Implement field index with compile time check

openmole · May 9, 2024 · ccf2eb0 · ccf2eb0
1 parent ae64fff
commit ccf2eb0
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Showing 3 changed files with 41 additions and 2 deletions.
diff --git a/byte-pack/src/main/scala/bytepack/FieldIndex.scala b/byte-pack/src/main/scala/bytepack/FieldIndex.scala
@@ -40,6 +40,41 @@ object FieldIndex:
 
     '{ $namesExpr.toMap }
 
+
+  inline def fieldIndex[F](f: F => Any)(using p: PackProduct[F]): Int = ${ fieldIndexImpl[F, Any]('f, 'p) }
+
+  def fieldIndexImpl[F, T](f: Expr[F => T], t: Expr[PackProduct[F]])(using quotes: Quotes, tpef: Type[F], typet: Type[T]): Expr[Int] =
+    // val term = f.show
+    import quotes.*
+    import quotes.reflect.*
+
+    val sym = TypeRepr.of[F].typeSymbol
+
+//    object CaseClass:
+//      def unapply(term: Term): Option[Term] =
+//        term.tpe.classSymbol.flatMap: sym =>
+//          Option.when(sym.flags.is(Flags.Case))(term)
+//
+//
+    //   f.asTerm match
+    //     case Select(_,_) => "test"
+
+    val source = f.asTerm.pos.sourceCode
+
+    val field = source.head.dropWhile(_ != '.').drop(1)
+    val index =
+      sym.caseFields.zipWithIndex.find((f, _) => f.name == field) match
+        case Some(f) => f._2 //if p.flags.is(Flags.HasDefault)
+        case None => report.errorAndAbort(s"No field named ${source} found in case class ${sym}", f.asTerm.pos)
+
+    //   val field = source.head.dropWhile(_ != '.').drop(1)
+
+    val v = Expr(index)
+
+    '{
+      Pack.indexOf[F]($v)(using $t)
+    }
+
 //
 //    val body = comp.tree.asInstanceOf[ClassDef].body
 //    val idents: List[Term] =

diff --git a/byte-pack/src/main/scala/bytepack/Pack.scala b/byte-pack/src/main/scala/bytepack/Pack.scala
@@ -86,13 +86,18 @@ object Pack:
     p.unpack(0, b)
 
   def indexOf[T: PackProduct](i: Int) = summon[PackProduct[T]].index(i)
+  inline def indexOf[F](f: F => Any)(using p: PackProduct[F]): Int = ${ FieldIndex.fieldIndexImpl[F, Any]('f, 'p) }
+
 
   // TODO find a way to check field name at compile time and get field type
   def indexOf[T: PackProduct](field: String): Int =
     val pack = summon[PackProduct[T]]
     val index = pack.fields.getOrElse(field, throw RuntimeException(s"Field $field not found among ${pack.fields}"))
     indexOf[T](index)
 
+
+  //inline def fieldName[F](inline f: F => Any) = FieldIndex.fieldName(f)
+
   def size[T: Pack] = summon[Pack[T]].size
 
 

diff --git a/byte-pack/src/test/scala/bytepack/PackTests.scala b/byte-pack/src/test/scala/bytepack/PackTests.scala
@@ -43,5 +43,4 @@ class PackTests extends AnyFunSuite:
     val packed = Pack.pack(p)
     assert(Pack.indexOf[UpperClass](1) == 11)
     assert(packed(Pack.indexOf[UpperClass](1)) == 8.toByte)
-    assert(Pack.indexOf[UpperClass]("j") == 11)
-
+    assert(Pack.indexOf[UpperClass](_.j) == 11)