Variant

Template for a codec for a sum type A.

Each constructor of A should get assigned a unique index when implementing this class. It is used to tag XML trees, so that the correct decoding function can be chosen.

In addition to the contract of Codec, instances of this class must also preserve the index, that is, any index returned by enc must produce a valid decoding function in dec.

Using this is simple: Instead of creating a new Codec object, create an object extending from this class and implement enc and dec accordingly. It is automatically a Codec.

Example usage

new Variant[Option[A]]("option") {
  def enc(a: Option[A]) = a match {
    case Some(a) => (0, Codec[A].encode(a))
    case None    => (1, Codec[Unit].encode(()))
  }
  def dec(idx: Int) = idx match {
    case 0 => Some(Codec[A].decode(_).right.map(Some.apply))
    case 1 => Some(Codec[Unit].decode(_).right.map(_ => None))
    case _ => None
  }
}

Linear Supertypes

Codec[A], AnyRef, Any

Instance Constructors

new Variant(tag: String)

Abstract Value Members

abstract def dec(idx: Int): Option[(Tree) ⇒ XMLResult[A]]

Given an index, produce the corresponding decoding function or nothing if the index is out of bounds.
Given an index, produce the corresponding decoding function or nothing if the index is out of bounds.

Attributes
protected
abstract def enc(a: A): (Int, Tree)

Encode a value of the sum type into a tree and the index.
Encode a value of the sum type into a tree and the index.

Attributes
protected

Concrete Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
def decode(tree: Tree): Either[(String, List[Tree]), A]

Decode a value from an XML tree, or produce an error.
Decode a value from an XML tree, or produce an error.

Definition Classes
Variant → Codec
See also
XMLResult
def encode(a: A): Tree

Encode a value into an XML tree.
Encode a value into an XML tree.
You may want to use one of the two constructors elem and text.

Definition Classes
Variant → Codec
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
AnyRef → Any
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
def list: Codec[List[A]]

Codec for a list of Ts, tagged with the string list.
Codec for a list of Ts, tagged with the string list.

Definition Classes
Codec
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
def ptransform[U](f: (A) ⇒ Option[U], g: (U) ⇒ A): Codec[U]

Definition Classes
Codec
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def tagged(tag: String): Codec[A]

Create an identical codec which adds (or expects, respectively) an additional top-level tag.
Create an identical codec which adds (or expects, respectively) an additional top-level tag.
The given tag can be anything acceptable as an XML attribute value, but should be globally unique. That is, no other codec should have the same tag. It is fine if there are multiple codecs for a type, as long as their tags are distinct, although that is not a requirement.

Definition Classes
Codec
def toString(): String

Definition Classes
AnyRef → Any
def transform[U](f: (A) ⇒ U, g: (U) ⇒ A): Codec[U]

Transform a codec for a type T into a codec for a type U by applying one of the two specified conversions.
Transform a codec for a type T into a codec for a type U by applying one of the two specified conversions.
After creating a new instance using transform, it is recommended to add a new tag.

Definition Classes
Codec
def tuple[U](that: Codec[U]): Codec[(A, U)]

Codec for a pair of T and U, tagged with the string tuple.
Codec for a pair of T and U, tagged with the string tuple.

Definition Classes
Codec
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

Related Doc: package Codec

abstract class Variant[A] extends Codec[A]

Instance Constructors

new Variant(tag: String)

Abstract Value Members

abstract def dec(idx: Int): Option[(Tree) ⇒ XMLResult[A]]

abstract def enc(a: A): (Int, Tree)

Concrete Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

def decode(tree: Tree): Either[(String, List[Tree]), A]

def encode(a: A): Tree

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

def list: Codec[List[A]]

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

def ptransform[U](f: (A) ⇒ Option[U], g: (U) ⇒ A): Codec[U]

final def synchronized[T0](arg0: ⇒ T0): T0

def tagged(tag: String): Codec[A]

def toString(): String

def transform[U](f: (A) ⇒ U, g: (U) ⇒ A): Codec[U]

def tuple[U](that: Codec[U]): Codec[(A, U)]

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from Codec[A]

Inherited from AnyRef

Inherited from Any

Ungrouped