spray.json.AdditionalFormats.scala Maven / Gradle / Ivy
/*
* Original implementation (C) 2009-2011 Debasish Ghosh
* Adapted and extended in 2011 by Mathias Doenitz
*
* 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 spray.json
/**
* Provides additional JsonFormats and helpers
*/
trait AdditionalFormats {
implicit object JsValueFormat extends JsonFormat[JsValue] {
def write(value: JsValue) = value
def read(value: JsValue) = value
}
implicit object RootJsObjectFormat extends RootJsonFormat[JsObject] {
def write(value: JsObject) = value
def read(value: JsValue) = value.asJsObject
}
implicit object RootJsArrayFormat extends RootJsonFormat[JsArray] {
def write(value: JsArray) = value
def read(value: JsValue) = value match {
case x: JsArray => x
case _ => deserializationError("JSON array expected")
}
}
/**
* Constructs a JsonFormat from its two parts, JsonReader and JsonWriter.
*/
def jsonFormat[T](reader: JsonReader[T], writer: JsonWriter[T]) = new JsonFormat[T] {
def write(obj: T) = writer.write(obj)
def read(json: JsValue) = reader.read(json)
}
/**
* Constructs a RootJsonFormat from its two parts, RootJsonReader and RootJsonWriter.
*/
def rootJsonFormat[T](reader: RootJsonReader[T], writer: RootJsonWriter[T]) =
rootFormat(jsonFormat(reader, writer))
/**
* Turns a JsonWriter into a JsonFormat that throws an UnsupportedOperationException for reads.
*/
def lift[T](writer :JsonWriter[T]) = new JsonFormat[T] {
def write(obj: T): JsValue = writer.write(obj)
def read(value: JsValue) =
throw new UnsupportedOperationException("JsonReader implementation missing")
}
/**
* Turns a RootJsonWriter into a RootJsonFormat that throws an UnsupportedOperationException for reads.
*/
def lift[T](writer :RootJsonWriter[T]): RootJsonFormat[T] =
rootFormat(lift(writer :JsonWriter[T]))
/**
* Turns a JsonReader into a JsonFormat that throws an UnsupportedOperationException for writes.
*/
def lift[T <: AnyRef](reader :JsonReader[T]) = new JsonFormat[T] {
def write(obj: T): JsValue =
throw new UnsupportedOperationException("No JsonWriter[" + obj.getClass + "] available")
def read(value: JsValue) = reader.read(value)
}
/**
* Turns a RootJsonReader into a RootJsonFormat that throws an UnsupportedOperationException for writes.
*/
def lift[T <: AnyRef](reader :RootJsonReader[T]): RootJsonFormat[T] =
rootFormat(lift(reader :JsonReader[T]))
/**
* Lazy wrapper around serialization. Useful when you want to serialize (mutually) recursive structures.
*/
def lazyFormat[T](format: => JsonFormat[T]) = new JsonFormat[T] {
lazy val delegate = format;
def write(x: T) = delegate.write(x);
def read(value: JsValue) = delegate.read(value);
}
/**
* Explicitly turns a JsonFormat into a RootJsonFormat.
*/
def rootFormat[T](format: JsonFormat[T]) = new RootJsonFormat[T] {
def write(obj: T) = format.write(obj)
def read(json: JsValue) = format.read(json)
}
/**
* Wraps an existing JsonReader with Exception protection.
*/
def safeReader[A :JsonReader] = new JsonReader[Either[Exception, A]] {
def read(json: JsValue) = {
try {
Right(json.convertTo[A])
} catch {
case e: Exception => Left(e)
}
}
}
}