Merge pull request #13 from alexarchambault/product-prefix

Override productPrefix and productElementName

Author: alexarchambault

src/main/scala/dataclass/Macros.scala

@@ -6,6 +6,8 @@ import scala.annotation.tailrec
 private[dataclass] class Macros(val c: Context) extends ImplTransformers {
   import c.universe._
 
+  import dataclass.Macros._
+
   private val debug = sys.env
     .get("DATACLASS_MACROS_DEBUG")
     .map(_.toBoolean)
@@ -165,12 +167,38 @@ private[dataclass] class Macros(val c: Context) extends ImplTransformers {
             }
 
           val productMethods = {
+
+            val prodElemNameMethods =
+              if (productElemNameAvailable) {
+                val elemNameCases = paramss.flatten.zipWithIndex
+                  .map {
+                    case (param, idx) =>
+                      val name = param.name.decodedName.toString
+                      cq"$idx => $name"
+                  }
+
+                Seq(
+                  q"""
+                    override def productElementName(n: _root_.scala.Int): _root_.java.lang.String =
+                      n match {
+                        case ..$elemNameCases
+                        case n => throw new _root_.java.lang.IndexOutOfBoundsException(n.toString)
+                      }
+                   """
+                )
+              } else
+                Nil
+
             val elemCases = paramss.flatten.zipWithIndex
               .map {
                 case (param, idx) =>
                   cq"$idx => this.${param.name}"
               }
             Seq(
+              q"""
+                override def productPrefix: _root_.java.lang.String =
+                  ${tpname.decodedName.toString}
+               """,
               q"""
                 override def productArity: _root_.scala.Int = ${allParams.length}
                """,
@@ -181,7 +209,7 @@ private[dataclass] class Macros(val c: Context) extends ImplTransformers {
                     case n => throw new _root_.java.lang.IndexOutOfBoundsException(n.toString)
                   }
                """
-            )
+            ) ++ prodElemNameMethods
           }
 
           val toStringMethod =
@@ -397,3 +425,13 @@ private[dataclass] class Macros(val c: Context) extends ImplTransformers {
   }
 
 }
+
+object Macros {
+
+  // productElementName added in 2.13
+  private[dataclass] val productElemNameAvailable = {
+    val sv = scala.util.Properties.versionNumberString
+    !sv.startsWith("2.11.") && !sv.startsWith("2.12.")
+  }
+
+}

src/test/scala/dataclass/MoreFieldsTests.scala

@@ -1,5 +1,6 @@
 package dataclass
 
+import dataclass.TestUtil._
 import shapeless.test.illTyped
 import utest._
 
@@ -117,6 +118,40 @@ object MoreFieldsTests extends TestSuite {
       } catch {
         case _: IndexOutOfBoundsException =>
       }
+
+      if (productElemNameAvailable) {
+        val names = foo.productElementNames.toVector
+        val expectedNames = Seq("n", "s", "b", "d")
+        assert(names == expectedNames)
+
+        try {
+          foo.productElementName(-1)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+
+        try {
+          foo.productElementName(4)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+      }
+    }
+
+    "productPrefix" - {
+      @data class Foo(
+          n: Int,
+          s: String,
+          @since("") b: Boolean = true,
+          d: Double = 1.0
+      )
+
+      val foo = Foo(1, "a")
+      val prefix = foo.productPrefix
+      val expectedPrefix = "Foo"
+      assert(prefix == expectedPrefix)
     }
 
     "has toString" - {

src/test/scala/dataclass/OneFieldTests.scala

@@ -1,5 +1,6 @@
 package dataclass
 
+import dataclass.TestUtil._
 import shapeless.test.illTyped
 import utest._
 
@@ -116,6 +117,33 @@ object OneFieldTests extends TestSuite {
       } catch {
         case _: IndexOutOfBoundsException =>
       }
+
+      if (productElemNameAvailable) {
+        val names = foo.productElementNames.toVector
+        val expectedNames = Seq("count")
+        assert(names == expectedNames)
+
+        try {
+          foo.productElementName(-1)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+
+        try {
+          foo.productElementName(1)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+      }
+    }
+
+    "productPrefix" - {
+      val foo = Foo(1)
+      val prefix = foo.productPrefix
+      val expectedPrefix = "Foo"
+      assert(prefix == expectedPrefix)
     }
 
     "type params" - {

src/test/scala/dataclass/TestUtil.scala

@@ -0,0 +1,12 @@
+package dataclass
+
+object TestUtil {
+
+  def productElemNameAvailable = dataclass.Macros.productElemNameAvailable
+
+  implicit class ProductElementName211_212(private val product: Product) {
+    def productElementName(n: Int): String = ???
+    def productElementNames: Iterator[String] = ???
+  }
+
+}

src/test/scala/dataclass/TwoFieldsTests.scala

@@ -1,5 +1,6 @@
 package dataclass
 
+import dataclass.TestUtil._
 import shapeless.test.illTyped
 import utest._
 
@@ -113,6 +114,33 @@ object TwoFieldsTests extends TestSuite {
       } catch {
         case _: IndexOutOfBoundsException =>
       }
+
+      if (productElemNameAvailable) {
+        val names = foo.productElementNames.toVector
+        val expectedNames = Seq("a", "other")
+        assert(names == expectedNames)
+
+        try {
+          foo.productElementName(-1)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+
+        try {
+          foo.productElementName(2)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+      }
+    }
+
+    "productPrefix" - {
+      val foo = Foo(1, "c")
+      val prefix = foo.productPrefix
+      val expectedPrefix = "Foo"
+      assert(prefix == expectedPrefix)
     }
 
     "type params" - {

src/test/scala/dataclass/ZeroFieldTests.scala

@@ -1,5 +1,6 @@
 package dataclass
 
+import dataclass.TestUtil._
 import shapeless.test.illTyped
 import utest._
 
@@ -111,6 +112,32 @@ object ZeroFieldTests extends TestSuite {
       } catch {
         case _: IndexOutOfBoundsException =>
       }
+
+      if (productElemNameAvailable) {
+        val names = foo.productElementNames.toVector
+        assert(names.isEmpty)
+
+        try {
+          foo.productElementName(-1)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+
+        try {
+          foo.productElementName(0)
+          assert(false)
+        } catch {
+          case _: IndexOutOfBoundsException =>
+        }
+      }
+    }
+
+    "productPrefix" - {
+      val foo = Foo()
+      val prefix = foo.productPrefix
+      val expectedPrefix = "Foo"
+      assert(prefix == expectedPrefix)
     }
 
     "serializable" - {