Merge pull request #721 from JordanMartinez/fixMultiPlainChanges

Prevent `multiPlainChanges()` from emitting an empty list

Author: JordanMartinez

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/JavaKeywords.java

@@ -1,5 +1,6 @@
 package org.fxmisc.richtext.demo;
 
+import java.time.Duration;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.regex.Matcher;
@@ -15,6 +16,7 @@
 import org.fxmisc.richtext.LineNumberFactory;
 import org.fxmisc.richtext.model.StyleSpans;
 import org.fxmisc.richtext.model.StyleSpansBuilder;
+import org.reactfx.Subscription;
 
 public class JavaKeywords extends Application {
 
@@ -80,13 +82,27 @@ public static void main(String[] args) {
     @Override
     public void start(Stage primaryStage) {
         CodeArea codeArea = new CodeArea();
+
+        // add line numbers to the left of area
         codeArea.setParagraphGraphicFactory(LineNumberFactory.get(codeArea));
 
-        codeArea.richChanges()
-                .filter(ch -> !ch.getInserted().equals(ch.getRemoved())) // XXX
-                .subscribe(change -> {
-                    codeArea.setStyleSpans(0, computeHighlighting(codeArea.getText()));
-                });
+        // recompute the syntax highlighting 500 ms after user stops editing area
+        Subscription cleanupWhenNoLongerNeedIt = codeArea
+
+                // plain changes = ignore style changes that are emitted when syntax highlighting is reapplied
+                // multi plain changes = save computation by not rerunning the code multiple times
+                //   when making multiple changes (e.g. renaming a method at multiple parts in file)
+                .multiPlainChanges()
+
+                // do not emit an event until 500 ms have passed since the last emission of previous stream
+                .successionEnds(Duration.ofMillis(500))
+
+                // run the following code block when previous stream emits an event
+                .subscribe(ignore -> codeArea.setStyleSpans(0, computeHighlighting(codeArea.getText())));
+
+        // when no longer need syntax highlighting and wish to clean up memory leaks
+        // run: `cleanupWhenNoLongerNeedIt.unsubscribe();`
+
         codeArea.replaceText(0, 0, sampleCode);
 
         Scene scene = new Scene(new StackPane(new VirtualizedScrollPane<>(codeArea)), 600, 400);

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/JavaKeywordsAsync.java

@@ -20,6 +20,7 @@
 import org.fxmisc.richtext.LineNumberFactory;
 import org.fxmisc.richtext.model.StyleSpans;
 import org.fxmisc.richtext.model.StyleSpansBuilder;
+import org.reactfx.Subscription;
 
 public class JavaKeywordsAsync extends Application {
 
@@ -90,11 +91,10 @@ public void start(Stage primaryStage) {
         executor = Executors.newSingleThreadExecutor();
         codeArea = new CodeArea();
         codeArea.setParagraphGraphicFactory(LineNumberFactory.get(codeArea));
-        codeArea.richChanges()
-                .filter(ch -> !ch.getInserted().equals(ch.getRemoved())) // XXX
+        Subscription cleanupWhenDone = codeArea.multiPlainChanges()
                 .successionEnds(Duration.ofMillis(500))
                 .supplyTask(this::computeHighlightingAsync)
-                .awaitLatest(codeArea.richChanges())
+                .awaitLatest(codeArea.multiPlainChanges())
                 .filterMap(t -> {
                     if(t.isSuccess()) {
                         return Optional.of(t.get());
@@ -104,6 +104,9 @@ public void start(Stage primaryStage) {
                     }
                 })
                 .subscribe(this::applyHighlighting);
+
+        // call when no longer need it: `cleanupWhenFinished.unsubscribe();`
+
         codeArea.replaceText(0, 0, sampleCode);
 
         Scene scene = new Scene(new StackPane(new VirtualizedScrollPane<>(codeArea)), 600, 400);

richtextfx-demos/src/main/java/org/fxmisc/richtext/demo/SpellChecking.java

@@ -5,6 +5,7 @@
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.text.BreakIterator;
+import java.time.Duration;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
@@ -19,6 +20,7 @@
 import javafx.scene.Scene;
 import javafx.scene.layout.StackPane;
 import javafx.stage.Stage;
+import org.reactfx.Subscription;
 
 public class SpellChecking extends Application {
 
@@ -33,12 +35,14 @@ public void start(Stage primaryStage) {
         StyleClassedTextArea textArea = new StyleClassedTextArea();
         textArea.setWrapText(true);
 
-        textArea.richChanges()
-                .filter(ch -> !ch.getInserted().equals(ch.getRemoved())) // XXX
+        Subscription cleanupWhenFinished = textArea.multiPlainChanges()
+                .successionEnds(Duration.ofMillis(500))
                 .subscribe(change -> {
                     textArea.setStyleSpans(0, computeHighlighting(textArea.getText()));
                 });
 
+        // call when no longer need it: `cleanupWhenFinished.unsubscribe();`
+
         // load the dictionary
         try (InputStream input = getClass().getResourceAsStream("spellchecking.dict");
              BufferedReader br = new BufferedReader(new InputStreamReader(input))) {

richtextfx/src/main/java/org/fxmisc/richtext/model/EditableStyledDocument.java

@@ -67,11 +67,14 @@ public interface EditableStyledDocument<PS, SEG, S> extends StyledDocument<PS, S
      */
     default EventStream<List<PlainTextChange>> multiPlainChanges() {
         return multiRichChanges()
+                // map to a List<PlainTextChange>
                 .map(list -> Arrays.asList(list.stream()
-                        .map(RichTextChange::toPlainTextChange)
                         // filter out rich changes where the style was changed but text wasn't added/removed
-                        .filter(pc -> !pc.isIdentity())
-                        .toArray(PlainTextChange[]::new)));
+                        .filter(rtc -> !rtc.isPlainTextIdentity())
+                        .map(RichTextChange::toPlainTextChange)
+                        .toArray(PlainTextChange[]::new)))
+                // only emit non-empty lists
+                .filter(list -> !list.isEmpty());
     }
 
     /**

richtextfx/src/main/java/org/fxmisc/richtext/model/RichTextChange.java

@@ -37,4 +37,12 @@ protected final RichTextChange<PS, SEG, S> create(int position, StyledDocument<P
     public final PlainTextChange toPlainTextChange() {
         return new PlainTextChange(position, removed.getText(), inserted.getText());
     }
+
+    /**
+     * Equivalent to {@code richChange.toPlainTextChange().isIdentity()} but without the additional object
+     * creation via {@link #toPlainTextChange()}.
+     */
+    public final boolean isPlainTextIdentity() {
+        return removed.getText().equals(inserted.getText());
+    }
 }