Reworked Handles to have only two classes: FileHandle and PathHandle.

FileHandle points at the File stored in Gimd's database and at the same
time at top-level message. It contains PathHandle which determines path to
a nested message in top-level message. PathHandle can store empty path
which means the whole Handle points just at top-level message.

Signed-off-by: Grzegorz Kossakowski <grek@google.com>

3 files changed, 28 insertions, 45 deletions

diff --git a/src/main/scala/com/google/gimd/query/Handle.scala b/src/main/scala/com/google/gimd/query/Handle.scala
index de42d5c..49a83b9 100644
--- a/src/main/scala/com/google/gimd/query/Handle.scala
+++ b/src/main/scala/com/google/gimd/query/Handle.scala
@@ -19,33 +19,23 @@ import com.google.gimd.file.File
 /** Any handle to a stored message. */
 abstract sealed class Handle
 
-/** Handle to a message contained within something else. */
-abstract case class InnerHandle() extends Handle
-
-/** Handle to a top-level message, that is not nested. */
-abstract case class RootHandle() extends Handle
-
-/** Handle to a message by itself. */
-final case class MessageHandle(
-  message: Message,
-  /** userType for Message that this handle is pointing at */
-  userType: UserType[_]
-) extends InnerHandle
-
-/** Handle to a message stored within a field. */
-final case class FieldHandle(
-  // TODO We may be able to do a more efficient binding to the field
-  // in the parent by taking advantage of position of field in the
-  // parent, rather than using the object.
-  //
-  field: MessageField,
-  child: InnerHandle,
-  /** userType defined for message which contains given field */
-  userType: UserType[_]
-) extends InnerHandle
-
-/** Handle to a top level message. */
-final case class FileHandle[T](
-  file: File[T],
-  child: InnerHandle
-) extends RootHandle
+/**
+ * <p>Handle to mested message determined by path given by list of
+ * MessageFields.</p>
+ *
+ * <p>In order to get message this handle is pointing at one should use
+ * <code>path.last.value</code></p>
+ *
+ * <p>Path stores also all UserTypes corresponding each to Message that contains
+ * given MessageField.</p>
+ */
+final case class PathHandle(path: List[(UserType[_], MessageField)])
+
+/**
+ * <p>Handle to a file that stores top level message.</p>
+ *
+ * <p>The top level message can be accessed using <code>file.message</code>.</p>
+ *
+ * <p>This handle stores also path to a nested message within the top level message.</p>
+ */
+final case class FileHandle[T](file: File[T], path: PathHandle) extends Handle
diff --git a/src/main/scala/com/google/gimd/query/MessageQuery.scala b/src/main/scala/com/google/gimd/query/MessageQuery.scala
index 9dfac04..7fceb4e 100644
--- a/src/main/scala/com/google/gimd/query/MessageQuery.scala
+++ b/src/main/scala/com/google/gimd/query/MessageQuery.scala
@@ -16,7 +16,7 @@ package com.google.gimd.query
 
 object MessageQuery {
   def simpleQuery[U, W](ut: UserType[W], m: Message, p: Predicate[U]):
-   Iterator[(InnerHandle,U)] = {
+   Iterator[(PathHandle,U)] = {
     val children = queryChildren(ut, m, p)
     val self = querySelf(ut, m, p)
     if (self.hasNext)
@@ -29,7 +29,7 @@ object MessageQuery {
     if (p.isType(ut.userTypeClass)) {
       val obj = ut.toUserObject(m).asInstanceOf[U]
       if (p.isMatch(obj))
-        Iterator.single( (MessageHandle(m, ut), obj) )
+        Iterator.single( (PathHandle(Nil), obj) )
       else
         Iterator.empty
     } else
@@ -44,6 +44,6 @@ object MessageQuery {
       field <- m.all(member.name).elements
       if field.isInstanceOf[MessageField]
       f = field.asInstanceOf[MessageField]
-      (handle, userObject) <- simpleQuery(member.userType, f.value, p)
-    } yield (FieldHandle(f, handle, ut), userObject)
+      (PathHandle(xs), userObject) <- simpleQuery(member.userType, f.value, p)
+    } yield (PathHandle((ut, f) :: xs), userObject)
 }
diff --git a/src/test/scala/com/google/gimd/query/MessageQueryTestCase.scala b/src/test/scala/com/google/gimd/query/MessageQueryTestCase.scala
index df1c5d6..f46d77d 100644
--- a/src/test/scala/com/google/gimd/query/MessageQueryTestCase.scala
+++ b/src/test/scala/com/google/gimd/query/MessageQueryTestCase.scala
@@ -52,7 +52,7 @@ class MessageQueryTestCase {
     val queryResult = query((n: TreeNode) => n.name == "a")
 
     val expectedResult = Set(
-      (handle(message), root),
+      (PathHandle(Nil), root),
       (handle(("node", child_msg0)), child_0),
       (handle(("node", child_msg2)), child_2)
     )
@@ -75,7 +75,7 @@ class MessageQueryTestCase {
     val queryResult = query((n: TreeNode) => n.name == "a" && n.id < 0)
 
     val expectedResult = Set(
-      (handle(message), root)
+      (PathHandle(Nil), root)
     )
     assertEquals(expectedResult, Set(queryResult.toList: _*))
   }
@@ -85,13 +85,6 @@ class MessageQueryTestCase {
     MessageQuery.simpleQuery(TreeNodeType, message, p)
   }
 
-  private def handle(message: Message): InnerHandle = MessageHandle(message, TreeNodeType)
-  private def handle(p: (String, Message)*): InnerHandle = {
-    val (name, message) = p(0)
-    val field = MessageField(name, message)
-    if (p.size == 1) {
-      FieldHandle(field, handle(message), TreeNodeType)
-    } else
-      FieldHandle(field, handle(p.drop(1): _*), TreeNodeType)
-  }
+  private def handle(p: (String, Message)*) =
+    PathHandle(p.map { case (name, msg) => (TreeNodeType, MessageField(name, msg)) } toList)
 }