Support correct type analysis with generic return type of Optional

billows-hu · Sep 1, 2020 · 98dae05 · 98dae05
1 parent 4e7ceea
commit 98dae05
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Showing 2 changed files with 20 additions and 1 deletion.
diff --git a/src/main/java/org/mvel2/compiler/PropertyVerifier.java b/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;
@@ -669,7 +670,14 @@ else if (typeArgs.containsKey(returnTypeArg)) {
   }
 
   private static Class type2Class(Type type) {
-    return type instanceof Class ? (Class) type : (Class) ((ParameterizedType) type).getRawType();
+    if (type instanceof Class) {
+      return (Class) type;
+    } else if(type instanceof TypeVariable) { // such as T in Optional<T>
+      GenericDeclaration genericDeclaration = ((TypeVariable) type).getGenericDeclaration();
+      return ((Method)genericDeclaration).getReturnType();
+    } else {
+      return (Class) ((ParameterizedType) type).getRawType();
+    }
   }
 
   private Class getWithProperty(Class ctx) {

diff --git a/src/test/java/org/mvel2/tests/core/TypesAndInferenceTests.java b/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);
+  }
 }