[DROOLS-5851] fix binding of a constant enum value during executable …

…model generation (apache#3266)

drools-model/drools-model-compiler/src/main/java/org/drools/modelcompiler/builder/generator/drlxparse/ConstraintParser.java

@@ -75,6 +75,7 @@
 import static org.drools.modelcompiler.builder.generator.DrlxParseUtil.getLiteralExpressionType;
 import static org.drools.modelcompiler.builder.generator.DrlxParseUtil.toClassOrInterfaceType;
 import static org.drools.modelcompiler.builder.generator.drlxparse.SpecialComparisonCase.specialComparisonFactory;
+import static org.drools.modelcompiler.builder.generator.expressiontyper.ExpressionTyper.tryParseAsConstantField;
 import static org.drools.mvel.parser.printer.PrintUtil.printConstraint;
 
 public class ConstraintParser {
@@ -260,13 +261,18 @@ private DrlxParseResult parseNameExpr(DrlNameExpr nameExpr, Class<?> patternType
     }
 
     private DrlxParseResult parseFieldAccessExpr( FieldAccessExpr fieldCallExpr, Class<?> patternType, String bindingId ) {
-        ToMethodCall toMethodCall = new ToMethodCall(context);
-        TypedExpression converted = toMethodCall.toMethodCallWithClassCheck(fieldCallExpr, bindingId, patternType);
-        Expression withThis = DrlxParseUtil.prepend(new NameExpr(THIS_PLACEHOLDER), converted.getExpression());
+        try {
+            ToMethodCall toMethodCall = new ToMethodCall(context);
+            TypedExpression converted = toMethodCall.toMethodCallWithClassCheck(fieldCallExpr, bindingId, patternType);
+            Expression withThis = DrlxParseUtil.prepend(new NameExpr(THIS_PLACEHOLDER), converted.getExpression());
 
-        return new SingleDrlxParseSuccess(patternType, bindingId, withThis, converted.getType())
-                .setLeft(converted)
-                .setImplicitCastExpression(toMethodCall.getImplicitCastExpression());
+            return new SingleDrlxParseSuccess(patternType, bindingId, withThis, converted.getType())
+                    .setLeft(converted)
+                    .setImplicitCastExpression(toMethodCall.getImplicitCastExpression());
+        } catch(ToMethodCall.CannotConvertException e) {
+            Optional<TypedExpression> parsed = tryParseAsConstantField(context.getTypeResolver(), fieldCallExpr.getScope(), fieldCallExpr.getNameAsString());
+            return parsed.map( expr -> new SingleDrlxParseSuccess(patternType, bindingId, expr.getExpression(), expr.getType()).setLeft(expr) ).orElseThrow( () -> e );
+        }
     }
 
     private DrlxParseResult parsePointFreeExpr(PointFreeExpr pointFreeExpr, Class<?> patternType, String bindingId, boolean isPositional) {

drools-model/drools-model-compiler/src/test/java/org/drools/modelcompiler/EnumTest.java

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2020. Red Hat, Inc. and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.drools.modelcompiler;
+
+import org.junit.Test;
+import org.kie.api.runtime.KieSession;
+
+import static org.junit.Assert.assertEquals;
+
+public class EnumTest extends BaseModelTest {
+
+    public EnumTest( RUN_TYPE testRunType ) {
+        super( testRunType );
+    }
+
+    @Test
+    public void testMatchEnum() {
+        String str =
+                "import " + Bus.class.getCanonicalName() + ";" +
+                "rule bus2 when\n" +
+                "       $bus : Bus( $maker : maker == Bus.Maker.HINO )\n" +
+                "   then\n" +
+                "       System.out.println(\"bus=\" + $bus + \", maker=\" + $maker);\n" +
+                "end";
+
+        KieSession ksession = getKieSession( str );
+
+        Bus a = new Bus("blue", 25, Bus.Maker.HINO);
+        ksession.insert(a);
+        Bus b = new Bus("red", 25, Bus.Maker.ISUZU);
+        ksession.insert(b);
+
+        assertEquals(1, ksession.fireAllRules());
+    }
+
+    @Test
+    public void testBindEnum() {
+        // DROOLS-5851
+        String str =
+                "import " + Bus.class.getCanonicalName() + ";" +
+                "rule bus2 when\n" +
+                "       $bus : Bus( $maker : Bus.Maker.HINO )\n" +
+                "   then\n" +
+                "       System.out.println(\"bus=\" + $bus + \", maker=\" + $maker);\n" +
+                "end";
+
+        KieSession ksession = getKieSession( str );
+
+        Bus a = new Bus("blue", 25, Bus.Maker.HINO);
+        ksession.insert(a);
+        Bus b = new Bus("red", 25, Bus.Maker.ISUZU);
+        ksession.insert(b);
+
+        assertEquals(2, ksession.fireAllRules());
+    }
+
+    public static class Bus {
+        private String name;
+        private int person;
+        private Maker maker;
+
+        public enum Maker {
+            FUSO,
+            HINO,
+            ISUZU
+        }
+
+        public Bus(String name, int person) {
+            this.name = name;
+            this.person = person;
+        }
+
+        public Bus(String name, int person, Maker maker) {
+            this.name = name;
+            this.person = person;
+            this.maker = maker;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public int getPerson() {
+            return person;
+        }
+
+        public void setPerson(int person) {
+            this.person = person;
+        }
+
+        public Maker getMaker() {
+            return maker;
+        }
+
+        public void setMaker(Maker maker) {
+            this.maker = maker;
+        }
+    }
+}