first implementation of meyers diff with linear space

wumpz · wumpz · commit 976505222683 · 2021-07-08T22:42:53.000+02:00
diff --git a/java-diff-utils/src/main/java/com/github/difflib/algorithm/Change.java b/java-diff-utils/src/main/java/com/github/difflib/algorithm/Change.java
@@ -36,4 +36,12 @@ public Change(DeltaType deltaType, int startOriginal, int endOriginal, int start
         this.startRevised = startRevised;
         this.endRevised = endRevised;
     }
+    
+    public Change withEndOriginal(int endOriginal) {
+        return new Change(deltaType, startOriginal, endOriginal, startRevised, endRevised);
+    }
+    
+    public Change withEndRevised(int endRevised) {
+        return new Change(deltaType, startOriginal, endOriginal, startRevised, endRevised);
+    }
 }
diff --git a/java-diff-utils/src/main/java/com/github/difflib/algorithm/myers/MeyersDiffWithLinearSpace.java b/java-diff-utils/src/main/java/com/github/difflib/algorithm/myers/MeyersDiffWithLinearSpace.java
@@ -65,11 +65,22 @@ private void buildScript(DiffData data, int start1, int end1, int start2, int en
                     //TODO: compress these commands.
                     if (end1 - start1 > end2 - start2) {
                         //script.append(new DeleteCommand<>(left.charAt(i)));
-                        data.script.add(new Change(DeltaType.DELETE, i, i + 1, j, j));
+                        if (data.script.isEmpty()
+                                || data.script.get(data.script.size() - 1).endOriginal != i
+                                || data.script.get(data.script.size() - 1).deltaType != DeltaType.DELETE) {
+                            data.script.add(new Change(DeltaType.DELETE, i, i + 1, j, j));
+                        } else {
+                            data.script.set(data.script.size() - 1, data.script.get(data.script.size() - 1).withEndOriginal(i + 1));
+                        }
                         ++i;
                     } else {
-                        //script.append(new InsertCommand<>(right.charAt(j)));
-                        data.script.add(new Change(DeltaType.INSERT, i, i, j, j + 1));
+                        if (data.script.isEmpty()
+                                || data.script.get(data.script.size() - 1).endRevised != j
+                                || data.script.get(data.script.size() - 1).deltaType != DeltaType.INSERT) {
+                            data.script.add(new Change(DeltaType.INSERT, i, i, j, j + 1));
+                        } else {
+                            data.script.set(data.script.size() - 1, data.script.get(data.script.size() - 1).withEndRevised(j + 1));
+                        }
                         ++j;
                     }
                 }
diff --git a/java-diff-utils/src/test/java/com/github/difflib/algorithm/myers/WithMeyersDiffWithLinearSpacePatchTest.java b/java-diff-utils/src/test/java/com/github/difflib/algorithm/myers/WithMeyersDiffWithLinearSpacePatchTest.java
@@ -93,7 +93,7 @@ public void testPatch_Change_withExceptionProcessor() {
 
         try {
             List<String> data = DiffUtils.patch(changeTest_from, patch);
-            assertEquals(9, data.size());
+            assertEquals(11, data.size());
             
             assertEquals(Arrays.asList("aaa", "<<<<<< HEAD", "bbb", "CDC", "======", "bbb", "ccc", ">>>>>>> PATCH", "ddd"), data);
             

Original file line number	Diff line number	Diff line change
`@@ -36,4 +36,12 @@ public Change(DeltaType deltaType, int startOriginal, int endOriginal, int start`
`36`	`36`	`this.startRevised = startRevised;`
`37`	`37`	`this.endRevised = endRevised;`
`38`	`38`	`}`
	`39`	`+`
	`40`	`+ public Change withEndOriginal(int endOriginal) {`
	`41`	`+ return new Change(deltaType, startOriginal, endOriginal, startRevised, endRevised);`
	`42`	`+ }`
	`43`	`+`
	`44`	`+ public Change withEndRevised(int endRevised) {`
	`45`	`+ return new Change(deltaType, startOriginal, endOriginal, startRevised, endRevised);`
	`46`	`+ }`
`39`	`47`	`}`