sbt.internal.util.Attributes.scala Maven / Gradle / Ivy
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/* sbt -- Simple Build Tool
* Copyright 2010 Mark Harrah
*/
package sbt.internal.util
import Types._
import scala.reflect.Manifest
// T must be invariant to work properly.
// Because it is sealed and the only instances go through AttributeKey.apply,
// a single AttributeKey instance cannot conform to AttributeKey[T] for different Ts
/**
* A key in an [[AttributeMap]] that constrains its associated value to be of type `T`.
* The key is uniquely defined by its [[label]] and type `T`, represented at runtime by [[manifest]].
*/
sealed trait AttributeKey[T] {
/** The runtime evidence for `T` */
def manifest: Manifest[T]
/** The label is the identifier for the key and is camelCase by convention. */
def label: String
/** An optional, brief description of the key. */
def description: Option[String]
/**
* In environments that support delegation, looking up this key when it has no associated value will delegate to the values associated with these keys.
* The delegation proceeds in order the keys are returned here.
*/
def extend: Seq[AttributeKey[_]]
/**
* Specifies whether this key is a local, anonymous key (`true`) or not (`false`).
* This is typically only used for programmatic, intermediate keys that should not be referenced outside of a specific scope.
*/
def isLocal: Boolean
/** Identifies the relative importance of a key among other keys.*/
def rank: Int
}
private[sbt] abstract class SharedAttributeKey[T] extends AttributeKey[T] {
override final def toString = label
override final def hashCode = label.hashCode
override final def equals(o: Any) = (this eq o.asInstanceOf[AnyRef]) || (o match {
case a: SharedAttributeKey[t] => a.label == this.label && a.manifest == this.manifest
case _ => false
})
final def isLocal: Boolean = false
}
object AttributeKey {
def apply[T](name: String)(implicit mf: Manifest[T]): AttributeKey[T] =
make(name, None, Nil, Int.MaxValue)
def apply[T](name: String, rank: Int)(implicit mf: Manifest[T]): AttributeKey[T] =
make(name, None, Nil, rank)
def apply[T](name: String, description: String)(implicit mf: Manifest[T]): AttributeKey[T] =
apply(name, description, Nil)
def apply[T](name: String, description: String, rank: Int)(implicit mf: Manifest[T]): AttributeKey[T] =
apply(name, description, Nil, rank)
def apply[T](name: String, description: String, extend: Seq[AttributeKey[_]])(implicit mf: Manifest[T]): AttributeKey[T] =
apply(name, description, extend, Int.MaxValue)
def apply[T](name: String, description: String, extend: Seq[AttributeKey[_]], rank: Int)(implicit mf: Manifest[T]): AttributeKey[T] =
make(name, Some(description), extend, rank)
private[this] def make[T](name: String, description0: Option[String], extend0: Seq[AttributeKey[_]], rank0: Int)(implicit mf: Manifest[T]): AttributeKey[T] = new SharedAttributeKey[T] {
def manifest = mf
val label = Util.hyphenToCamel(name)
def description = description0
def extend = extend0
def rank = rank0
}
private[sbt] def local[T](implicit mf: Manifest[T]): AttributeKey[T] = new AttributeKey[T] {
def manifest = mf
def label = LocalLabel
def description = None
def extend = Nil
override def toString = label
def isLocal: Boolean = true
def rank = Int.MaxValue
}
private[sbt] final val LocalLabel = "$" + "local"
}
/**
* An immutable map where a key is the tuple `(String,T)` for a fixed type `T` and can only be associated with values of type `T`.
* It is therefore possible for this map to contain mappings for keys with the same label but different types.
* Excluding this possibility is the responsibility of the client if desired.
*/
trait AttributeMap {
/**
* Gets the value of type `T` associated with the key `k`.
* If a key with the same label but different type is defined, this method will fail.
*/
def apply[T](k: AttributeKey[T]): T
/**
* Gets the value of type `T` associated with the key `k` or `None` if no value is associated.
* If a key with the same label but a different type is defined, this method will return `None`.
*/
def get[T](k: AttributeKey[T]): Option[T]
/**
* Returns this map without the mapping for `k`.
* This method will not remove a mapping for a key with the same label but a different type.
*/
def remove[T](k: AttributeKey[T]): AttributeMap
/**
* Returns true if this map contains a mapping for `k`.
* If a key with the same label but a different type is defined in this map, this method will return `false`.
*/
def contains[T](k: AttributeKey[T]): Boolean
/**
* Adds the mapping `k -> value` to this map, replacing any existing mapping for `k`.
* Any mappings for keys with the same label but different types are unaffected.
*/
def put[T](k: AttributeKey[T], value: T): AttributeMap
/** All keys with defined mappings. There may be multiple keys with the same `label`, but different types. */
def keys: Iterable[AttributeKey[_]]
/** Adds the mappings in `o` to this map, with mappings in `o` taking precedence over existing mappings.*/
def ++(o: Iterable[AttributeEntry[_]]): AttributeMap
/** Combines the mappings in `o` with the mappings in this map, with mappings in `o` taking precedence over existing mappings.*/
def ++(o: AttributeMap): AttributeMap
/** All mappings in this map. The [[AttributeEntry]] type preserves the typesafety of mappings, although the specific types are unknown.*/
def entries: Iterable[AttributeEntry[_]]
/** `true` if there are no mappings in this map, `false` if there are. */
def isEmpty: Boolean
}
object AttributeMap {
/** An [[AttributeMap]] without any mappings. */
val empty: AttributeMap = new BasicAttributeMap(Map.empty)
/** Constructs an [[AttributeMap]] containing the given `entries`. */
def apply(entries: Iterable[AttributeEntry[_]]): AttributeMap = empty ++ entries
/** Constructs an [[AttributeMap]] containing the given `entries`.*/
def apply(entries: AttributeEntry[_]*): AttributeMap = empty ++ entries
/** Presents an `AttributeMap` as a natural transformation. */
implicit def toNatTrans(map: AttributeMap): AttributeKey ~> Id = new (AttributeKey ~> Id) {
def apply[T](key: AttributeKey[T]): T = map(key)
}
}
private class BasicAttributeMap(private val backing: Map[AttributeKey[_], Any]) extends AttributeMap {
def isEmpty: Boolean = backing.isEmpty
def apply[T](k: AttributeKey[T]) = backing(k).asInstanceOf[T]
def get[T](k: AttributeKey[T]) = backing.get(k).asInstanceOf[Option[T]]
def remove[T](k: AttributeKey[T]): AttributeMap = new BasicAttributeMap(backing - k)
def contains[T](k: AttributeKey[T]) = backing.contains(k)
def put[T](k: AttributeKey[T], value: T): AttributeMap = new BasicAttributeMap(backing.updated(k, value))
def keys: Iterable[AttributeKey[_]] = backing.keys
def ++(o: Iterable[AttributeEntry[_]]): AttributeMap =
{
val newBacking = (backing /: o) { case (b, AttributeEntry(key, value)) => b.updated(key, value) }
new BasicAttributeMap(newBacking)
}
def ++(o: AttributeMap): AttributeMap =
o match {
case bam: BasicAttributeMap => new BasicAttributeMap(backing ++ bam.backing)
case _ => o ++ this
}
def entries: Iterable[AttributeEntry[_]] =
for ((k: AttributeKey[kt], v) <- backing) yield AttributeEntry(k, v.asInstanceOf[kt])
override def toString = entries.mkString("(", ", ", ")")
}
// type inference required less generality
/** A map entry where `key` is constrained to only be associated with a fixed value of type `T`. */
final case class AttributeEntry[T](key: AttributeKey[T], value: T) {
override def toString = key.label + ": " + value
}
/** Associates a `metadata` map with `data`. */
final case class Attributed[D](data: D)(val metadata: AttributeMap) {
/** Retrieves the associated value of `key` from the metadata. */
def get[T](key: AttributeKey[T]): Option[T] = metadata.get(key)
/** Defines a mapping `key -> value` in the metadata. */
def put[T](key: AttributeKey[T], value: T): Attributed[D] = Attributed(data)(metadata.put(key, value))
/** Transforms the data by applying `f`. */
def map[T](f: D => T): Attributed[T] = Attributed(f(data))(metadata)
}
object Attributed {
/** Extracts the underlying data from the sequence `in`. */
def data[T](in: Seq[Attributed[T]]): Seq[T] = in.map(_.data)
/** Associates empty metadata maps with each entry of `in`.*/
def blankSeq[T](in: Seq[T]): Seq[Attributed[T]] = in map blank
/** Associates an empty metadata map with `data`. */
def blank[T](data: T): Attributed[T] = Attributed(data)(AttributeMap.empty)
}
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