Fast binary encoding and decoding interfaces

fastcodec.scala

package fastcodecs

import java.nio.{ByteBuffer, BufferUnderflowException}

abstract class Decoder[+A] {
  /**
   * Read a value from the `ByteBuffer`, advancing the offset if successful.
   * Result is stored in `result`, unboxed if possible.
   * On failure, a `DecodingFailure` is thrown.
   */
  def apply(bytes: ByteBuffer, result: Result): Unboxed[A]
}

abstract class Encoder[-A] {
  /**
   * Write an `A` value to the `output` buffer, advancing the offset.
   * If `output` is not large enough to contain the encoded value,
   * an `EncodingBufferOverflow` is thrown and this function should be
   * called again with a larger buffer.
   */
  def apply(a: A, output: ByteBuffer): Unit
}

object decoders {
  def double = new Decoder[Double] {
    val err = DecodingFailure(List("double"))
    def apply(bytes: ByteBuffer, result: Result) =
      try { result.unboxed = bytes.getDouble }
      catch { case e: BufferUnderflowException => throw err }
  }
}

type Unboxed[+A] = Unit // would put this in package object

case class DecodingFailure(msgs: List[String]) extends Throwable {
  override def fillInStackTrace = this
}

case object EncodingBufferOverflow extends Throwable {
  override def fillInStackTrace = this
}

case class Result(var boxed: Any = null, var unboxed: Double = 0.0)