Merge pull request #473 from wiwa/f/rsccompat-perf

Cache member lookup in RscCompat Scopes

scalafix/rules/src/main/scala/rsc/rules/semantics/Scopes.scala

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0 (see LICENSE.md).
 package rsc.rules.semantics
 
+import rsc.rules.util.memoize
 import scala.collection.mutable
 import scala.meta._
 import scala.meta.internal.{semanticdb => s}
@@ -10,11 +11,18 @@ import scala.meta.internal.semanticdb.Scala.{Descriptor => d}
 import scala.meta.internal.semanticdb.Scala.{Names => n}
 
 sealed trait Scope {
+  import Scope.MemberKey
+
   def lookup(name: n.Name): String
 
   def getRename(name: n.Name): String = ""
 
-  protected def member(symtab: Symtab, sym: String, name: n.Name): String = {
+  protected def member(symtab: Symtab, sym: String, name: n.Name): String =
+    _member(MemberKey(symtab, sym, name))
+
+  private val _member: MemberKey => String = memoize { key: MemberKey =>
+    val MemberKey(symtab, sym, name) = key
+
     def getInfo(desc: Descriptor): Option[s.SymbolInformation] =
       symtab
         .info(Symbols.Global(sym, desc))
@@ -27,6 +35,9 @@ sealed trait Scope {
     info.map(_.symbol).getOrElse(Symbols.None)
   }
 }
+object Scope {
+  private[Scope] final case class MemberKey(symtab: Symtab, sym: String, name: n.Name)
+}
 
 final class AddedImportsScope extends Scope {
 

scalafix/rules/src/main/scala/rsc/rules/util/MemoizeUtil.scala

@@ -0,0 +1,14 @@
+package rsc.rules.util
+
+trait MemoizeUtil {
+
+  /**
+   * Memoize the results of a function call to prevent repeated calls
+   */
+  def memoize[I, O](f: I => O): I => O = {
+    val _cache = new java.util.HashMap[I, O]
+
+    key =>
+      _cache.computeIfAbsent(key, _ => f(key))
+  }
+}

scalafix/rules/src/main/scala/rsc/rules/util/package.scala

@@ -0,0 +1,3 @@
+package rsc.rules
+
+package object util extends MemoizeUtil