Easier custom object support

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

@@ -1,68 +1,21 @@
 package org.fxmisc.richtext.demo.richtext;
 
-import java.util.Optional;
+import org.fxmisc.richtext.model.NodeSegmentOpsBase;
 
-import org.fxmisc.richtext.model.SegmentOps;
+public class LinkedImageOps<S> extends NodeSegmentOpsBase<LinkedImage<S>, S> {
 
-public class LinkedImageOps<S> implements SegmentOps<LinkedImage<S>, S> {
-
-    private final EmptyLinkedImage<S> emptySeg = new EmptyLinkedImage<>();
-
-    @Override
-    public int length(LinkedImage<S> seg) {
-        return seg == emptySeg ? 0 : 1;
-    }
-
-    @Override
-    public char charAt(LinkedImage<S> seg, int index) {
-        return seg == emptySeg ? '\0' : '\ufffc';
-    }
-
-    @Override
-    public String getText(LinkedImage<S> seg) {
-        return seg == emptySeg ? "" : "\ufffc";
-    }
-
-    @Override
-    public LinkedImage<S> subSequence(LinkedImage<S> seg, int start, int end) {
-        if (start < 0) {
-            throw new IllegalArgumentException("Start cannot be negative. Start = " + start);
-        }
-        if (end > length(seg)) {
-            throw new IllegalArgumentException("End cannot be greater than segment's length");
-        }
-        return start == 0 && end == 1
-                ? seg
-                : emptySeg;
-    }
-
-    @Override
-    public LinkedImage<S> subSequence(LinkedImage<S> seg, int start) {
-        if (start < 0) {
-            throw new IllegalArgumentException("Start cannot be negative. Start = " + start);
-        }
-        return start == 0
-                ? seg
-                : emptySeg;
+    public LinkedImageOps() {
+        super(new EmptyLinkedImage<>());
     }
 
     @Override
-    public S getStyle(LinkedImage<S> seg) {
-        return seg.getStyle();
+    public S realGetStyle(LinkedImage<S> linkedImage) {
+        return linkedImage.getStyle();
     }
 
     @Override
-    public LinkedImage<S> setStyle(LinkedImage<S> seg, S style) {
-        return seg == emptySeg ? emptySeg : seg.setStyle(style);
+    public LinkedImage<S> realSetStyle(LinkedImage<S> linkedImage, S style) {
+        return linkedImage.setStyle(style);
     }
 
-    @Override
-    public Optional<LinkedImage<S>> join(LinkedImage<S> currentSeg, LinkedImage<S> nextSeg) {
-        return Optional.empty();
-    }
-
-    @Override
-    public LinkedImage<S> createEmpty() {
-        return emptySeg;
-    }
 }

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

@@ -0,0 +1,41 @@
+package org.fxmisc.richtext.model;
+
+/**
+ * Properly implements {@link SegmentOps} when implementing a non-text custom object (e.g. shape, circle, image)
+ * and reduces boilerplate. Developers only need to override {@link #realGetStyle(Object)} and
+ * {@link #realSetStyle(Object, Object)}. Developers may also want to override {@link #join(Object, Object)}.
+ *
+ * @param <SEG> type of segment
+ * @param <S> type of style
+ */
+public abstract class NodeSegmentOpsBase<SEG, S> extends SegmentOpsBase<SEG, S> {
+
+    public NodeSegmentOpsBase(SEG empty) {
+        super(empty);
+    }
+
+    @Override
+    public int realLength(SEG seg) {
+        return 1;
+    }
+
+    @Override
+    public char realCharAt(SEG seg, int index) {
+        return '\ufffc';
+    }
+
+    @Override
+    public String realGetText(SEG seg) {
+        return "\ufffc";
+    }
+
+    @Override
+    public SEG realSubsequence(SEG seg, int start, int end) {
+        return seg;
+    }
+
+    @Override
+    public SEG realSubsequence(SEG seg, int start) {
+        return seg;
+    }
+}

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

@@ -0,0 +1,86 @@
+package org.fxmisc.richtext.model;
+
+import java.util.Optional;
+
+/**
+ * Properly implements the {@link SegmentOps} interface and reduces boilerplate, so that developer only needs to
+ * implement methods for real segments, not empty ones. Optionally, {@link #join(Object, Object)} can be overridden
+ * as well.
+ *
+ * @param <SEG> the type of segment
+ * @param <S> the type of style
+ */
+public abstract class SegmentOpsBase<SEG, S> implements SegmentOps<SEG, S> {
+
+    private final SEG empty;
+
+    public SegmentOpsBase(SEG emptySEg) {
+        this.empty = emptySEg;
+    }
+
+    @Override
+    public final int length(SEG seg) {
+        return seg == empty ? 0 : realLength(seg);
+    }
+    public abstract int realLength(SEG seg);
+
+    @Override
+    public final char charAt(SEG seg, int index) {
+        return seg == empty ? '\0' : realCharAt(seg, index);
+    }
+    public abstract char realCharAt(SEG seg, int index);
+
+    @Override
+    public final String getText(SEG seg) {
+        return seg == empty ? "\0" : realGetText(seg);
+    }
+    public abstract String realGetText(SEG seg);
+
+    @Override
+    public final SEG subSequence(SEG seg, int start, int end) {
+        if (start < 0) {
+            throw new IllegalArgumentException("Start cannot be negative. Start=" + start);
+        }
+        if (end > length(seg)) {
+            throw new IllegalArgumentException(
+                    String.format("End cannot be greater than segment's length. End=%s Length=%s", end, length(seg))
+            );
+        }
+        return seg == empty || start == end
+                ? empty
+                : realSubsequence(seg, start, end);
+    }
+    public abstract SEG realSubsequence(SEG seg, int start, int end);
+
+    @Override
+    public final SEG subSequence(SEG seg, int start) {
+        return seg == empty || length(seg) == start
+                ? empty
+                : realSubsequence(seg, start);
+    }
+    public SEG realSubsequence(SEG seg, int start) {
+        return realSubsequence(seg, start, length(seg));
+    }
+
+    @Override
+    public final S getStyle(SEG seg) {
+        return seg == empty ? null : realGetStyle(seg);
+    }
+    public abstract S realGetStyle(SEG seg);
+
+    @Override
+    public final SEG setStyle(SEG seg, S style) {
+        return seg == empty ? empty : realSetStyle(seg, style);
+    }
+    public abstract SEG realSetStyle(SEG seg, S style);
+
+    @Override
+    public final Optional<SEG> join(SEG currentSeg, SEG nextSeg) {
+        return Optional.empty();
+    }
+
+    @Override
+    public final SEG createEmpty() {
+        return empty;
+    }
+}