Fix Replace/Find behavior for RegEx search eclipse-platform#1540

The replace functionality of the FindAndReplaceLogic checks whether the
current selection fits to the current search string and otherwise
performs a find operation first. To this end, it compares the text
selection with the search string, even if regex search is used. In regex
search mode, this check will usually fail and a find operation is
performed even though a correct string is already selected. This results
in the replacement of the next instead of the current match.

With this change, the check for whether the currently selected string
fits to the search string properly considers regex search mode. It also
adds an according regression test.

Fixes eclipse-platform#1540

bundles/org.eclipse.ui.workbench.texteditor/src/org/eclipse/ui/internal/findandreplace/FindReplaceLogic.java

@@ -18,6 +18,7 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
 
 import org.eclipse.swt.custom.BusyIndicator;
@@ -593,13 +594,23 @@ public boolean performReplaceAndFind(String findString, String replaceString) {
 	@Override
 	public boolean performSelectAndReplace(String findString, String replaceString) {
 		resetStatus();
-		boolean needToSelectFirst = !getCurrentSelection().equals(findString);
-		if (needToSelectFirst) {
+		if (!isFindStringSelected(findString)) {
 			performSearch(findString);
 		}
 		return replaceSelection(replaceString);
 	}
 
+	private boolean isFindStringSelected(String findString) {
+		String selectedString = getCurrentSelection();
+		if (isActive(SearchOptions.REGEX)) {
+			int patternFlags = isActive(SearchOptions.CASE_SENSITIVE) ? 0 : Pattern.CASE_INSENSITIVE;
+			Pattern pattern = Pattern.compile(findString, patternFlags);
+			return pattern.matcher(selectedString).find();
+		} else {
+			return getCurrentSelection().equals(findString);
+		}
+	}
+
 	@Override
 	public void updateTarget(IFindReplaceTarget newTarget, boolean canEditTarget) {
 		resetStatus();

tests/org.eclipse.ui.workbench.texteditor.tests/src/org/eclipse/ui/internal/findandreplace/FindReplaceLogicTest.java

@@ -213,7 +213,6 @@ public void testPerformSelectAndReplaceBackward() {
 		expectStatusEmpty(findReplaceLogic);
 	}
 
-
 	@Test
 	public void testPerformReplaceAndFind() {
 		TextViewer textViewer= setupTextViewer("Hello<replace>World<replace>!");
@@ -237,6 +236,36 @@ public void testPerformReplaceAndFind() {
 		expectStatusIsCode(findReplaceLogic, FindStatus.StatusCode.NO_MATCH);
 	}
 
+	@Test
+	public void testPerformReplaceAndFindRegEx() {
+		TextViewer textViewer= setupTextViewer("Hello<replace>World<replace>!<replace>!");
+		IFindReplaceLogic findReplaceLogic= setupFindReplaceLogicObject(textViewer);
+		findReplaceLogic.activate(SearchOptions.FORWARD);
+		findReplaceLogic.activate(SearchOptions.REGEX);
+
+		boolean status= findReplaceLogic.performReplaceAndFind("<(\\w*)>", " ");
+		assertThat(status, is(true));
+		assertThat(textViewer.getDocument().get(), equalTo("Hello World<replace>!<replace>!"));
+		assertThat(findReplaceLogic.getTarget().getSelectionText(), equalTo("<replace>"));
+		expectStatusEmpty(findReplaceLogic);
+
+		status= findReplaceLogic.performReplaceAndFind("<(\\w*)>", " ");
+		assertThat(status, is(true));
+		assertThat(textViewer.getDocument().get(), equalTo("Hello World !<replace>!"));
+		assertThat(findReplaceLogic.getTarget().getSelectionText(), equalTo("<replace>"));
+		expectStatusEmpty(findReplaceLogic);
+
+		status= findReplaceLogic.performReplaceAndFind("<(\\w*)>", " ");
+		assertThat(status, is(true));
+		assertThat(textViewer.getDocument().get(), equalTo("Hello World ! !"));
+		expectStatusIsCode(findReplaceLogic, FindStatus.StatusCode.NO_MATCH);
+
+		status= findReplaceLogic.performReplaceAndFind("<(\\w*)>", " ");
+		assertEquals("Status wasn't correctly returned", false, status);
+		assertEquals("Text shouldn't have been changed", "Hello World ! !", textViewer.getDocument().get());
+		expectStatusIsCode(findReplaceLogic, FindStatus.StatusCode.NO_MATCH);
+	}
+
 	@Test
 	public void testPerformSelectAllForward() {
 		TextViewer textViewer= setupTextViewer("AbAbAbAb");