Scala example source code file (Members.scala)

This example Scala source code file (Members.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

basicblock, boolean, imember, imethod, int, int, io, list, list, local, nil, nil, option, symbol, symbol

The Scala Members.scala source code

/* NSC -- new scala compiler
 * Copyright 2005-2011 LAMP/EPFL
 * @author  Martin Odersky
 */


package scala.tools.nsc
package backend
package icode

import java.io.PrintWriter
import scala.collection.{ mutable, immutable }
import mutable.{ HashMap, ListBuffer }
import symtab.Flags.{ DEFERRED }
  
trait ReferenceEquality {
  override def hashCode = System.identityHashCode(this)
  override def equals(that: Any) = this eq that.asInstanceOf[AnyRef]
}

trait Members { self: ICodes =>
  import global._

  /** 
   * This class represents the intermediate code of a method or
   * other multi-block piece of code, like exception handlers.
   */
  class Code(label: String, method: IMethod) {
    def this(method: IMethod) = this(method.symbol.simpleName.toString, method)

    /** The set of all blocks */
    val blocks: ListBuffer[BasicBlock] = new ListBuffer

    /** The start block of the method */
    var startBlock: BasicBlock = null

    /** The stack produced by this method */
    var producedStack: TypeStack = null
    
    private var currentLabel: Int = 0
    private var _touched = false

    def touched = _touched
    def touched_=(b: Boolean): Unit = {
      if (b)
        blocks foreach (_.touched = true)
      
      _touched = b
    }

    // Constructor code
    startBlock = newBlock

    def removeBlock(b: BasicBlock) {
      if (settings.debug.value) {
        assert(blocks forall (p => !(p.successors contains b)),
          "Removing block that is still referenced in method code " + b + "preds: " + b.predecessors
        )
        assert(b != startBlock || b.successors.length == 1,
          "Removing start block with more than one successor."
        )
      }

      if (b == startBlock)
        startBlock = b.successors.head
        
      blocks -= b      
      assert(!blocks.contains(b))
      method.exh filter (_ covers b) foreach (_.covered -= b)
      touched = true
    }

    /** This methods returns a string representation of the ICode */
    override def toString() : String = "ICode '" + label + "'";
    
    /* Compute a unique new label */
    def nextLabel: Int = {
      currentLabel += 1
      currentLabel
    }

    /* Create a new block and append it to the list
     */
    def newBlock: BasicBlock = {
      touched = true
      val block = new BasicBlock(nextLabel, method);
      blocks += block;
      block
    }    
  }
  
  /** Common interface for IClass/IField/IMethod. */
  trait IMember extends Ordered[IMember] {
    def symbol: Symbol
      
    def compare(other: IMember) = 
      if (symbol eq other.symbol) 0
      else if (symbol isLess other.symbol) -1
      else 1
  }

  /** Represent a class in ICode */
  class IClass(val symbol: Symbol) extends IMember {
    var fields: List[IField] = Nil
    var methods: List[IMethod] = Nil
    var cunit: CompilationUnit = _
    var bootstrapClass: Option[String] = None

    def addField(f: IField): this.type = {
      fields = f :: fields;
      this
    }

    def addMethod(m: IMethod): this.type = {
      methods = m :: methods;
      this
    }

    def setCompilationUnit(unit: CompilationUnit): this.type = {
      this.cunit = unit;
      this
    }

    override def toString() = symbol.fullName

    def lookupField(s: Symbol)  = fields find (_.symbol == s)
    def lookupMethod(s: Symbol) = methods find (_.symbol == s)
    def lookupMethod(s: Name)   = methods find (_.symbol.name == s)

    /* returns this methods static ctor if it has one. */
    def lookupStaticCtor: Option[IMethod] = methods find (_.symbol.isStaticConstructor)
  }

  /** Represent a field in ICode */
  class IField(val symbol: Symbol) extends IMember { }

  /** 
   * Represents a method in ICode. Local variables contain
   * both locals and parameters, similar to the way the JVM 
   * 'sees' them.
   * 
   * Locals and parameters are added in reverse order, as they
   * are kept in cons-lists. The 'builder' is responsible for
   * reversing them and putting them back, when the generation is
   * finished (GenICode does that).
   */
  class IMethod(val symbol: Symbol) extends IMember {
    var code: Code = null
    var native = false

    /** The list of exception handlers, ordered from innermost to outermost. */
    var exh: List[ExceptionHandler] = Nil
    var sourceFile: String = _
    var returnType: TypeKind = _

    var recursive: Boolean = false

    /** local variables and method parameters */
    var locals: List[Local] = Nil

    /** method parameters */
    var params: List[Local] = Nil

    def hasCode = code != null
    def setCode(code: Code): IMethod = {
      this.code = code;
      this
    }

    def addLocal(l: Local): Local =
      locals find (_ == l) getOrElse {
        locals ::= l
        l
      }


    def addParam(p: Local): Unit =
      if (params contains p) ()
      else {
        params ::= p
        locals ::= p
      }

    def addLocals(ls: List[Local]) = ls foreach addLocal
    def addParams(as: List[Local]) = as foreach addParam

    def lookupLocal(n: Name): Option[Local]     = locals find (_.sym.name == n)
    def lookupLocal(sym: Symbol): Option[Local] = locals find (_.sym == sym)

    def addHandler(e: ExceptionHandler) = exh ::= e

    /** Is this method deferred ('abstract' in Java sense)?
     */
    def isAbstractMethod = symbol.isDeferred || symbol.owner.isInterface || native
    
    def isStatic: Boolean = symbol.isStaticMember
    
    override def toString() = symbol.fullName
    
    import opcodes._
    def checkLocals(): Unit = {
      def localsSet = code.blocks.flatten collect {
        case LOAD_LOCAL(l)  => l
        case STORE_LOCAL(l) => l
      } toSet
      
      if (code != null) {
        log("[checking locals of " + this + "]")
        locals filterNot localsSet foreach { l =>
          log("Local " + l + " is not declared in " + this)
        }
      }
    }

    /** Merge together blocks that have a single successor which has a 
     * single predecessor. Exception handlers are taken into account (they
     * might force to break a block of straight line code like that).
     *
     * This method should be most effective after heavy inlining.
     */
    def normalize(): Unit = if (this.code ne null) {
      val nextBlock: mutable.Map[BasicBlock, BasicBlock] = mutable.HashMap.empty
      for (b <- code.blocks.toList
        if b.successors.length == 1; 
        val succ = b.successors.head; 
        if succ ne b;
        if succ.predecessors.length == 1;
        if succ.predecessors.head eq b;
        if !(exh.exists { (e: ExceptionHandler) => 
            (e.covers(succ) && !e.covers(b)) || (e.covers(b) && !e.covers(succ)) })) {
          nextBlock(b) = succ
      }
          
      var bb = code.startBlock
      while (!nextBlock.isEmpty) {
        if (nextBlock.isDefinedAt(bb)) {
          bb.open
          var succ = bb
          do {
            succ = nextBlock(succ);
            bb.removeLastInstruction
            succ.toList foreach { i => bb.emit(i, i.pos) }
            code.removeBlock(succ)
            nextBlock -= bb
            exh foreach { e => e.covered = e.covered - succ }
          } while (nextBlock.isDefinedAt(succ))
          bb.close
        } else 
          bb = nextBlock.keysIterator.next
      }
      checkValid(this)
    }
    
    def dump() {
      val printer = new TextPrinter(new PrintWriter(Console.out, true),
                                    new DumpLinearizer)
      printer.printMethod(this)
    }    
  }

  /** Represent local variables and parameters */
  class Local(val sym: Symbol, val kind: TypeKind, val arg: Boolean) {
    var index: Int = -1

    /** Starting PC for this local's visibility range. */
    var start: Int = _
    
    /** Ending PC for this local's visibility range. */
    var end: Int = _
    
    /** PC-based ranges for this local variable's visibility */
    var ranges: List[(Int, Int)] = Nil

    override def equals(other: Any): Boolean = other match {
      case x: Local => sym == x.sym
      case _        => false
    }
    override def hashCode = sym.hashCode
    override def toString(): String = sym.toString
  }
}