Refactor getSource and withSource

Author: odersky

compiler/src/dotty/tools/dotc/Run.scala

@@ -99,22 +99,8 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
   /** Actions that need to be performed at the end of the current compilation run */
   private[this] var finalizeActions = mutable.ListBuffer[() => Unit]()
 
-  def getSource(fileName: String): SourceFile = {
-    val f = new PlainFile(io.Path(fileName))
-    if (f.isDirectory) {
-      ctx.error(s"expected file, received directory '$fileName'")
-      NoSource
-    }
-    else if (f.exists)
-      ctx.getSource(f)
-    else {
-      ctx.error(s"not found: $fileName")
-      NoSource
-    }
-  }
-
   def compile(fileNames: List[String]): Unit = try {
-    val sources = fileNames map getSource
+    val sources = fileNames.map(ctx.getSource)
     compileSources(sources)
   } catch {
     case NonFatal(ex) =>
@@ -206,7 +192,7 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
   def lateCompile(file: AbstractFile, typeCheck: Boolean)(implicit ctx: Context): Unit =
     if (!files.contains(file) && !lateFiles.contains(file)) {
       lateFiles += file
-      val unit = new CompilationUnit(getSource(file.path))
+      val unit = new CompilationUnit(ctx.getSource(file.path))
       def process()(implicit ctx: Context) = {
         unit.untpdTree =
           if (unit.isJava) new JavaParser(unit.source).parse()

compiler/src/dotty/tools/dotc/core/Contexts.scala

@@ -20,7 +20,7 @@ import config.Settings._
 import config.Config
 import reporting._
 import reporting.diagnostic.Message
-import io.AbstractFile
+import io.{AbstractFile, PlainFile, Path}
 import scala.io.Codec
 import collection.mutable
 import printing._
@@ -268,6 +268,20 @@ object Contexts {
     def getSource(file: AbstractFile, codec: => Codec = Codec(settings.encoding.value)) =
       base.sources.getOrElseUpdate(file, new SourceFile(file, codec))
 
+    def getSource(fileName: String): SourceFile = {
+      val f = new PlainFile(Path(fileName))
+      if (f.isDirectory) {
+        error(s"expected file, received directory '$fileName'")
+        NoSource
+      }
+      else if (f.exists)
+        getSource(f)
+      else {
+        error(s"not found: $fileName")
+        NoSource
+      }
+    }
+
     /** Those fields are used to cache phases created in withPhase.
       * phasedCtx is first phase with altered phase ever requested.
       * phasedCtxs is array that uses phaseId's as indexes,
@@ -452,8 +466,19 @@ object Contexts {
     final def withOwner(owner: Symbol): Context =
       if (owner ne this.owner) fresh.setOwner(owner) else this
 
+    private[this] var sourceCtx: SimpleIdentityMap[SourceFile, Context] = SimpleIdentityMap.Empty
+
     final def withSource(source: SourceFile): Context =
-      if (source ne this.source) fresh.setSource(source) else this
+      if (source `eq` this.source) this
+      else {
+        val prev = sourceCtx(source)
+        if (prev != null) prev
+        else {
+          val newCtx = fresh.setSource(source)
+          sourceCtx = sourceCtx.updated(source, newCtx)
+          newCtx
+        }
+      }
 
     final def withProperty[T](key: Key[T], value: Option[T]): Context =
       if (property(key) == value) this

compiler/src/dotty/tools/dotc/core/SymbolLoaders.scala

@@ -159,7 +159,7 @@ object SymbolLoaders {
             Nil)
         }
 
-        val unit = new CompilationUnit(ctx.run.getSource(src.path))
+        val unit = new CompilationUnit(ctx.getSource(src.path))
         enterScanned(unit)(ctx.run.runContext.fresh.setCompilationUnit(unit))
       }
     }