review: feat: Spoon CtRole based attributes access

src/main/java/spoon/reflect/declaration/CtElement.java

@@ -32,6 +32,7 @@
 import java.lang.annotation.Annotation;
 import java.util.Collection;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 import static spoon.reflect.path.CtRole.ANNOTATION;
@@ -314,4 +315,21 @@ <E extends CtElement> List<E> getAnnotatedChildren(
 	 * Clone the element which calls this method in a new object.
 	 */
 	CtElement clone();
+
+	/**
+	 * @return a a single value (eg a CtElement), List, Set or Map depending on this `element` and `role`. Returned collections are read-only.
+	 * @param the role of the returned attribute with respect to this element.
+	 *
+	 * For instance, "klass.getValueByRole(CtRole.METHOD)" returns a list of methods.
+	 *
+	 * See {@link spoon.reflect.meta.impl.RoleHandlerHelper} for more advanced methods.
+	 */
+	<T> T getValueByRole(CtRole role);
+
+	/**
+	 * Sets a field according to a role.
+	 * @param the role of the field to be set
+	 * @param value to be assigned to this field.
+	 */
+	<E extends CtElement, T> E  setValueByRole(CtRole role, T value);
 }

src/main/java/spoon/reflect/meta/ContainerKind.java

@@ -0,0 +1,43 @@
+/**
+ * Copyright (C) 2006-2017 INRIA and contributors
+ * Spoon - http://spoon.gforge.inria.fr/
+ *
+ * This software is governed by the CeCILL-C License under French law and
+ * abiding by the rules of distribution of free software. You can use, modify
+ * and/or redistribute the software under the terms of the CeCILL-C license as
+ * circulated by CEA, CNRS and INRIA at http://www.cecill.info.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the CeCILL-C License for more details.
+ *
+ * The fact that you are presently reading this means that you have had
+ * knowledge of the CeCILL-C license and that you accept its terms.
+ */
+package spoon.reflect.meta;
+
+/**
+ * Defines kind of container, which is used in an attribute of Spoon model
+ */
+public enum ContainerKind {
+	/**
+	 * it is a single value field
+	 * Example: CtClassImpl.simpleName
+	 */
+	SINGLE,
+	/**
+	 * It is a list of values
+	 * Example: CtClassImpl.typeMembers
+	 */
+	LIST,
+	/**
+	 * It is a set of values
+	 * Example: CtPackageImpl.types
+	 */
+	SET,
+	/**
+	 * It is a map<String, T> of values
+	 * Example: CtAnnotationImpl.elementValues
+	 */
+	MAP;
+}

src/main/java/spoon/reflect/meta/RoleHandler.java

@@ -0,0 +1,87 @@
+/**
+ * Copyright (C) 2006-2017 INRIA and contributors
+ * Spoon - http://spoon.gforge.inria.fr/
+ *
+ * This software is governed by the CeCILL-C License under French law and
+ * abiding by the rules of distribution of free software. You can use, modify
+ * and/or redistribute the software under the terms of the CeCILL-C license as
+ * circulated by CEA, CNRS and INRIA at http://www.cecill.info.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the CeCILL-C License for more details.
+ *
+ * The fact that you are presently reading this means that you have had
+ * knowledge of the CeCILL-C license and that you accept its terms.
+ */
+package spoon.reflect.meta;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import spoon.reflect.path.CtRole;
+
+/**
+ * Enables client code to get and set a field based on a role for a CtElement.
+ *
+ * One obtains instances of {@link RoleHandler} using the methods of {@link spoon.reflect.meta.impl.RoleHandlerHelper}.
+ *
+ * There is one role handler per role of {@link CtRole}, they are set by {@link spoon.reflect.meta.impl.RoleHandlerHelper}.
+ */
+public interface RoleHandler {
+	// the main methods, responsible to get and set the field corresponding to this role
+	/**
+	 * @param element a element from which the value will be get for this role
+	 * @return a value of the element on the role defined by {@link #getRole()}
+	 */
+	<T, U> U getValue(T element);
+	/**
+	 * @param element a element whose value will be set for this role
+	 * @param value new value, which will be assigned to the element's attribute defined by role defined by {@link #getRole()}
+	 */
+	<T, U> void setValue(T element, U value);
+
+	// introspection methods
+	/**
+	 * @return the role handled by this handler
+	 */
+	CtRole getRole();
+
+	/**
+	 * @return the type of the class, which this handler can be applied to (eg CtMethod)
+	 */
+	Class<?> getTargetType();
+
+	/**
+	 * @return the type of returned value defined by {@link #getRole()}
+	 */
+	Class<?> getValueClass();
+
+	/**
+	 * @return the container kind, to know whether an element, a list, a map, etc is returned.
+	 */
+	ContainerKind getContainerKind();
+
+	// utility methods
+	/**
+	 * @return a value for this role adapted as a modifiable Collection
+	 */
+	<T, U> Collection<U> asCollection(T element);
+
+	/**
+	 * @return a value for this role adapted as a modifiable Set
+	 */
+	<T, U> Set<U> asSet(T element);
+
+	/**
+	 * @return a value for this role adapted as a modifiable List
+	 */
+	<T, U> List<U> asList(T element);
+
+	/**
+	 * @return a value for this role adapted as a modifiable Map
+	 */
+	<T, U> Map<String, U> asMap(T element);
+}