Add an option to inspect "has" state upon parse.

If has is set, also always serialize.

Change-Id: I2c8450f7ab9e837d722123dd1042991c0258ede3

2 files changed, 104 insertions, 0 deletions

diff --git a/java/README.txt b/java/README.txt
index dac2e3c9..58ccb88e 100644
--- a/java/README.txt
+++ b/java/README.txt
@@ -301,6 +301,22 @@ message's constructor or clear() function is called, the default value
 penalty. This is not a problem if the field has no default or is an
 empty default.
 
+Nano Generator options
+
+java_nano_generate_has:
+  If true, generates a public boolean variable has<fieldname>
+  accompanying the optional or required field (not present for
+  repeated fields, groups or messages). It is set to false initially
+  and upon clear(). If parseFrom(...) reads the field from the wire,
+  it is set to true. This is a way for clients to inspect the "has"
+  value upon parse. If it is set to true, writeTo(...) will ALWAYS
+  output that field (even if field value is equal to its
+  default).
+
+  IMPORTANT: This option costs an extra 4 bytes per primitive field in
+  the message. Think carefully about whether you really need this. In
+  many cases reading the default works and determining whether the
+  field was received over the wire is irrelevant.
 
 To use nano protobufs:
 
diff --git a/java/src/test/java/com/google/protobuf/NanoTest.java b/java/src/test/java/com/google/protobuf/NanoTest.java
index 0ea80d40..80f091bf 100644
--- a/java/src/test/java/com/google/protobuf/NanoTest.java
+++ b/java/src/test/java/com/google/protobuf/NanoTest.java
@@ -37,6 +37,7 @@ import com.google.protobuf.nano.InternalNano;
 import com.google.protobuf.nano.MessageNano;
 import com.google.protobuf.nano.MultipleImportingNonMultipleNano1;
 import com.google.protobuf.nano.MultipleImportingNonMultipleNano2;
+import com.google.protobuf.nano.NanoHasOuterClass.TestAllTypesNanoHas;
 import com.google.protobuf.nano.NanoOuterClass;
 import com.google.protobuf.nano.NanoOuterClass.TestAllTypesNano;
 import com.google.protobuf.nano.RecursiveMessageNano;
@@ -2095,6 +2096,93 @@ public class NanoTest extends TestCase {
     }
   }
 
+  public void testNanoWithHasParseFrom() throws Exception {
+    TestAllTypesNanoHas msg = null;
+    // Test false on creation, after clear and upon empty parse.
+    for (int i = 0; i < 3; i++) {
+      if (i == 0) {
+        msg = new TestAllTypesNanoHas();
+      } else if (i == 1) {
+        msg.clear();
+      } else if (i == 2) {
+        msg = TestAllTypesNanoHas.parseFrom(new byte[0]);
+      }
+      assertFalse(msg.hasOptionalInt32);
+      assertFalse(msg.hasOptionalString);
+      assertFalse(msg.hasOptionalBytes);
+      assertFalse(msg.hasOptionalNestedEnum);
+      assertFalse(msg.hasDefaultInt32);
+      assertFalse(msg.hasDefaultString);
+      assertFalse(msg.hasDefaultBytes);
+      assertFalse(msg.hasDefaultFloatNan);
+      assertFalse(msg.hasDefaultNestedEnum);
+      assertFalse(msg.hasId);
+      msg.optionalInt32 = 123;
+      msg.optionalNestedMessage = new TestAllTypesNanoHas.NestedMessage();
+      msg.optionalNestedMessage.bb = 2;
+      msg.optionalNestedEnum = TestAllTypesNano.BAZ;
+    }
+
+    byte [] result = MessageNano.toByteArray(msg);
+    int msgSerializedSize = msg.getSerializedSize();
+    //System.out.printf("mss=%d result.length=%d\n", msgSerializedSize, result.length);
+    assertTrue(msgSerializedSize == 13);
+    assertEquals(result.length, msgSerializedSize);
+
+    // Has fields true upon parse.
+    TestAllTypesNanoHas newMsg = TestAllTypesNanoHas.parseFrom(result);
+    assertEquals(123, newMsg.optionalInt32);
+    assertTrue(newMsg.hasOptionalInt32);
+    assertEquals(2, newMsg.optionalNestedMessage.bb);
+    assertTrue(newMsg.optionalNestedMessage.hasBb);
+    assertEquals(TestAllTypesNanoHas.BAZ, newMsg.optionalNestedEnum);
+    assertTrue(newMsg.hasOptionalNestedEnum);
+  }
+
+  public void testNanoWithHasSerialize() throws Exception {
+    TestAllTypesNanoHas msg = new TestAllTypesNanoHas();
+    msg.hasOptionalInt32 = true;
+    msg.hasOptionalString = true;
+    msg.hasOptionalBytes = true;
+    msg.optionalNestedMessage = new TestAllTypesNanoHas.NestedMessage();
+    msg.optionalNestedMessage.hasBb = true;
+    msg.hasOptionalNestedEnum = true;
+    msg.hasDefaultInt32 = true;
+    msg.hasDefaultString = true;
+    msg.hasDefaultBytes = true;
+    msg.hasDefaultFloatNan = true;
+    msg.hasDefaultNestedEnum = true;
+
+    byte [] result = MessageNano.toByteArray(msg);
+    int msgSerializedSize = msg.getSerializedSize();
+    assertEquals(result.length, msgSerializedSize);
+
+    // Now deserialize and find that all fields are set and equal to their defaults.
+    TestAllTypesNanoHas newMsg = TestAllTypesNanoHas.parseFrom(result);
+    assertTrue(newMsg.hasOptionalInt32);
+    assertTrue(newMsg.hasOptionalString);
+    assertTrue(newMsg.hasOptionalBytes);
+    assertTrue(newMsg.optionalNestedMessage.hasBb);
+    assertTrue(newMsg.hasOptionalNestedEnum);
+    assertTrue(newMsg.hasDefaultInt32);
+    assertTrue(newMsg.hasDefaultString);
+    assertTrue(newMsg.hasDefaultBytes);
+    assertTrue(newMsg.hasDefaultFloatNan);
+    assertTrue(newMsg.hasDefaultNestedEnum);
+    assertTrue(newMsg.hasId);
+    assertEquals(0, newMsg.optionalInt32);
+    assertEquals(0, newMsg.optionalString.length());
+    assertEquals(0, newMsg.optionalBytes.length);
+    assertEquals(0, newMsg.optionalNestedMessage.bb);
+    assertEquals(TestAllTypesNanoHas.FOO, newMsg.optionalNestedEnum);
+    assertEquals(41, newMsg.defaultInt32);
+    assertEquals("hello", newMsg.defaultString);
+    assertEquals("world", new String(newMsg.defaultBytes, "UTF-8"));
+    assertEquals(TestAllTypesNanoHas.BAR, newMsg.defaultNestedEnum);
+    assertEquals(Float.NaN, newMsg.defaultFloatNan);
+    assertEquals(0, newMsg.id);
+  }
+
   /**
    * 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