added javadoc

src/main/java/spoon/reflect/visitor/printer/change/ChangesAwareDefaultJavaPrettyPrinter.java

@@ -18,6 +18,7 @@
 
 import java.util.ArrayDeque;
 import java.util.Deque;
+import java.util.Set;
 
 import spoon.SpoonException;
 import spoon.compiler.Environment;
@@ -153,8 +154,6 @@ private void onTokenWriterWrite(String tokenWriterMethodName, String token, CtCo
 		printAction.run();
 	}
 
-	private final SourceFragmentContextNormal EMPTY_FRAGMENT_CONTEXT = new SourceFragmentContextNormal();
-
 	/**
 	 * Called whenever {@link DefaultJavaPrettyPrinter} scans/prints an element
 	 */
@@ -177,17 +176,17 @@ private void scanInternal(CtElement element) {
 		if (mutableTokenWriter.isMuted()) {
 			//it is already muted by an parent. Simply scan and ignore all tokens,
 			//because the content is not modified and was already copied from source
-			sourceFragmentContextStack.push(EMPTY_FRAGMENT_CONTEXT);
+			sourceFragmentContextStack.push(SourceFragmentContextNormal.EMPTY_FRAGMENT_CONTEXT);
 			super.scan(element);
 			sourceFragmentContextStack.pop();
 			return;
 		}
-		//it is not muted yet, so some this element or any sibling was modified
+		//it is not muted yet, so this element or any sibling is modified
 		//detect SourceFragments of element and whether they are modified or not
-		SourceFragment rootFragmentOfElement = SourcePositionUtils.getSourceFragmentsOfElement(changeCollector, element);
+		SourceFragment rootFragmentOfElement = getSourceFragmentsOfElementUsableForPrintingOfOriginCode(changeCollector, element);
 		if (rootFragmentOfElement == null) {
 			//we have no origin sources or this element has one source fragment only and it is modified. Use normal printing
-			sourceFragmentContextStack.push(EMPTY_FRAGMENT_CONTEXT);
+			sourceFragmentContextStack.push(SourceFragmentContextNormal.EMPTY_FRAGMENT_CONTEXT);
 			super.scan(element);
 			sourceFragmentContextStack.pop();
 			return;
@@ -201,4 +200,45 @@ private void scanInternal(CtElement element) {
 		//at the end we always un-mute the token writer
 		mutableTokenWriter.setMuted(false);
 	}
+
+	/**
+	 * @param changeCollector holds information about modified elements
+	 * @param element to be printed element
+	 * @return {@link SourceFragment} or chain of {@link SourceFragment} siblings which wraps all the source parts of the `element`
+	 * It returns null when there are no sources at all or when all are modified so we cannot use them anyway
+	 */
+	private static SourceFragment getSourceFragmentsOfElementUsableForPrintingOfOriginCode(ChangeCollector changeCollector, CtElement element) {
+		//detect source code fragments of this element
+		SourceFragment rootFragmentOfElement = SourcePositionUtils.getSourceFragmentOfElement(element);
+		if (rootFragmentOfElement == null) {
+			//we have no origin sources for this element
+			return null;
+		}
+		//The origin sources of this element are available
+		//check if this element was changed
+		Set<CtRole> changedRoles = changeCollector.getChanges(element);
+		if (changedRoles.isEmpty()) {
+			//element was not changed and we know origin sources
+			//use origin source instead of printed code
+			return rootFragmentOfElement;
+		}
+		//element is changed. Detect source fragments of this element
+		SourceFragment childSourceFragmentsOfSameElement = rootFragmentOfElement.getChildFragmentOfSameElement();
+		if (childSourceFragmentsOfSameElement == null || childSourceFragmentsOfSameElement.getNextFragmentOfSameElement() == null) {
+			//there is only one source fragment and it is modified.
+			//So we cannot use origin sources
+			return null;
+		}
+		/*
+		 * there are more fragments. So may be some of them are not modified and we can use origin source to print them
+		 * e.g. when only type members of class are modified, we can still print the class header from the origin sources
+		 * Mark which fragments contains source code of data from modified roles
+		 */
+		//detect which roles of this element contains a change
+		if (SourcePositionUtils.markChangedFragments(element, childSourceFragmentsOfSameElement, changedRoles)) {
+			return childSourceFragmentsOfSameElement;
+		}
+		//this kind of changes is not supported for this element yet. We cannot use origin sources :-(
+		return null;
+	}
 }

src/main/java/spoon/reflect/visitor/printer/change/SourceFragmentContextNormal.java

@@ -7,10 +7,14 @@
 import spoon.reflect.path.CtRole;
 import spoon.reflect.visitor.printer.change.SourcePositionUtils.FragmentDescriptor;
 
+/**
+ * Knows how to handle actually printed {@link CtElement}.
+ * It drives printing of main element and single value attributes,
+ * while {@link SourceFragmentContextList} is used to drive printing of lists of attribute values
+ */
 class SourceFragmentContextNormal extends SourceFragmentContext {
-	/**
-	 *
-	 */
+	static final SourceFragmentContextNormal EMPTY_FRAGMENT_CONTEXT = new SourceFragmentContextNormal();
+
 	private final MutableTokenWriter mutableTokenWriter;
 	private SourceFragment currentFragment;
 	private CtElement element;
@@ -19,6 +23,11 @@ class SourceFragmentContextNormal extends SourceFragmentContext {
 	 */
 	private SourceFragmentContext childContext;
 
+	/**
+	 * @param mutableTokenWriter {@link MutableTokenWriter}, which is used for printing
+	 * @param element the {@link CtElement} which is printed
+	 * @param rootFragment the {@link SourceFragment}, which represents whole elements. E.g. whole type or method
+	 */
 	SourceFragmentContextNormal(MutableTokenWriter mutableTokenWriter, CtElement element, SourceFragment rootFragment) {
 		super();
 		this.mutableTokenWriter = mutableTokenWriter;
@@ -27,12 +36,15 @@ class SourceFragmentContextNormal extends SourceFragmentContext {
 		handlePrinting();
 	}
 
-	SourceFragmentContextNormal() {
+	private SourceFragmentContextNormal() {
 		mutableTokenWriter = null;
 		currentFragment = null;
 	}
 
-	SourceFragment getNextFragment() {
+	/**
+	 * @return next {@link SourceFragment} of the actually printed element.
+	 */
+	private SourceFragment getNextFragment() {
 		if (currentFragment != null) {
 			return currentFragment.getNextFragmentOfSameElement();
 		}
@@ -42,12 +54,17 @@ SourceFragment getNextFragment() {
 	/**
 	 * Called when next fragment is going to be printed
 	 */
-	void nextFragment() {
+	private void nextFragment() {
 		currentFragment = getNextFragment();
 		handlePrinting();
 	}
 
-	void handlePrinting() {
+	/**
+	 * checks if current fragment is modified
+	 * If not modified, then origin source code is directly printed and token writer is muted
+	 * If modified, then token writer is enabled and code is printed normally
+	 */
+	private void handlePrinting() {
 		if (currentFragment != null) {
 			if (currentFragment.isModified() == false) {
 				//we are going to print not modified fragment
@@ -72,14 +89,6 @@ void handlePrinting() {
 		}
 	}
 
-	boolean testFagmentDescriptor(SourceFragment sourceFragment, Predicate<FragmentDescriptor> predicate) {
-		if (sourceFragment != null) {
-			if (sourceFragment.fragmentDescriptor != null) {
-				return predicate.test(sourceFragment.fragmentDescriptor);
-			}
-		}
-		return false;
-	}
 
 	@Override
 	void onTokenWriterToken(String tokenWriterMethodName, String token, Runnable printAction) {
@@ -129,4 +138,13 @@ void onParentFinished() {
 		//we will see if it is true... I (Pavel) am not sure yet
 		throw new SpoonException("SourceFragmentContextNormal shouldn't be used as child context");
 	}
+
+	private boolean testFagmentDescriptor(SourceFragment sourceFragment, Predicate<FragmentDescriptor> predicate) {
+		if (sourceFragment != null) {
+			if (sourceFragment.fragmentDescriptor != null) {
+				return predicate.test(sourceFragment.fragmentDescriptor);
+			}
+		}
+		return false;
+	}
 }