refactor SubstitutionVisitor

src/main/java/spoon/generating/replace/ReplacementVisitor.java

@@ -126,13 +126,7 @@ private <T extends CtElement> void replaceInListIfExist(List<T> listProtected, R
 
 	private void replaceElementIfExist(CtElement candidate, ReplaceListener listener) {
 		if (candidate == original) {
-			if (replace.size() > 1) {
-				throw new SpoonException("Cannot replace single value by multiple values in " + listener.getClass().getSimpleName());
-			}
-			CtElement val = null;
-			if (replace.size() == 1) {
-				val = replace.iterator().next();
-			}
+			CtElement val = candidate.getFactory().Code().convertToSingle(replace);
 			listener.set(val);
 			if (val != null) {
 				val.setParent(candidate.getParent());

src/main/java/spoon/reflect/factory/CodeFactory.java

@@ -16,6 +16,7 @@
  */
 package spoon.reflect.factory;
 
+import spoon.SpoonException;
 import spoon.reflect.code.BinaryOperatorKind;
 import spoon.reflect.code.CtAssignment;
 import spoon.reflect.code.CtBinaryOperator;
@@ -43,6 +44,7 @@
 import spoon.reflect.code.CtVariableAccess;
 import spoon.reflect.declaration.CtAnnotation;
 import spoon.reflect.declaration.CtClass;
+import spoon.reflect.declaration.CtElement;
 import spoon.reflect.declaration.CtField;
 import spoon.reflect.declaration.CtNamedElement;
 import spoon.reflect.declaration.CtVariable;
@@ -60,6 +62,7 @@
 import java.lang.annotation.Annotation;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.HashSet;
@@ -714,4 +717,44 @@ public CtJavaDocTag createJavaDocTag(String content, CtJavaDocTag.TagType type)
 		return docTag.setContent(content.trim()).setType(type);
 	}
 
+	/**
+	 * Converts collection of elements to single element.
+	 * It actually supports conversion of {@link CtStatement}s to {@link CtBlock}
+	 *
+	 * @param elements a to be converted collection of elements
+	 * @return single element which represents input `elements`
+	 * @throws SpoonException if conversion is not possible
+	 */
+	@SuppressWarnings("unchecked")
+	public <T extends CtElement, E extends CtElement> T convertToSingle(Collection<E> elements) {
+		if (elements.isEmpty()) {
+			return null;
+		}
+		if (elements.size() == 1) {
+			return (T) elements.iterator().next();
+		}
+		if (isAllSubtypeOf(elements, CtStatement.class)) {
+			CtBlock block = factory.Core().createBlock();
+			block.setStatements(toList((Collection<CtStatement>) elements));
+			return (T) block;
+		}
+		throw new SpoonException("Cannot convert collection to single");
+	}
+
+	private <E> List<E> toList(Collection<E> col) {
+		if (col instanceof List) {
+			return (List<E>) col;
+		}
+		return new ArrayList<>(col);
+	}
+
+	private boolean isAllSubtypeOf(Collection<?> elements, Class<CtStatement> clazz) {
+		for (Object ele : elements) {
+			if (clazz.isInstance(ele) == false) {
+				return false;
+			}
+		}
+		return true;
+	}
+
 }