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, 34 insertions, 4 deletions

diff --git a/java/README.txt b/java/README.txt
index 9728f48..e2e698e 100644
--- a/java/README.txt
+++ b/java/README.txt
@@ -93,8 +93,9 @@ Micro version
 The runtime and generated code for MICRO_RUNTIME is smaller
 because it does not include support for the descriptor and
 reflection, and enums are generated as integer constants in
-the parent message or the file's outer class. Also, not
-currently supported are packed repeated elements or
+the parent message or the file's outer class, with no
+protection against invalid values set to enum fields. Also,
+not currently supported are packed repeated elements or
 extensions.
 
 To create a jar file for the runtime and run tests invoke
@@ -409,12 +410,20 @@ Nano version
 ============================
 
 Nano is even smaller than micro, especially in the number of generated
-functions. It is like micro except:
+functions. It is like micro:
+
+- No support for descriptors and reflection;
+- Enum constants are integers with no protection against invalid
+  values set to enum fields.
+
+Except:
 
 - Setter/getter/hazzer/clearer functions are opt-in.
 - If not opted in, has state is not available. Serialization outputs
-  all fields not  equal to their default. (See important implications
+  all fields not equal to their default. (See important implications
   below.)
+- Enum constants can be generated into container interfaces bearing
+  the enum's name (so the referencing code is in Java style).
 - CodedInputStreamMicro is renamed to CodedInputByteBufferNano and can
   only take byte[] (not InputStream).
 - Similar rename from CodedOutputStreamMicro to
diff --git a/java/pom.xml b/java/pom.xml
index f36d65f..a34c164 100644
--- a/java/pom.xml
+++ b/java/pom.xml
@@ -144,6 +144,7 @@
                   <arg value="../src/google/protobuf/unittest_single_nano.proto" />
                   <arg value="../src/google/protobuf/unittest_multiple_nano.proto" />
                   <arg value="../src/google/protobuf/unittest_multiple_nameclash_nano.proto" />
+                  <arg value="../src/google/protobuf/unittest_enum_class_nano.proto" />
                 </exec>
                 <exec executable="../src/protoc">
                   <arg value="--javanano_out=store_unknown_fields=true:target/generated-test-sources" />
@@ -163,6 +164,13 @@
                   <arg value="--proto_path=src/test/java" />
                   <arg value="../src/google/protobuf/unittest_accessors_nano.proto" />
                 </exec>
+                <exec executable="../src/protoc">
+                  <arg value="--javanano_out=enum_style=java:target/generated-test-sources" />
+                  <arg value="--proto_path=../src" />
+                  <arg value="--proto_path=src/test/java" />
+                  <arg value="../src/google/protobuf/unittest_enum_class_nano.proto" />
+                  <arg value="../src/google/protobuf/unittest_enum_class_multiple_nano.proto" />
+                </exec>
               </tasks>
               <testSourceRoot>target/generated-test-sources</testSourceRoot>
               <!--testSourceRoot>target/generated-test-sources/opt-space</testSourceRoot-->
diff --git a/java/src/test/java/com/google/protobuf/NanoTest.java b/java/src/test/java/com/google/protobuf/NanoTest.java
index fb6cccb..8483619 100644
--- a/java/src/test/java/com/google/protobuf/NanoTest.java
+++ b/java/src/test/java/com/google/protobuf/NanoTest.java
@@ -31,8 +31,11 @@
 package com.google.protobuf;
 
 import com.google.protobuf.nano.CodedInputByteBufferNano;
+import com.google.protobuf.nano.EnumClassNanoMultiple;
+import com.google.protobuf.nano.EnumClassNanos;
 import com.google.protobuf.nano.Extensions;
 import com.google.protobuf.nano.Extensions.AnotherMessage;
+import com.google.protobuf.nano.FileScopeEnumMultiple;
 import com.google.protobuf.nano.FileScopeEnumRefNano;
 import com.google.protobuf.nano.InternalNano;
 import com.google.protobuf.nano.MessageNano;
@@ -2391,6 +2394,16 @@ public class NanoTest extends TestCase {
     assertEquals(0, newMsg.id);
   }
 
+  public void testNanoJavaEnumStyle() throws Exception {
+    EnumClassNanos.EnumClassNano msg = new EnumClassNanos.EnumClassNano();
+    assertEquals(EnumClassNanos.FileScopeEnum.ONE, msg.one);
+    assertEquals(EnumClassNanos.EnumClassNano.MessageScopeEnum.TWO, msg.two);
+
+    EnumClassNanoMultiple msg2 = new EnumClassNanoMultiple();
+    assertEquals(FileScopeEnumMultiple.THREE, msg2.three);
+    assertEquals(EnumClassNanoMultiple.MessageScopeEnumMultiple.FOUR, msg2.four);
+  }
+
   /**
    * Tests that fields with a default value of NaN are not serialized when
    * set to NaN. This is a special case as NaN != NaN, so normal equality