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package scala.tools.reflect
package quasiquotes
import java.util.UUID.randomUUID
import scala.collection.{immutable, mutable}
/** Emulates hole support (see Holes.scala) in the quasiquote parser (see Parsers.scala).
* A principled solution to splicing into Scala syntax would be a parser that natively supports holes.
* Unfortunately, that's outside of our reach in Scala 2.11, so we have to emulate.
* This trait stores knowledge of how to represent the holes as something understandable by the parser
* and how to recover holes from the results of parsing the produced representation.
*/
trait Placeholders { self: Quasiquotes =>
import global._
import Cardinality._
// Step 1: Transform Scala source with holes into vanilla Scala source
lazy val holeMap = new HoleMap()
lazy val posMap = mutable.ListMap[Position, (Int, Int)]()
lazy val code = {
val sb = new StringBuilder()
val sessionSuffix = randomUUID().toString.replace("-", "").substring(0, 8) + "$"
def appendPart(value: String, pos: Position) = {
val start = sb.length
sb.append(value)
val end = sb.length
posMap += pos -> (start, end)
}
def appendHole(tree: Tree, cardinality: Cardinality) = {
val placeholderName = c.freshName(TermName(nme.QUASIQUOTE_PREFIX + sessionSuffix))
sb.append(placeholderName)
holeMap(placeholderName) = Hole(tree, cardinality)
}
foreach2(args, parts.init) { case (tree, (p, pos)) =>
val (part, cardinality) = parseDots(p)
appendPart(part, pos)
appendHole(tree, cardinality)
}
val (p, pos) = parts.last
appendPart(p, pos)
sb.toString
}
class HoleMap {
private val underlying = mutable.ListMap[String, Hole]()
private val accessed = mutable.Set[String]()
def unused: Set[Name] = (underlying.keys.toSet -- accessed).map(TermName(_))
def contains(key: Name) = underlying.contains(key.toString)
def apply(key: Name) = {
val s = key.toString
accessed += s
underlying(s)
}
def update(key: Name, hole: Hole) = {
underlying += key.toString -> hole
}
def get(key: Name) = {
val s = key.toString
accessed += s
underlying.get(s)
}
}
// Step 2: Transform vanilla Scala AST into an AST with holes
trait HolePlaceholder {
def matching: PartialFunction[Any, Name]
def unapply(scrutinee: Any): Option[(Tree, Location, Cardinality)] = {
val name = matching.lift(scrutinee)
name.flatMap { holeMap.get(_).map { case Hole(repr, loc, card) => (repr, loc, card) } }
}
}
object Placeholder extends HolePlaceholder {
def matching = {
case name: Name => name
case Ident(name) => name
case Bind(name, Ident(nme.WILDCARD)) => name
case TypeDef(_, name, List(), TypeBoundsTree(EmptyTree, EmptyTree)) => name
case ValDef(_, name, TypeTree(), EmptyTree) => name
}
}
object ModsPlaceholder extends HolePlaceholder {
def matching = {
case Apply(Select(New(Ident(tpnme.QUASIQUOTE_MODS)), nme.CONSTRUCTOR), List(Literal(Constant(s: String)))) => TermName(s)
}
}
object AnnotPlaceholder {
def unapply(tree: Tree): Option[(Tree, Location, Cardinality, List[Tree])] = tree match {
case Apply(Select(New(Placeholder(tree, loc, card)), nme.CONSTRUCTOR), args) => Some(tree, loc, card, args)
case _ => None
}
}
object TuplePlaceholder {
def unapply(tree: Tree): Option[List[Tree]] = tree match {
case Apply(Ident(nme.QUASIQUOTE_TUPLE), args) => Some(args)
case _ => None
}
}
object TupleTypePlaceholder {
def unapply(tree: Tree): Option[List[Tree]] = tree match {
case AppliedTypeTree(Ident(tpnme.QUASIQUOTE_TUPLE), args) => Some(args)
case _ => None
}
}
object FunctionTypePlaceholder {
def unapply(tree: Tree): Option[(List[Tree], Tree)] = tree match {
case AppliedTypeTree(Ident(tpnme.QUASIQUOTE_FUNCTION), args :+ res) => Some((args, res))
case _ => None
}
}
object SymbolPlaceholder {
def unapply(scrutinee: Any): Option[Tree] = scrutinee match {
case Placeholder(tree, SymbolLocation, _) => Some(tree)
case _ => None
}
}
object CasePlaceholder {
def unapply(tree: Tree): Option[(Tree, Location, Cardinality)] = tree match {
case CaseDef(Apply(Ident(nme.QUASIQUOTE_CASE), List(Placeholder(tree, location, card))), EmptyTree, EmptyTree) => Some((tree, location, card))
case _ => None
}
}
object RefineStatPlaceholder {
def unapply(tree: Tree): Option[(Tree, Location, Cardinality)] = tree match {
case ValDef(_, Placeholder(tree, location, card), Ident(tpnme.QUASIQUOTE_REFINE_STAT), _) => Some((tree, location, card))
case _ => None
}
}
object EarlyDefPlaceholder {
def unapply(tree: Tree): Option[(Tree, Location, Cardinality)] = tree match {
case ValDef(_, Placeholder(tree, location, card), Ident(tpnme.QUASIQUOTE_EARLY_DEF), _) => Some((tree, location, card))
case _ => None
}
}
}
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