Combine cases of several states into a single partial function

Author: phaller

src/async/library/scala/async/Async.scala

@@ -49,7 +49,7 @@ object Async extends AsyncUtils {
           vprintln(s"states of current method:")
           asyncBlockBuilder.asyncStates foreach vprintln
 
-          val handlerExpr = asyncBlockBuilder.mkHandlerExpr()
+          val handlerExpr = asyncBlockBuilder.mkCombinedHandlerExpr()
 
           vprintln(s"GENERATED handler expr:")
           vprintln(handlerExpr)

src/async/library/scala/async/ExprBuilder.scala

@@ -60,47 +60,56 @@ class ExprBuilder[C <: Context with Singleton](val c: C) extends AsyncUtils {
     ValDef(Modifiers(Flag.MUTABLE), resultName, TypeTree(resultType), rhs)
   }
 
-  def mkHandlerTree(num: Int, rhs: c.Tree): c.Tree = {
+  def mkHandlerCase(num: Int, rhs: c.Tree): CaseDef =
+    CaseDef(
+      // pattern
+      Bind(newTermName("any"), Typed(Ident(nme.WILDCARD), Ident(definitions.IntClass))),
+      // guard
+      Apply(Select(Ident(newTermName("any")), newTermName("$eq$eq")), List(Literal(Constant(num)))),
+      rhs
+    )
+  
+  def mkHandlerTreeFor(cases: List[(CaseDef, Int)]): c.Tree = {
     val partFunIdent = Ident(c.mirror.staticClass("scala.PartialFunction"))
     val intIdent = Ident(definitions.IntClass)
     val unitIdent = Ident(definitions.UnitClass)
 
+    val caseCheck =
+      Apply(Select(Apply(Select(Ident(newTermName("List")), newTermName("apply")),
+      cases.map(p => Literal(Constant(p._2)))), newTermName("contains")), List(Ident(newTermName("x$1"))))
+    
     Block(List(
       // anonymous subclass of PartialFunction[Int, Unit]
       ClassDef(Modifiers(FINAL), newTypeName("$anon"), List(), Template(List(AppliedTypeTree(partFunIdent, List(intIdent, unitIdent))),
         emptyValDef, List(
-
           DefDef(Modifiers(), nme.CONSTRUCTOR, List(), List(List()), TypeTree(),
             Block(List(Apply(Select(Super(This(tpnme.EMPTY), tpnme.EMPTY), nme.CONSTRUCTOR), List())), Literal(Constant(())))),
-
+          
           DefDef(Modifiers(), newTermName("isDefinedAt"), List(), List(List(ValDef(Modifiers(PARAM), newTermName("x$1"), intIdent, EmptyTree))), TypeTree(),
-            Apply(Select(Ident(newTermName("x$1")), newTermName("$eq$eq")), List(Literal(Constant(num))))),
+              caseCheck),
 
           DefDef(Modifiers(), newTermName("apply"), List(), List(List(ValDef(Modifiers(PARAM), newTermName("x$1"), intIdent, EmptyTree))), TypeTree(),
-            Match(Ident(newTermName("x$1")), List(
-              CaseDef(
-                // pattern
-                Bind(newTermName("any"), Typed(Ident(nme.WILDCARD), intIdent)),
-                // guard
-                Apply(Select(Ident(newTermName("any")), newTermName("$eq$eq")), List(Literal(Constant(num)))),
-                rhs
-              )
-            ))
+            Match(Ident(newTermName("x$1")), cases.map(_._1)) // combine all cases into a single match
           )
-          
         ))
       )),
       Apply(Select(New(Ident(newTypeName("$anon"))), nme.CONSTRUCTOR), List())
     )
   }
 
+  def mkHandlerTree(num: Int, rhs: c.Tree): c.Tree =
+    mkHandlerTreeFor(List(mkHandlerCase(num, rhs) -> num))
+  
   class AsyncState(stats: List[c.Tree], val state: Int, val nextState: Int) {
     val body: c.Tree =
       if (stats.size == 1) stats.head
       else Block(stats: _*)
 
     val varDefs: List[(c.universe.TermName, c.universe.Type)] = List()
 
+    def mkHandlerCaseForState(): CaseDef =
+      mkHandlerCase(state, Block((stats :+ mkStateTree(nextState) :+ Apply(Ident("resume"), List())): _*))
+    
     def mkHandlerTreeForState(): c.Tree =
       mkHandlerTree(state, Block((stats :+ mkStateTree(nextState) :+ Apply(Ident("resume"), List())): _*))
 
@@ -125,6 +134,9 @@ class ExprBuilder[C <: Context with Singleton](val c: C) extends AsyncUtils {
 
     //TODO mkHandlerTreeForState(nextState: Int)
 
+    override def mkHandlerCaseForState(): CaseDef =
+      mkHandlerCase(state, Block(stats: _*))
+    
     override val toString: String =
       s"AsyncStateWithIf #$state, next = $nextState"
   }
@@ -267,6 +279,11 @@ class ExprBuilder[C <: Context with Singleton](val c: C) extends AsyncUtils {
       mkHandlerTree(state, Block((stats :+ mkOnCompleteStateTree(nextState)): _*))
     }
 
+    override def mkHandlerCaseForState(): CaseDef = {
+      assert(awaitable != null)
+      mkHandlerCase(state, Block((stats :+ mkOnCompleteIncrStateTree): _*))
+    }
+    
     override def varDefForResult: Option[c.Tree] = {
       val rhs =
         if (resultType <:< definitions.IntTpe) Literal(Constant(0))
@@ -469,6 +486,13 @@ class ExprBuilder[C <: Context with Singleton](val c: C) extends AsyncUtils {
     val lastState = stateBuilder.complete(endState).result
     asyncStates += lastState
 
+    def mkCombinedHandlerExpr(): c.Expr[PartialFunction[Int, Unit]] = {
+      assert(asyncStates.size > 1)
+      
+      val cases = for (state <- asyncStates.toList) yield state.mkHandlerCaseForState()
+      c.Expr(mkHandlerTreeFor(cases zip asyncStates.init.map(_.state))).asInstanceOf[c.Expr[PartialFunction[Int, Unit]]]
+    }
+    
     /* Builds the handler expression for a sequence of async states.
      */
     def mkHandlerExpr(): c.Expr[PartialFunction[Int, Unit]] = {