Implement decompiler from Tasty relect

Author: nicolasstucki

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

@@ -7,6 +7,7 @@ import dotty.tools.dotc.core.Contexts._
 import dotty.tools.dotc.core.Phases.Phase
 import dotty.tools.dotc.core.tasty.TastyPrinter
 import dotty.tools.dotc.printing.DecompilerPrinter
+import dotty.tools.dotc.tasty.TastyImpl
 import dotty.tools.io.{File, Path}
 
 /** Phase that prints the trees in all loaded compilation units.
@@ -36,12 +37,9 @@ class DecompilationPrinter extends Phase {
 
   private def printToOutput(out: PrintStream)(implicit ctx: Context): Unit = {
     val unit = ctx.compilationUnit
-    val pageWidth = ctx.settings.pageWidth.value
-    val printLines = ctx.settings.printLines.value
 
     out.println(s"/** Decompiled from $unit */")
-    val printer = new DecompilerPrinter(ctx)
-    out.println(printer.toText(unit.tpdTree).mkString(pageWidth, printLines))
+    out.print(TastyImpl.showSourceCode.showTree(unit.tpdTree)(ctx))
 
     if (ctx.settings.printTasty.value) {
       out.println("/*")

compiler/src/dotty/tools/dotc/quoted/QuoteDriver.scala

@@ -5,13 +5,12 @@ import dotty.tools.dotc.Driver
 import dotty.tools.dotc.core.Contexts.Context
 import dotty.tools.io.{AbstractFile, Directory, PlainDirectory, VirtualDirectory}
 import dotty.tools.repl.AbstractFileClassLoader
-import dotty.tools.dotc.printing.DecompilerPrinter
 
 import scala.quoted.{Expr, Type}
-
 import java.net.URLClassLoader
 
-import Toolbox.{Settings, Run, Show}
+import Toolbox.{Run, Settings, Show}
+import dotty.tools.dotc.tasty.TastyImpl
 
 class QuoteDriver extends Driver {
   import tpd._
@@ -42,10 +41,8 @@ class QuoteDriver extends Driver {
 
   def show(expr: Expr[_], settings: Settings[Show]): String = {
     def show(tree: Tree, ctx: Context): String = {
-      val printer = new DecompilerPrinter(ctx)
-      val pageWidth = ctx.settings.pageWidth.value(ctx)
       val tree1 = if (settings.rawTree) tree else (new TreeCleaner).transform(tree)(ctx)
-      printer.toText(tree1).mkString(pageWidth, false)
+      TastyImpl.showSourceCode.showTree(tree1)(ctx)
     }
     withTree(expr, show, settings)
   }

compiler/src/dotty/tools/dotc/tasty/FlagSet.scala

@@ -31,6 +31,8 @@ class FlagSet(flags: Flags.FlagSet) extends scala.tasty.FlagSet {
   def isScala2X: Boolean = flags.is(Scala2x)
   def isDefaultParameterized: Boolean = flags.is(DefaultParameterized)
   def isStable: Boolean = flags.is(Stable)
+  def isParam: Boolean = flags.is(Param)
+  def isParamAccessor: Boolean = flags.is(ParamAccessor)
 
   override def toString: String = {
     val flags = List.newBuilder[String]
@@ -60,6 +62,8 @@ class FlagSet(flags: Flags.FlagSet) extends scala.tasty.FlagSet {
     if (isScala2X) flags += "scala2x"
     if (isDefaultParameterized) flags += "defaultParameterized"
     if (isStable) flags += "stable"
+    if (isParam) flags += "param"
+    if (isParamAccessor) flags += "paramAccessor"
     flags.result().mkString("<", ",", ">")
   }
 

compiler/src/dotty/tools/dotc/tasty/FromSymbol.scala

@@ -20,7 +20,9 @@ object FromSymbol {
   def packageDef(sym: Symbol)(implicit ctx: Context): PackageDefinition = PackageDefinitionImpl(sym)
 
   def classDef(cls: ClassSymbol)(implicit ctx: Context): tpd.Tree = {
-    val constr = tpd.DefDef(cls.unforcedDecls.find(_.isPrimaryConstructor).asTerm)
+    val constrSym = cls.unforcedDecls.find(_.isPrimaryConstructor)
+    if (!constrSym.exists) return tpd.EmptyTree
+    val constr = tpd.DefDef(constrSym.asTerm)
     val body = cls.unforcedDecls.filter(!_.isPrimaryConstructor).map(s => definition(s))
     val superArgs = Nil // TODO
     tpd.ClassDef(cls, constr, body, superArgs)

compiler/src/dotty/tools/dotc/tasty/TastyImpl.scala

@@ -9,9 +9,9 @@ import dotty.tools.dotc.core.Decorators._
 import dotty.tools.dotc.core.quoted.PickledQuotes
 import dotty.tools.dotc.util.SourcePosition
 
-import scala.quoted
+import scala.{quoted, tasty}
 import scala.reflect.ClassTag
-import scala.tasty.util.{Show, ShowExtractors}
+import scala.tasty.util.{Show, ShowExtractors, ShowSourceCode}
 
 object TastyImpl extends scala.tasty.Tasty {
 
@@ -31,8 +31,7 @@ object TastyImpl extends scala.tasty.Tasty {
 
   def showExtractors: Show[this.type] = new ShowExtractors(this)
 
-  // TODO
-  // def showSourceCode: Show[this.type] = ???
+  def showSourceCode: Show[this.type] = new ShowSourceCode(this)
 
   // ===== Contexts =================================================
 
@@ -127,10 +126,18 @@ object TastyImpl extends scala.tasty.Tasty {
 
   type Definition = tpd.Tree
 
+  object Definition extends DefinitionExtractor {
+    def unapply(x: Definition)(implicit ctx: Context): Boolean =
+      x.isInstanceOf[Trees.MemberDef[_]]
+  }
+
   def DefinitionDeco(x: Definition): AbstractDefinition = new AbstractDefinition {
 
     def owner(implicit ctx: Context): Definition = FromSymbol.definition(x.symbol.owner)
 
+    def flags(implicit ctx: Contexts.Context): FlagSet =
+      new FlagSet(x.symbol.flags)
+
     def mods(implicit ctx: Context): List[Modifier] = {
       val privateWithin = x.symbol.privateWithin
       val isProtected = x.symbol.is(core.Flags.Protected)

compiler/test/dotty/tools/dotc/FromTastyTests.scala

@@ -38,7 +38,8 @@ class FromTastyTests extends ParallelTesting {
         "t3612.scala",
       ),
       recompilationBlacklist = Set(
-        "simpleCaseObject"
+        "simpleCaseObject",
+        "annot-bootstrap.scala",
       )
     ).checkCompile()
   }

library/src/scala/tasty/FlagSet.scala

@@ -27,4 +27,6 @@ trait FlagSet {
   def isScala2X: Boolean               // Imported from Scala2.x
   def isDefaultParameterized: Boolean  // Method with default parameters
   def isStable: Boolean                // Method that is assumed to be stable
+  def isParam: Boolean
+  def isParamAccessor: Boolean
 }

library/src/scala/tasty/Tasty.scala

@@ -23,8 +23,7 @@ abstract class Tasty { tasty =>
 
   def showExtractors: Show[tasty.type]
 
-  // TODO
-  // def showSourceCode: Show[tasty.type]
+  def showSourceCode: Show[tasty.type]
 
   // ===== Contexts =================================================
 
@@ -108,9 +107,15 @@ abstract class Tasty { tasty =>
 
   type Definition <: Statement
 
+  val Definition: DefinitionExtractor
+  abstract class DefinitionExtractor {
+    def unapply(x: Definition)(implicit ctx: Context): Boolean
+  }
+
   implicit def definitionClassTag: ClassTag[Definition]
 
   trait AbstractDefinition {
+    def flags(implicit ctx: Context): FlagSet
     def mods(implicit ctx: Context): List[Modifier]
     def owner(implicit ctx: Context): Definition
     def localContext(implicit ctx: Context): Context