added minimal support for es6 import_style

Author: safanaj

generator/js_generator.cc

@@ -224,7 +224,8 @@ std::string MaybeCrossFileRef(const GeneratorOptions& options,
                               const FileDescriptor* from_file,
                               const Descriptor* to_message) {
   if ((options.import_style == GeneratorOptions::kImportCommonJs ||
-       options.import_style == GeneratorOptions::kImportCommonJsStrict) &&
+       options.import_style == GeneratorOptions::kImportCommonJsStrict ||
+       options.import_style == GeneratorOptions::kImportEs6) &&
       from_file != to_message->file()) {
     // Cross-file ref in CommonJS needs to use the module alias instead of
     // the global name.
@@ -3618,8 +3619,14 @@ void Generator::GenerateFile(const GeneratorOptions& options,
 
   // Generate "require" statements.
   if ((options.import_style == GeneratorOptions::kImportCommonJs ||
-       options.import_style == GeneratorOptions::kImportCommonJsStrict)) {
-    printer->Print("var jspb = require('google-protobuf');\n");
+       options.import_style == GeneratorOptions::kImportCommonJsStrict ||
+       options.import_style == GeneratorOptions::kImportEs6)) {
+
+    if (options.import_style == GeneratorOptions::kImportEs6) {
+      printer->Print("import * as jspb from 'google-protobuf';\n");
+    } else {
+      printer->Print("var jspb = require('google-protobuf');\n");
+    }
     printer->Print("var goog = jspb;\n");
 
     // Do not use global scope in strict mode
@@ -3648,13 +3655,22 @@ void Generator::GenerateFile(const GeneratorOptions& options,
           "    Function('return this')();\n\n");
     }
 
-    for (int i = 0; i < file->dependency_count(); i++) {
-      const std::string& name = file->dependency(i)->name();
-      printer->Print(
-          "var $alias$ = require('$file$');\n"
-          "goog.object.extend(proto, $alias$);\n",
-          "alias", ModuleAlias(name), "file",
-          GetRootPath(file->name(), name) + GetJSFilename(options, name));
+    if (options.import_style == GeneratorOptions::kImportEs6) {
+      for (int i = 0; i < file->dependency_count(); i++) {
+        const std::string& name = file->dependency(i)->name();
+        printer->Print("import * as $alias$ from '$file$';\n"
+                       "goog.object.extend(proto, $alias$);\n",
+                       "alias", ModuleAlias(name), "file",
+                       GetRootPath(file->name(), name) + GetJSFilename(options, name));
+      }
+    } else {
+      for (int i = 0; i < file->dependency_count(); i++) {
+        const std::string& name = file->dependency(i)->name();
+        printer->Print("var $alias$ = require('$file$');\n"
+                       "goog.object.extend(proto, $alias$);\n",
+                       "alias", ModuleAlias(name), "file",
+                       GetRootPath(file->name(), name) + GetJSFilename(options, name));
+      }
     }
   }
 
@@ -3698,6 +3714,20 @@ void Generator::GenerateFile(const GeneratorOptions& options,
   } else if (options.import_style == GeneratorOptions::kImportCommonJsStrict) {
     printer->Print("goog.object.extend(exports, proto);\n", "package",
                    GetNamespace(options, file));
+  } else if (options.import_style == GeneratorOptions::kImportEs6) {
+    std::string package = GetNamespace(options, file);
+    for (std::set<std::string>::iterator it = provided.begin();
+         it != provided.end(); ++it) {
+      std::string fullname = *it;
+      std::string name = fullname.substr(package.length());
+
+      std::string::iterator iend = std::remove(name.begin(), name.end(), '.');
+      name.resize(name.length()-(name.end()-iend));
+      name.shrink_to_fit();
+
+      printer->Print("export const $name$ = $fullname$;\n",
+                     "name", name, "fullname", fullname);
+    }
   }
 
   // Emit well-known type methods.