path: root/src/dotty/tools/dotc/core/pickling/ClassfileParser.scala

package dotty.tools
package dotc
package core
package pickling

import Contexts._, Symbols._, Types._, Names._, StdNames._, NameOps._, Scopes._, Decorators._
import SymDenotations._, UnPickler._, Constants._, Annotations._, Positions._
import TypedTrees.tpd._
import java.io.{ File, IOException }
import java.lang.Integer.toHexString
import scala.collection.{ mutable, immutable }
import scala.collection.mutable.{ ListBuffer, ArrayBuffer }
import scala.annotation.switch
import io.AbstractFile

class ClassfileParser(
    classfile: AbstractFile,
    classRoot: ClassDenotation,
    moduleRoot: ClassDenotation)(implicit cctx: CondensedContext) {

  import ClassfileConstants._
  import cctx.base.{settings, loaders, definitions => defn}
  import cctx.{debug, verbose}

  protected val in = new AbstractFileReader(classfile)

  protected val staticModule: Symbol = moduleRoot.sourceModule

  protected val instanceScope: MutableScope = newScope     // the scope of all instance definitions
  protected val staticScope: MutableScope = newScope       // the scope of all static definitions
  protected var pool: ConstantPool = _              // the classfile's constant pool

  protected var currentClassName: Name = _      // JVM name of the current class
  protected var classTParams = Map[Name,Symbol]()
  protected var srcfile0 : Option[AbstractFile] = None //needs fleshing out

  def srcfile = srcfile0

  private def currentIsTopLevel = !(classRoot.name contains '$')

  private def mismatchError(c: Symbol) = {
    throw new IOException("class file '%s' has location not matching its contents: contains ".format(in.file) + c)
  }

  def run(): Unit = try {
    cctx.debuglog("[class] >> " + classRoot.fullName)
    parseHeader
    this.pool = new ConstantPool
    parseClass()
  } catch {
    case e: RuntimeException =>
      if (debug) e.printStackTrace()
      throw new IOException(
        s"""class file $classfile is broken, reading aborted with $e.getClass
           |${Option(e.getMessage).getOrElse("")}""".stripMargin)
  }

  private def parseHeader() {
    val magic = in.nextInt
    if (magic != JAVA_MAGIC)
      throw new IOException("class file '" + in.file + "' "
                            + "has wrong magic number 0x" + toHexString(magic)
                            + ", should be 0x" + toHexString(JAVA_MAGIC))
    val minorVersion = in.nextChar.toInt
    val majorVersion = in.nextChar.toInt
    if ((majorVersion < JAVA_MAJOR_VERSION) ||
        ((majorVersion == JAVA_MAJOR_VERSION) &&
         (minorVersion < JAVA_MINOR_VERSION)))
      throw new IOException("class file '" + in.file + "' "
                            + "has unknown version "
                            + majorVersion + "." + minorVersion
                            + ", should be at least "
                            + JAVA_MAJOR_VERSION + "." + JAVA_MINOR_VERSION)
  }

  /** Return the class symbol of the given name. */
  def classNameToSymbol(name: Name): Symbol = innerClasses.get(name) match {
    case Some(entry) => innerClasses.classSymbol(entry.externalName)
    case None => cctx.requiredClass(name)
  }

  var sawPrivateConstructor = false

  def parseClass() {
    val jflags       = in.nextChar
    val isAnnotation = hasAnnotation(jflags)
    val sflags       = FlagTranslation.classFlags(jflags)
    val nameIdx      = in.nextChar
    currentClassName = pool.getClassName(nameIdx)

    if (currentIsTopLevel) {
      val c = pool.getClassSymbol(nameIdx)
      if (c != classRoot.symbol) mismatchError(c)
    }

    addEnclosingTParams

    if (unpickleOrParseInnerClasses()) return

    /** Parse parents for Java classes. For Scala, return AnyRef, since the real type will be unpickled.
     *  Updates the read pointer of 'in'. */
    def parseParents: List[Type] = {
      val superType = if (isAnnotation) { in.nextChar; defn.AnnotationClass.typeConstructor }
                      else pool.getSuperClass(in.nextChar).typeConstructor
      val ifaceCount = in.nextChar
      var ifaces = for (i <- List.range(0, ifaceCount)) yield pool.getSuperClass(in.nextChar).typeConstructor
      if (isAnnotation) ifaces = defn.ClassfileAnnotationClass.typeConstructor :: ifaces
      superType :: ifaces
    }

    var classInfo: Type = TempClassInfoType(parseParents, instanceScope, classRoot.symbol) // might be overridden by later parseAttributes
    val staticInfo = TempClassInfoType(List(), staticScope, moduleRoot.symbol)

    enterOwnInnerClasses

    classRoot.flags = sflags
    moduleRoot.flags = Flags.JavaDefined
    setPrivateWithin(classRoot, jflags)
    setPrivateWithin(moduleRoot, jflags)

    for (i <- 0 until in.nextChar) parseMember(method = false)
    for (i <- 0 until in.nextChar) parseMember(method = true)

    val needsConstructor =
      instanceScope.lookup(nme.CONSTRUCTOR) == NoSymbol && !(sflags is Flags.Interface)

    if (needsConstructor)
      instanceScope enter cctx.newDefaultConstructor(classRoot.symbol.asClass)

    classInfo = parseAttributes(classRoot.symbol, classInfo)
    setClassInfo(classRoot, classInfo)
    setClassInfo(moduleRoot, staticInfo)
  }

  /** Add type parameters of enclosing classes */
  def addEnclosingTParams {
    var sym = classRoot.owner
    while (sym.isClass && !sym.isModuleClass) {
      for (tparam <- sym.typeParams) {
        classTParams = classTParams.updated(tparam.name, tparam)
      }
      sym = sym.owner
    }
  }

  def parseMember(method: Boolean): Unit = {
    val start = indexCoord(in.bp)
    val jflags = in.nextChar
    val sflags =
      if (method) FlagTranslation.methodFlags(jflags)
      else FlagTranslation.fieldFlags(jflags)
    val name = pool.getName(in.nextChar)
    if (!(sflags is Flags.Private) || name == nme.CONSTRUCTOR || settings.optimise.value)
      cctx.newSymbol(
        getOwner(jflags), name, sflags, memberCompleter, coord = start).entered
  }

  val memberCompleter = new LazyType {
    def complete(denot: SymDenotation): Unit = {
      val oldbp = in.bp
      try {
        in.bp = denot.symbol.coord.toIndex
        val sym = denot.symbol
        val jflags = in.nextChar
        val isEnum = (jflags & JAVA_ACC_ENUM) != 0
        val name = pool.getName(in.nextChar)
        val info = pool.getType(in.nextChar)

        denot.info = if (isEnum) ConstantType(Constant(sym)) else info
        if (name == nme.CONSTRUCTOR)
          // if this is a non-static inner class, remove the explicit outer parameter
          innerClasses.get(currentClassName) match {
            case Some(entry) if !isStatic(entry.jflags) =>
              val mt @ MethodType(paramnames, paramtypes) = info
              denot.info = mt.derivedMethodType(paramnames.tail, paramtypes.tail, mt.resultType)

          }
        setPrivateWithin(denot, jflags)
        denot.info = parseAttributes(sym, info)

        if ((denot is Flags.Method) && (jflags & JAVA_ACC_VARARGS) != 0)
          denot.info = arrayToRepeated(denot.info)

        // seal java enums
        if (isEnum) {
          val enumClass = sym.owner.linkedClass
          if (!(enumClass is Flags.Sealed)) enumClass.setFlag(Flags.AbstractSealed)
          enumClass.addAnnotation(Annotation.makeChild(sym))
        }
      } finally {
        in.bp = oldbp
      }
    }
  }

  private def sigToType(sig: TermName, owner: Symbol = null): Type = {
    var index = 0
    val end = sig.length
    def accept(ch: Char) {
      assert(sig(index) == ch, (sig(index), ch))
      index += 1
    }
    def subName(isDelimiter: Char => Boolean): TermName = {
      val start = index
      while (!isDelimiter(sig(index))) { index += 1 }
      sig.slice(start, index)
    }
    def sig2type(tparams: immutable.Map[Name,Symbol], skiptvs: Boolean): Type = {
      val tag = sig(index); index += 1
      (tag: @switch) match {
        case BYTE_TAG   => defn.ByteType
        case CHAR_TAG   => defn.CharType
        case DOUBLE_TAG => defn.DoubleType
        case FLOAT_TAG  => defn.FloatType
        case INT_TAG    => defn.IntType
        case LONG_TAG   => defn.LongType
        case SHORT_TAG  => defn.ShortType
        case VOID_TAG   => defn.UnitType
        case BOOL_TAG   => defn.BooleanType
        case 'L' =>
          def processInner(tp: Type): Type = tp match {
            case tp @ TypeRef(pre, name) if !tp.symbol.isStatic =>
              TypeRef(pre.widen, name)
            case _ =>
              tp
          }
          def processClassType(tp: Type): Type = tp match {
            case tp @ TypeRef(pre, name) =>
              if (sig(index) == '<') {
                accept('<')
                var tp1: Type = tp
                var formals = tp.typeParams
                while (sig(index) != '>') {
                  sig(index) match {
                    case variance @ ('+' | '-' | '*') =>
                      index += 1
                      val bounds = variance match {
                        case '+' => TypeBounds.upper(sig2type(tparams, skiptvs).objToAny)
                        case '-' =>
                          val tp = sig2type(tparams, skiptvs)
                          // sig2type seems to return AnyClass regardless of the situation:
                          // we don't want Any as a LOWER bound.
                          if (tp.typeSymbol == defn.AnyClass) TypeBounds.empty
                          else TypeBounds.lower(tp)
                        case '*' => TypeBounds.empty
                      }
                      tp1 = RefinedType(tp, formals.head.name, bounds)
                    case _ =>
                      tp1 = RefinedType(tp, formals.head.name, TypeAlias(sig2type(tparams, skiptvs)))
                  }
                  formals = formals.tail
                }
                accept('>')
                tp1
              } else tp
            case tp =>
              assert(sig(index) != '<', tp)
              tp
          }

          val classSym = classNameToSymbol(subName(c => c == ';' || c == '<'))
          var tpe = processClassType(processInner(classSym.typeConstructor))
          while (sig(index) == '.') {
            accept('.')
            val name = subName(c => c == ';' || c == '<' || c == '.').toTypeName
            val clazz = tpe.member(name).symbol
            tpe = processClassType(processInner(clazz.typeConstructor))
          }
          accept(';')
          tpe
        case ARRAY_TAG =>
          while ('0' <= sig(index) && sig(index) <= '9') index += 1
          var elemtp = sig2type(tparams, skiptvs)
          // make unbounded Array[T] where T is a type variable into Ar ray[T with Object]
          // (this is necessary because such arrays have a representation which is incompatible
          // with arrays of primitive types.
          // NOTE that the comparison to Object only works for abstract types bounded by classes that are strict subclasses of Object
          // if the bound is exactly Object, it will have been converted to Any, and the comparison will fail
          // see also RestrictJavaArraysMap (when compiling java sources directly)
          if (elemtp.typeSymbol.isAbstractType && !(elemtp <:< defn.ObjectType)) {
            elemtp = AndType(elemtp, defn.ObjectType)
          }

          defn.ArrayType.appliedTo(elemtp)
        case '(' =>
          // we need a method symbol. given in line 486 by calling getType(methodSym, ..)
          val paramtypes = new ListBuffer[Type]()
          var paramnames = new ListBuffer[TermName]()
          while (sig(index) != ')') {
            paramnames += nme.syntheticParamName(paramtypes.length)
            paramtypes += sig2type(tparams, skiptvs).objToAny
          }
          index += 1
          val restype = sig2type(tparams, skiptvs)
          JavaMethodType(paramnames.toList, paramtypes.toList)(_ => restype)
        case 'T' =>
          val n = subName(';'.==).toTypeName
          index += 1
          if (skiptvs) defn.AnyType else tparams(n).typeConstructor
      }
    } // sig2type(tparams, skiptvs)

    def sig2typeBounds(tparams: immutable.Map[Name, Symbol], skiptvs: Boolean): Type = {
      val ts = new ListBuffer[Type]
      while (sig(index) == ':') {
        index += 1
        if (sig(index) != ':') // guard against empty class bound
          ts += sig2type(tparams, skiptvs).objToAny
      }
      TypeBounds.upper((defn.AnyType /: ts)(_ & _))
    }

    var tparams = classTParams

    def typeParamCompleter(start: Int) = new LazyType {
      def complete(denot: SymDenotation): Unit = {
        val savedIndex = index
        try {
          index = start
          denot.info = sig2typeBounds(tparams, skiptvs = false)
        } finally {
          index = savedIndex
        }
      }
    }

    val newTParams = new ListBuffer[Symbol]()
    if (sig(index) == '<') {
      assert(owner != null)
      index += 1
      val start = index
      while (sig(index) != '>') {
        val tpname = subName(':'.==).toTypeName
        val s = cctx.newSymbol(
          owner, tpname, Flags.TypeParamCreationFlags,
          typeParamCompleter(index), coord = indexCoord(index))
        tparams = tparams + (tpname -> s)
        sig2typeBounds(tparams, skiptvs = true)
        newTParams += s
      }
    }
    val ownTypeParams = newTParams.toList
    val tpe =
      if ((owner == null) || !owner.isClass)
        sig2type(tparams, skiptvs = false)
      else {
        classTParams = tparams
        val parents = new ListBuffer[Type]()
        while (index < end) {
          parents += sig2type(tparams, skiptvs = false)  // here the variance doesnt'matter
        }
        TempClassInfoType(parents.toList, instanceScope, owner)
      }
    if (ownTypeParams.isEmpty) tpe else TempPolyType(ownTypeParams, tpe)
  } // sigToType

  def parseAnnotArg(skip: Boolean = false): Option[Tree] = {
    val tag = in.nextByte.toChar
    val index = in.nextChar
    tag match {
      case STRING_TAG =>
        if (skip) None else Some(Literal(Constant(pool.getName(index).toString)))
      case BOOL_TAG | BYTE_TAG | CHAR_TAG | SHORT_TAG | INT_TAG |
        LONG_TAG | FLOAT_TAG | DOUBLE_TAG =>
        if (skip) None else Some(Literal(pool.getConstant(index)))
      case CLASS_TAG =>
        if (skip) None else Some(Literal(Constant(pool.getType(index))))
      case ENUM_TAG =>
        val t = pool.getType(index)
        val n = pool.getName(in.nextChar)
        val s = t.typeSymbol.companionModule.info.decls.lookup(n)
        assert(s != NoSymbol, t)
        if (skip) None else Some(Literal(Constant(s)))
      case ARRAY_TAG =>
        val arr = new ArrayBuffer[Tree]()
        var hasError = false
        for (i <- 0 until index)
          parseAnnotArg(skip) match {
            case Some(c) => arr += c
            case None => hasError = true
          }
        if (hasError) None
        else if (skip) None else Some(SeqLiteral(arr.toList))
      case ANNOTATION_TAG =>
        parseAnnotation(index, skip) map (_.tree)
    }
  }

  /** Parse and return a single annotation.  If it is malformed,
   *  return None.
   */
  def parseAnnotation(attrNameIndex: Char, skip: Boolean = false): Option[Annotation] = try {
    val attrType = pool.getType(attrNameIndex)
    val nargs = in.nextChar
    val argbuf = new ListBuffer[Tree]
    var hasError = false
    for (i <- 0 until nargs) {
      val name = pool.getName(in.nextChar)
      parseAnnotArg(skip) match {
        case Some(arg) => argbuf += NamedArg(name, arg)
        case None => hasError = !skip
      }
    }
    if (hasError || skip) None
    else Some(Annotation(attrType, argbuf.toList))
  } catch {
    case f: FatalError => throw f // don't eat fatal errors, they mean a class was not found
    case ex: Throwable =>
      // We want to be robust when annotations are unavailable, so the very least
      // we can do is warn the user about the exception
      // There was a reference to ticket 1135, but that is outdated: a reference to a class not on
      // the classpath would *not* end up here. A class not found is signaled
      // with a `FatalError` exception, handled above. Here you'd end up after a NPE (for example),
      // and that should never be swallowed silently.
      cctx.warning("Caught: " + ex + " while parsing annotations in " + in.file)
      if (debug) ex.printStackTrace()

      None // ignore malformed annotations
  }

  def parseAttributes(sym: Symbol, symtype: Type): Type = {
    def convertTo(c: Constant, pt: Type): Constant = {
      if (pt.typeSymbol == defn.BooleanClass && c.tag == IntTag)
        Constant(c.value != 0)
      else
        c convertTo pt
    }
    var newType = symtype

    def parseAttribute() {
      val attrName = pool.getName(in.nextChar).toTypeName
      val attrLen = in.nextInt
      val end = in.bp + attrLen
      attrName match {
        case tpnme.SignatureATTR =>
          val sig = pool.getExternalName(in.nextChar)
          newType = sigToType(sig, sym)
          if (debug && verbose)
            println("" + sym + "; signature = " + sig + " type = " + newType)
        case tpnme.SyntheticATTR =>
          sym.setFlag(Flags.SyntheticArtifact)
        case tpnme.BridgeATTR =>
          sym.setFlag(Flags.Bridge)
        case tpnme.DeprecatedATTR =>
          val msg = Literal(Constant("see corresponding Javadoc for more information."))
          val since = Literal(Constant(""))
          sym.addAnnotation(Annotation(defn.DeprecatedAnnot, msg, since))
        case tpnme.ConstantValueATTR =>
          val c = pool.getConstant(in.nextChar)
          val c1 = convertTo(c, symtype)
          if (c1 ne null) newType = ConstantType(c1)
          else println("failure to convert " + c + " to " + symtype); //debug
        case tpnme.AnnotationDefaultATTR =>
          sym.addAnnotation(Annotation(defn.AnnotationDefaultAnnot, Nil))
        // Java annotations on classes / methods / fields with RetentionPolicy.RUNTIME
        case tpnme.RuntimeAnnotationATTR =>
          parseAnnotations(attrLen)

        // TODO 1: parse runtime visible annotations on parameters
        // case tpnme.RuntimeParamAnnotationATTR

        // TODO 2: also parse RuntimeInvisibleAnnotation / RuntimeInvisibleParamAnnotation,
        // i.e. java annotations with RetentionPolicy.CLASS?

        case tpnme.ExceptionsATTR =>
          parseExceptions(attrLen)

        case _ =>
      }
      in.bp = end
    }

    /**
     * Parse the "Exceptions" attribute which denotes the exceptions
     * thrown by a method.
     */
    def parseExceptions(len: Int) {
      val nClasses = in.nextChar
      for (n <- 0 until nClasses) {
        // FIXME: this performs an equivalent of getExceptionTypes instead of getGenericExceptionTypes (SI-7065)
        val cls = pool.getClassSymbol(in.nextChar.toInt)
        sym.addAnnotation(ThrowsAnnotation(cls.asClass))
      }
    }

    /** Parse a sequence of annotations and attaches them to the
     *  current symbol sym, except for the ScalaSignature annotation that it returns, if it is available. */
    def parseAnnotations(len: Int): Unit =  {
      val nAttr = in.nextChar
      for (n <- 0 until nAttr)
        parseAnnotation(in.nextChar) match {
          case Some(annot) =>
            sym.addAnnotation(annot)
          case None =>
        }
    }

    // begin parseAttributes
    for (i <- 0 until in.nextChar) {
      parseAttribute()
    }
    newType
  }

  /** Enter own inner classes in the right scope. It needs the scopes to be set up,
   *  and implicitly current class' superclasses.
   */
  private def enterOwnInnerClasses() {
    def className(name: Name): Name = name.drop(name.lastIndexOf('.') + 1)

    def enterClassAndModule(entry: InnerClassEntry, file: AbstractFile, jflags: Int) =
      loaders.enterClassAndModule(
          getOwner(jflags),
          entry.originalName,
          new ClassfileLoader(file),
          FlagTranslation.classFlags(jflags))

    for (entry <- innerClasses.values) {
      // create a new class member for immediate inner classes
      if (entry.outerName == currentClassName) {
        val file = cctx.platform.classPath.findSourceFile(entry.externalName.toString) getOrElse {
          throw new AssertionError(entry.externalName)
        }
        enterClassAndModule(entry, file, entry.jflags)
      }
    }
  }

  /** Parse inner classes. Expects `in.bp` to point to the superclass entry.
   *  Restores the old `bp`.
   *  @return true iff classfile is from Scala, so no Java info needs to be read.
   */
  def unpickleOrParseInnerClasses(): Boolean = {
    val oldbp = in.bp
    try {
      skipSuperclasses()
      skipMembers() // fields
      skipMembers() // methods
      val attrs = in.nextChar
      val attrbp = in.bp

      def scan(target: TypeName): Boolean = {
        in.bp = attrbp
        var i = 0
        while (i < attrs && pool.getName(in.nextChar).toTypeName != target) {
          val attrLen = in.nextInt
          in.skip(attrLen)
          i += 1
        }
        i < attrs
      }

      def unpickle(bytes: Array[Byte]): Boolean = {
        new UnPickler(bytes, classRoot, moduleRoot).run()
        true
      }

      def parseScalaSigBytes: Array[Byte] = {
        val tag = in.nextByte.toChar
        assert(tag == STRING_TAG, tag)
        pool getBytes in.nextChar
      }

      def parseScalaLongSigBytes: Array[Byte] = {
        val tag = in.nextByte.toChar
        assert(tag == ARRAY_TAG, tag)
        val stringCount = in.nextChar
        val entries =
          for (i <- 0 until stringCount) yield {
            val stag = in.nextByte.toChar
            assert(stag == STRING_TAG, stag)
            in.nextChar.toInt
          }
        pool.getBytes(entries.toList)
      }

      if (scan(tpnme.RuntimeAnnotationATTR)) {
        val attrLen = in.nextInt
        val nAnnots = in.nextChar
        var i = 0
        while (i < nAnnots) {
          val attrClass = pool.getType(in.nextChar).typeSymbol
          val nArgs = in.nextChar
          var j = 0
          while (j < nArgs) {
            val argName = pool.getName(in.nextChar)
            if (attrClass == defn.ScalaSignatureAnnot && argName == nme.bytes)
              return unpickle(parseScalaSigBytes)
            else if (attrClass == defn.ScalaLongSignatureAnnot && argName == nme.bytes)
              return unpickle(parseScalaLongSigBytes)
            else
              parseAnnotArg(skip = true)
            j += 1
          }
          i += 1
        }
      }

      if (scan(tpnme.InnerClassesATTR)) {
        val entries = in.nextChar.toInt
        for (i <- 0 until entries) {
          val innerIndex = in.nextChar
          val outerIndex = in.nextChar
          val nameIndex = in.nextChar
          val jflags = in.nextChar
          if (innerIndex != 0 && outerIndex != 0 && nameIndex != 0) {
            val entry = InnerClassEntry(innerIndex, outerIndex, nameIndex, jflags)
            innerClasses(pool.getClassName(innerIndex)) = entry
          }
        }
      }
      false
    } finally in.bp = oldbp
  }

  /** An entry in the InnerClasses attribute of this class file. */
  case class InnerClassEntry(external: Int, outer: Int, name: Int, jflags: Int) {
    def externalName = pool.getClassName(external)
    def outerName    = pool.getClassName(outer)
    def originalName = pool.getName(name)

    override def toString =
      originalName + " in " + outerName + "(" + externalName +")"
  }

  object innerClasses extends scala.collection.mutable.HashMap[Name, InnerClassEntry] {
    /** Return the Symbol of the top level class enclosing `name`,
     *  or 'name's symbol if no entry found for `name`.
     */
    def topLevelClass(name: Name): Symbol = {
      val tlName = if (isDefinedAt(name)) {
        var entry = this(name)
        while (isDefinedAt(entry.outerName))
          entry = this(entry.outerName)
        entry.outerName
      } else
        name
      classNameToSymbol(tlName)
    }

    /** Return the class symbol for `externalName`. It looks it up in its outer class.
     *  Forces all outer class symbols to be completed.
     *
     *  If the given name is not an inner class, it returns the symbol found in `defn`.
     */
    def classSymbol(externalName: Name): Symbol = {
      /** Return the symbol of `innerName`, having the given `externalName`. */
      def innerSymbol(externalName: Name, innerName: Name, static: Boolean): Symbol = {
        def getMember(sym: Symbol, name: Name): Symbol =
          if (static)
            if (sym == classRoot.symbol) staticScope.lookup(name)
            else sym.companionModule.info.member(name).symbol
          else
            if (sym == classRoot.symbol) instanceScope.lookup(name)
            else sym.info.member(name).symbol

        innerClasses.get(externalName) match {
          case Some(entry) =>
            val outerName = entry.outerName.stripModuleSuffix
            val owner = classSymbol(outerName)
            val result = cctx.atPhaseNotLaterThanTyper { implicit ctx =>
              getMember(owner, innerName.toTypeName)
            }
            assert(result ne NoSymbol,
              s"""failure to resolve inner class:
                 |externalName = $externalName,
                 |outerName = $outerName,
                 |innerName = $innerName
                 |owner.fullName = owner.showFullName
                 |while parsing ${classfile}""".stripMargin)
            result

          case None =>
            classNameToSymbol(externalName)
        }
      }

      get(externalName) match {
        case Some(entry) =>
          innerSymbol(entry.externalName, entry.originalName, isStatic(entry.jflags))
        case None =>
          classNameToSymbol(externalName)
      }
    }
  }

 def skipAttributes() {
    val attrCount = in.nextChar
    for (i <- 0 until attrCount) {
      in.skip(2); in.skip(in.nextInt)
    }
  }

  def skipMembers() {
    val memberCount = in.nextChar
    for (i <- 0 until memberCount) {
      in.skip(6); skipAttributes()
    }
  }

  def skipSuperclasses() {
    in.skip(2) // superclass
    val ifaces = in.nextChar
    in.skip(2 * ifaces)
  }

  protected def getOwner(flags: Int): Symbol =
    if (isStatic(flags)) moduleRoot.symbol else classRoot.symbol

  protected def getScope(flags: Int): MutableScope =
    if (isStatic(flags)) staticScope else instanceScope

  private def setPrivateWithin(denot: SymDenotation, jflags: Int) {
    if ((jflags & (JAVA_ACC_PRIVATE | JAVA_ACC_PUBLIC)) == 0)
      // See ticket #1687 for an example of when topLevelClass is NoSymbol: it
      // apparently occurs when processing v45.3 bytecode.
      if (denot.topLevelClass != NoSymbol)
        denot.privateWithin = denot.topLevelClass.owner
  }

  private def isPrivate(flags: Int)     = (flags & JAVA_ACC_PRIVATE) != 0
  private def isStatic(flags: Int)      = (flags & JAVA_ACC_STATIC) != 0
  private def hasAnnotation(flags: Int) = (flags & JAVA_ACC_ANNOTATION) != 0

  class ConstantPool {
    private val len = in.nextChar
    private val starts = new Array[Int](len)
    private val values = new Array[AnyRef](len)
    private val internalized = new Array[TermName](len)

    { var i = 1
      while (i < starts.length) {
        starts(i) = in.bp
        i += 1
        (in.nextByte.toInt: @switch) match {
          case CONSTANT_UTF8 | CONSTANT_UNICODE =>
            in.skip(in.nextChar)
          case CONSTANT_CLASS | CONSTANT_STRING =>
            in.skip(2)
          case CONSTANT_FIELDREF | CONSTANT_METHODREF | CONSTANT_INTFMETHODREF
             | CONSTANT_NAMEANDTYPE | CONSTANT_INTEGER | CONSTANT_FLOAT =>
            in.skip(4)
          case CONSTANT_LONG | CONSTANT_DOUBLE =>
            in.skip(8)
            i += 1
          case _ =>
            errorBadTag(in.bp - 1)
        }
      }
    }

    /** Return the name found at given index. */
    def getName(index: Int): TermName = {
      if (index <= 0 || len <= index)
        errorBadIndex(index)

      values(index) match {
        case name: TermName => name
        case null   =>
          val start = starts(index)
          if (in.buf(start).toInt != CONSTANT_UTF8) errorBadTag(start)
          val name = termName(in.buf, start + 3, in.getChar(start + 1))
          values(index) = name
          name
      }
    }

    /** Return the name found at given index in the constant pool, with '/' replaced by '.'. */
    def getExternalName(index: Int): TermName = {
      if (index <= 0 || len <= index)
        errorBadIndex(index)

      if (internalized(index) == null)
        internalized(index) = getName(index).replace('/', '.')

      internalized(index)
    }

    def getClassSymbol(index: Int): Symbol = {
      if (index <= 0 || len <= index) errorBadIndex(index)
      var c = values(index).asInstanceOf[Symbol]
      if (c eq null) {
        val start = starts(index)
        if (in.buf(start).toInt != CONSTANT_CLASS) errorBadTag(start)
        val name = getExternalName(in.getChar(start + 1))
        if (name.isModuleName) c = cctx.requiredModule(name.stripModuleSuffix.asTermName)
        else c = classNameToSymbol(name)
        values(index) = c
      }
      c
    }

    /** Return the external name of the class info structure found at 'index'.
     *  Use 'getClassSymbol' if the class is sure to be a top-level class.
     */
    def getClassName(index: Int): TermName = {
      val start = starts(index)
      if (in.buf(start).toInt != CONSTANT_CLASS) errorBadTag(start)
      getExternalName(in.getChar(start + 1))
    }

    /** Return a name and a type at the given index.
     */
    private def getNameAndType(index: Int, ownerTpe: Type): (Name, Type) = {
      if (index <= 0 || len <= index) errorBadIndex(index)
      var p = values(index).asInstanceOf[(Name, Type)]
      if (p eq null) {
        val start = starts(index)
        if (in.buf(start).toInt != CONSTANT_NAMEANDTYPE) errorBadTag(start)
        val name = getName(in.getChar(start + 1).toInt)
        var tpe  = getType(in.getChar(start + 3).toInt)
        // fix the return type, which is blindly set to the class currently parsed
        if (name == nme.CONSTRUCTOR)
          tpe match {
            case tp: MethodType =>
              tp.derivedMethodType(tp.paramNames, tp.paramTypes, ownerTpe)
          }
        p = (name, tpe)
        values(index) = p
      }
      p
    }

    /** Return the type of a class constant entry. Since
     *  arrays are considered to be class types, they might
     *  appear as entries in 'newarray' or 'cast' opcodes.
     */
    def getClassOrArrayType(index: Int): Type = {
      if (index <= 0 || len <= index) errorBadIndex(index)
      val value = values(index)
      var c: Type = null
      if (value eq null) {
        val start = starts(index)
        if (in.buf(start).toInt != CONSTANT_CLASS) errorBadTag(start)
        val name = getExternalName(in.getChar(start + 1))
        if (name(0) == ARRAY_TAG) {
          c = sigToType(name)
          values(index) = c
        } else {
          val sym = classNameToSymbol(name)
          values(index) = sym
          c = sym.typeConstructor
        }
      } else c = value match {
          case tp: Type => tp
          case cls: Symbol => cls.typeConstructor
      }
      c
    }

    def getType(index: Int): Type =
      sigToType(getExternalName(index))

    def getSuperClass(index: Int): Symbol =
      if (index == 0) defn.AnyClass else getClassSymbol(index)

    def getConstant(index: Int): Constant = {
      if (index <= 0 || len <= index) errorBadIndex(index)
      var value = values(index)
      if (value eq null) {
        val start = starts(index)
        value = (in.buf(start).toInt: @switch) match {
          case CONSTANT_STRING =>
            Constant(getName(in.getChar(start + 1).toInt).toString)
          case CONSTANT_INTEGER =>
            Constant(in.getInt(start + 1))
          case CONSTANT_FLOAT =>
            Constant(in.getFloat(start + 1))
          case CONSTANT_LONG =>
            Constant(in.getLong(start + 1))
          case CONSTANT_DOUBLE =>
            Constant(in.getDouble(start + 1))
          case CONSTANT_CLASS =>
            getClassOrArrayType(index).typeSymbol
          case _ =>
            errorBadTag(start)
        }
        values(index) = value
      }
      value match {
        case  ct: Constant => ct
        case cls: Symbol   => Constant(cls.typeConstructor)
        case arr: Type     => Constant(arr)
      }
    }

    private def getSubArray(bytes: Array[Byte]): Array[Byte] = {
      val decodedLength = ByteCodecs.decode(bytes)
      val arr           = new Array[Byte](decodedLength)
      System.arraycopy(bytes, 0, arr, 0, decodedLength)
      arr
    }

    def getBytes(index: Int): Array[Byte] = {
      if (index <= 0 || len <= index) errorBadIndex(index)
      var value = values(index).asInstanceOf[Array[Byte]]
      if (value eq null) {
        val start = starts(index)
        if (in.buf(start).toInt != CONSTANT_UTF8) errorBadTag(start)
        val len   = in.getChar(start + 1)
        val bytes = new Array[Byte](len)
        System.arraycopy(in.buf, start + 3, bytes, 0, len)
        value = getSubArray(bytes)
        values(index) = value
      }
      value
    }

    def getBytes(indices: List[Int]): Array[Byte] = {
      assert(!indices.isEmpty, indices)
      var value = values(indices.head).asInstanceOf[Array[Byte]]
      if (value eq null) {
        val bytesBuffer = ArrayBuffer.empty[Byte]
        for (index <- indices) {
          if (index <= 0 || ConstantPool.this.len <= index) errorBadIndex(index)
          val start = starts(index)
          if (in.buf(start).toInt != CONSTANT_UTF8) errorBadTag(start)
          val len = in.getChar(start + 1)
          bytesBuffer ++= in.buf.view(start + 3, start + 3 + len)
        }
        value = getSubArray(bytesBuffer.toArray)
        values(indices.head) = value
      }
      value
    }

    /** Throws an exception signaling a bad constant index. */
    private def errorBadIndex(index: Int) =
      throw new RuntimeException("bad constant pool index: " + index + " at pos: " + in.bp)

    /** Throws an exception signaling a bad tag at given address. */
    private def errorBadTag(start: Int) =
      throw new RuntimeException("bad constant pool tag " + in.buf(start) + " at byte " + start)
  }
}