Implement most of the Scala.js IR code generator.

Notable things that are missing at this point:

* Pattern matching
* Try
* Most of the JavaScript interop

1 files changed, 19 insertions, 0 deletions

diff --git a/src/dotty/tools/backend/sjs/JSDefinitions.scala b/src/dotty/tools/backend/sjs/JSDefinitions.scala
index 0f4415b31..f38f89987 100644
--- a/src/dotty/tools/backend/sjs/JSDefinitions.scala
+++ b/src/dotty/tools/backend/sjs/JSDefinitions.scala
@@ -5,6 +5,7 @@ import dotty.tools.dotc.core._
 import Types._
 import Contexts._
 import Symbols._
+import Names._
 import StdNames._
 import Decorators._
 
@@ -172,4 +173,22 @@ final class JSDefinitions()(implicit ctx: Context) {
   lazy val BoxesRunTime_unboxToCharR = defn.BoxesRunTimeModule.requiredMethodRef("unboxToChar")
   def BoxesRunTime_unboxToChar(implicit ctx: Context): Symbol = BoxesRunTime_unboxToCharR.symbol
 
+  /** If `cls` is a class in the scala package, its name, otherwise EmptyTypeName */
+  private def scalajsClassName(cls: Symbol)(implicit ctx: Context): TypeName =
+    if (cls.isClass && cls.owner == ScalaJSJSPackageClass) cls.asClass.name
+    else EmptyTypeName
+
+  private def isScalaJSVarArityClass(cls: Symbol, prefix: Name): Boolean = {
+    val name = scalajsClassName(cls)
+    name.startsWith(prefix) && name.drop(prefix.length).forall(_.isDigit)
+  }
+
+  def isJSFunctionClass(cls: Symbol): Boolean =
+    isScalaJSVarArityClass(cls, nme.Function)
+
+  private val ThisFunctionName = termName("ThisFunction")
+
+  def isJSThisFunctionClass(cls: Symbol): Boolean =
+    isScalaJSVarArityClass(cls, ThisFunctionName)
+
 }