Add an option not to wrap some values in Options when generating Scal…

…a values (#383)

Add an option not to wrap some values in Options when generating Scala values

Fixes #40

compiler-plugin/src/main/scala/scalapb/compiler/DescriptorPimps.scala

@@ -107,11 +107,11 @@ trait DescriptorPimps {
     // Is this field boxed inside an Option in Scala. Equivalent, does the Java API
     // support hasX methods for this field.
     def supportsPresence: Boolean =
-      fd.isOptional && !fd.isInOneof && (!fd.getFile.isProto3 || fd.isMessage)
+      fd.isOptional && !fd.isInOneof && (!fd.getFile.isProto3 || fd.isMessage) && !fieldOptions.getNoBox
 
-    // Is the Scala representation of this field is a singular type.
+    // Is the Scala representation of this field a singular type.
     def isSingular = fd.isRequired || (
-      fd.getFile.isProto3 && !fd.isInOneof && fd.isOptional && !fd.isMessage)
+      fd.getFile.isProto3 && !fd.isInOneof && fd.isOptional && !fd.isMessage) || (fieldOptions.getNoBox && fd.isOptional)
 
     def enclosingType: EnclosingType =
       if (isSingular) EnclosingType.None

compiler-plugin/src/main/scala/scalapb/compiler/ProtoValidation.scala

@@ -48,5 +48,8 @@ class ProtoValidation(val params: GeneratorParams) extends DescriptorPimps {
     if (fd.isMapField && fd.fieldOptions.hasType)
       throw new GeneratorException(
         s"${fd.getFullName}: Field ${fd.getName} is a map and has type specified. Use key_type or value_type instead.")
+    if (!fd.isOptional && fd.fieldOptions.hasNoBox)
+      throw new GeneratorException(
+        s"${fd.getFullName}: Field ${fd.getName} has no_box set but is not an optional field.")
   }
 }

e2e/src/main/protobuf/no_box.proto

@@ -0,0 +1,14 @@
+syntax = "proto3";
+
+package com.trueaccord.proto.e2e;
+
+import "scalapb/scalapb.proto";
+
+message Tyre {
+    int32 size = 1;
+}
+
+message Car {
+    Tyre tyre1 = 1 [(scalapb.field).no_box = true];
+    Tyre tyre2 = 2 [(scalapb.field).no_box = false];
+}

e2e/src/test/scala/NoBoxSpec.scala

@@ -0,0 +1,39 @@
+import com.trueaccord.proto.e2e.NoBox
+import com.trueaccord.proto.e2e.no_box.Car
+import com.trueaccord.proto.e2e.no_box.Tyre
+import org.scalatest._
+
+class NoBoxSpec extends FlatSpec with MustMatchers {
+  val car = Car(tyre1 = Tyre(size = 10), tyre2 = Some(Tyre(size = 20)))
+
+  "no_box" should "create correct methods" in {
+    car.tyre1 must be(Tyre(size = 10))
+    car.tyre2 must be(Some(Tyre(size = 20)))
+  }
+
+  "fields with no_box" should "parseFrom byte array correctly" in {
+    val serialized = car.toByteArray
+    Car.parseFrom(serialized) must be(car)
+  }
+
+  "Scala representation of Java message with no_box field with default value" should "have that field with default value" in {
+    val javaCar = NoBox.Car.getDefaultInstance()
+    javaCar.hasTyre1 must be(false)
+
+    val scalaCar = Car.parseFrom(javaCar.toByteArray)
+    scalaCar.tyre1 must be(Tyre.defaultInstance)
+  }
+
+  "Java representation of Scala message with a no_box field with default value" should "not have that field" in {
+    val scalaCar = Car(tyre1 = Tyre.defaultInstance)
+    scalaCar.tyre1 must be(Tyre.defaultInstance)
+
+    val javaCar = NoBox.Car.parseFrom(scalaCar.toByteArray)
+    javaCar.hasTyre1 must be(false)
+  }
+
+  "Scala message with a no_box field with null value" should "throw exception when being serialized" in {
+    val car = Car(tyre1 = null)
+    a[NullPointerException] shouldBe thrownBy(car.toByteArray)
+  }
+}

protobuf/scalapb/scalapb.proto

@@ -105,6 +105,9 @@ message FieldOptions {
 
   // Custom annotations to add to the field.
   repeated string annotations = 6;
+
+  // Do not box this value in Option[T]
+  optional bool no_box = 30;
 }
 
 extend google.protobuf.FieldOptions {