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package scala.tools
package reflect
import scala.reflect.reify.Taggers
import scala.tools.nsc.typechecker.{Analyzer, Macros}
/** Optimizes system macro expansions by hardwiring them directly to their implementations
* bypassing standard reflective load and invoke to avoid the overhead of Java/Scala reflection.
*/
trait FastTrack {
self: Macros with Analyzer =>
import global._
import definitions._
import language.implicitConversions
private implicit def context2taggers(c0: MacroContext) : Taggers { val c: c0.type } = new { val c: c0.type = c0 } with Taggers
implicit def fastTrackEntry2MacroRuntime(entry: FastTrackEntry): MacroRuntime = args => entry.run(args)
type FastTrackExpander = PartialFunction[(MacroContext, Tree), Tree]
case class FastTrackEntry(sym: Symbol, expander: FastTrackExpander) {
def validate(argss: List[List[Any]]): Boolean = {
val c = argss.flatten.apply(0).asInstanceOf[MacroContext]
val isValid = expander isDefinedAt (c, c.expandee)
isValid
}
def run(args: List[Any]): Any = {
val c = args(0).asInstanceOf[MacroContext]
val result = expander((c, c.expandee))
c.Expr[Nothing](result)(c.TypeTag.Nothing)
}
}
lazy val fastTrack: Map[Symbol, FastTrackEntry] = {
var registry = Map[Symbol, FastTrackEntry]()
implicit class BindTo(sym: Symbol) { def bindTo(expander: FastTrackExpander): Unit = if (sym != NoSymbol) registry += sym -> FastTrackEntry(sym, expander) }
MacroInternal_materializeArrayTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeArrayTag(u, tt.tpe) }
MacroInternal_materializeClassTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeClassTag(u, tt.tpe) }
MacroInternal_materializeTypeTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeTypeTag(u, tt.tpe, concrete = false) }
MacroInternal_materializeConcreteTypeTag bindTo { case (c, Apply(TypeApply(_, List(tt)), List(u))) => c.materializeTypeTag(u, tt.tpe, concrete = true) }
ApiUniverseReify bindTo { case (c, Apply(TypeApply(_, List(tt)), List(expr))) => c.materializeExpr(c.prefix.tree, expr) }
MacroContextReify bindTo { case (c, Apply(TypeApply(_, List(tt)), List(expr))) => c.materializeExpr(c.prefix.tree, expr) }
registry
}
}
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