Feature request: set() and clear() accessors return this

Also pre-inlines set() and has() in serialization code. This could
theoretically help ProGuard: the message class size is usually large,
and because of this only, it may refuse to inline an accessor into
the serialization code, and as a result keeps the accessor intact.
Chances are, after pre-inlining all accessor calls within the message
class, those accessors become unused or single-use, so there are more
reasons for ProGuard to inline and then remove them.

Change-Id: I57decbe0b2533c1be21439de0aad15f49c7024dd

java/src/test/java/com/google/protobuf/NanoTest.java

@@ -2322,6 +2322,12 @@ public class NanoTest extends TestCase {
     assertFalse(msg.hasOptionalString());
     assertFalse(msg.hasDefaultString());
     assertFalse(msg.hasBitFieldCheck());
+
+    // Test set() and clear() returns itself (compiles = success)
+    msg.clear()
+        .setOptionalInt32(3)
+        .clearDefaultBytes()
+        .setOptionalString("4");
   }
 
   public void testNanoWithAccessorsParseFrom() throws Exception {

src/google/protobuf/compiler/javanano/javanano_enum_field.cc

@@ -182,16 +182,18 @@ GenerateMembers(io::Printer* printer) const {
     "public int get$capitalized_name$() {\n"
     "  return $name$_;\n"
     "}\n"
-    "public void set$capitalized_name$(int value) {\n"
+    "public $message_name$ set$capitalized_name$(int value) {\n"
     "  $name$_ = value;\n"
     "  $set_has$;\n"
+    "  return this;\n"
     "}\n"
     "public boolean has$capitalized_name$() {\n"
     "  return $get_has$;\n"
     "}\n"
-    "public void clear$capitalized_name$() {\n"
+    "public $message_name$ clear$capitalized_name$() {\n"
     "  $name$_ = $default$;\n"
     "  $clear_has$;\n"
+    "  return this;\n"
     "}\n");
 }
 
@@ -204,13 +206,14 @@ GenerateClearCode(io::Printer* printer) const {
 void AccessorEnumFieldGenerator::
 GenerateMergingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "set$capitalized_name$(input.readInt32());\n");
+    "$name$_ = input.readInt32();\n"
+    "$set_has$;\n");
 }
 
 void AccessorEnumFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if (has$capitalized_name$()) {\n"
+    "if ($get_has$) {\n"
     "  output.writeInt32($number$, $name$_);\n"
     "}\n");
 }
@@ -218,7 +221,7 @@ GenerateSerializationCode(io::Printer* printer) const {
 void AccessorEnumFieldGenerator::
 GenerateSerializedSizeCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if (has$capitalized_name$()) {\n"
+    "if ($get_has$) {\n"
     "  size += com.google.protobuf.nano.CodedOutputByteBufferNano\n"
     "    .computeInt32Size($number$, $name$_);\n"
     "}\n");

src/google/protobuf/compiler/javanano/javanano_message_field.cc

@@ -148,17 +148,19 @@ GenerateMembers(io::Printer* printer) const {
     "public $type$ get$capitalized_name$() {\n"
     "  return $name$_;\n"
     "}\n"
-    "public void set$capitalized_name$($type$ value) {\n"
+    "public $message_name$ set$capitalized_name$($type$ value) {\n"
     "  if (value == null) {\n"
     "    throw new java.lang.NullPointerException();\n"
     "  }\n"
     "  $name$_ = value;\n"
+    "  return this;\n"
     "}\n"
     "public boolean has$capitalized_name$() {\n"
     "  return $name$_ != null;\n"
     "}\n"
-    "public void clear$capitalized_name$() {\n"
+    "public $message_name$ clear$capitalized_name$() {\n"
     "  $name$_ = null;\n"
+    "  return this;"
     "}\n");
 }
 
@@ -171,8 +173,8 @@ GenerateClearCode(io::Printer* printer) const {
 void AccessorMessageFieldGenerator::
 GenerateMergingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if (!has$capitalized_name$()) {\n"
-    "  set$capitalized_name$(new $type$());\n"
+    "if ($name$_ == null) {\n"
+    "  $name$_ = new $type$();\n"
     "}\n");
 
   if (descriptor_->type() == FieldDescriptor::TYPE_GROUP) {
@@ -187,7 +189,7 @@ GenerateMergingCode(io::Printer* printer) const {
 void AccessorMessageFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if (has$capitalized_name$()) {\n"
+    "if ($name$_ != null) {\n"
     "  output.write$group_or_message$($number$, $name$_);\n"
     "}\n");
 }
@@ -195,7 +197,7 @@ GenerateSerializationCode(io::Printer* printer) const {
 void AccessorMessageFieldGenerator::
 GenerateSerializedSizeCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if (has$capitalized_name$()) {\n"
+    "if ($name$_ != null) {\n"
     "  size += com.google.protobuf.nano.CodedOutputByteBufferNano\n"
     "    .compute$group_or_message$Size($number$, $name$_);\n"
     "}\n");

src/google/protobuf/compiler/javanano/javanano_primitive_field.cc

@@ -431,21 +431,25 @@ GenerateMembers(io::Printer* printer) const {
     "public $type$ get$capitalized_name$() {\n"
     "  return $name$_;\n"
     "}\n"
-    "public void set$capitalized_name$($type$ value) {\n");
+    "public $message_name$ set$capitalized_name$($type$ value) {\n");
   if (IsReferenceType(GetJavaType(descriptor_))) {
     printer->Print(variables_,
-      "  if (value == null) throw new java.lang.NullPointerException();\n");
+      "  if (value == null) {\n"
+      "    throw new java.lang.NullPointerException();\n"
+      "  }\n");
   }
   printer->Print(variables_,
     "  $name$_ = value;\n"
     "  $set_has$;\n"
+    "  return this;\n"
     "}\n"
     "public boolean has$capitalized_name$() {\n"
     "  return $get_has$;\n"
     "}\n"
-    "public void clear$capitalized_name$() {\n"
+    "public $message_name$ clear$capitalized_name$() {\n"
     "  $name$_ = $default_copy_if_needed$;\n"
     "  $clear_has$;\n"
+    "  return this;\n"
     "}\n");
 }
 
@@ -458,13 +462,14 @@ GenerateClearCode(io::Printer* printer) const {
 void AccessorPrimitiveFieldGenerator::
 GenerateMergingCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "set$capitalized_name$(input.read$capitalized_type$());\n");
+    "$name$_ = input.read$capitalized_type$();\n"
+    "$set_has$;\n");
 }
 
 void AccessorPrimitiveFieldGenerator::
 GenerateSerializationCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if (has$capitalized_name$()) {\n"
+    "if ($get_has$) {\n"
     "  output.write$capitalized_type$($number$, $name$_);\n"
     "}\n");
 }
@@ -472,7 +477,7 @@ GenerateSerializationCode(io::Printer* printer) const {
 void AccessorPrimitiveFieldGenerator::
 GenerateSerializedSizeCode(io::Printer* printer) const {
   printer->Print(variables_,
-    "if (has$capitalized_name$()) {\n"
+    "if ($get_has$) {\n"
     "  size += com.google.protobuf.nano.CodedOutputByteBufferNano\n"
     "      .compute$capitalized_type$Size($number$, $name$_);\n"
     "}\n");