From 51524055f795bb333520af75c93c217c8666eb80 Mon Sep 17 00:00:00 2001
From: Adriaan Moors <adriaan.moors@typesafe.com>
Date: Tue, 1 Dec 2015 14:54:47 -0800
Subject: [PATCH] Reduce memory usage of ExtractDependenciesTraverser

---
 .../interface/src/main/scala/xsbt/Dependency.scala  | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/compile/interface/src/main/scala/xsbt/Dependency.scala b/compile/interface/src/main/scala/xsbt/Dependency.scala
index a72f615a6..89e02d6d3 100644
--- a/compile/interface/src/main/scala/xsbt/Dependency.scala
+++ b/compile/interface/src/main/scala/xsbt/Dependency.scala
@@ -95,12 +95,9 @@ final class Dependency(val global: CallbackGlobal) extends LocateClassFile {
   }
 
   private abstract class ExtractDependenciesTraverser extends Traverser {
-    protected val depBuf = collection.mutable.ArrayBuffer.empty[Symbol]
-    protected def addDependency(dep: Symbol): Unit = depBuf += dep
-    def dependencies: collection.immutable.Set[Symbol] = {
-      // convert to immutable set and remove NoSymbol if we have one
-      depBuf.toSet - NoSymbol
-    }
+    private val deps = collection.mutable.HashSet.empty[Symbol]
+    protected def addDependency(dep: Symbol): Unit = if (dep ne NoSymbol) deps += dep
+    def dependencies: Iterator[Symbol] = deps.iterator
   }
 
   private class ExtractDependenciesByMemberRefTraverser extends ExtractDependenciesTraverser {
@@ -158,7 +155,7 @@ final class Dependency(val global: CallbackGlobal) extends LocateClassFile {
     }
   }
 
-  private def extractDependenciesByMemberRef(unit: CompilationUnit): collection.immutable.Set[Symbol] = {
+  private def extractDependenciesByMemberRef(unit: CompilationUnit): Iterator[Symbol] = {
     val traverser = new ExtractDependenciesByMemberRefTraverser
     traverser.traverse(unit.body)
     val dependencies = traverser.dependencies
@@ -184,7 +181,7 @@ final class Dependency(val global: CallbackGlobal) extends LocateClassFile {
     }
   }
 
-  private def extractDependenciesByInheritance(unit: CompilationUnit): collection.immutable.Set[Symbol] = {
+  private def extractDependenciesByInheritance(unit: CompilationUnit): Iterator[Symbol] = {
     val traverser = new ExtractDependenciesByInheritanceTraverser
     traverser.traverse(unit.body)
     val dependencies = traverser.dependencies