mirror of https://github.com/sbt/sbt.git
65 lines
2.1 KiB
Scala
65 lines
2.1 KiB
Scala
/* sbt -- Simple Build Tool
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* Copyright 2010 Mark Harrah
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*/
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package sbt
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import Types._
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// T must be invariant to work properly.
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// Because it is sealed and the only instances go through make,
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// a single AttributeKey instance cannot conform to AttributeKey[T] for different Ts
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sealed trait AttributeKey[T] {
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def label: String
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}
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object AttributeKey
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{
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def apply[T](name: String): AttributeKey[T] = new AttributeKey[T] { def label = name }
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}
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trait AttributeMap
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{
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def apply[T](k: AttributeKey[T]): T
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def get[T](k: AttributeKey[T]): Option[T]
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def contains[T](k: AttributeKey[T]): Boolean
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def put[T](k: AttributeKey[T], value: T): AttributeMap
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def keys: Iterable[AttributeKey[_]]
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def ++(o: AttributeMap): AttributeMap
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def entries: Iterable[AttributeEntry[_]]
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def isEmpty: Boolean
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}
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object AttributeMap
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{
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val empty: AttributeMap = new BasicAttributeMap(Map.empty)
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}
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private class BasicAttributeMap(private val backing: Map[AttributeKey[_], Any]) extends AttributeMap
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{
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def isEmpty: Boolean = backing.isEmpty
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def apply[T](k: AttributeKey[T]) = backing(k).asInstanceOf[T]
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def get[T](k: AttributeKey[T]) = backing.get(k).asInstanceOf[Option[T]]
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def contains[T](k: AttributeKey[T]) = backing.contains(k)
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def put[T](k: AttributeKey[T], value: T): AttributeMap = new BasicAttributeMap( backing.updated(k, value) )
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def keys: Iterable[AttributeKey[_]] = backing.keys
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def ++(o: AttributeMap): AttributeMap =
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o match {
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case bam: BasicAttributeMap => new BasicAttributeMap(backing ++ bam.backing)
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case _ => o ++ this
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}
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def entries: Iterable[AttributeEntry[_]] =
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for( (k: AttributeKey[kt], v) <- backing) yield AttributeEntry(k, v.asInstanceOf[kt])
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override def toString = entries.mkString("(", ", ", ")")
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}
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// type inference required less generality
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final case class AttributeEntry[T](a: AttributeKey[T], b: T)
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{
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override def toString = a.label + ": " + b
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}
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final case class Attributed[D](data: D)(val metadata: AttributeMap)
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{
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def put[T](key: AttributeKey[T], value: T): Attributed[D] = Attributed(data)(metadata.put(key, value))
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}
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object Attributed
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{
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implicit def blank[T](data: T): Attributed[T] = Attributed(data)(AttributeMap.empty)
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} |