From e2bfa0649815a46021c05f436235d459d1b4658a Mon Sep 17 00:00:00 2001
From: Luca Molteni <volothamp@gmail.com>
Date: Sun, 8 Jul 2018 17:43:12 +0200
Subject: [PATCH] [DROOLS-2625] Support reverse in exec model's accumulator
 (#1976)

* Support reverse

* If not present in the reverse map take it from the memory
---
 .../constraints/LambdaAccumulator.java        | 21 +++++++++++++++++--
 .../modelcompiler/domain/TargetPolicy.java    |  9 ++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/drools-model/drools-model-compiler/src/main/java/org/drools/modelcompiler/constraints/LambdaAccumulator.java b/drools-model/drools-model-compiler/src/main/java/org/drools/modelcompiler/constraints/LambdaAccumulator.java
index 2fa749cfd00..7dda335c1a9 100644
--- a/drools-model/drools-model-compiler/src/main/java/org/drools/modelcompiler/constraints/LambdaAccumulator.java
+++ b/drools-model/drools-model-compiler/src/main/java/org/drools/modelcompiler/constraints/LambdaAccumulator.java
@@ -2,7 +2,9 @@
 
 import java.io.Serializable;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import org.drools.core.WorkingMemory;
 import org.drools.core.common.InternalFactHandle;
@@ -16,6 +18,8 @@ public abstract class LambdaAccumulator implements Accumulator {
 
     private final org.kie.api.runtime.rule.AccumulateFunction accumulateFunction;
     protected final List<String> sourceVariables;
+    private Map<Integer, Object> reverseSupport;
+
 
     protected LambdaAccumulator(org.kie.api.runtime.rule.AccumulateFunction accumulateFunction, List<String> sourceVariables) {
         this.accumulateFunction = accumulateFunction;
@@ -40,11 +44,18 @@ public Serializable createContext() {
     @Override
     public void init(Object workingMemoryContext, Object context, Tuple leftTuple, Declaration[] declarations, WorkingMemory workingMemory) throws Exception {
         accumulateFunction.init((Serializable) context);
+        if(supportsReverse()) {
+            reverseSupport = new HashMap<>();
+        }
     }
 
     @Override
     public void accumulate(Object workingMemoryContext, Object context, Tuple leftTuple, InternalFactHandle handle, Declaration[] declarations, Declaration[] innerDeclarations, WorkingMemory workingMemory) throws Exception {
-        accumulateFunction.accumulate((Serializable) context, getAccumulatedObject( declarations, innerDeclarations, handle, leftTuple, ( InternalWorkingMemory ) workingMemory ));
+        final Object accumulatedObject = getAccumulatedObject(declarations, innerDeclarations, handle, leftTuple, (InternalWorkingMemory) workingMemory);
+        if (supportsReverse()) {
+            reverseSupport.put(handle.getId(), accumulatedObject);
+        }
+        accumulateFunction.accumulate((Serializable) context, accumulatedObject);
     }
 
     protected abstract Object getAccumulatedObject( Declaration[] declarations, Declaration[] innerDeclarations, InternalFactHandle handle, Tuple tuple, InternalWorkingMemory wm );
@@ -56,7 +67,13 @@ public boolean supportsReverse() {
 
     @Override
     public void reverse(Object workingMemoryContext, Object context, Tuple leftTuple, InternalFactHandle handle, Declaration[] declarations, Declaration[] innerDeclarations, WorkingMemory workingMemory) throws Exception {
-        accumulateFunction.reverse((Serializable) context, getAccumulatedObject( declarations, innerDeclarations, handle, leftTuple, ( InternalWorkingMemory ) workingMemory ));
+        final Object accumulatedObject = reverseSupport.remove(handle.getId());
+        if(accumulatedObject == null) {
+            final Object accumulatedObject2 = getAccumulatedObject(declarations, innerDeclarations, handle, leftTuple, (InternalWorkingMemory) workingMemory);
+            accumulateFunction.reverse((Serializable) context, accumulatedObject2);
+        } else {
+            accumulateFunction.reverse((Serializable) context, accumulatedObject);
+        }
     }
 
     @Override
diff --git a/drools-model/drools-model-compiler/src/test/java/org/drools/modelcompiler/domain/TargetPolicy.java b/drools-model/drools-model-compiler/src/test/java/org/drools/modelcompiler/domain/TargetPolicy.java
index c49685fddb7..848901974ad 100644
--- a/drools-model/drools-model-compiler/src/test/java/org/drools/modelcompiler/domain/TargetPolicy.java
+++ b/drools-model/drools-model-compiler/src/test/java/org/drools/modelcompiler/domain/TargetPolicy.java
@@ -47,5 +47,14 @@ public int getCoefficient() {
     public void setCoefficient(int coefficient) {
         this.coefficient = coefficient;
     }
+
+    @Override
+    public String toString() {
+        return "TargetPolicy{" +
+                "customerCode='" + customerCode + '\'' +
+                ", productCode='" + productCode + '\'' +
+                ", coefficient=" + coefficient +
+                '}';
+    }
 }