IntraLineLoader: remove special-casing of whitespace

The heuristic for presentation of identation spaces was broken.
It is quite complicated code and produces incorrect edits.
So remove it in order to make it easier to refactor the code.

The goal of presenting whitespace changes in one visual block
is still good, but we should try to find a better heuristic.

Bug: Issue 3423
Bug-tracked-down-by: Patrick Steinhardt <ps@pks.im>
Change-Id: Ifd18c33579c47342092a139a44eb1855ebb124ef

gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineLoader.java

@@ -186,80 +186,34 @@ class IntraLineLoader implements Callable<IntraLineDiff> {
 
           // The leading part of an edit and its trailing part in the same
           // text might be identical. Slide down that edit and use the tail
-          // rather than the leading bit. If however the edit is only on a
-          // whitespace block try to shift it to the left margin, assuming
-          // that it is an indentation change.
+          // rather than the leading bit.
           //
-          boolean aShift = true;
-          if (ab < ae && isOnlyWhitespace(a, ab, ae)) {
-            int lf = findLF(wordEdits, j, a, ab);
-            if (lf < ab && a.charAt(lf) == '\n') {
-              int nb = lf + 1;
-              int p = 0;
-              while (p < ae - ab) {
-                if (cmp.equals(a, ab + p, a, ab + p)) {
-                  p++;
-                } else {
-                  break;
-                }
-              }
-              if (p == ae - ab) {
-                ab = nb;
-                ae = nb + p;
-                aShift = false;
-              }
-            }
+          while (0 < ab && ab < ae && a.charAt(ab - 1) != '\n'
+              && cmp.equals(a, ab - 1, a, ae - 1)) {
+            ab--;
+            ae--;
           }
-          if (aShift) {
-            while (0 < ab && ab < ae && a.charAt(ab - 1) != '\n'
-                && cmp.equals(a, ab - 1, a, ae - 1)) {
-              ab--;
-              ae--;
-            }
-            if (!a.isLineStart(ab) || !a.contains(ab, ae, '\n')) {
-              while (ab < ae && ae < a.size() && cmp.equals(a, ab, a, ae)) {
-                ab++;
-                ae++;
-                if (a.charAt(ae - 1) == '\n') {
-                  break;
-                }
+          if (!a.isLineStart(ab) || !a.contains(ab, ae, '\n')) {
+            while (ab < ae && ae < a.size() && cmp.equals(a, ab, a, ae)) {
+              ab++;
+              ae++;
+              if (a.charAt(ae - 1) == '\n') {
+                break;
               }
             }
           }
 
-          boolean bShift = true;
-          if (bb < be && isOnlyWhitespace(b, bb, be)) {
-            int lf = findLF(wordEdits, j, b, bb);
-            if (lf < bb && b.charAt(lf) == '\n') {
-              int nb = lf + 1;
-              int p = 0;
-              while (p < be - bb) {
-                if (cmp.equals(b, bb + p, b, bb + p)) {
-                  p++;
-                } else {
-                  break;
-                }
-              }
-              if (p == be - bb) {
-                bb = nb;
-                be = nb + p;
-                bShift = false;
-              }
-            }
+          while (0 < bb && bb < be && b.charAt(bb - 1) != '\n'
+              && cmp.equals(b, bb - 1, b, be - 1)) {
+            bb--;
+            be--;
           }
-          if (bShift) {
-            while (0 < bb && bb < be && b.charAt(bb - 1) != '\n'
-                && cmp.equals(b, bb - 1, b, be - 1)) {
-              bb--;
-              be--;
-            }
-            if (!b.isLineStart(bb) || !b.contains(bb, be, '\n')) {
-              while (bb < be && be < b.size() && cmp.equals(b, bb, b, be)) {
-                bb++;
-                be++;
-                if (b.charAt(be - 1) == '\n') {
-                  break;
-                }
+          if (!b.isLineStart(bb) || !b.contains(bb, be, '\n')) {
+            while (bb < be && be < b.size() && cmp.equals(b, bb, b, be)) {
+              bb++;
+              be++;
+              if (b.charAt(be - 1) == '\n') {
+                break;
               }
             }
           }
@@ -342,22 +296,4 @@ class IntraLineLoader implements Callable<IntraLineDiff> {
     }
     return true;
   }
-
-  private static int findLF(List<Edit> edits, int j, CharText t, int b) {
-    int lf = b;
-    int limit = 0 < j ? edits.get(j - 1).getEndB() : 0;
-    while (limit < lf && t.charAt(lf) != '\n') {
-      lf--;
-    }
-    return lf;
-  }
-
-  private static boolean isOnlyWhitespace(CharText t, final int b, final int e) {
-    for (int c = b; c < e; c++) {
-      if (!Character.isWhitespace(t.charAt(c))) {
-        return false;
-      }
-    }
-    return b < e;
-  }
 }

gerrit-server/src/test/java/com/google/gerrit/server/patch/IntraLineLoaderTest.java

@@ -128,10 +128,7 @@ public class IntraLineLoaderTest {
     );
   }
 
-  //TODO: expected failure, issue #3423
-  // The current code wrongly marks the first space of the second line,
-  // instead of the one inserted after the '*'.
-  @Test(expected = AssertionError.class)
+  @Test
   public void insertedWhitespaceIsRecognizedInMultipleLines() throws Exception {
     //         |0    5   10  |  5   20    5   30
     String a = " int *foobar\n int *foobar\n";