path: root/src/dotty/tools/dotc/core/tasty/TreePickler.scala

package dotty.tools
package dotc
package core
package tasty

import ast.Trees._
import ast.untpd
import TastyFormat._
import Contexts._, Symbols._, Types._, Names._, Constants._, Decorators._, Annotations._, StdNames.tpnme, NameOps._
import collection.mutable
import typer.Inliner
import NameOps._
import TastyBuffer._
import TypeApplications._

class TreePickler(pickler: TastyPickler) {
  val buf = new TreeBuffer
  pickler.newSection("ASTs", buf)
  import buf._
  import pickler.nameBuffer.{nameIndex, fullNameIndex}
  import ast.tpd._

  private val symRefs = new mutable.HashMap[Symbol, Addr]
  private val forwardSymRefs = new mutable.HashMap[Symbol, List[Addr]]
  private val pickledTypes = new java.util.IdentityHashMap[Type, Any] // Value type is really Addr, but that's not compatible with null

  private def withLength(op: => Unit) = {
    val lengthAddr = reserveRef(relative = true)
    op
    fillRef(lengthAddr, currentAddr, relative = true)
  }

  def addrOfSym(sym: Symbol): Option[Addr] = {
    symRefs.get(sym)
  }

  def preRegister(tree: Tree)(implicit ctx: Context): Unit = tree match {
    case tree: MemberDef =>
      if (!symRefs.contains(tree.symbol)) symRefs(tree.symbol) = NoAddr
    case _ =>
  }

  def registerDef(sym: Symbol): Unit = {
    symRefs(sym) = currentAddr
    forwardSymRefs.get(sym) match {
      case Some(refs) =>
        refs.foreach(fillRef(_, currentAddr, relative = false))
        forwardSymRefs -= sym
      case None =>
    }
  }
  
  def rhs(tdef: TypeDef)(implicit ctx: Context) = 
    if (tdef.symbol.isClass) tdef.rhs
    else TypeTree(tdef.symbol.info).withPos(tdef.rhs.pos)

  private def pickleName(name: Name): Unit = writeNat(nameIndex(name).index)
  private def pickleName(name: TastyName): Unit = writeNat(nameIndex(name).index)
  private def pickleNameAndSig(name: Name, sig: Signature) = {
    val Signature(params, result) = sig
    pickleName(TastyName.Signed(nameIndex(name), params.map(fullNameIndex), fullNameIndex(result)))
  }

  private def pickleName(sym: Symbol)(implicit ctx: Context): Unit = {
    def encodeSuper(name: Name): TastyName.NameRef =
      if (sym is Flags.SuperAccessor) {
        val SuperAccessorName(n) = name
        nameIndex(TastyName.SuperAccessor(nameIndex(n)))
      }
      else nameIndex(name)
    val nameRef =
      if (sym is Flags.ExpandedName)
        nameIndex(
          TastyName.Expanded(
            nameIndex(sym.name.expandedPrefix),
            encodeSuper(sym.name.unexpandedName)))
      else encodeSuper(sym.name)
    writeNat(nameRef.index)
  }

  private def pickleSymRef(sym: Symbol)(implicit ctx: Context) = symRefs.get(sym) match {
    case Some(label) =>
      if (label != NoAddr) writeRef(label) else pickleForwardSymRef(sym)
    case None =>
      // See pos/t1957.scala for an example where this can happen.
      // I believe it's a bug in typer: the type of an implicit argument refers
      // to a closure parameter outside the closure itself. TODO: track this down, so that we
      // can eliminate this case.
      ctx.log(i"pickling reference to as yet undefined $sym in ${sym.owner}", sym.pos)
      pickleForwardSymRef(sym)
  }

  private def pickleForwardSymRef(sym: Symbol)(implicit ctx: Context) = {
    val ref = reserveRef(relative = false)
    assert(!sym.is(Flags.Package), sym)
    forwardSymRefs(sym) = ref :: forwardSymRefs.getOrElse(sym, Nil)
  }

  private def isLocallyDefined(sym: Symbol)(implicit ctx: Context) = symRefs.get(sym) match {
    case Some(label) => assert(sym.exists); label != NoAddr
    case None => false
  }

  def pickleConstant(c: Constant)(implicit ctx: Context): Unit = c.tag match {
    case UnitTag =>
      writeByte(UNITconst)
    case BooleanTag =>
      writeByte(if (c.booleanValue) TRUEconst else FALSEconst)
    case ByteTag =>
      writeByte(BYTEconst)
      writeInt(c.byteValue)
    case ShortTag =>
      writeByte(SHORTconst)
      writeInt(c.shortValue)
    case CharTag =>
      writeByte(CHARconst)
      writeNat(c.charValue)
    case IntTag =>
      writeByte(INTconst)
      writeInt(c.intValue)
    case LongTag =>
      writeByte(LONGconst)
      writeLongInt(c.longValue)
    case FloatTag =>
      writeByte(FLOATconst)
      writeInt(java.lang.Float.floatToRawIntBits(c.floatValue))
    case DoubleTag =>
      writeByte(DOUBLEconst)
      writeLongInt(java.lang.Double.doubleToRawLongBits(c.doubleValue))
    case StringTag =>
      writeByte(STRINGconst)
      writeNat(nameIndex(c.stringValue).index)
    case NullTag =>
      writeByte(NULLconst)
    case ClazzTag =>
      writeByte(CLASSconst)
      pickleType(c.typeValue)
    case EnumTag =>
      writeByte(ENUMconst)
      pickleType(c.symbolValue.termRef)
  }

  def pickleType(tpe0: Type, richTypes: Boolean = false)(implicit ctx: Context): Unit = try {
    val tpe = tpe0.stripTypeVar
    val prev = pickledTypes.get(tpe)
    if (prev == null) {
      pickledTypes.put(tpe, currentAddr)
      pickleNewType(tpe, richTypes)
    }
    else {
      writeByte(SHARED)
      writeRef(prev.asInstanceOf[Addr])
    }
  } catch {
    case ex: AssertionError =>
      println(i"error when pickling type $tpe0")
      throw ex
  }

  def pickleTypeWithPos(tpe: Type, tree: Tree)(implicit ctx: Context): Unit = {
    registerTreeAddr(tree)
    pickleType(tpe)
  }

  private def pickleNewType(tpe: Type, richTypes: Boolean)(implicit ctx: Context): Unit = try { tpe match {
    case AppliedType(tycon, args) =>
      writeByte(APPLIEDtype)
      withLength { pickleType(tycon); args.foreach(pickleType(_)) }
    case ConstantType(value) =>
      pickleConstant(value)
    case tpe: TypeRef if tpe.info.isAlias && tpe.symbol.is(Flags.AliasPreferred) =>
      pickleType(tpe.superType)
    case tpe: WithFixedSym =>
      val sym = tpe.symbol
      def pickleRef() =
        if (tpe.prefix == NoPrefix) {
          writeByte(if (tpe.isType) TYPEREFdirect else TERMREFdirect)
          pickleSymRef(sym)
        }
        else {
          assert(tpe.symbol.isClass)
          assert(tpe.symbol.is(Flags.Scala2x), tpe.symbol.showLocated)
          writeByte(TYPEREF) // should be changed to a new entry that keeps track of prefix, symbol & owner
          pickleName(tpe.name)
          pickleType(tpe.prefix)
        }
      if (sym.is(Flags.Package)) {
        writeByte(if (tpe.isType) TYPEREFpkg else TERMREFpkg)
        pickleName(qualifiedName(sym))
      }
      else if (sym is Flags.BindDefinedType) {
        registerDef(sym)
        writeByte(BIND)
        withLength {
          pickleName(sym.name)
          pickleType(sym.info)
          pickleRef()
        }
      }
      else pickleRef()
    case tpe: TermRefWithSignature =>
      if (tpe.symbol.is(Flags.Package)) picklePackageRef(tpe.symbol)
      else {
        writeByte(TERMREF)
        pickleNameAndSig(tpe.name, tpe.signature); pickleType(tpe.prefix)
      }
    case tpe: NamedType =>
      if (isLocallyDefined(tpe.symbol)) {
        writeByte(if (tpe.isType) TYPEREFsymbol else TERMREFsymbol)
        pickleSymRef(tpe.symbol); pickleType(tpe.prefix)
      } else {
        writeByte(if (tpe.isType) TYPEREF else TERMREF)
        pickleName(tpe.name); pickleType(tpe.prefix)
      }
    case tpe: ThisType =>
      if (tpe.cls.is(Flags.Package) && !tpe.cls.isEffectiveRoot)
        picklePackageRef(tpe.cls)
      else {
        writeByte(THIS)
        pickleType(tpe.tref)
      }
    case tpe: SuperType =>
      writeByte(SUPERtype)
      withLength { pickleType(tpe.thistpe); pickleType(tpe.supertpe)}
    case tpe: RecThis =>
      writeByte(RECthis)
      val binderAddr = pickledTypes.get(tpe.binder)
      assert(binderAddr != null, tpe.binder)
      writeRef(binderAddr.asInstanceOf[Addr])
    case tpe: SkolemType =>
      pickleType(tpe.info)
    case tpe: RefinedType =>
      writeByte(REFINEDtype)
      withLength {
        pickleName(tpe.refinedName)
        pickleType(tpe.parent)
        pickleType(tpe.refinedInfo, richTypes = true)
      }
    case tpe: RecType =>
      writeByte(RECtype)
      pickleType(tpe.parent)
    case tpe: TypeAlias =>
      writeByte(TYPEALIAS)
      withLength {
        pickleType(tpe.alias, richTypes)
        tpe.variance match {
          case 1 => writeByte(COVARIANT)
          case -1 => writeByte(CONTRAVARIANT)
          case 0 =>
        }
      }
    case tpe: TypeBounds =>
      writeByte(TYPEBOUNDS)
      withLength { pickleType(tpe.lo, richTypes); pickleType(tpe.hi, richTypes) }
    case tpe: AnnotatedType =>
      writeByte(ANNOTATED)
      withLength { pickleType(tpe.tpe, richTypes); pickleTree(tpe.annot.tree) }
    case tpe: AndOrType =>
      writeByte(if (tpe.isAnd) ANDtype else ORtype)
      withLength { pickleType(tpe.tp1, richTypes); pickleType(tpe.tp2, richTypes) }
    case tpe: ExprType =>
      writeByte(BYNAMEtype)
      pickleType(tpe.underlying)
    case tpe: PolyType =>
      writeByte(POLYtype)
      val paramNames = tpe.typeParams.map(tparam =>
        varianceToPrefix(tparam.paramVariance) +: tparam.paramName)
      pickleMethodic(tpe.resultType, paramNames, tpe.paramBounds)
    case tpe: MethodType if richTypes =>
      writeByte(METHODtype)
      pickleMethodic(tpe.resultType, tpe.paramNames, tpe.paramTypes)
    case tpe: PolyParam =>
      if (!pickleParamType(tpe))
      // TODO figure out why this case arises in e.g. pickling AbstractFileReader.
        ctx.typerState.constraint.entry(tpe) match {
          case TypeBounds(lo, hi) if lo eq hi => pickleNewType(lo, richTypes)
          case _ => assert(false, s"orphan poly parameter: $tpe")
        }
    case tpe: MethodParam =>
      assert(pickleParamType(tpe), s"orphan method parameter: $tpe")
    case tpe: LazyRef =>
      pickleType(tpe.ref)
  }} catch {
    case ex: AssertionError =>
      println(i"error while pickling type $tpe")
      throw ex
  }

  def picklePackageRef(pkg: Symbol)(implicit ctx: Context): Unit = {
    writeByte(TERMREFpkg)
    pickleName(qualifiedName(pkg))
  }

  def pickleMethodic(result: Type, names: List[Name], types: List[Type])(implicit ctx: Context) =
    withLength {
      pickleType(result, richTypes = true)
      (names, types).zipped.foreach { (name, tpe) =>
        pickleName(name); pickleType(tpe)
      }
    }

  def pickleParamType(tpe: ParamType)(implicit ctx: Context): Boolean = {
    val binder = pickledTypes.get(tpe.binder)
    val pickled = binder != null
    if (pickled) {
      writeByte(PARAMtype)
      withLength { writeRef(binder.asInstanceOf[Addr]); writeNat(tpe.paramNum) }
    }
    pickled
  }

  def pickleTpt(tpt: Tree)(implicit ctx: Context): Unit =
    pickleTypeWithPos(tpt.tpe, tpt) // TODO correlate with original when generating positions

  def pickleTreeUnlessEmpty(tree: Tree)(implicit ctx: Context): Unit =
    if (!tree.isEmpty) pickleTree(tree)

  def pickleDef(tag: Int, sym: Symbol, tpt: Tree, rhs: Tree = EmptyTree, pickleParams: => Unit = ())(implicit ctx: Context) = {
    assert(symRefs(sym) == NoAddr, sym)
    registerDef(sym)
    writeByte(tag)
    withLength {
      pickleName(sym)
      pickleParams
      tpt match {
        case templ: Template => pickleTree(tpt)
        case _ if tpt.isType => pickleTpt(tpt)
      }
      pickleTreeUnlessEmpty(rhs)
      pickleModifiers(sym)
    }
  }

  def pickleParam(tree: Tree)(implicit ctx: Context): Unit = {
    registerTreeAddr(tree)
    tree match {
      case tree: ValDef => pickleDef(PARAM, tree.symbol, tree.tpt)
      case tree: DefDef => pickleDef(PARAM, tree.symbol, tree.tpt, tree.rhs)
      case tree: TypeDef => pickleDef(TYPEPARAM, tree.symbol, rhs(tree))
    }
  }

  def pickleParams(trees: List[Tree])(implicit ctx: Context): Unit = {
    trees.foreach(preRegister)
    trees.foreach(pickleParam)
  }

  def pickleStats(stats: List[Tree])(implicit ctx: Context) = {
    stats.foreach(preRegister)
    stats.foreach(stat => if (!stat.isEmpty) pickleTree(stat))
  }

  def pickleTree(tree: Tree)(implicit ctx: Context): Unit = try {
    registerTreeAddr(tree)
    tree match {
      case tree if tree.isType =>
        pickleTpt(tree)
      case Ident(name) =>
        tree.tpe match {
          case tp: TermRef => pickleType(tp)
          case _ =>
            writeByte(IDENT)
            pickleName(name)
            pickleType(tree.tpe)
        }
      case This(_) =>
        pickleType(tree.tpe)
      case Select(qual, name) =>
        writeByte(SELECT)
        val realName = tree.tpe match {
          case tp: NamedType if tp.name.isShadowedName => tp.name
          case _ => name
        }
        val sig = tree.tpe.signature
        if (sig == Signature.NotAMethod) pickleName(realName)
        else pickleNameAndSig(realName, sig)
        pickleTree(qual)
      case Apply(fun, args) =>
        writeByte(APPLY)
        withLength {
          pickleTree(fun)
          args.foreach(pickleTree)
        }
      case TypeApply(fun, args) =>
        writeByte(TYPEAPPLY)
        withLength {
          pickleTree(fun)
          args.foreach(pickleTpt)
        }
      case Literal(const1) =>
        pickleConstant {
          tree.tpe match {
            case ConstantType(const2) => const2
            case _ => const1
          }
        }
      case Super(qual, mix) =>
        writeByte(SUPER)
        withLength {
          pickleTree(qual);
          if (!mix.isEmpty) {
            val SuperType(_, mixinType) = tree.tpe
            pickleType(mixinType)
          }
        }
      case New(tpt) =>
        writeByte(NEW)
        pickleTpt(tpt)
      case Typed(expr, tpt) =>
        writeByte(TYPED)
        withLength { pickleTree(expr); pickleTpt(tpt) }
      case NamedArg(name, arg) =>
        writeByte(NAMEDARG)
        withLength { pickleName(name); pickleTree(arg) }
      case Assign(lhs, rhs) =>
        writeByte(ASSIGN)
        withLength { pickleTree(lhs); pickleTree(rhs) }
      case Block(stats, expr) =>
        writeByte(BLOCK)
        stats.foreach(preRegister)
        withLength { pickleTree(expr); stats.foreach(pickleTree) }
      case If(cond, thenp, elsep) =>
        writeByte(IF)
        withLength{ pickleTree(cond); pickleTree(thenp); pickleTree(elsep) }
      case Closure(env, meth, tpt) =>
        writeByte(LAMBDA)
        assert(env.isEmpty)
        withLength{
          pickleTree(meth)
          if (tpt.tpe.exists) pickleTpt(tpt)
        }
      case Match(selector, cases) =>
        writeByte(MATCH)
        withLength { pickleTree(selector); cases.foreach(pickleTree) }
      case CaseDef(pat, guard, rhs) =>
        writeByte(CASEDEF)
        withLength { pickleTree(pat); pickleTree(rhs); pickleTreeUnlessEmpty(guard) }
      case Return(expr, from) =>
        writeByte(RETURN)
        withLength { pickleSymRef(from.symbol); pickleTreeUnlessEmpty(expr) }
      case Try(block, cases, finalizer) =>
        writeByte(TRY)
        withLength { pickleTree(block); cases.foreach(pickleTree); pickleTreeUnlessEmpty(finalizer) }
      case SeqLiteral(elems, elemtpt) =>
        writeByte(REPEATED)
        withLength { pickleTree(elemtpt); elems.foreach(pickleTree) }
      case Inlined(call, bindings, expansion) =>
        writeByte(INLINED)
        bindings.foreach(preRegister)
        withLength { pickleTree(call); pickleTree(expansion); bindings.foreach(pickleTree) }
      case Bind(name, body) =>
        registerDef(tree.symbol)
        writeByte(BIND)
        withLength { pickleName(name); pickleType(tree.symbol.info); pickleTree(body) }
      case Alternative(alts) =>
        writeByte(ALTERNATIVE)
        withLength { alts.foreach(pickleTree) }
      case UnApply(fun, implicits, patterns) =>
        writeByte(UNAPPLY)
        withLength {
          pickleTree(fun)
          for (implicitArg <- implicits) {
            writeByte(IMPLICITarg)
            pickleTree(implicitArg)
          }
          pickleType(tree.tpe)
          patterns.foreach(pickleTree)
        }
      case tree: ValDef =>
        pickleDef(VALDEF, tree.symbol, tree.tpt, tree.rhs)
      case tree: DefDef =>
        def pickleAllParams = {
          pickleParams(tree.tparams)
          for (vparams <- tree.vparamss) {
            writeByte(PARAMS)
            withLength { pickleParams(vparams) }
          }
        }
        pickleDef(DEFDEF, tree.symbol, tree.tpt, tree.rhs, pickleAllParams)
      case tree: TypeDef =>
        pickleDef(TYPEDEF, tree.symbol, rhs(tree))
      case tree: Template =>
        registerDef(tree.symbol)
        writeByte(TEMPLATE)
        val (params, rest) = tree.body partition {
          case stat: TypeDef => stat.symbol is Flags.Param
          case stat: ValOrDefDef =>
            stat.symbol.is(Flags.ParamAccessor) && !stat.symbol.isSetter
          case _ => false
        }
        withLength {
          pickleParams(params)
          tree.parents.foreach(pickleTree)
          val cinfo @ ClassInfo(_, _, _, _, selfInfo) = tree.symbol.owner.info
          if ((selfInfo ne NoType) || !tree.self.isEmpty) {
            writeByte(SELFDEF)
            pickleName(tree.self.name)
            if (!tree.self.isEmpty) registerTreeAddr(tree.self.tpt)
            pickleType {
              cinfo.selfInfo match {
                case sym: Symbol => sym.info
                case tp: Type => tp
              }
            }
          }
          pickleStats(tree.constr :: rest)
        }
      case Import(expr, selectors) =>
        writeByte(IMPORT)
        withLength {
          pickleTree(expr)
          selectors foreach {
            case Thicket((from @ Ident(_)) :: (to @ Ident(_)) :: Nil) =>
              pickleSelector(IMPORTED, from)
              pickleSelector(RENAMED, to)
            case id @ Ident(_) =>
              pickleSelector(IMPORTED, id)
          }
        }
      case PackageDef(pid, stats) =>
        writeByte(PACKAGE)
        withLength { pickleType(pid.tpe); pickleStats(stats) }
    }}
  catch {
    case ex: AssertionError =>
      println(i"error when pickling tree $tree")
      throw ex
  }

  def pickleSelector(tag: Int, id: untpd.Ident)(implicit ctx: Context): Unit = {
    registerTreeAddr(id)
    writeByte(tag)
    pickleName(id.name)
  }

  def qualifiedName(sym: Symbol)(implicit ctx: Context): TastyName =
    if (sym.isRoot || sym.owner.isRoot) TastyName.Simple(sym.name.toTermName)
    else TastyName.Qualified(nameIndex(qualifiedName(sym.owner)), nameIndex(sym.name))

  def pickleModifiers(sym: Symbol)(implicit ctx: Context): Unit = {
    import Flags._
    val flags = sym.flags
    val privateWithin = sym.privateWithin
    if (privateWithin.exists) {
      writeByte(if (flags is Protected) PROTECTEDqualified else PRIVATEqualified)
      pickleType(privateWithin.typeRef)
    }
    if (flags is Private) writeByte(PRIVATE)
    if (flags is Protected) if (!privateWithin.exists) writeByte(PROTECTED)
    if ((flags is Final) && !(sym is Module)) writeByte(FINAL)
    if (flags is Case) writeByte(CASE)
    if (flags is Override) writeByte(OVERRIDE)
    if (flags is Inline) writeByte(INLINE)
    if (flags is JavaStatic) writeByte(STATIC)
    if (flags is Module) writeByte(OBJECT)
    if (flags is Local) writeByte(LOCAL)
    if (flags is Synthetic) writeByte(SYNTHETIC)
    if (flags is Artifact) writeByte(ARTIFACT)
    if (flags is Scala2x) writeByte(SCALA2X)
    if (flags is InSuperCall) writeByte(INSUPERCALL)
    if (sym.isTerm) {
      if (flags is Implicit) writeByte(IMPLICIT)
      if ((flags is Lazy) && !(sym is Module)) writeByte(LAZY)
      if (flags is AbsOverride) { writeByte(ABSTRACT); writeByte(OVERRIDE) }
      if (flags is Mutable) writeByte(MUTABLE)
      if (flags is Accessor) writeByte(FIELDaccessor)
      if (flags is CaseAccessor) writeByte(CASEaccessor)
      if (flags is DefaultParameterized) writeByte(DEFAULTparameterized)
      if (flags is Stable) writeByte(STABLE)
    } else {
      if (flags is Sealed) writeByte(SEALED)
      if (flags is Abstract) writeByte(ABSTRACT)
      if (flags is Trait) writeByte(TRAIT)
      if (flags is Covariant) writeByte(COVARIANT)
      if (flags is Contravariant) writeByte(CONTRAVARIANT)
    }
    sym.annotations.foreach(pickleAnnotation)
  }

  def pickleAnnotation(ann: Annotation)(implicit ctx: Context) =
    if (ann.symbol != defn.BodyAnnot) { // inline bodies are reconstituted automatically when unpickling
      writeByte(ANNOTATION)
      withLength { pickleType(ann.symbol.typeRef); pickleTree(ann.tree) }
    }

  def pickle(trees: List[Tree])(implicit ctx: Context) = {
    trees.foreach(tree => if (!tree.isEmpty) pickleTree(tree))
    assert(forwardSymRefs.isEmpty, i"unresolved symbols: ${forwardSymRefs.keySet.toList}%, % when pickling ${ctx.source}")
  }

  def compactify() = {
    buf.compactify()

    def updateMapWithDeltas[T](mp: collection.mutable.Map[T, Addr]) =
      for (key <- mp.keysIterator.toBuffer[T]) mp(key) = adjusted(mp(key))

    updateMapWithDeltas(symRefs)
  }
}