raw.compiler.utils.Attribution.scala Maven / Gradle / Ivy
/*
* Copyright 2023 RAW Labs S.A.
*
* Use of this software is governed by the Business Source License
* included in the file licenses/BSL.txt.
*
* As of the Change Date specified in that file, in accordance with
* the Business Source License, use of this software will be governed
* by the Apache License, Version 2.0, included in the file
* licenses/APL.txt.
*/
package raw.compiler.utils
import com.typesafe.scalalogging.StrictLogging
import org.bitbucket.inkytonik.kiama.attribution.Attribute
import org.bitbucket.inkytonik.kiama.util.Memoiser.makeIdMemoiser
class Attribution extends org.bitbucket.inkytonik.kiama.attribution.Attribution with StrictLogging {
/**
* Attribute that supports cycles: instead of throwing exception, caches and returns cycle.
*/
class SafeCachedAttribute[T <: AnyRef, U](cycle: U)(f: T => U) extends Attribute[T, U]() {
/**
* Backing memo table.
*/
val memo = makeIdMemoiser[T, Option[U]]
/**
* Return the value of this attribute for node `t`, raising an error if
* it depends on itself.
*/
def apply(t: T): U = {
t.synchronized {
memo.get(t) match {
case Some(Some(u)) => u
case Some(None) =>
val u = cycle
memo.put(t, Some(u))
u
case None =>
memo.put(t, None)
val u = f(t)
memo.put(t, Some(u))
u
}
}
}
/**
* Has the value of this attribute at `t` already been computed or not?
* If the table contains `Some (u)` then we've computed it and the value
* was `u`. If the memo table contains `None` we are in the middle of
* computing it. Otherwise the memo table contains no entry for `t`.
*/
def hasBeenComputedAt(t: T): Boolean = memo.get(t) match {
case Some(Some(_)) => true
case _ => false
}
/**
* Reset the cache for this attribute.
*/
def reset() {
memo.reset()
}
}
def safeAttr[T <: AnyRef, U](s: U)(f: T => U): SafeCachedAttribute[T, U] = new SafeCachedAttribute(s)(f)
}