Merge pull request #4399 from dotty-staging/explore-tasty-extractors

Add sample extractors to tasty/definitions test.

Author: odersky

tests/pos/tasty/definitions.scala

@@ -2,7 +2,7 @@ package tasty
 
 object definitions {
 
-// ------ Names --------------------------------
+// ====== Names ======================================
 
   trait Name
   trait PossiblySignedName
@@ -23,45 +23,62 @@ object definitions {
 
   case class TypeName(name: TermName) extends Name
 
-// ------ Positions ---------------------------
+// ====== Positions ==================================
 
-  case class Position(firstOffset: Int, lastOffset: Int)
+  case class Position(firstOffset: Int, lastOffset: Int, sourceFile: String) {
+    def startLine: Int = ???
+    def startColumn: Int = ???
+    def endLine: Int = ???
+    def endColumn: Int = ???
+  }
 
   trait Positioned {
     def pos: Position = ???
   }
 
+// ====== Trees ======================================
+
+  trait Tree extends Positioned
+
 // ------ Statements ---------------------------------
 
-  sealed trait TopLevelStatement extends Positioned
+  sealed trait TopLevelStatement extends Tree
   sealed trait Statement extends TopLevelStatement
 
-  case class Package(pkg: Term, body: List[TopLevelStatement]) extends TopLevelStatement
+  case class PackageClause(pkg: Term, body: List[TopLevelStatement]) extends TopLevelStatement
 
   case class Import(expr: Term, selector: List[ImportSelector]) extends Statement
 
   enum ImportSelector {
-    case Simple(id: Id)
-    case Rename(id1: Id, id2: Id)
-    case Omit(id1: Id)
+    case SimpleSelector(id: Id)
+    case RenameSelector(id1: Id, id2: Id)
+    case OmitSelector(id1: Id)
   }
 
   case class Id(name: String) extends Positioned     // untyped ident
 
 // ------ Definitions ---------------------------------
 
-  trait Definition  extends Statement {
-    def name: Name
+  trait Definition {
     def owner: Definition = ???
   }
 
-  case class ValDef(name: TermName, tpt: Term, rhs: Option[Term], mods: List[Modifier]) extends Definition
+  // Does DefDef need a `def tpe: MethodType | PolyType`?
+  case class ValDef(name: TermName, tpt: TypeTree, rhs: Option[Term]) extends Definition {
+    def mods: List[Modifier] = ???
+  }
   case class DefDef(name: TermName, typeParams: List[TypeDef], paramss: List[List[ValDef]],
-                    returnTpt: Term, rhs: Option[Term], mods: List[Modifier]) extends Definition
-  case class TypeDef(name: TypeName, rhs: Term, mods: List[Modifier]) extends Definition
-  case class ClassDef(name: TypeName, constructor: DefDef, parents: List[Term],
-                      self: Option[ValDef], body: List[Statement], mods: List[Modifier]) extends Definition
-
+                    returnTpt: TypeTree, rhs: Option[Term]) extends Definition {
+    def mods: List[Modifier] = ???
+  }
+  case class TypeDef(name: TypeName, rhs: TypeTree | TypeBoundsTree) extends Definition {
+    def mods: List[Modifier] = ???
+  }
+  case class ClassDef(name: TypeName, constructor: DefDef, parents: List[Term | TypeTree],
+                      self: Option[ValDef], body: List[Statement]) extends Definition {
+    def mods: List[Modifier] = ???
+  }
+  case class PackageDef(name: TermName, members: List[Statement]) extends Definition
 
 // ------ Terms ---------------------------------
 
@@ -92,35 +109,39 @@ object definitions {
   }
 
   /** Trees denoting types */
-  enum TypeTree extends Positioned {
+  enum TypeTree extends Tree {
     def tpe: Type = ???
     case Synthetic()
     case Ident(name: TypeName, override val tpe: Type)
     case Select(prefix: Term, name: TypeName)
     case Singleton(ref: Term)
     case Refined(underlying: TypeTree, refinements: List[Definition])
     case Applied(tycon: TypeTree, args: List[TypeTree])
-    case TypeBounds(loBound: TypeTree, hiBound: TypeTree)
     case Annotated(tpt: TypeTree, annotation: Term)
     case And(left: TypeTree, right: TypeTree)
     case Or(left: TypeTree, right: TypeTree)
     case ByName(tpt: TypeTree)
   }
 
+  /** Trees denoting type bounds*/
+  case class TypeBoundsTree(loBound: TypeTree, hiBound: TypeTree) extends Tree {
+    def tpe: Type.TypeBounds = ???
+  }
+
   /** Trees denoting patterns */
-  enum Pattern extends Positioned {
+  enum Pattern extends Tree {
     def tpe: Type = ???
     case Value(v: Term)
     case Bind(name: TermName, pat: Pattern)
     case Unapply(unapply: Term, implicits: List[Term], pats: List[Pattern])
     case Alternative(pats: List[Pattern])
     case TypeTest(tpt: TypeTree)
-    case Wildcard()
   }
 
-  case class CaseDef(pat: Pattern, guard: Option[Term], rhs: Term) extends Positioned
+  /** Tree denoting pattern match case */
+  case class CaseDef(pat: Pattern, guard: Option[Term], rhs: Term) extends Tree
 
-// ------ Types ---------------------------------
+// ====== Types ======================================
 
   sealed trait Type
 
@@ -138,6 +159,7 @@ object definitions {
     case class OrType(left: Type, right: Type) extends Type
     case class ByNameType(underlying: Type) extends Type
     case class ParamRef(binder: LambdaType[_, _, _], idx: Int) extends Type
+    case class ThisType(tp: Type) extends Type
     case class RecursiveThis(binder: RecursiveType) extends Type
 
     case class RecursiveType private (private var _underlying: Type) extends Type {
@@ -198,43 +220,56 @@ object definitions {
     object ErasedImplicitMethodType extends SpecializedMethodTypeCompanion
 
     case class TypeBounds(loBound: Type, hiBound: Type)
+
     case class NoPrefix()
     object NoPrefix extends NoPrefix
   }
 
-// ------ Modifiers ---------------------------------
-
-  enum Modifier extends Positioned {
-    case Private, Protected, Abstract, Final, Sealed, Case, Implicit, Erased, Lazy, Override, Inline,
-         Macro,                 // inline method containing toplevel splices
-         Static,                // mapped to static Java member
-         Object,                // an object or its class (used for a ValDef or a ClassDef, respectively)
-         Trait,                 // a trait (used for a ClassDef)
-         Local,                 // used in conjunction with Private/private[Type] to mean private[this], proctected[this]
-         Synthetic,             // generated by Scala compiler
-         Artifact,              // to be tagged Java Synthetic
-         Mutable,               // when used on a ValDef: a var
-         Label,                 // method generated as a label
-         FieldAccessor,         // a getter or setter
-         CaseAcessor,           // getter for case class parameter
-         Covariant,             // type parameter marked “+”
-         Contravariant,         // type parameter marked “-”
-         Scala2X,               // Imported from Scala2.x
-         DefaultParameterized,  // Method with default parameters
-         Stable                 // Method that is assumed to be stable
+// ====== Modifiers ==================================
+
 
+  enum Modifier {
+    case Flags(flags: FlagSet)
     case QualifiedPrivate(boundary: Type)
     case QualifiedProtected(boundary: Type)
     case Annotation(tree: Term)
   }
 
-// ------ Constants ---------------------------------
+  trait FlagSet {
+    def isProtected: Boolean
+    def isAbstract: Boolean
+    def isFinal: Boolean
+    def isSealed: Boolean
+    def isCase: Boolean
+    def isImplicit: Boolean
+    def isErased: Boolean
+    def isLazy: Boolean
+    def isOverride: Boolean
+    def isInline: Boolean
+    def isMacro: Boolean                 // inline method containing toplevel splices
+    def isStatic: Boolean                // mapped to static Java member
+    def isObject: Boolean                // an object or its class (used for a ValDef or a ClassDef extends Modifier respectively)
+    def isTrait: Boolean                 // a trait (used for a ClassDef)
+    def isLocal: Boolean                 // used in conjunction with Private/private[Type] to mean private[this] extends Modifier proctected[this]
+    def isSynthetic: Boolean             // generated by Scala compiler
+    def isArtifact: Boolean              // to be tagged Java Synthetic
+    def isMutable: Boolean               // when used on a ValDef: a var
+    def isLabel: Boolean                 // method generated as a label
+    def isFieldAccessor: Boolean         // a getter or setter
+    def isCaseAcessor: Boolean           // getter for class parameter
+    def isCovariant: Boolean             // type parameter marked “+”
+    def isContravariant: Boolean         // type parameter marked “-”
+    def isScala2X: Boolean               // Imported from Scala2.x
+    def isDefaultParameterized: Boolean  // Method with default parameters
+    def isStable: Boolean                // Method that is assumed to be stable
+  }
+
+// ====== Constants ==================================
 
   enum Constant(val value: Any) {
     case Unit                        extends Constant(())
-    case False                       extends Constant(false)
-    case True                        extends Constant(true)
     case Null                        extends Constant(null)
+    case Boolean(v: scala.Boolean)   extends Constant(v)
     case Byte(v: scala.Byte)         extends Constant(v)
     case Short(v: scala.Short)       extends Constant(v)
     case Char(v: scala.Char)         extends Constant(v)
@@ -247,3 +282,170 @@ object definitions {
     case Enum(v: Type)               extends Constant(v)
   }
 }
+
+// --- A sample extractor ------------------
+
+// The abstract class, that's what we export to macro users
+abstract class Tasty {
+
+  type Type
+  trait AbstractType {
+    // exported type fields
+  }
+  implicit def TypeDeco(x: Type): AbstractType
+
+  type Symbol
+  trait AbstractSymbol {
+    // exported symbol fields
+  }
+  implicit def SymbolDeco(s: Symbol): AbstractSymbol
+
+  type Context
+  trait AbstractContext {
+    val owner: Symbol
+    // more exported fields
+  }
+  implicit def ContextDeco(x: Context): AbstractContext
+
+  type Position
+  trait AbstractPosition {
+    val start: Int
+    val end: Int
+    // more fields
+  }
+  implicit def PositionDeco(p: Position): AbstractPosition
+
+  trait TypedPositioned {
+    val pos: Position
+    val tpe: Type
+  }
+
+  type Pattern
+  implicit def PatternDeco(p: Pattern): TypedPositioned
+
+  type Term
+  implicit def TermDeco(t: Term): TypedPositioned
+
+  type CaseDef
+  implicit def CaseDefDeco(c: CaseDef): TypedPositioned
+
+  val CaseDef: CaseDefExtractor
+  abstract class CaseDefExtractor {
+    def apply(pat: Pattern, guard: Term, rhs: Term)(implicit ctx: Context): CaseDef
+    def unapply(x: CaseDef): Some[(Pattern, Term, Term)]
+  }
+  // and analogously for all other concrete trees, patterns, types, etc
+}
+
+// The concrete implementation - hidden from users.
+object TastyImpl extends Tasty {
+  import definitions._
+  import dotty.tools.dotc._
+  import ast.tpd
+  import core.{Types, Symbols, Contexts}
+  import util.{Positions}
+
+  type Type = Types.Type
+  implicit class TypeDeco(x: Type) extends AbstractType {}
+
+  type Symbol = Symbols.Symbol
+  implicit class SymbolDeco(s: Symbol) extends AbstractSymbol {}
+
+  type Context = Contexts.Context
+  implicit class ContextDeco(c: Context) extends AbstractContext {
+    val owner = c.owner
+  }
+
+  type Position = Positions.Position
+  implicit class PositionDeco(p: Position) extends AbstractPosition {
+    val start = p.start
+    val end = p.end
+  }
+
+  type Pattern = tpd.Tree
+  implicit class PatternDeco(p: Pattern) extends TypedPositioned {
+    val pos = p.pos
+    val tpe = p.tpe
+  }
+
+  type Term = tpd.Tree
+  implicit class TermDeco(t: Term) extends TypedPositioned {
+    val pos = t.pos
+    val tpe = t.tpe
+  }
+
+  type CaseDef = tpd.CaseDef
+  implicit class CaseDefDeco(c: CaseDef) extends TypedPositioned {
+    val pos = c.pos
+    val tpe = c.tpe
+  }
+
+  object CaseDef extends CaseDefExtractor {
+    def apply(pat: Pattern, guard: Term, rhs: Term)(implicit ctx: Context): CaseDef =
+      tpd.CaseDef(pat, guard, rhs)
+    def unapply(x: CaseDef): Some[(Pattern, Term, Term)] =
+      Some((x.pat, x.guard, x.body))
+  }
+}
+
+/* Dependencies:
+
+    the reflect library (which is probably part of stdlib) contains a
+
+      val tasty: Tasty
+
+    this val is implemented reflectively, loading TastyImpl on demand. TastyImpl in turn
+    depends on `tools.dotc`.
+
+*/
+
+
+/* If the dotty implementations all inherit the ...Abstract traits,
+   and the Abstract traits inherit thmeselves from ProductN, we can
+   also do the following, faster implementation.
+   This still does full information hiding, but should be almost
+   as fast as native access.
+
+object TastyImpl extends TastyAST {
+  import definitions._
+  import dotty.tools.dotc._
+  import ast.tpd
+  import core.{Types, Symbols, Contexts}
+  import util.{Positions}
+
+  type Type = Types.Type
+  implicit def TypeDeco(x: Type) = x
+
+  type Symbol = Symbols.Symbol
+  implicit def SymbolDeco(s: Symbol) = s
+
+  type Context = Contexts.Context
+  implicit def ContextDeco(c: Context) = c
+
+  type Position = Positions.Position
+  implicit def PositionDeco(p: Position) = p
+
+  type Pattern = tpd.Tree
+  implicit def PatternDeco(p: Pattern) = p
+
+  type Term = tpd.Tree
+  implicit def TermDeco(t: Term) = t
+
+  type CaseDef = tpd.CaseDef
+  implicit def CaseDefDeco(c: CaseDef) = c
+
+  object CaseDef extends CaseDefExtractor {
+    def apply(pat: Pattern, guard: Term, rhs: Term)(implicit ctx: Context): CaseDef =
+      tpd.CaseDef(pat, guard, rhs)
+    def unapply(x: CaseDef): AbstractCaseDef = x
+  }
+}
+
+This approach is fast because all accesses work without boxing. But there are also downsides:
+
+1. The added reflect supertypes for the dotty types might have a negative performance
+   impact for normal compilation.
+
+2. There would be an added dependency from compiler to reflect library, which
+   complicates things.
+*/