Merge pull request fwcd#47 from fwcd/better-cyclic-representation

Reuse variable references for better representation of cyclic references

Author: fwcd

adapter/src/main/kotlin/org/javacs/ktda/core/scope/VariableTreeNode.kt

@@ -1,10 +1,12 @@
 package org.javacs.ktda.core.scope
 
+import org.javacs.ktda.util.Identifiable
+
 /**
  * A descriptor for a collection of child variables.
  * (usually a scope or a variable's fields)
  */
-interface VariableTreeNode {
+interface VariableTreeNode : Identifiable {
 	val name: String
 	val value: String?
 		get() = null

adapter/src/main/kotlin/org/javacs/ktda/jdi/scope/JDIVariable.kt

@@ -11,12 +11,13 @@ import com.sun.jdi.Type
 
 class JDIVariable(
 	override val name: String,
-	jdiValue: Value?,
+	private val jdiValue: Value?,
 	jdiType: Type? = null
 ) : VariableTreeNode {
 	override val value: String = jdiValue?.toString() ?: "null" // TODO: Better string representation
 	override val type: String = (jdiType?.name() ?: jdiValue?.type()?.name()) ?: "Unknown type"
 	override val childs: List<VariableTreeNode>? by lazy { jdiValue?.let(::childrenOf) }
+	override val id: Long? = (jdiValue as? ObjectReference)?.uniqueID() ?: (jdiValue as? ArrayReference)?.uniqueID()
 
 	private fun childrenOf(jdiValue: Value): List<VariableTreeNode> {
 		val jdiType = jdiValue.type()

adapter/src/main/kotlin/org/javacs/ktda/util/Identifiable.kt

@@ -0,0 +1,6 @@
+package org.javacs.ktda.util
+
+public interface Identifiable {
+    val id: Long?
+        get() = null
+}

adapter/src/main/kotlin/org/javacs/ktda/util/ObjectPool.kt

@@ -1,5 +1,7 @@
 package org.javacs.ktda.util
 
+import org.javacs.ktda.util.Identifiable
+
 private data class ObjectKey<O>(
 	val id: Long,
 	val owner: O
@@ -32,16 +34,14 @@ class ObjectPool<O, V> {
 
 	/** Stores an object and returns its (unique) id */
 	fun store(owner: O, value: V): Long {
-		val id = currentID
+		val id = (value as? Identifiable)?.id ?: nextID()
 		val key = ObjectKey(id, owner)
 		val mapping = ObjectMapping(key, value)
 
 		mappingsByID[id] = mapping
 		mappingsByOwner.putIfAbsent(owner, mutableSetOf())
 		mappingsByOwner[owner]!!.add(mapping)
 
-		currentID += 1
-		
 		return id
 	}
 
@@ -74,4 +74,14 @@ class ObjectPool<O, V> {
 		.orEmpty()
 
 	fun containsID(id: Long) = mappingsByID.contains(id)
+
+	private fun nextID(): Long {
+		var id = currentID
+
+		while (containsID(id)) {
+			id += 1
+		}
+
+		return id
+	}
 }