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package webm
import scala.collection.{GenMap, GenTraversableOnce}
import scala.language.experimental.macros
import scala.reflect.macros.blackbox
import scala.scalajs.js
import scala.scalajs.js.|
object FunctionMacro {
val REGULAR = "regular"
val UNDEFS = "undefs"
type TOJS = {
val toJS: js.Object
}
def apply(): js.Object = macro macroImpl
def macroImpl(c: blackbox.Context)(): c.Tree = {
import c.universe._
val f = c.internal.enclosingOwner
if (!f.owner.isMethod) {
c.abort(c.enclosingPosition, "This macro can only be used directly within a method.")
}
val p = f.owner.asMethod.paramLists
if (p.isEmpty) {
c.abort(
c.enclosingPosition,
"This macro can only be used in a function that has at least one parameter list with one item.")
}
def isNotPrimitiveAnyVal(tpe: Type) = {
!tpe.typeSymbol.fullName.startsWith("scala.")
}
def customName(sym: c.Symbol): Option[String] = {
sym.annotations.find(_.tree.tpe == typeOf[rename]).flatMap(_.tree.children.tail.headOption).map {
case Literal(Constant(s)) => s.toString
}
}
val finalTerm = TermName(c.freshName())
val rawParams = p.head.filterNot(s => s.annotations.exists(a => a.tree.tpe == typeOf[exclude])).map { field =>
val name = field.asTerm.name
val decoded = customName(field).getOrElse(name.decodedName.toString)
val symToJs = typeOf[TOJS].typeSymbol
val returnType = field.typeSignature
def getJSValueTree(returnType: Type, undef: Boolean = false) = {
if (returnType <:< typeOf[TOJS])
if (undef) q"""v.toJS""" else q"""if($name == null) null else $name.toJS"""
else if (returnType <:< typeOf[Enumeration#Value])
if (undef) q"""v.toString()""" else q"""$name.toString()"""
else if (returnType <:< typeOf[AnyVal] && isNotPrimitiveAnyVal(returnType))
if (undef) q"""v.value""" else q"""$name.value"""
else if (returnType <:< typeOf[GenMap[String, _]] &&
returnType.typeArgs(1) <:< typeOf[TOJS])
if (undef) q"""v.map{ case (k, o) => k -> (if(o == null) null else o.toJS)}.toJSDictionary"""
else q"""$name.map{ case (k, o) => k -> (if(o == null) null else o.toJS) }.toJSDictionary"""
else if (returnType <:< typeOf[GenMap[String, _]])
if (undef) q"""v.toJSDictionary""" else q"""$name.toJSDictionary"""
else if ((returnType <:< typeOf[GenTraversableOnce[_]] ||
returnType <:< typeOf[Array[_]]) &&
returnType.typeArgs.head <:< typeOf[TOJS])
if (undef) q"""v.map((o: $symToJs) => if(o == null) null else o.toJS).toJSArray"""
else q"""$name.map((o: $symToJs) => if(o == null) null else o.toJS).toJSArray"""
else if (returnType <:< typeOf[GenTraversableOnce[_]] ||
returnType <:< typeOf[Array[_]])
if (undef) q"""v.toJSArray""" else q"""$name.toJSArray"""
else if (returnType <:< typeOf[js.Dictionary[_]] &&
returnType.typeArgs.head <:< typeOf[TOJS])
if (undef) q"""v.map{ case(k, o) => (k, if(o == null) null else o.toJS)}.toJSDictionary"""
else q"""$name.map{ case (k: String, o: $symToJs) => (k, if(o == null) null else o.toJS)}.toJSDictionary"""
else if (returnType <:< typeOf[js.Array[_]] &&
returnType.typeArgs.head <:< typeOf[TOJS])
if (undef) q"""v.map((o: $symToJs) => if(o == null) null else o.toJS)"""
else q"""$name.map((o: $symToJs) => if(o == null) null else o.toJS)"""
else if (returnType <:< typeOf[|[_, _]])
if (undef) q"""v.asInstanceOf[js.Any]"""
else q"""$name.asInstanceOf[js.Any]"""
else if (undef) q"""v"""
else q"""$name"""
}
if (returnType <:< typeOf[Option[_]] ||
returnType <:< typeOf[js.UndefOr[_]]) {
val arg0 = returnType.typeArgs(0)
val valueTree = getJSValueTree(arg0, true)
(UNDEFS, q"""$name.foreach(v => $finalTerm.updateDynamic($decoded)($valueTree))""")
} else {
val jsValueTree = getJSValueTree(returnType)
(REGULAR, q"""$decoded -> $jsValueTree """)
}
}
def getTrees(key: String) = rawParams.filter(_._1 == key).map(_._2)
val params = getTrees(REGULAR)
val undefs = getTrees(UNDEFS)
val result = q"""
{
import scala.language.reflectiveCalls
import scalajs.js.JSConverters._
val $finalTerm = scala.scalajs.js.Dynamic.literal(..$params)
..$undefs
$finalTerm
}
"""
result
}
}
@dispalt

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@dispalt dispalt commented Oct 18, 2020

def(a: String, b: Option[String]) = {
  val o = FunctionMacro()
  // o: js.Object = {a: .., b: ... }
}
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