add structured debug representation

README.md

@@ -486,3 +486,8 @@ linked above). They exist only at compile time. Hence, it's safe to cast a given
 
 (n.b. these marker traits do not define any members or functions, otherwise their usage would result in a ClasscastException at runtime)
 
+## This looks so bad in the debugger / object inspector!
+
+Yes, properties are no longer fields of stored nodes. Hence the debugger cannot find them.
+
+But despair not! We have attached the `_debugChildren()` method to the GNode class. In order to see anything useful, you need to tell your debugger to use that in its object inspector. So in intellij, you need to add a custom java type renderer, make it apply to all `flatgraph.GNode` instances, and then tell it to use the expression `_debugChildren()` when expanding a node. See e.g. https://www.jetbrains.com/help/idea/customizing-views.html.

core/src/main/java/flatgraph/GNode.java

@@ -1,5 +1,9 @@
 package flatgraph;
 
+import flatgraph.misc.DebugDump;
+
+import java.util.ArrayList;
+import java.util.Map;
 import java.util.Objects;
 
 /**
@@ -47,7 +51,7 @@ public String label() {
 
     @Override
     public String toString() {
-        return getClass().getName() + "[label=" + label() + "; id=" + id() + "]";
+        return getClass().getName() + "[label=" + label() + "; seq=" + seq() + "; id=" + id() + "]";
     }
 
     @Override
@@ -84,4 +88,8 @@ public KindAndSeq(int kind, int seq) {
             this.seq = seq;
         }
     }
+
+    public Object[] _debugChildren(){
+        return DebugDump.debugChildrenScala(this);
+    }
 }

core/src/main/scala/flatgraph/misc/DebugDump.scala

@@ -3,10 +3,43 @@ package flatgraph.misc
 import flatgraph.Edge.Direction.{Incoming, Outgoing}
 import flatgraph.{AccessHelpers, Accessors, GNode, Graph}
 
+import scala.annotation.unchecked.uncheckedVariance
 import scala.collection.mutable
 
 object DebugDump {
 
+  private def unpack(s: Any): Option[Object] = {
+    s match {
+      case iter: IterableOnce[AnyRef @uncheckedVariance] =>
+        val res = iter.iterator.toSeq
+        if (res.isEmpty) None
+        else if (res.size == 1) Some(res.head)
+        else Some(res)
+      case obj: java.lang.Object => Some(obj)
+      case _                     => null
+    }
+  }
+  def debugChildrenScala(n: GNode): Array[Object] = {
+    import java.util.Map.Entry
+    val res = mutable.ArrayBuffer[(String, Object)]()
+    res.addOne(("label", n.label()))
+    res.addOne("kind", java.lang.Integer.valueOf(n.nodeKind.toInt))
+    res.addOne("seq", java.lang.Integer.valueOf(n.seq()))
+    res.addOne("id", java.lang.Long.valueOf(n.id()))
+
+    for (pid <- n.graph.schema.propertyKinds) {
+      val propertyname = n.graph.schema.getPropertyLabel(n.nodeKind, pid)
+      unpack(Accessors.getNodeProperty(n, pid)).foreach { obj => res.addOne((propertyname, obj)) }
+    }
+
+    for (eid <- n.graph.schema.edgeKinds) {
+      val edgename = n.graph.schema.getEdgeLabel(n.nodeKind, eid)
+      unpack(Accessors.getNeighborsOut(n, eid)).foreach { obj => res.addOne((edgename + "_out", obj)) }
+      unpack(Accessors.getNeighborsIn(n, eid)).foreach { obj => res.addOne((edgename + "_in", obj)) }
+    }
+    res.map { t => new java.util.AbstractMap.SimpleEntry[String, Object](t._1, t._2) }.toArray
+  }
+
   def printNode(n: GNode): String = printNode(n, null)
 
   def printNode(n: GNode, edgeproperty: Any): String = {