1 files changed, 110 insertions, 0 deletions
diff --git a/sjs/backend/sjs/JSInterop.scala b/sjs/backend/sjs/JSInterop.scala
new file mode 100644
index 000000000..6d66c3206
--- /dev/null
+++ b/sjs/backend/sjs/JSInterop.scala
@@ -0,0 +1,110 @@
+package dotty.tools.backend.sjs
+
+import dotty.tools.dotc.core._
+import Contexts._
+import Flags._
+import Symbols._
+import NameOps._
+import StdNames._
+
+import JSDefinitions._
+
+/** Management of the interoperability with JavaScript. */
+object JSInterop {
+
+  /** Is this symbol a JavaScript type? */
+  def isJSType(sym: Symbol)(implicit ctx: Context): Boolean = {
+    //sym.hasAnnotation(jsdefn.RawJSTypeAnnot)
+    ctx.atPhase(ctx.erasurePhase) { implicit ctx =>
+      sym.derivesFrom(jsdefn.JSAnyClass)
+    }
+  }
+
+  /** Is this symbol a Scala.js-defined JS class, i.e., a non-native JS class? */
+  def isScalaJSDefinedJSClass(sym: Symbol)(implicit ctx: Context): Boolean =
+    isJSType(sym) && !sym.hasAnnotation(jsdefn.JSNativeAnnot)
+
+  /** Should this symbol be translated into a JS getter?
+   *
+   *  This is true for any parameterless method, i.e., defined without `()`.
+   *  Unlike `SymDenotations.isGetter`, it applies to user-defined methods as
+   *  much as *accessor* methods created for `val`s and `var`s.
+   */
+  def isJSGetter(sym: Symbol)(implicit ctx: Context): Boolean = {
+    sym.info.firstParamTypes.isEmpty && ctx.atPhase(ctx.erasurePhase) { implicit ctx =>
+      sym.info.isParameterless
+    }
+  }
+
+  /** Should this symbol be translated into a JS setter?
+   *
+   *  This is true for any method whose name ends in `_=`.
+   *  Unlike `SymDenotations.isGetter`, it applies to user-defined methods as
+   *  much as *accessor* methods created for `var`s.
+   */
+  def isJSSetter(sym: Symbol)(implicit ctx: Context): Boolean =
+    sym.name.isSetterName && sym.is(Method)
+
+  /** Should this symbol be translated into a JS bracket access?
+   *
+   *  This is true for methods annotated with `@JSBracketAccess`.
+   */
+  def isJSBracketAccess(sym: Symbol)(implicit ctx: Context): Boolean =
+    sym.hasAnnotation(jsdefn.JSBracketAccessAnnot)
+
+  /** Should this symbol be translated into a JS bracket call?
+   *
+   *  This is true for methods annotated with `@JSBracketCall`.
+   */
+  def isJSBracketCall(sym: Symbol)(implicit ctx: Context): Boolean =
+    sym.hasAnnotation(jsdefn.JSBracketCallAnnot)
+
+  /** Is this symbol a default param accessor for a JS method?
+   *
+   *  For default param accessors of *constructors*, we need to test whether
+   *  the companion *class* of the owner is a JS type; not whether the owner
+   *  is a JS type.
+   */
+  def isJSDefaultParam(sym: Symbol)(implicit ctx: Context): Boolean = {
+    sym.name.isDefaultGetterName && {
+      val owner = sym.owner
+      if (owner.is(ModuleClass) &&
+          sym.name.asTermName.defaultGetterToMethod == nme.CONSTRUCTOR) {
+        isJSType(owner.linkedClass)
+      } else {
+        isJSType(owner)
+      }
+    }
+  }
+
+  /** Gets the unqualified JS name of a symbol.
+   *
+   *  If it is not explicitly specified with an `@JSName` annotation, the
+   *  JS name is inferred from the Scala name.
+   */
+  def jsNameOf(sym: Symbol)(implicit ctx: Context): String = {
+    sym.getAnnotation(jsdefn.JSNameAnnot).flatMap(_.argumentConstant(0)).fold {
+      val base = sym.name.unexpandedName.decode.toString.stripSuffix("_=")
+      if (sym.is(ModuleClass)) base.stripSuffix("$")
+      else if (!sym.is(Method)) base.stripSuffix(" ")
+      else base
+    } { constant =>
+      constant.stringValue
+    }
+  }
+
+  /** Gets the fully qualified JS name of a static class of module Symbol.
+   *
+   *  This is the JS name of the symbol qualified by the fully qualified JS
+   *  name of its original owner if the latter is a native JS object.
+   */
+  def fullJSNameOf(sym: Symbol)(implicit ctx: Context): String = {
+    assert(sym.isClass, s"fullJSNameOf called for non-class symbol $sym")
+    sym.getAnnotation(jsdefn.JSFullNameAnnot).flatMap(_.argumentConstant(0)).fold {
+      jsNameOf(sym)
+    } { constant =>
+      constant.stringValue
+    }
+  }
+
+}