fix some tinkerpop logic and add attribute test

workflow-state/src/commonMain/kotlin/center/sciprog/workflow/state/StateNode.kt

@@ -26,6 +26,7 @@ public interface ConnectionAttribute : Attribute<NodeConnection>
 
 
 public interface StateNode : AttributeContainer {
+    public val id: NodeId
 
     public val type: NodeType
 

workflow-tinkerpop/src/jvmMain/kotlin/center/sciprog/workflow/state/TinkerAttributes.kt

@@ -3,9 +3,11 @@ package center.sciprog.workflow.state
 import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal
 import org.apache.tinkerpop.gremlin.structure.Edge
 import org.apache.tinkerpop.gremlin.structure.Element
+import org.apache.tinkerpop.gremlin.structure.Vertex
 import space.kscience.attributes.Attribute
 import space.kscience.attributes.Attributes
 import space.kscience.attributes.UnsafeAPI
+import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.__ as TinkerPop
 
 public interface TinkerAttributeAccessor<T> {
     /**
@@ -53,7 +55,7 @@ public class SimpleTinkerAttributeAccessor<T>(
 
     override fun Element.readAttribute(): T = this.value<T>(key)
 
-    override fun <E : Element> GraphTraversal<*, E>.readAttribute(): GraphTraversal<*, T?> = values<T>(key)
+    override fun <E : Element> GraphTraversal<*, E>.readAttribute(): GraphTraversal<*, T?> = valueOrNull(key)
 
     override fun <E : Element> GraphTraversal<*, E>.writeAttribute(
         attribute: Attribute<T>,
@@ -87,7 +89,7 @@ public interface TinkerConnectionAttributeAccessor<T : NodeConnection> : TinkerA
 
     override fun <E : Element> GraphTraversal<*, E>.writeAttributeFrom(
         attributes: Attributes
-    ): GraphTraversal<*, E> = writeAttribute(attribute,attributes[attribute])
+    ): GraphTraversal<*, E> = writeAttribute(attribute, attributes[attribute])
 }
 
 public class SimpleTinkerConnectionAttributeAccessor(
@@ -159,3 +161,9 @@ public class TinkerAttributes(
 
     public companion object
 }
+
+public fun <E, T> GraphTraversal<E, *>.valueOrNull(propertyKey: String): GraphTraversal<E, T?> = choose<T>(
+    TinkerPop.has<Vertex>(propertyKey),
+    TinkerPop.values<Vertex, T>(propertyKey),
+    TinkerPop.constant(null)
+)

workflow-tinkerpop/src/jvmMain/kotlin/center/sciprog/workflow/state/TinkerRegistry.kt

@@ -0,0 +1,41 @@
+package center.sciprog.workflow.state
+
+import space.kscience.attributes.Attribute
+
+public interface TinkerRegistry {
+    public fun attributePipeByLabel(label: String): TinkerAttributeAccessor<*>
+    public fun <T> attributePipeByAttribute(attribute: Attribute<T>): TinkerAttributeAccessor<T>
+}
+
+private class SimpleTinkerRegistry(val accessors: Set<TinkerAttributeAccessor<*>>) : TinkerRegistry {
+    override fun attributePipeByLabel(label: String): TinkerAttributeAccessor<*> = accessors.single { it.key == label }
+
+    @Suppress("UNCHECKED_CAST")
+    override fun <T> attributePipeByAttribute(attribute: Attribute<T>): TinkerAttributeAccessor<T> = accessors.single {
+        it.attribute == attribute
+    } as TinkerAttributeAccessor<T>
+
+}
+
+/**
+ * Constructs a TinkerRegistry with the provided set of attribute accessors.
+ *
+ * @param accessors A set of TinkerAttributeAccessor objects that define the mapping
+ * between graph elements and their corresponding attributes.
+ * @return A TinkerRegistry instance that maps attributes to their corresponding keys or labels.
+ */
+public fun TinkerRegistry(
+    accessors: Set<TinkerAttributeAccessor<*>>
+): TinkerRegistry = SimpleTinkerRegistry(accessors)
+
+public fun <T> MutableSet<TinkerAttributeAccessor<*>>.attribute(
+    key: String,
+    attribute: Attribute<T>
+) {
+    add(SimpleTinkerAttributeAccessor(key, attribute))
+}
+
+public fun TinkerRegistry(
+    registryBuilder: MutableSet<TinkerAttributeAccessor<*>>.() -> Unit
+): TinkerRegistry = TinkerRegistry(buildSet(registryBuilder))
+

workflow-tinkerpop/src/jvmMain/kotlin/center/sciprog/workflow/state/TinkerStateGraph.kt

@@ -14,18 +14,12 @@ import space.kscience.attributes.Attributes
 import kotlin.uuid.ExperimentalUuidApi
 import kotlin.uuid.Uuid
 
-public interface TinkerRegistry {
-    public fun attributePipeByLabel(label: String): TinkerAttributeAccessor<*>
-    public fun <T> attributePipeByAttribute(attribute: Attribute<T>): TinkerAttributeAccessor<T>
-}
-
-
 public class TinkerNode(
     private val vertex: Vertex,
     private val registry: TinkerRegistry
 ) : StateNode {
 
-    public val id: NodeId get() = vertex.id().toString()
+    override val id: NodeId get() = vertex.id().toString()
 
     override val type: NodeType get() = vertex.label()
 
@@ -36,7 +30,7 @@ public class TinkerStateGraph(
     private val ts: GraphTraversalSource,
     public val registry: TinkerRegistry,
     override val clock: Clock = Clock.System,
-) : MutableStateGraph {
+) : MutableStateGraph, AutoCloseable by ts.graph {
 
     private val sharedEventFlow = MutableSharedFlow<GraphHistoryEvent>()
 
@@ -97,7 +91,7 @@ public class TinkerStateGraph(
         value: T,
         time: Instant
     ): Unit = with(registry.attributePipeByAttribute(attribute)) {
-        val oldValue = ts.V(nodeId)
+        val oldValue: T? = ts.V(nodeId)
             .readAttribute()
             .choose<T>(
                 P.neq(value),

workflow-tinkerpop/src/jvmTest/kotlin/center/sciprog/workflow/state/AttributesTest.kt

@@ -1,4 +1,37 @@
 package center.sciprog.workflow.state
 
-class AttributesTest {
+import kotlinx.coroutines.test.runTest
+import org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerFactory
+import space.kscience.attributes.Attribute
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+internal class AttributesTest {
+
+    object AttributeA : Attribute<Double>
+    object AttributeB : Attribute<String>
+
+    @Test
+    fun tinkerAttributesWriteRead() = runTest {
+        val graph = TinkerFactory.createModern()
+
+        val registry = TinkerRegistry {
+            attribute("a", AttributeA)
+            attribute("b", AttributeB)
+        }
+
+        TinkerStateGraph(graph.traversal(), registry).use { state ->
+            val node = state.createNode("test")
+
+            state.setAttribute(node.id, AttributeA, 1.0)
+
+            assertEquals(1.0, node.attributes[AttributeA])
+
+            state.removeAttribute(node.id, AttributeA)
+
+            assertEquals(null, node.attributes[AttributeA])
+        }
+
+
+    }
 }