From b94874635483b2864aabd86140e51e7bdd916b40 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 23 Oct 2013 12:34:45 +0200
Subject: Caching asSeenFrom on denotations.

The last asSeenFrom on a SingleDenotation is cached.
Also, correction of effectiveOwner in SymDenotation, which needs to understand that module classes now end in a "$".
---
 src/dotty/tools/dotc/core/Denotations.scala    | 23 ++++++++++++++++++++---
 src/dotty/tools/dotc/core/StdNames.scala       |  1 +
 src/dotty/tools/dotc/core/SymDenotations.scala | 12 ++++++++----
 3 files changed, 29 insertions(+), 7 deletions(-)

(limited to 'src')

diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala
index bc2d1a41e..045f74300 100644
--- a/src/dotty/tools/dotc/core/Denotations.scala
+++ b/src/dotty/tools/dotc/core/Denotations.scala
@@ -552,7 +552,9 @@ object Denotations {
       }
     final def dropUniqueRefsIn(denots: PreDenotation): SingleDenotation =
       if (hasUniqueSym && denots.containsSym(symbol)) NoDenotation else this
-    def asSeenFrom(pre: Type)(implicit ctx: Context): SingleDenotation = {
+
+    type AsSeenFromResult = SingleDenotation
+    protected def computeAsSeenFrom(pre: Type)(implicit ctx: Context): SingleDenotation = {
       val owner = this match {
         case thisd: SymDenotation => thisd.owner
         case _ => if (symbol.exists) symbol.owner else NoSymbol
@@ -633,8 +635,22 @@ object Denotations {
      */
     def dropUniqueRefsIn(denots: PreDenotation): PreDenotation
 
+    private var cachedPrefix: Type = _
+    private var cachedAsSeenFrom: AsSeenFromResult = _
+    private var validAsSeenFrom: Period = Nowhere
+    type AsSeenFromResult <: PreDenotation
+
     /** The denotation with info(s) as seen from prefix type */
-    def asSeenFrom(pre: Type)(implicit ctx: Context): PreDenotation
+    final def asSeenFrom(pre: Type)(implicit ctx: Context): AsSeenFromResult = {
+      if ((cachedPrefix ne pre) || ctx.period != validAsSeenFrom) {
+        cachedAsSeenFrom = computeAsSeenFrom(pre)
+        cachedPrefix = pre
+        validAsSeenFrom = ctx.period
+      }
+      cachedAsSeenFrom
+    }
+
+    protected def computeAsSeenFrom(pre: Type)(implicit ctx: Context): AsSeenFromResult
 
     /** The union of two groups. */
     def union(that: PreDenotation) =
@@ -662,7 +678,8 @@ object Denotations {
       derivedUnion(denots1.filterExcluded(excluded), denots2.filterExcluded(excluded))
     def dropUniqueRefsIn(denots: PreDenotation): PreDenotation =
       derivedUnion(denots1.dropUniqueRefsIn(denots), denots2.dropUniqueRefsIn(denots))
-    def asSeenFrom(pre: Type)(implicit ctx: Context): PreDenotation =
+    type AsSeenFromResult = PreDenotation
+    protected def computeAsSeenFrom(pre: Type)(implicit ctx: Context): PreDenotation =
       derivedUnion(denots1.asSeenFrom(pre), denots2.asSeenFrom(pre))
     private def derivedUnion(denots1: PreDenotation, denots2: PreDenotation) =
       if ((denots1 eq this.denots1) && (denots2 eq this.denots2)) this
diff --git a/src/dotty/tools/dotc/core/StdNames.scala b/src/dotty/tools/dotc/core/StdNames.scala
index b5f776e13..e10758810 100644
--- a/src/dotty/tools/dotc/core/StdNames.scala
+++ b/src/dotty/tools/dotc/core/StdNames.scala
@@ -110,6 +110,7 @@ object StdNames {
     val NAME_JOIN: N                  = NameTransformer.NAME_JOIN_STRING
     val USCORE_PARAM_PREFIX: N        = "_$"
     val PACKAGE: N                    = "package"
+    val PACKAGE_CLS: N                = "package$"
     val PROTECTED_PREFIX: N           = "protected$"
     val PROTECTED_SET_PREFIX: N       = PROTECTED_PREFIX + "set"
     val ROOT: N                       = "<root>"
diff --git a/src/dotty/tools/dotc/core/SymDenotations.scala b/src/dotty/tools/dotc/core/SymDenotations.scala
index 9142e3185..ab58ec3b0 100644
--- a/src/dotty/tools/dotc/core/SymDenotations.scala
+++ b/src/dotty/tools/dotc/core/SymDenotations.scala
@@ -258,8 +258,10 @@ object SymDenotations {
       initial.asSymDenotation.name startsWith tpnme.ANON_CLASS
 
     /** Is this symbol a package object or its module class? */
-    def isPackageObject(implicit ctx: Context): Boolean =
-      (name.toTermName == nme.PACKAGEkw) && (owner is Package) && (this is Module)
+    def isPackageObject(implicit ctx: Context): Boolean = {
+      val poName = if (isType) nme.PACKAGE_CLS else nme.PACKAGE
+      (name.toTermName == poName) && (owner is Package) && (this is Module)
+    }
 
     /** Is this symbol an abstract type? */
     final def isAbstractType = isType && (this is Deferred)
@@ -956,7 +958,9 @@ object SymDenotations {
       } else NoDenotation
 
     override final def findMember(name: Name, pre: Type, excluded: FlagSet)(implicit ctx: Context): Denotation =
-      membersNamed(name).filterExcluded(excluded).asSeenFrom(pre).toDenot(pre)
+      //ctx.typeComparer.traceIndented(s"($this).findMember($name, $pre)") { // DEBUG
+        membersNamed(name).filterExcluded(excluded).asSeenFrom(pre).toDenot(pre)
+      //}
 
     private[this] var baseTypeCache: java.util.HashMap[CachedType, Type] = null
     private[this] var baseTypeValid: RunId = NoRunId
@@ -1064,7 +1068,7 @@ object SymDenotations {
     override def isTerm = false
     override def isType = false
     override def owner: Symbol = throw new AssertionError("NoDenotation.owner")
-    override def asSeenFrom(pre: Type)(implicit ctx: Context): SingleDenotation = this
+    override def computeAsSeenFrom(pre: Type)(implicit ctx: Context): SingleDenotation = this
     validFor = Period.allInRun(NoRunId) // will be brought forward automatically
   }
 
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