From 121aecc4a8485571bb9337919372b903510afb25 Mon Sep 17 00:00:00 2001
From: Giovanni Ciatto <giovanni.ciatto@unibo.it>
Date: Thu, 18 Jun 2020 16:01:38 +0200
Subject: [PATCH] improve backtracking

---
 .../tuprolog/solve/ChoicePointContext.kt      | 28 ++++++++++++++-----
 .../tuprolog/solve/fsm/StateBacktracking.kt   |  2 +-
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/ChoicePointContext.kt b/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/ChoicePointContext.kt
index 07533ec87..198395e6b 100644
--- a/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/ChoicePointContext.kt
+++ b/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/ChoicePointContext.kt
@@ -56,7 +56,7 @@ sealed class ChoicePointContext(
 
     protected abstract val typeName: String
 
-    abstract fun backtrack(nextStep: Long, startTime: Long): ClassicExecutionContext
+    abstract fun backtrack(context: ClassicExecutionContext): ClassicExecutionContext
 
     data class Primitives(
         override val alternatives: Cursor<out Solve.Response>,
@@ -72,11 +72,18 @@ sealed class ChoicePointContext(
         override val typeName: String
             get() = "Primitives"
 
-        override fun backtrack(nextStep: Long, startTime: Long): ClassicExecutionContext {
+        override fun backtrack(context: ClassicExecutionContext): ClassicExecutionContext {
             val tempContext = executionContext!!.copy(
                 primitives = alternatives,
-                step = nextStep,
-                startTime = startTime
+                step = context.step + 1,
+                startTime = context.startTime,
+                flags = context.flags,
+                dynamicKb = context.dynamicKb,
+                staticKb = context.staticKb,
+                operators = context.operators,
+                inputChannels = context.inputChannels,
+                outputChannels = context.outputChannels,
+                libraries = context.libraries
             )
 
             val nextChoicePointContext = copy(
@@ -102,11 +109,18 @@ sealed class ChoicePointContext(
         override val typeName: String
             get() = "Rules"
 
-        override fun backtrack(nextStep: Long, startTime: Long): ClassicExecutionContext {
+        override fun backtrack(context: ClassicExecutionContext): ClassicExecutionContext {
             val tempContext = executionContext!!.copy(
                 rules = alternatives,
-                step = nextStep,
-                startTime = startTime
+                step = context.step + 1,
+                startTime = context.startTime,
+                flags = context.flags,
+                dynamicKb = context.dynamicKb,
+                staticKb = context.staticKb,
+                operators = context.operators,
+                inputChannels = context.inputChannels,
+                outputChannels = context.outputChannels,
+                libraries = context.libraries
             )
 
             val nextChoicePointContext = copy(
diff --git a/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/fsm/StateBacktracking.kt b/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/fsm/StateBacktracking.kt
index c32248482..5b9732016 100644
--- a/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/fsm/StateBacktracking.kt
+++ b/solve-classic/src/commonMain/kotlin/it/unibo/tuprolog/solve/fsm/StateBacktracking.kt
@@ -13,7 +13,7 @@ internal data class StateBacktracking(override val context: ClassicExecutionCont
             )
         } else {
             val choicePointContext = choicePoints!!.pathToRoot.first { it.alternatives.hasNext }
-            val nextContext = choicePointContext.backtrack(nextStep(), context.startTime)
+            val nextContext = choicePointContext.backtrack(context)
             if (nextContext.primitives.hasNext) {
                 StatePrimitiveExecution(nextContext)
             } else {