Implement enum_style=java option.

This javanano_out command line option creates a container interface
at the normal place where the enum constants would reside, per enum
definition. The java_multiple_files flag would now affect the file-
scope enums with the shells. If the flag is true then file-scope
container interfaces are created in their own files.

Change-Id: Id52258fcff8d3dee9db8f3d8022147a811bf3565

3 files changed, 65 insertions, 19 deletions

diff --git a/src/google/protobuf/compiler/javanano/javanano_enum.cc b/src/google/protobuf/compiler/javanano/javanano_enum.cc
index 634943b..18f688a 100644
--- a/src/google/protobuf/compiler/javanano/javanano_enum.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_enum.cc
@@ -68,25 +68,40 @@ EnumGenerator::EnumGenerator(const EnumDescriptor* descriptor, const Params& par
 EnumGenerator::~EnumGenerator() {}
 
 void EnumGenerator::Generate(io::Printer* printer) {
-  printer->Print("// enum $classname$\n", "classname", descriptor_->name());
-  for (int i = 0; i < canonical_values_.size(); i++) {
-    map<string, string> vars;
-    vars["name"] = RenameJavaKeywords(canonical_values_[i]->name());
-    vars["canonical_value"] = SimpleItoa(canonical_values_[i]->number());
-    printer->Print(vars,
-      "public static final int $name$ = $canonical_value$;\n");
+  printer->Print(
+      "// enum $classname$\n",
+      "classname", descriptor_->name());
+
+  // Start of container interface
+  bool use_shell_class = params_.java_enum_style();
+  if (use_shell_class) {
+    printer->Print(
+      "public interface $classname$ {\n",
+      "classname", RenameJavaKeywords(descriptor_->name()));
+    printer->Indent();
   }
 
-  // -----------------------------------------------------------------
+  // Canonical values
+  for (int i = 0; i < canonical_values_.size(); i++) {
+    printer->Print(
+      "public static final int $name$ = $canonical_value$;\n",
+      "name", RenameJavaKeywords(canonical_values_[i]->name()),
+      "canonical_value", SimpleItoa(canonical_values_[i]->number()));
+  }
 
+  // Aliases
   for (int i = 0; i < aliases_.size(); i++) {
-    map<string, string> vars;
-    vars["name"] = RenameJavaKeywords(aliases_[i].value->name());
-    vars["canonical_name"] = aliases_[i].canonical_value->name();
-    printer->Print(vars,
-      "public static final int $name$ = $canonical_name$;\n");
+    printer->Print(
+      "public static final int $name$ = $canonical_name$;\n",
+      "name", RenameJavaKeywords(aliases_[i].value->name()),
+      "canonical_name", RenameJavaKeywords(aliases_[i].canonical_value->name()));
   }
 
+  // End of container interface
+  if (use_shell_class) {
+    printer->Outdent();
+    printer->Print("}\n");
+  }
   printer->Print("\n");
 }
 
diff --git a/src/google/protobuf/compiler/javanano/javanano_file.cc b/src/google/protobuf/compiler/javanano/javanano_file.cc
index 1a7b2a7..75d0e44 100644
--- a/src/google/protobuf/compiler/javanano/javanano_file.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_file.cc
@@ -138,6 +138,13 @@ bool FileGenerator::Validate(string* error) {
       found_conflict = true;
     }
   }
+  if (params_.java_enum_style()) {
+    for (int i = 0; !found_conflict && i < file_->enum_type_count(); i++) {
+      if (file_->enum_type(i)->name() == classname_) {
+        found_conflict = true;
+      }
+    }
+  }
   if (found_conflict) {
     error->assign(file_->name());
     error->append(
@@ -237,6 +244,14 @@ void FileGenerator::GenerateSiblings(const string& package_dir,
                                         file_->message_type(i),
                                         output_directory, file_list, params_);
     }
+
+    if (params_.java_enum_style()) {
+      for (int i = 0; i < file_->enum_type_count(); i++) {
+        GenerateSibling<EnumGenerator>(package_dir, java_package_,
+                                       file_->enum_type(i),
+                                       output_directory, file_list, params_);
+      }
+    }
   }
 }
 
diff --git a/src/google/protobuf/compiler/javanano/javanano_helpers.cc b/src/google/protobuf/compiler/javanano/javanano_helpers.cc
index 630ecd1..c424165 100644
--- a/src/google/protobuf/compiler/javanano/javanano_helpers.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_helpers.cc
@@ -197,12 +197,23 @@ string FileJavaPackage(const Params& params, const FileDescriptor* file) {
 }
 
 bool IsOuterClassNeeded(const Params& params, const FileDescriptor* file) {
-  // Enums and extensions need the outer class as the scope.
-  if (file->enum_type_count() != 0 || file->extension_count() != 0) {
+  // If java_multiple_files is false, the outer class is always needed.
+  if (!params.java_multiple_files(file->name())) {
     return true;
   }
-  // Messages need the outer class only if java_multiple_files is false.
-  return !params.java_multiple_files(file->name());
+
+  // File-scope extensions need the outer class as the scope.
+  if (file->extension_count() != 0) {
+    return true;
+  }
+
+  // If container interfaces are not generated, file-scope enums need the
+  // outer class as the scope.
+  if (file->enum_type_count() != 0 && !params.java_enum_style()) {
+    return true;
+  }
+
+  return false;
 }
 
 string ToJavaName(const Params& params, const string& name, bool is_class,
@@ -228,9 +239,14 @@ string ClassName(const Params& params, const FileDescriptor* descriptor) {
 }
 
 string ClassName(const Params& params, const EnumDescriptor* descriptor) {
-  // An enum's class name is the enclosing message's class name or the outer
-  // class name.
   const Descriptor* parent = descriptor->containing_type();
+  // When using Java enum style, an enum's class name contains the enum name.
+  // Use the standard ToJavaName translation.
+  if (params.java_enum_style()) {
+    return ToJavaName(params, descriptor->name(), true, parent,
+                      descriptor->file());
+  }
+  // Otherwise the enum members are accessed from the enclosing class.
   if (parent != NULL) {
     return ClassName(params, parent);
   } else {