Merge pull request #3634 from dotty-staging/add-meta

A symmetric meta programming framework

Author: odersky

compiler/src/dotty/tools/dotc/CompilationUnit.scala

@@ -21,6 +21,11 @@ class CompilationUnit(val source: SourceFile) {
 
   /** Pickled TASTY binaries, indexed by class. */
   var pickled: Map[ClassSymbol, Array[Byte]] = Map()
+
+  /** Will be reset to `true` if `untpdTree` contains `Quote` trees. The information
+   *  is used in phase ReifyQuotes in order to avoid traversing a quote-less tree.
+   */
+  var containsQuotesOrSplices: Boolean = false
 }
 
 object CompilationUnit {

compiler/src/dotty/tools/dotc/Compiler.scala

@@ -47,9 +47,10 @@ class Compiler {
       List(new sbt.ExtractAPI),     // Sends a representation of the API of classes to sbt via callbacks
       List(new Pickler),            // Generate TASTY info
       List(new LinkAll),            // Reload compilation units from TASTY for library code (if needed)
+      List(new ReifyQuotes),        // Turn quoted trees into explicit run-time data structures
       List(new FirstTransform,      // Some transformations to put trees into a canonical form
            new CheckReentrant,      // Internal use only: Check that compiled program has no data races involving global vars
-           new ElimJavaPackages),   // Eliminate syntactic references to Java packages
+           new ElimPackagePrefixes), // Eliminate references to package prefixes in Select nodes
       List(new CheckStatic,         // Check restrictions that apply to @static members
            new ElimRepeated,        // Rewrite vararg parameters and arguments
            new NormalizeFlags,      // Rewrite some definition flags
@@ -59,16 +60,16 @@ class Compiler {
            new ByNameClosures,      // Expand arguments to by-name parameters to closures
            new LiftTry,             // Put try expressions that might execute on non-empty stacks into their own methods
            new HoistSuperArgs,      // Hoist complex arguments of supercalls to enclosing scope
-           new ClassOf,            // Expand `Predef.classOf` calls.
-           new RefChecks),           // Various checks mostly related to abstract members and overriding
+           new ClassOf,             // Expand `Predef.classOf` calls.
+           new RefChecks),          // Various checks mostly related to abstract members and overriding
       List(new TryCatchPatterns,    // Compile cases in try/catch
            new PatternMatcher,      // Compile pattern matches
            new ExplicitOuter,       // Add accessors to outer classes from nested ones.
            new ExplicitSelf,        // Make references to non-trivial self types explicit as casts
            new ShortcutImplicits,   // Allow implicit functions without creating closures
            new CrossCastAnd,        // Normalize selections involving intersection types.
            new Splitter),           // Expand selections involving union types into conditionals
-      List(new PhantomArgLift, // Extracts the evaluation of phantom arguments placing them before the call.
+      List(new PhantomArgLift,      // Extracts the evaluation of phantom arguments placing them before the call.
            new VCInlineMethods,     // Inlines calls to value class methods
            new SeqLiterals,         // Express vararg arguments as arrays
            new InterceptedMethods,  // Special handling of `==`, `|=`, `getClass` methods

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -1069,7 +1069,8 @@ object desugar {
           Select(t, op.name)
         }
       case PrefixOp(op, t) =>
-        Select(t, nme.UNARY_PREFIX ++ op.name)
+        val nspace = if (ctx.mode.is(Mode.Type)) tpnme else nme
+        Select(t, nspace.UNARY_PREFIX ++ op.name)
       case Tuple(ts) =>
         val arity = ts.length
         def tupleTypeRef = defn.TupleType(arity)

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -264,7 +264,7 @@ trait UntypedTreeInfo extends TreeInfo[Untyped] { self: Trees.Instance[Untyped]
    */
   def lacksDefinition(mdef: MemberDef)(implicit ctx: Context) = mdef match {
     case mdef: ValOrDefDef =>
-      mdef.unforcedRhs == EmptyTree && !mdef.name.isConstructorName && !mdef.mods.is(ParamAccessor)
+      mdef.unforcedRhs == EmptyTree && !mdef.name.isConstructorName && !mdef.mods.is(TermParamOrAccessor)
     case mdef: TypeDef =>
       def isBounds(rhs: Tree): Boolean = rhs match {
         case _: TypeBoundsTree => true

compiler/src/dotty/tools/dotc/ast/TreeTypeMap.scala

@@ -31,7 +31,7 @@ import dotty.tools.dotc.transform.SymUtils._
  *  gets two different denotations in the same period. Hence, if -Yno-double-bindings is
  *  set, we would get a data race assertion error.
  */
-final class TreeTypeMap(
+class TreeTypeMap(
   val typeMap: Type => Type = IdentityTypeMap,
   val treeMap: tpd.Tree => tpd.Tree = identity _,
   val oldOwners: List[Symbol] = Nil,
@@ -154,7 +154,7 @@ final class TreeTypeMap(
       assert(!to.exists(substFrom contains _))
       assert(!from.exists(newOwners contains _))
       assert(!to.exists(oldOwners contains _))
-      new TreeTypeMap(
+      newMap(
         typeMap,
         treeMap,
         from ++ oldOwners,
@@ -163,6 +163,16 @@ final class TreeTypeMap(
         to ++ substTo)
     }
 
+  /** A new map of the same class this one */
+  protected def newMap(
+      typeMap: Type => Type,
+      treeMap: Tree => Tree,
+      oldOwners: List[Symbol],
+      newOwners: List[Symbol],
+      substFrom: List[Symbol],
+      substTo: List[Symbol])(implicit ctx: Context) =
+    new TreeTypeMap(typeMap, treeMap, oldOwners, newOwners, substFrom, substTo)
+
   /** Apply `typeMap` and `ownerMap` to given symbols `syms`
    *  and return a treemap that contains the substitution
    *  between original and mapped symbols.

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -104,6 +104,12 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       Closure(Nil, call, targetTpt))
   }
 
+  /** A closure whole anonymous function has the given method type */
+  def Lambda(tpe: MethodType, rhsFn: List[Tree] => Tree)(implicit ctx: Context): Block = {
+    val meth = ctx.newSymbol(ctx.owner, nme.ANON_FUN, Synthetic | Method, tpe)
+    Closure(meth, tss => rhsFn(tss.head).changeOwner(ctx.owner, meth))
+  }
+
   def CaseDef(pat: Tree, guard: Tree, body: Tree)(implicit ctx: Context): CaseDef =
     ta.assignType(untpd.CaseDef(pat, guard, body), body)
 

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -69,7 +69,10 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
 
   case class InfixOp(left: Tree, op: Ident, right: Tree) extends OpTree
   case class PostfixOp(od: Tree, op: Ident) extends OpTree
-  case class PrefixOp(op: Ident, od: Tree) extends OpTree
+  case class PrefixOp(op: Ident, od: Tree) extends OpTree {
+    override def isType = op.isType
+    override def isTerm = op.isTerm
+  }
   case class Parens(t: Tree) extends ProxyTree {
     def forwardTo = t
   }
@@ -78,6 +81,7 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
     override def isType = !isTerm
   }
   case class Throw(expr: Tree) extends TermTree
+  case class Quote(expr: Tree) extends TermTree
   case class WhileDo(cond: Tree, body: Tree) extends TermTree
   case class DoWhile(body: Tree, cond: Tree) extends TermTree
   case class ForYield(enums: List[Tree], expr: Tree) extends TermTree
@@ -449,6 +453,10 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
       case tree: Throw if expr eq tree.expr => tree
       case _ => finalize(tree, untpd.Throw(expr))
     }
+    def Quote(tree: Tree)(expr: Tree) = tree match {
+      case tree: Quote if expr eq tree.expr => tree
+      case _ => finalize(tree, untpd.Quote(expr))
+    }
     def WhileDo(tree: Tree)(cond: Tree, body: Tree) = tree match {
       case tree: WhileDo if (cond eq tree.cond) && (body eq tree.body) => tree
       case _ => finalize(tree, untpd.WhileDo(cond, body))
@@ -507,6 +515,8 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
         cpy.Tuple(tree)(transform(trees))
       case Throw(expr) =>
         cpy.Throw(tree)(transform(expr))
+      case Quote(expr) =>
+        cpy.Quote(tree)(transform(expr))
       case WhileDo(cond, body) =>
         cpy.WhileDo(tree)(transform(cond), transform(body))
       case DoWhile(body, cond) =>
@@ -554,6 +564,8 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
         this(x, trees)
       case Throw(expr) =>
         this(x, expr)
+      case Quote(expr) =>
+        this(x, expr)
       case WhileDo(cond, body) =>
         this(this(x, cond), body)
       case DoWhile(body, cond) =>

compiler/src/dotty/tools/dotc/config/Printers.scala

@@ -11,26 +11,27 @@ object Printers {
   }
 
   val default: Printer = new Printer
-  val dottydoc: Printer = noPrinter
-  val core: Printer = noPrinter
-  val typr: Printer = noPrinter
+
   val constr: Printer = noPrinter
+  val core: Printer = noPrinter
   val checks: Printer = noPrinter
-  val overload: Printer = noPrinter
-  val implicits: Printer = noPrinter
-  val implicitsDetailed: Printer = noPrinter
-  val subtyping: Printer = noPrinter
-  val unapp: Printer = noPrinter
-  val gadts: Printer = noPrinter
-  val hk: Printer = noPrinter
-  val variances: Printer = noPrinter
-  val incremental: Printer = noPrinter
   val config: Printer = noPrinter
-  val transforms: Printer = noPrinter
   val cyclicErrors: Printer = noPrinter
-  val pickling: Printer = noPrinter
-  val inlining: Printer = noPrinter
+  val dottydoc: Printer = noPrinter
   val exhaustivity: Printer = noPrinter
+  val incremental: Printer = noPrinter
+  val gadts: Printer = noPrinter
+  val hk: Printer = noPrinter
+  val implicits: Printer = noPrinter
+  val implicitsDetailed: Printer = noPrinter
+  val inlining: Printer = noPrinter
+  val overload: Printer = noPrinter
   val patmatch: Printer = noPrinter
+  val pickling: Printer = noPrinter
   val simplify: Printer = noPrinter
+  val subtyping: Printer = noPrinter
+  val transforms: Printer = noPrinter
+  val typr: Printer = noPrinter
+  val unapp: Printer = noPrinter
+  val variances: Printer = noPrinter
 }

compiler/src/dotty/tools/dotc/core/Contexts.scala

@@ -359,6 +359,15 @@ object Contexts {
       else if (untpd.isSuperConstrCall(stat) && this.owner.isClass) superCallContext
       else ctx.fresh.setOwner(exprOwner)
 
+    /** A new context that summarizes an import statement */
+    def importContext(imp: Import[_], sym: Symbol) = {
+      val impNameOpt = imp.expr match {
+        case ref: RefTree[_] => Some(ref.name.asTermName)
+        case _               => None
+      }
+      ctx.fresh.setImportInfo(new ImportInfo(implicit ctx => sym, imp.selectors, impNameOpt))
+    }
+
     /** The current source file; will be derived from current
      *  compilation unit.
      */

compiler/src/dotty/tools/dotc/core/Decorators.scala

@@ -175,6 +175,10 @@ object Decorators {
     recur(enclosingInlineds, pos)
   }
 
+  implicit class reportingDeco[T](val x: T) extends AnyVal {
+    def reporting(op: T => String): T = { println(op(x)); x }
+  }
+
   implicit class StringInterpolators(val sc: StringContext) extends AnyVal {
 
     /** General purpose string formatting */

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -5,7 +5,6 @@ package core
 import Types._, Contexts._, Symbols._, Denotations._, SymDenotations._, StdNames._, Names._
 import Flags._, Scopes._, Decorators._, NameOps._, util.Positions._, Periods._
 import unpickleScala2.Scala2Unpickler.ensureConstructor
-import scala.annotation.{ switch, meta }
 import scala.collection.{ mutable, immutable }
 import PartialFunction._
 import collection.mutable
@@ -146,11 +145,20 @@ class Definitions {
   }
 
   private def enterPolyMethod(cls: ClassSymbol, name: TermName, typeParamCount: Int,
-                    resultTypeFn: PolyType => Type, flags: FlagSet = EmptyFlags) = {
+                    resultTypeFn: PolyType => Type, flags: FlagSet = EmptyFlags,
+                    useCompleter: Boolean = false) = {
     val tparamNames = PolyType.syntheticParamNames(typeParamCount)
     val tparamInfos = tparamNames map (_ => TypeBounds.empty)
-    val ptype = PolyType(tparamNames)(_ => tparamInfos, resultTypeFn)
-    enterMethod(cls, name, ptype, flags)
+    def ptype = PolyType(tparamNames)(_ => tparamInfos, resultTypeFn)
+    val info =
+      if (useCompleter)
+        new LazyType {
+          def complete(denot: SymDenotation)(implicit ctx: Context): Unit = {
+            denot.info = ptype
+          }
+        }
+      else ptype
+    enterMethod(cls, name, info, flags)
   }
 
   private def enterT1ParameterlessMethod(cls: ClassSymbol, name: TermName, resultTypeFn: PolyType => Type, flags: FlagSet) =
@@ -290,14 +298,23 @@ class Definitions {
   /** Marker method to indicate an argument to a call-by-name parameter.
    *  Created by byNameClosures and elimByName, eliminated by Erasure,
    */
-  lazy val cbnArg = enterPolyMethod(
-      OpsPackageClass, nme.cbnArg, 1,
+  lazy val cbnArg = enterPolyMethod(OpsPackageClass, nme.cbnArg, 1,
       pt => MethodType(List(FunctionOf(Nil, pt.paramRefs(0))), pt.paramRefs(0)))
 
   /** Method representing a throw */
   lazy val throwMethod = enterMethod(OpsPackageClass, nme.THROWkw,
       MethodType(List(ThrowableType), NothingType))
 
+  /** Method representing a term quote */
+  lazy val quoteMethod = enterPolyMethod(OpsPackageClass, nme.QUOTE, 1,
+      pt => MethodType(pt.paramRefs(0) :: Nil, QuotedExprType.appliedTo(pt.paramRefs(0) :: Nil)),
+      useCompleter = true)
+
+  /** Method representing a type quote */
+  lazy val typeQuoteMethod = enterPolyMethod(OpsPackageClass, nme.TYPE_QUOTE, 1,
+      pt => QuotedTypeType.appliedTo(pt.paramRefs(0) :: Nil),
+      useCompleter = true)
+
   lazy val NothingClass: ClassSymbol = enterCompleteClassSymbol(
     ScalaPackageClass, tpnme.Nothing, AbstractFinal, List(AnyClass.typeRef))
   def NothingType = NothingClass.typeRef
@@ -585,6 +602,21 @@ class Definitions {
   def ClassTagClass(implicit ctx: Context) = ClassTagType.symbol.asClass
   def ClassTagModule(implicit ctx: Context) = ClassTagClass.companionModule
 
+  lazy val QuotedExprType = ctx.requiredClassRef("scala.quoted.Expr")
+  def QuotedExprClass(implicit ctx: Context) = QuotedExprType.symbol.asClass
+
+    def QuotedExpr_~(implicit ctx: Context) = QuotedExprClass.requiredMethod(nme.UNARY_~)
+    def QuotedExpr_run(implicit ctx: Context) = QuotedExprClass.requiredMethod(nme.run)
+
+  lazy val QuotedTypeType = ctx.requiredClassRef("scala.quoted.Type")
+  def QuotedTypeClass(implicit ctx: Context) = QuotedTypeType.symbol.asClass
+
+    def QuotedType_~(implicit ctx: Context) =
+      QuotedTypeClass.info.member(tpnme.UNARY_~).symbol.asType
+
+  def Unpickler_unpickleExpr = ctx.requiredMethod("scala.runtime.quoted.Unpickler.unpickleExpr")
+  def Unpickler_unpickleType = ctx.requiredMethod("scala.runtime.quoted.Unpickler.unpickleType")
+
   lazy val EqType = ctx.requiredClassRef("scala.Eq")
   def EqClass(implicit ctx: Context) = EqType.symbol.asClass
   def EqModule(implicit ctx: Context) = EqClass.companionModule
@@ -1071,7 +1103,8 @@ class Definitions {
     OpsPackageClass)
 
   /** Lists core methods that don't have underlying bytecode, but are synthesized on-the-fly in every reflection universe */
-  lazy val syntheticCoreMethods = AnyMethods ++ ObjectMethods ++ List(String_+, throwMethod)
+  lazy val syntheticCoreMethods =
+    AnyMethods ++ ObjectMethods ++ List(String_+, throwMethod, quoteMethod, typeQuoteMethod)
 
   lazy val reservedScalaClassNames: Set[Name] = syntheticScalaClasses.map(_.name).toSet
 
@@ -1081,13 +1114,13 @@ class Definitions {
   def init()(implicit ctx: Context) = {
     this.ctx = ctx
     if (!_isInitialized) {
-      // force initialization of every symbol that is synthesized or hijacked by the compiler
-      val forced = syntheticCoreClasses ++ syntheticCoreMethods ++ ScalaValueClasses()
-
       // Enter all symbols from the scalaShadowing package in the scala package
       for (m <- ScalaShadowingPackageClass.info.decls)
         ScalaPackageClass.enter(m)
 
+      // force initialization of every symbol that is synthesized or hijacked by the compiler
+      val forced = syntheticCoreClasses ++ syntheticCoreMethods ++ ScalaValueClasses()
+
       _isInitialized = true
     }
   }

compiler/src/dotty/tools/dotc/core/Flags.scala

@@ -414,7 +414,7 @@ object Flags {
   /** A Scala 2.12 or higher trait */
   final val Scala_2_12_Trait = typeFlag(58, "<scala_2_12_trait>")
 
-  /** A macro (Scala 2.x only) */
+  /** A macro */
   final val Macro = commonFlag(59, "<macro>")
 
   /** A method that is known to have inherited default parameters */
@@ -575,7 +575,7 @@ object Flags {
   final val SyntheticOrPrivate = Synthetic | Private
 
   /** A deferred member or a parameter accessor (these don't have right hand sides) */
-  final val DeferredOrParamAccessor = Deferred | ParamAccessor
+  final val DeferredOrParamOrAccessor = Deferred | Param | ParamAccessor
 
   /** value that's final or inline */
   final val FinalOrInline = Final | Inline
@@ -598,6 +598,9 @@ object Flags {
   /** Is a default parameter in Scala 2*/
   final val DefaultParameter = allOf(Param, DefaultParameterized)
 
+  /** A Scala 2 Macro */
+  final val Scala2Macro = allOf(Macro, Scala2x)
+
   /** A trait that does not need to be initialized */
   final val NoInitsTrait = allOf(Trait, NoInits)
 

compiler/src/dotty/tools/dotc/core/Phases.scala

@@ -276,6 +276,10 @@ object Phases {
      *  and type applications.
      */
     def relaxedTyping: Boolean = false
+
+    /** If set, implicit search is enabled */
+    def allowsImplicitSearch: Boolean = false
+
      /** List of names of phases that should precede this phase */
     def runsAfter: Set[Class[_ <: Phase]] = Set.empty
 

compiler/src/dotty/tools/dotc/core/StdNames.scala

@@ -143,6 +143,8 @@ object StdNames {
     val INITIALIZER_PREFIX: N         = "initial$"
     val COMPANION_MODULE_METHOD: N    = "companion$module"
     val COMPANION_CLASS_METHOD: N     = "companion$class"
+    val QUOTE: N                      = "'"
+    val TYPE_QUOTE: N                = "type_'"
     val TRAIT_SETTER_SEPARATOR: N     = str.TRAIT_SETTER_SEPARATOR
 
     // value types (and AnyRef) are all used as terms as well
@@ -484,6 +486,7 @@ object StdNames {
     val reflect : N             = "reflect"
     val reify : N               = "reify"
     val rootMirror : N          = "rootMirror"
+    val run: N                  = "run"
     val runOrElse: N            = "runOrElse"
     val runtime: N              = "runtime"
     val runtimeClass: N         = "runtimeClass"