QName and EName are now enums

shared/src/main/scala/eu/cdevreeze/xpathparser/ast/EQName.scala

@@ -43,8 +43,8 @@ object EQName:
     def localPart: String = ename.localPart
 
     override def toString: String = ename match
-      case common.EName(None, localPart)     => s"Q{}$localPart"
-      case common.EName(Some(ns), localPart) => s"Q{$ns}$localPart"
+      case common.EName.WithoutNamespace(localPart)  => s"Q{}$localPart"
+      case common.EName.WithNamespace(ns, localPart) => s"Q{$ns}$localPart"
 
   object QName:
 

shared/src/main/scala/eu/cdevreeze/xpathparser/ast/xpathElem.scala

@@ -17,6 +17,7 @@
 package eu.cdevreeze.xpathparser.ast
 
 import cats.data.NonEmptyVector
+import eu.cdevreeze.xpathparser.queryapi.ElemApi
 import eu.cdevreeze.xpathparser.queryapi.ElemLike
 
 /**
@@ -51,7 +52,7 @@ import eu.cdevreeze.xpathparser.queryapi.ElemLike
  * @author
  *   Chris de Vreeze
  */
-sealed trait XPathElem extends ElemLike[XPathElem]:
+sealed trait XPathElem extends ElemApi[XPathElem], ElemLike[XPathElem]:
 
   /**
    * Returns the (immediate) child elements of this element.

shared/src/main/scala/eu/cdevreeze/xpathparser/common/EName.scala

@@ -22,9 +22,9 @@ package eu.cdevreeze.xpathparser.common
  * @author
  *   Chris de Vreeze
  */
-final case class EName(namespaceUriOption: Option[String], localPart: String):
-  require(namespaceUriOption ne null) // scalastyle:off null
-  require(localPart ne null) // scalastyle:off null
+enum EName(val namespaceUriOption: Option[String], val localPart: String):
+  case WithoutNamespace(override val localPart: String) extends EName(None, localPart)
+  case WithNamespace(namespace: String, override val localPart: String) extends EName(Some(namespace), localPart)
 
   /** Given an optional prefix, creates a `QName` from this `EName` */
   def toQName(prefixOption: Option[String]): QName =
@@ -41,11 +41,12 @@ final case class EName(namespaceUriOption: Option[String], localPart: String):
 
 object EName:
 
-  /** Creates an `EName` from a namespaceUri and a localPart */
-  def apply(namespaceUri: String, localPart: String): EName = EName(Some(namespaceUri), localPart)
+  def apply(namespaceUriOption: Option[String], localPart: String): EName = namespaceUriOption match
+    case None     => EName.WithoutNamespace(localPart)
+    case Some(ns) => EName.WithNamespace(ns, localPart)
 
-  /** Shorthand for `parse(s)` */
-  def apply(s: String): EName = parse(s)
+  /** Creates an `EName` from a namespaceUri and a localPart */
+  def apply(namespaceUri: String, localPart: String): EName = EName.WithNamespace(namespaceUri, localPart)
 
   /**
    * Parses a `String` into an `EName`. The `String` (after trimming) must conform to the `toString` format of an
@@ -59,8 +60,8 @@ object EName:
       require(idx >= 2 && idx < st.length - 1, s"Opening brace not closed or at incorrect location in EName '${st}'")
       val ns = st.substring(1, idx)
       val localPart = st.substring(idx + 1)
-      EName(Some(ns), localPart)
+      EName.WithNamespace(ns, localPart)
     else
       require(st.indexOf("{") < 0, s"No opening brace allowed unless at the beginning in EName '${st}'")
       require(st.indexOf("}") < 0, s"Closing brace without matching opening brace not allowed in EName '${st}'")
-      EName(None, st)
+      EName.WithoutNamespace(st)

shared/src/main/scala/eu/cdevreeze/xpathparser/common/qname.scala

@@ -22,47 +22,30 @@ package eu.cdevreeze.xpathparser.common
  * @author
  *   Chris de Vreeze
  */
-sealed trait QName extends Serializable:
+enum QName(val prefixOption: Option[String], val localPart: String):
+  case Unprefixed(override val localPart: String) extends QName(None, localPart)
+  case Prefixed(prefix: String, override val localPart: String) extends QName(Some(prefix), localPart)
 
-  def localPart: String
-  def prefixOption: Option[String]
-
-final case class UnprefixedName(override val localPart: String) extends QName:
-  require(localPart ne null) // scalastyle:off null
-
-  override def prefixOption: Option[String] = None
-
-  /** The `String` representation as it appears in XML, that is, the localPart */
-  override def toString: String = localPart
-
-final case class PrefixedName(prefix: String, override val localPart: String) extends QName:
-  require(prefix ne null) // scalastyle:off null
-  require(localPart ne null) // scalastyle:off null
-
-  override def prefixOption: Option[String] = Some(prefix)
-
-  /** The `String` representation as it appears in XML. For example, <code>xs:schema</code> */
-  override def toString: String = s"${prefix}:${localPart}"
+  override def toString: String = this match
+    case Unprefixed(localPart)       => localPart
+    case Prefixed(prefix, localPart) => s"$prefix:$localPart"
 
 object QName:
 
   /** Creates a `QName` from an optional prefix and a localPart */
   def apply(prefixOption: Option[String], localPart: String): QName =
     prefixOption
       .map { pref =>
-        PrefixedName(pref, localPart)
+        Prefixed(pref, localPart)
       }
-      .getOrElse(UnprefixedName(localPart))
-
-  /** Creates a `PrefixedName` from a prefix and a localPart */
-  def apply(prefix: String, localPart: String): QName = PrefixedName(prefix, localPart)
+      .getOrElse(Unprefixed(localPart))
 
-  /** Shorthand for `parse(s)` */
-  def apply(s: String): QName = parse(s)
+  /** Creates a `Prefixed` from a prefix and a localPart */
+  def apply(prefix: String, localPart: String): QName = Prefixed(prefix, localPart)
 
   /**
    * Parses a `String` into a `QName`. The `String` (after trimming) must conform to the `toString` format of a
-   * `PrefixedName` or `UnprefixedName`.
+   * `Prefixed` or `Unprefixed`.
    */
   def parse(s: String): QName =
     val st = s.trim
@@ -71,8 +54,8 @@ object QName:
     require(arr.size <= 2, s"Expected at most 1 colon in QName '${st}'")
 
     arr.size match
-      case 1 => UnprefixedName(st)
-      case 2 => PrefixedName(arr(0), arr(1))
+      case 1 => Unprefixed(st)
+      case 2 => Prefixed(arr(0), arr(1))
       case _ => sys.error(s"Did not expect more than 1 colon in QName '${st}'")
 
   /**
@@ -81,6 +64,6 @@ object QName:
    * With this extractor one can pattern match on arbitrary QNames, and not just on prefixed or unprefixed names.
    */
   def unapply(qname: QName): Option[(Option[String], String)] = qname match
-    case UnprefixedName(localPart)       => Some((None, localPart))
-    case PrefixedName(prefix, localPart) => Some((Some(prefix), localPart))
-    case null                            => None
+    case Unprefixed(localPart)       => Some((None, localPart))
+    case Prefixed(prefix, localPart) => Some((Some(prefix), localPart))
+    case null                        => None

shared/src/main/scala/eu/cdevreeze/xpathparser/util/EQNameUtil.scala

@@ -43,7 +43,6 @@ import eu.cdevreeze.xpathparser.ast.VarRef
 import eu.cdevreeze.xpathparser.ast.VariableBinding
 import eu.cdevreeze.xpathparser.ast.XPathElem
 import eu.cdevreeze.xpathparser.ast.XPathExpr
-import eu.cdevreeze.xpathparser.common.PrefixedName
 import eu.cdevreeze.xpathparser.common.QName
 
 /**
@@ -203,7 +202,7 @@ object EQNameUtil:
    */
   val eqnameProducerFromXsQName: XPathElem => Option[Set[EQName]] =
     case FunctionCall(
-          EQName.QName(PrefixedName("xs", "QName")),
+          EQName.QName(QName.Prefixed("xs", "QName")),
           ArgumentList(IndexedSeq(ExprSingleArgument(StringLiteral(s))))
         ) =>
       val qn = QName.parse(s)