Replace splicing of local ValDefs with explicit trees

Other changes:
- Move class ExprBuilder to its own source file
- Adapt build script

1 files changed, 495 insertions, 0 deletions

diff --git a/src/async/library/scala/async/ExprBuilder.scala b/src/async/library/scala/async/ExprBuilder.scala
new file mode 100644
index 0000000..32af1b3
--- /dev/null
+++ b/src/async/library/scala/async/ExprBuilder.scala
@@ -0,0 +1,495 @@
+/**
+ * Copyright (C) 2012 Typesafe Inc. <http://www.typesafe.com>
+ */
+package scala.async
+
+import scala.reflect.macros.Context
+import scala.collection.mutable.{ ListBuffer, Builder }
+
+/*
+ * @author Philipp Haller
+ */
+class ExprBuilder[C <: Context with Singleton](val c: C) extends AsyncUtils {
+  builder =>
+  
+  import c.universe._
+  import Flag._
+  
+  private val awaitMethod = awaitSym(c)
+  
+  /* Make a partial function literal handling case #num:
+   * 
+   *     {
+   *       case any if any == num => rhs
+   *     }
+   */
+  def mkHandler(num: Int, rhs: c.Expr[Unit]): c.Expr[PartialFunction[Int, Unit]] = {
+/*
+    val numLiteral = c.Expr[Int](Literal(Constant(num)))
+    
+    reify(new PartialFunction[Int, Unit] {
+      def isDefinedAt(`x$1`: Int) =
+        `x$1` == numLiteral.splice
+      def apply(`x$1`: Int) = `x$1` match {
+        case any: Int if any == numLiteral.splice =>
+          rhs.splice
+      }
+    })
+*/
+    val rhsTree = c.resetAllAttrs(rhs.tree.duplicate)
+    val handlerTree = mkHandlerTree(num, rhsTree)
+    c.Expr(handlerTree).asInstanceOf[c.Expr[PartialFunction[Int, Unit]]]
+  }
+  
+  def mkIncrStateTree(): c.Tree =
+    Assign(
+      Ident(newTermName("state")),
+      Apply(Select(Ident(newTermName("state")), newTermName("$plus")), List(Literal(Constant(1)))))
+  
+  def mkStateTree(nextState: Int): c.Tree =
+    Assign(
+      Ident(newTermName("state")),
+      Literal(Constant(nextState)))
+  
+  def mkVarDefTree(resultType: c.universe.Type, resultName: c.universe.TermName): c.Tree = {
+    val rhs =
+      if (resultType <:< definitions.IntTpe) Literal(Constant(0))
+      else if (resultType <:< definitions.LongTpe) Literal(Constant(0L))
+      else if (resultType <:< definitions.BooleanTpe) Literal(Constant(false))
+      else Literal(Constant(null))
+    ValDef(Modifiers(Flag.MUTABLE), resultName, TypeTree(resultType), rhs)
+  }
+  
+  def mkHandlerTree(num: Int, rhs: c.Tree): c.Tree = {
+    val partFunIdent = Ident(c.mirror.staticClass("scala.PartialFunction"))
+    val intIdent = Ident(definitions.IntClass)
+    val unitIdent = Ident(definitions.UnitClass)
+    
+    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))))),
+          
+          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$eq")), List(Literal(Constant(num)))),
+                rhs
+              )
+            ))
+          )
+          
+        ))
+      )),
+      Apply(Select(New(Ident(newTypeName("$anon"))), nme.CONSTRUCTOR), List())
+    )
+  }
+  
+  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 mkHandlerTreeForState(): c.Tree =
+      mkHandlerTree(state, Block((stats :+ mkStateTree(nextState) :+ Apply(Ident("resume"), List())): _*))
+    
+    def mkHandlerTreeForState(nextState: Int): c.Tree =
+      mkHandlerTree(state, Block((stats :+ mkStateTree(nextState) :+ Apply(Ident("resume"), List())): _*))
+    
+    def varDefForResult: Option[c.Tree] =
+      None
+    
+    def allVarDefs: List[c.Tree] =
+      varDefForResult.toList ++ varDefs.map(p => mkVarDefTree(p._2, p._1))
+    
+    override val toString: String =
+      s"AsyncState #$state, next = $nextState"
+  }
+  
+  class AsyncStateWithIf(stats: List[c.Tree], state: Int)
+      extends AsyncState(stats, state, 0) { // nextState unused, since encoded in then and else branches
+    
+    override def mkHandlerTreeForState(): c.Tree =
+      mkHandlerTree(state, Block(stats: _*))
+    
+    //TODO mkHandlerTreeForState(nextState: Int)
+    
+    override val toString: String =
+      s"AsyncStateWithIf #$state, next = $nextState"
+  }
+  
+  abstract class AsyncStateWithAwait(stats: List[c.Tree], state: Int, nextState: Int)
+      extends AsyncState(stats, state, nextState) {
+    val awaitable: c.Tree
+    val resultName: c.universe.TermName
+    val resultType: c.universe.Type
+    
+    override val toString: String =
+      s"AsyncStateWithAwait #$state, next = $nextState"
+    
+    /* Make an `onComplete` invocation:
+     * 
+     *     awaitable.onComplete {
+     *       case tr =>
+     *         resultName = tr.get
+     *         resume()
+     *     }
+     */
+    def mkOnCompleteTree: c.Tree = {
+      val assignTree =
+        Assign(
+          Ident(resultName.toString),
+          Select(Ident("tr"), c.universe.newTermName("get"))
+        )
+      val handlerTree =
+        Match(
+          EmptyTree,
+          List(
+            CaseDef(Bind(c.universe.newTermName("tr"), Ident("_")), EmptyTree,
+              Block(assignTree, Apply(Ident("resume"), List())) // rhs of case
+            )
+          )
+        )
+      Apply(
+        Select(awaitable, c.universe.newTermName("onComplete")),
+        List(handlerTree)
+      )
+    }
+    
+    /* Make an `onComplete` invocation which increments the state upon resuming:
+     * 
+     *     awaitable.onComplete {
+     *       case tr =>
+     *         resultName = tr.get
+     *         state += 1
+     *         resume()
+     *     }
+     */
+    def mkOnCompleteIncrStateTree: c.Tree = {
+      val tryGetTree =
+        Assign(
+          Ident(resultName.toString),
+          Select(Ident("tr"), c.universe.newTermName("get"))
+        )
+      val handlerTree =
+        Match(
+          EmptyTree,
+          List(
+            CaseDef(Bind(c.universe.newTermName("tr"), Ident("_")), EmptyTree,
+              Block(tryGetTree, mkIncrStateTree(), Apply(Ident("resume"), List())) // rhs of case
+            )
+          )
+        )
+      Apply(
+        Select(awaitable, c.universe.newTermName("onComplete")),
+        List(handlerTree)
+      )
+    }
+
+    /* Make an `onComplete` invocation which sets the state to `nextState` upon resuming:
+     * 
+     *     awaitable.onComplete {
+     *       case tr =>
+     *         resultName = tr.get
+     *         state = `nextState`
+     *         resume()
+     *     }
+     */
+    def mkOnCompleteStateTree(nextState: Int): c.Tree = {
+      val tryGetTree =
+        Assign(
+          Ident(resultName.toString),
+          Select(Ident("tr"), c.universe.newTermName("get"))
+        )
+      val handlerTree =
+        Match(
+          EmptyTree,
+          List(
+            CaseDef(Bind(c.universe.newTermName("tr"), Ident("_")), EmptyTree,
+              Block(tryGetTree, mkStateTree(nextState), Apply(Ident("resume"), List())) // rhs of case
+            )
+          )
+        )
+      Apply(
+        Select(awaitable, c.universe.newTermName("onComplete")),
+        List(handlerTree)
+      )
+    }
+
+    /* Make a partial function literal handling case #num:
+     * 
+     *     {
+     *       case any if any == num =>
+     *         stats
+     *         awaitable.onComplete {
+     *           case tr =>
+     *             resultName = tr.get
+     *             resume()
+     *         }
+     *     }
+     */
+    def mkHandlerForState(num: Int): c.Expr[PartialFunction[Int, Unit]] = {
+      assert(awaitable != null)
+      builder.mkHandler(num, c.Expr[Unit](Block((stats :+ mkOnCompleteTree): _*)))
+    }
+    
+    /* Make a partial function literal handling case #num:
+     * 
+     *     {
+     *       case any if any == num =>
+     *         stats
+     *         awaitable.onComplete {
+     *           case tr =>
+     *             resultName = tr.get
+     *             state += 1
+     *             resume()
+     *         }
+     *     }
+     */
+    override def mkHandlerTreeForState(): c.Tree = {
+      assert(awaitable != null)
+      mkHandlerTree(state, Block((stats :+ mkOnCompleteIncrStateTree): _*))
+    }
+    
+    override def mkHandlerTreeForState(nextState: Int): c.Tree = {
+      assert(awaitable != null)
+      mkHandlerTree(state, Block((stats :+ mkOnCompleteStateTree(nextState)): _*))
+    }
+    
+    //TODO: complete for other primitive types, how to handle value classes?
+    override def varDefForResult: Option[c.Tree] = {
+      val rhs =
+        if (resultType <:< definitions.IntTpe) Literal(Constant(0))
+        else if (resultType <:< definitions.LongTpe) Literal(Constant(0L))
+        else if (resultType <:< definitions.BooleanTpe) Literal(Constant(false))
+        else Literal(Constant(null))
+      Some(
+        ValDef(Modifiers(Flag.MUTABLE), resultName, TypeTree(resultType), rhs)
+      )
+    }
+  }
+  
+  /*
+   * Builder for a single state of an async method.
+   */
+  class AsyncStateBuilder(state: Int) extends Builder[c.Tree, AsyncState] {
+    self =>
+    
+    /* Statements preceding an await call. */
+    private val stats = ListBuffer[c.Tree]()
+    
+    /* Argument of an await call. */
+    var awaitable: c.Tree = null
+    
+    /* Result name of an await call. */
+    var resultName: c.universe.TermName = null
+    
+    /* Result type of an await call. */
+    var resultType: c.universe.Type = null
+    
+    var nextState: Int = state + 1
+    
+    private val varDefs = ListBuffer[(c.universe.TermName, c.universe.Type)]()
+    
+    def += (stat: c.Tree): this.type = {
+      stats += c.resetAllAttrs(stat.duplicate)
+      this
+    }
+    
+    //TODO do not ignore `mods`
+    def addVarDef(mods: Any, name: c.universe.TermName, tpt: c.Tree): this.type = {
+      varDefs += (name -> tpt.tpe)
+      this
+    }
+    
+    def result(): AsyncState =
+      if (awaitable == null)
+        new AsyncState(stats.toList, state, nextState) {
+          override val varDefs = self.varDefs.toList
+        }
+      else
+        new AsyncStateWithAwait(stats.toList, state, nextState) {
+          val awaitable = self.awaitable
+          val resultName = self.resultName
+          val resultType = self.resultType
+          override val varDefs = self.varDefs.toList
+        }
+    
+    def clear(): Unit = {
+      stats.clear()
+      awaitable = null
+      resultName = null
+      resultType = null
+    }
+    
+    /* Result needs to be created as a var at the beginning of the transformed method body, so that
+     * it is visible in subsequent states of the state machine.
+     *
+     * @param awaitArg         the argument of await
+     * @param awaitResultName  the name of the variable that the result of await is assigned to
+     * @param awaitResultType  the type of the result of await
+     */
+    def complete(awaitArg: c.Tree, awaitResultName: c.universe.TermName, awaitResultType: Tree, nextState: Int = state + 1): this.type = {
+      awaitable = c.resetAllAttrs(awaitArg.duplicate)
+      resultName = awaitResultName
+      resultType = awaitResultType.tpe
+      this.nextState = nextState
+      this
+    }
+    
+    def complete(nextState: Int): this.type = {
+      this.nextState = nextState
+      this
+    }
+    
+    def resultWithIf(condTree: c.Tree, thenState: Int, elseState: Int): AsyncState = {
+      // 1. build changed if-else tree
+      // 2. insert that tree at the end of the current state
+      val cond = c.resetAllAttrs(condTree.duplicate)
+      this += If(cond,
+          Block(mkStateTree(thenState), Apply(Ident("resume"), List())),
+          Block(mkStateTree(elseState), Apply(Ident("resume"), List())))
+      new AsyncStateWithIf(stats.toList, state) {
+        override val varDefs = self.varDefs.toList
+      }
+    }
+    
+    override def toString: String = {
+      val statsBeforeAwait = stats.mkString("\n")
+      s"ASYNC STATE:\n$statsBeforeAwait \nawaitable: $awaitable \nresult name: $resultName"
+    }
+  }
+
+  class AsyncBlockBuilder(stats: List[c.Tree], expr: c.Tree, startState: Int, endState: Int, budget: Int) {
+    val asyncStates = ListBuffer[builder.AsyncState]()
+    
+    private var stateBuilder = new builder.AsyncStateBuilder(startState) // current state builder
+    private var currState = startState
+    
+    private var remainingBudget = budget
+    
+    // populate asyncStates
+    for (stat <- stats) stat match {
+      // the val name = await(..) pattern
+      case ValDef(mods, name, tpt, Apply(fun, args)) if fun.symbol == awaitMethod =>
+        asyncStates += stateBuilder.complete(args(0), name, tpt).result // complete with await
+        if (remainingBudget > 0)
+          remainingBudget -= 1
+        else
+          assert(false, "too many invocations of `await` in current method")
+        currState += 1
+        stateBuilder = new builder.AsyncStateBuilder(currState)
+        
+      case ValDef(mods, name, tpt, rhs) =>
+        stateBuilder.addVarDef(mods, name, tpt)
+        stateBuilder += // instead of adding `stat` we add a simple assignment
+          Assign(Ident(name), c.resetAllAttrs(rhs.duplicate))
+        
+      case If(cond, thenp, elsep) =>
+        val ifBudget: Int = remainingBudget / 2
+        remainingBudget -= ifBudget //TODO test if budget > 0
+        vprintln(s"ASYNC IF: ifBudget = $ifBudget")
+        // state that we continue with after if-else: currState + ifBudget
+        
+        val thenBudget: Int = ifBudget / 2
+        val elseBudget = ifBudget - thenBudget
+        
+        asyncStates +=
+          // the two Int arguments are the start state of the then branch and the else branch, respectively
+          stateBuilder.resultWithIf(cond, currState + 1, currState + thenBudget)
+        
+        val thenBuilder = thenp match {
+          case Block(thenStats, thenExpr) =>
+            new AsyncBlockBuilder(thenStats, thenExpr, currState + 1, currState + ifBudget, thenBudget)
+          case _ =>
+            new AsyncBlockBuilder(List(thenp), Literal(Constant(())), currState + 1, currState + ifBudget, thenBudget)
+        }
+        vprintln("ASYNC IF: thenBuilder: "+thenBuilder)
+        vprintln("ASYNC IF: states of thenp:")
+        for (s <- thenBuilder.asyncStates)
+          vprintln(s.toString)
+        
+        // insert states of thenBuilder into asyncStates
+        asyncStates ++= thenBuilder.asyncStates
+        
+        val elseBuilder = elsep match {
+          case Block(elseStats, elseExpr) =>
+            new AsyncBlockBuilder(elseStats, elseExpr, currState + thenBudget, currState + ifBudget, elseBudget)
+          case _ =>
+            new AsyncBlockBuilder(List(elsep), Literal(Constant(())), currState + thenBudget, currState + ifBudget, elseBudget)
+        }
+        vprintln("ASYNC IF: elseBuilder: "+elseBuilder)
+        vprintln("ASYNC IF: states of elsep:")
+        for (s <- elseBuilder.asyncStates)
+          vprintln(s.toString)
+        
+        // insert states of elseBuilder into asyncStates
+        asyncStates ++= elseBuilder.asyncStates
+        
+        // create new state builder for state `currState + ifBudget`
+        currState = currState + ifBudget
+        stateBuilder = new builder.AsyncStateBuilder(currState)
+        
+      case _ =>
+        stateBuilder += stat
+    }
+    // complete last state builder (representing the expressions after the last await)
+    stateBuilder += expr
+    val lastState = stateBuilder.complete(endState).result
+    vprintln("ASYNC: last state of current AsyncBlockBuilder "+this+":")
+    vprintln("ASYNC: "+lastState)
+    asyncStates += lastState
+    
+    /* Builds the handler expression for a sequence of async states.
+     */
+    def mkHandlerExpr(): c.Expr[PartialFunction[Int, Unit]] = {
+      assert(asyncStates.size > 1)
+      
+      vprintln(s"!!ASYNC mkHandlerExpr: asyncStates.size = ${asyncStates.size}")
+      vprintln(s"!!ASYNC state 0: ${asyncStates(0)}")
+      
+      var handlerTree =
+        if (asyncStates.size > 2) asyncStates(0).mkHandlerTreeForState()
+        else asyncStates(0).mkHandlerTreeForState()
+      var handlerExpr =
+        c.Expr(handlerTree).asInstanceOf[c.Expr[PartialFunction[Int, Unit]]]
+      
+      if (asyncStates.size == 2)
+        handlerExpr
+      else if (asyncStates.size == 3) {
+        // asyncStates(1) must continue with endState
+        val handlerTreeForLastState = asyncStates(1).mkHandlerTreeForState()
+        val currentHandlerTreeNaked = c.resetAllAttrs(handlerExpr.tree.duplicate)
+        c.Expr(
+          Apply(Select(currentHandlerTreeNaked, newTermName("orElse")),
+                List(handlerTreeForLastState))).asInstanceOf[c.Expr[PartialFunction[Int, Unit]]]
+      } else { // asyncStates.size > 3
+        vprintln("!!ASYNC start for loop")
+        
+        // do not traverse first state: asyncStates.tail
+        // do not traverse last state:  asyncStates.tail.init
+        for (asyncState <- asyncStates.tail.init) {
+          vprintln(s"!!ASYNC current asyncState: $asyncState")
+          val handlerTreeForNextState = asyncState.mkHandlerTreeForState()
+          val currentHandlerTreeNaked = c.resetAllAttrs(handlerExpr.tree.duplicate)
+          handlerExpr = c.Expr(
+            Apply(Select(currentHandlerTreeNaked, newTermName("orElse")),
+                  List(handlerTreeForNextState))).asInstanceOf[c.Expr[PartialFunction[Int, Unit]]]
+        }
+        handlerExpr
+      }
+    }
+
+  }
+}