Merge pull request mvel#244 from lucamolteni/master

Support correct type analysis with generic return type of Optional

src/main/java/org/mvel2/compiler/PropertyVerifier.java

@@ -19,6 +19,7 @@
 package org.mvel2.compiler;
 
 import java.lang.reflect.Field;
+import java.lang.reflect.GenericDeclaration;
 import java.lang.reflect.Member;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
@@ -668,8 +669,21 @@ else if (typeArgs.containsKey(returnTypeArg)) {
     return getReturnType(ctx, m);
   }
 
-  private static Class type2Class(Type type) {
-    return type instanceof Class ? (Class) type : (Class) ((ParameterizedType) type).getRawType();
+  private static Class<?> type2Class(Type type) {
+    if (type == null) {
+      return null;
+    }
+    if (type instanceof Class<?>) {
+      return (Class) type;
+    }
+    if (type instanceof ParameterizedType) {
+      return type2Class(((ParameterizedType) type).getRawType());
+    }
+    if (type instanceof TypeVariable) { // this is T in Optional<T>
+      GenericDeclaration genericDeclaration = ((TypeVariable) type).getGenericDeclaration();
+      return genericDeclaration instanceof Method ? ((Method) genericDeclaration).getReturnType() : Object.class;
+    }
+    throw new UnsupportedOperationException("Unknown type " + type);
   }
 
   private Class getWithProperty(Class ctx) {

src/test/java/org/mvel2/tests/core/TypesAndInferenceTests.java

@@ -33,6 +33,7 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 
 import static org.mvel2.MVEL.*;
@@ -1595,4 +1596,14 @@ public void testGenerics1() {
     assertTrue(result);
   }
 
+  public void testOptionalOfGenerics() {
+    String str = "Optional.of(\"mystring\").orElse(\"anotherstring\")";
+
+    ParserConfiguration pconf = new ParserConfiguration();
+    ParserContext pctx = new ParserContext(pconf);
+    pctx.setStrongTyping(true);
+    pctx.addImport(Optional.class);
+    Class resultType =  analyze(str, pctx);
+    assertEquals(java.util.Optional.class, resultType);
+  }
 }