#3: Do not ignore missing TypeMirror silently

Due to a bug in javac (JDK-8229535) for an annotation with Class values, instead of returning a TypeMirror with TypeKind#ERROR the compiler returns the string "<error>". Eclipse doesn't have this problem currently.

Author: filiphr

api/src/main/java/org/mapstruct/tools/gem/GemValue.java

@@ -5,13 +5,14 @@
  */
 package org.mapstruct.tools.gem;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Function;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.AnnotationValue;
+import javax.lang.model.element.AnnotationValueVisitor;
 import javax.lang.model.element.VariableElement;
+import javax.lang.model.util.SimpleAnnotationValueVisitor8;
 
 /**
  * Class representing a annotation value
@@ -22,85 +23,66 @@ public class GemValue<T> {
 
     public static <V> GemValue<V> create(AnnotationValue annotationValue,
         AnnotationValue annotationDefaultValue, Class<V> valueClass) {
-        V value = annotationValue == null ? null : valueClass.cast( annotationValue.getValue() );
-        V defaultValue = annotationDefaultValue == null ? null : valueClass.cast( annotationDefaultValue.getValue() );
+        ValueAnnotationValueVisitor<V, V> visitor = new ValueAnnotationValueVisitor<>( Function.identity() );
+        V value = visit( annotationValue, visitor, valueClass );
+        V defaultValue = visit( annotationDefaultValue, visitor, valueClass );
         return new GemValue<>( value, defaultValue, annotationValue );
     }
 
     public static <V> GemValue<List<V>> createArray(AnnotationValue annotationValue,
         AnnotationValue annotationDefaultValue, Class<V> valueClass) {
-        List<V> value = extractListValues( annotationValue, valueClass, Function.identity() );
-        List<V> defaultValue = extractListValues( annotationDefaultValue, valueClass, Function.identity() );
+        ValueAnnotationValueListVisitor<V, V> visitor = new ValueAnnotationValueListVisitor<>( Function.identity() );
+        List<V> value = visitList( annotationValue, visitor, valueClass );
+        List<V> defaultValue = visitList( annotationDefaultValue, visitor, valueClass );
 
         return new GemValue<>( value, defaultValue, annotationValue );
     }
 
     public static GemValue<String> createEnum(AnnotationValue annotationValue,
         AnnotationValue annotationDefaultValue) {
-        String value = annotationValue == null ? null :
-            ( (VariableElement) annotationValue.getValue() ).getSimpleName().toString();
-        String defaultValue = annotationDefaultValue == null ? null :
-            ( (VariableElement) annotationDefaultValue.getValue() ).getSimpleName().toString();
+        ValueAnnotationValueVisitor<VariableElement, String> visitor = new ValueAnnotationValueVisitor<>(
+            variableElement -> variableElement.getSimpleName().toString() );
+        String value = visit( annotationValue, visitor, VariableElement.class );
+        String defaultValue = visit( annotationDefaultValue, visitor, VariableElement.class );
         return new GemValue<>( value, defaultValue, annotationValue );
     }
 
     public static GemValue<List<String>> createEnumArray(AnnotationValue annotationValue,
         AnnotationValue annotationDefaultValue) {
-        List<String> value = extractListValues(
-            annotationValue,
-            VariableElement.class,
-            variableElement -> variableElement.getSimpleName().toString()
-        );
-        List<String> defaultValue = extractListValues(
-            annotationDefaultValue,
-            VariableElement.class,
-            variableElement -> variableElement.getSimpleName().toString()
-        );
+        ValueAnnotationValueListVisitor<VariableElement, String> visitor = new ValueAnnotationValueListVisitor<>(
+            variableElement -> variableElement.getSimpleName().toString() );
+        List<String> value = visitList( annotationValue, visitor, VariableElement.class );
+        List<String> defaultValue = visitList( annotationDefaultValue, visitor, VariableElement.class );
 
         return new GemValue<>( value, defaultValue, annotationValue );
     }
 
     public static <V> GemValue<V> create(AnnotationValue annotationValue, AnnotationValue annotationDefaultValue,
         Function<AnnotationMirror, V> creator) {
-        V value = annotationValue == null ? null : creator.apply( (AnnotationMirror) annotationValue.getValue() );
-        V defaultValue = annotationDefaultValue == null ? null :
-            creator.apply( (AnnotationMirror) annotationDefaultValue.getValue() );
+        ValueAnnotationValueVisitor<AnnotationMirror, V> visitor = new ValueAnnotationValueVisitor<>( creator );
+        V value = visit( annotationValue, visitor, AnnotationMirror.class );
+        V defaultValue = visit( annotationDefaultValue, visitor, AnnotationMirror.class );
         return new GemValue<>( value, defaultValue, annotationValue );
     }
 
     public static <V> GemValue<List<V>> createArray(AnnotationValue annotationValue,
-        AnnotationValue annotationDefaultValue,
-        Function<AnnotationMirror, V> creator) {
-        List<V> value = extractListValues( annotationValue, AnnotationMirror.class, creator );
-        List<V> defaultValue = extractListValues( annotationDefaultValue, AnnotationMirror.class, creator );
+                                                    AnnotationValue annotationDefaultValue,
+                                                    Function<AnnotationMirror, V> creator) {
+        ValueAnnotationValueListVisitor<AnnotationMirror, V> visitor = new ValueAnnotationValueListVisitor<>( creator );
+        List<V> value = visitList( annotationValue, visitor, AnnotationMirror.class );
+        List<V> defaultValue = visitList( annotationDefaultValue, visitor, AnnotationMirror.class );
         return new GemValue<>( value, defaultValue, annotationValue );
     }
 
-    private static <V, R> List<R> extractListValues(AnnotationValue annotationValue, Class<V> valueClass,
-        Function<V, R> mapper) {
-        List<R> value;
-        if ( annotationValue != null ) {
-            Object definedValue = annotationValue.getValue();
-            if ( definedValue instanceof List ) {
-                value = toStream( (List) definedValue, valueClass ).map( mapper ).collect( Collectors.toList() );
-            }
-            else {
-                value = null;
-            }
-        }
-        else {
-            value = null;
-        }
-        return value;
+    private static <V, R> R visit(AnnotationValue annotationValue,
+                                  AnnotationValueVisitor<R, Class<V>> visitor, Class<V> vClass) {
+        return annotationValue == null ? null : annotationValue.accept( visitor, vClass );
     }
 
-    private static <T> Stream<T> toStream(List<?> annotationValues, Class<T> clz) {
-        return annotationValues.stream()
-            .filter( AnnotationValue.class::isInstance )
-            .map( AnnotationValue.class::cast )
-            .map( AnnotationValue::getValue )
-            .filter( clz::isInstance )
-            .map( clz::cast );
+    private static <V, R> List<R> visitList(AnnotationValue annotationValue,
+                                            AnnotationValueVisitor<List<R>, Class<V>> visitor,
+                                            Class<V> vClass) {
+        return annotationValue == null ? null : annotationValue.accept( visitor, vClass );
     }
 
     private final T value;
@@ -165,4 +147,48 @@ public boolean isValid() {
         return value != null || defaultValue != null;
     }
 
+    private static class ValueAnnotationValueVisitor<V, R> extends SimpleAnnotationValueVisitor8<R, Class<V>> {
+
+        private final Function<V, R> valueMapper;
+
+        private ValueAnnotationValueVisitor(Function<V, R> valueMapper) {
+            this.valueMapper = valueMapper;
+        }
+
+        @Override
+        protected R defaultAction(Object o, Class<V> vClass) {
+            if ( o == null ) {
+                return null;
+            }
+            else if ( vClass.isInstance( o ) ) {
+                return valueMapper.apply( vClass.cast( o ) );
+            }
+            else {
+                return null;
+            }
+        }
+    }
+
+    private static class ValueAnnotationValueListVisitor<V, R>
+        extends SimpleAnnotationValueVisitor8<List<R>, Class<V>> {
+
+        private final ValueAnnotationValueVisitor<V, R> arrayVisitor;
+
+        private ValueAnnotationValueListVisitor(Function<V, R> valueMapper) {
+            arrayVisitor = new ValueAnnotationValueVisitor<>( valueMapper );
+        }
+
+        @Override
+        public List<R> visitArray(List<? extends AnnotationValue> vals, Class<V> vClass) {
+            boolean valid = true;
+            List<R> values = new ArrayList<>( vals.size() );
+            for ( AnnotationValue val : vals ) {
+                R value = val.accept( arrayVisitor, vClass );
+                values.add( value );
+            }
+
+            return values;
+        }
+    }
+
 }