like [List.get] or [List.getOrNull] to obtain Json elements.
+ */
+@Serializable(JsonArraySerializer::class)
+public data class JsonArray(val content: List<JsonElement>) : JsonElement(), List<JsonElement> by content {
+
+    public override val jsonArray: JsonArray = this
+
+    /**
+     * Returns [index]-th element of an array as [JsonPrimitive]
+     * @throws IndexOutOfBoundsException if there is no element with given index
+     * @throws JsonElementTypeMismatchException if element has invalid type
+     */
+    public fun getPrimitive(index: Int) = content[index] as? JsonPrimitive
+            ?: unexpectedJson("at $index", "JsonPrimitive")
+
+    /**
+     * Returns [index]-th element of an array as [JsonObject]
+     * @throws IndexOutOfBoundsException if there is no element with given index
+     * @throws JsonElementTypeMismatchException if element has invalid type
+     */
+    public fun getObject(index: Int) = content[index] as? JsonObject
+            ?: unexpectedJson("at $index", "JsonObject")
+
+    /**
+     * Returns [index]-th element of an array as [JsonArray]
+     * @throws IndexOutOfBoundsException if there is no element with given index
+     * @throws JsonElementTypeMismatchException if element has invalid type
+     */
+    public fun getArray(index: Int) = content[index] as? JsonArray
+            ?: unexpectedJson("at $index", "JsonArray")
+
+    /**
+     * Returns [index]-th element of an array as [JsonPrimitive] or `null` if element is missing or has different type
+     */
+    public fun getPrimitiveOrNull(index: Int) = content.getOrNull(index) as? JsonPrimitive
+
+    /**
+     * Returns [index]-th element of an array as [JsonObject] or `null` if element is missing or has different type
+     */
+    public fun getObjectOrNull(index: Int) = content.getOrNull(index) as? JsonObject
+
+    /**
+     * Returns [index]-th element of an array as [JsonArray] or `null` if element is missing or has different type
+     */
+    public fun getArrayOrNull(index: Int) = content.getOrNull(index) as? JsonArray
+
+    /**
+     * Returns [index]-th element of an array as [J]
+     * @throws JsonElementTypeMismatchException if element has invalid type
+     */
+    public inline fun <reified J : JsonElement> getAs(index: Int): J = content[index] as? J
+            ?: unexpectedJson("at $index", J::class.toString())
+
+    /**
+     * Returns [index]-th element of an array as [J] or `null` if element is missing or has different type
+     */
+    public inline fun <reified J : JsonElement> getAsOrNull(index: Int): J? = content.getOrNull(index) as? J
+
+    public override fun toString() = content.joinToString(prefix = "[", postfix = "]", separator = ",")
+
+    public override fun equals(other: Any?): Boolean = content == other
+
+    public override fun hashCode(): Int = content.hashCode()
+}
+
+@PublishedApi
+internal fun unexpectedJson(key: String, expected: String): Nothing =
+    throw JsonElementTypeMismatchException(key, expected)