Create Decompiler Driver for IDE

PartialTASTYDecompiler stops where the normal decompiler would traverse the tree

Author: Tobias Bordenca

compiler/src/dotty/tools/dotc/core/tasty/TastyHTMLPrinter.scala

@@ -0,0 +1,16 @@
+package dotty.tools.dotc
+package core
+package tasty
+
+import Contexts._, Decorators._
+import Names.Name
+import TastyUnpickler._
+import TastyBuffer.NameRef
+import util.Positions.offsetToInt
+import printing.Highlighting._
+
+class TastyHTMLPrinter(bytes: Array[Byte])(implicit ctx: Context) extends TastyPrinter(bytes) {
+  override protected def nameColor(str: String): String = s"<span class='name'>$str</span>"
+  override protected def treeColor(str: String): String = s"<span class='tree'>$str</span>"
+  override protected def lengthColor(str: String): String = s"<span class='length'>$str</span>"
+}

compiler/src/dotty/tools/dotc/decompiler/IDEDecompilerDriver.scala

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+package dotty.tools
+package dotc
+package decompiler
+
+import dotty.tools.dotc.core.Contexts._
+import dotty.tools.dotc.core._
+import dotty.tools.dotc.core.tasty.TastyHTMLPrinter
+import dotty.tools.dotc.reporting._
+import dotty.tools.dotc.tastyreflect.ReflectionImpl
+
+/**
+  * Decompiler to be used with IDEs
+  */
+class IDEDecompilerDriver(val settings: List[String]) extends dotc.Driver {
+
+  private val myInitCtx: Context = {
+    val rootCtx = initCtx.fresh.addMode(Mode.Interactive).addMode(Mode.ReadPositions).addMode(Mode.ReadComments)
+    rootCtx.setSetting(rootCtx.settings.YretainTrees, true)
+    rootCtx.setSetting(rootCtx.settings.fromTasty, true)
+    val ctx = setup(settings.toArray :+ "dummy.scala", rootCtx)._2
+    ctx.initialize()(ctx)
+    ctx
+  }
+
+  private val decompiler = new PartialTASTYDecompiler
+
+  def run(className: String): (String, String) = {
+    val reporter = new StoreReporter(null) with HideNonSensicalMessages
+
+    val run = decompiler.newRun(myInitCtx.fresh.setReporter(reporter))
+
+    implicit val ctx = run.runContext
+
+    run.compile(List(className))
+    run.printSummary()
+    val unit = ctx.run.units.head
+
+    val decompiled = new ReflectionImpl(ctx).showSourceCode.showTree(unit.tpdTree)
+    val tree = new TastyHTMLPrinter(unit.pickled.head._2).printContents()
+
+    reporter.removeBufferedMessages.foreach(message => System.err.println(message))
+    (tree, decompiled)
+  }
+}

compiler/src/dotty/tools/dotc/decompiler/PartialTASTYDecompiler.scala

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+package dotty.tools.dotc.decompiler
+
+import dotty.tools.dotc.core.Phases.Phase
+
+/** Partial TASTYDecompiler that doesn't execute the backendPhases
+  * allowing to control decompiler output by manually running it
+  * on the CompilationUnits
+ */
+class PartialTASTYDecompiler extends TASTYDecompiler {
+  override def phases: List[List[Phase]] =
+    frontendPhases ::: picklerPhases ::: transformPhases
+}