Add parser support for imports

Author: sbrunk

samples/import.ts

@@ -0,0 +1,17 @@
+// Import variants from https://www.typescriptlang.org/docs/handbook/modules.html#import
+
+import { ZipCodeValidator } from "./ZipCodeValidator";
+
+import { ZipCodeValidator as ZCV } from "./ZipCodeValidator";
+
+import * as validator from "./ZipCodeValidator";
+
+import "./my-module.js";
+
+declare const hello: String;
+
+declare module mod {
+    import { NestedImport } from "./SomeModule";
+
+    export function f(x: Number): String;
+}

samples/import.ts.scala

@@ -0,0 +1,24 @@
+
+import scala.scalajs.js
+import js.annotation._
+import js.|
+
+package `import` {
+
+package mod {
+
+@js.native
+@JSGlobal("mod")
+object Mod extends js.Object {
+  def f(x: Number): String = js.native
+}
+
+}
+
+@js.native
+@JSGlobalScope
+object Import extends js.Object {
+  val hello: String = js.native
+}
+
+}

src/main/scala/org/scalajs/tools/tsimporter/Importer.scala

@@ -116,6 +116,8 @@ class Importer(val output: java.io.PrintWriter) {
       case FunctionDecl(IdentName(name), signature) =>
         processDefDecl(owner, name, signature)
 
+      case ImportDecl => // Ignore imports
+
       case _ =>
         owner.members += new CommentSymbol("??? "+declaration)
     }

src/main/scala/org/scalajs/tools/tsimporter/Trees.scala

@@ -86,6 +86,8 @@ object Trees {
 
   case class FunctionDecl(name: Ident, signature: FunSignature) extends DeclTree
 
+  case object ImportDecl extends DeclTree
+
   // Function signature
 
   case class FunSignature(tparams: List[TypeParam], params: List[FunParam],

src/main/scala/org/scalajs/tools/tsimporter/parser/TSDefParser.scala

@@ -45,7 +45,7 @@ class TSDefParser extends StdTokenParsers with ImplicitConversions {
 
   lexical.delimiters ++= List(
       "{", "}", "(", ")", "[", "]", "<", ">",
-      ".", ";", ",", "?", ":", "=", "|",
+      ".", ";", ",", "?", ":", "=", "|", "*",
       // TypeScript-specific
       "...", "=>"
   )
@@ -83,6 +83,7 @@ class TSDefParser extends StdTokenParsers with ImplicitConversions {
       ambientModuleDecl | ambientVarDecl | ambientFunctionDecl
     | ambientEnumDecl | ambientClassDecl | ambientInterfaceDecl
     | ambientConstDecl | ambientLetDecl | typeAliasDecl
+    | importDecl
   )
 
   lazy val ambientVarDecl: Parser[DeclTree] =
@@ -112,6 +113,13 @@ class TSDefParser extends StdTokenParsers with ImplicitConversions {
   lazy val typeAliasDecl: Parser[DeclTree] =
     "type" ~> typeName ~ tparams ~ ("=" ~> typeDesc) <~ opt(";") ^^ TypeAliasDecl
 
+  lazy val importDecl: Parser[DeclTree] =
+    "import" ~> (
+        "{" ~ identifier ~ opt(lexical.Identifier("as") ~ identifier) ~ "}" ~ lexical.Identifier("from") ~ stringLiteral
+      | "*" ~ lexical.Identifier("as") ~ identifier ~ lexical.Identifier("from") ~ stringLiteral
+      | stringLiteral
+    ) <~ ";" ^^^ ImportDecl
+
   lazy val tparams = (
       "<" ~> rep1sep(typeParam, ",") <~ ">"
     | success(Nil)