Revert "Faster and simpler replace in SSB"

Bug 6300658

This change reveals a weird race condition where sometimes the
text is entered twice. Adding a debugger slows down everything,
and the problem is no longer reproducable. Reverting for now.

This reverts commit ebd9a23.

Author: Gilles Debunne

core/java/android/text/SpannableStringBuilder.java

@@ -50,8 +50,6 @@ public SpannableStringBuilder(CharSequence text) {
     public SpannableStringBuilder(CharSequence text, int start, int end) {
         int srclen = end - start;
 
-        if (srclen < 0) throw new StringIndexOutOfBoundsException();
-
         int len = ArrayUtils.idealCharArraySize(srclen + 1);
         mText = new char[len];
         mGapStart = srclen;
@@ -155,7 +153,7 @@ private void moveGapTo(int where) {
         if (where == mGapStart)
             return;
 
-        boolean atEnd = (where == length());
+        boolean atend = (where == length());
 
         if (where < mGapStart) {
             int overlap = mGapStart - where;
@@ -181,7 +179,7 @@ private void moveGapTo(int where) {
             else if (start == where) {
                 int flag = (mSpanFlags[i] & START_MASK) >> START_SHIFT;
 
-                if (flag == POINT || (atEnd && flag == PARAGRAPH))
+                if (flag == POINT || (atend && flag == PARAGRAPH))
                     start += mGapLength;
             }
 
@@ -192,7 +190,7 @@ else if (start == where) {
             else if (end == where) {
                 int flag = (mSpanFlags[i] & END_MASK);
 
-                if (flag == POINT || (atEnd && flag == PARAGRAPH))
+                if (flag == POINT || (atend && flag == PARAGRAPH))
                     end += mGapLength;
             }
 
@@ -399,7 +397,7 @@ public SpannableStringBuilder replace(int start, int end, CharSequence tb) {
 
     // Documentation from interface
     public SpannableStringBuilder replace(final int start, final int end,
-            CharSequence tb, int tbstart, int tbend) {
+                        CharSequence tb, int tbstart, int tbend) {
         int filtercount = mFilters.length;
         for (int i = 0; i < filtercount; i++) {
             CharSequence repl = mFilters[i].filter(tb, tbstart, tbend, this, start, end);
@@ -421,26 +419,53 @@ public SpannableStringBuilder replace(final int start, final int end,
         TextWatcher[] textWatchers = getSpans(start, start + origLen, TextWatcher.class);
         sendBeforeTextChanged(textWatchers, start, origLen, newLen);
 
-        // Try to keep the cursor / selection at the same relative position during
-        // a text replacement. If replaced or replacement text length is zero, this
-        // is already taken care of.
-        boolean adjustSelection = origLen != 0 && newLen != 0;
-        int selstart = 0;
-        int selend = 0;
-        if (adjustSelection) {
-            selstart = Selection.getSelectionStart(this);
-            selend = Selection.getSelectionEnd(this);
-        }
+        if (origLen == 0 || newLen == 0) {
+            change(start, end, tb, tbstart, tbend);
+        } else {
+            int selstart = Selection.getSelectionStart(this);
+            int selend = Selection.getSelectionEnd(this);
 
-        checkRange("replace", start, end);
+            // XXX just make the span fixups in change() do the right thing
+            // instead of this madness!
+
+            checkRange("replace", start, end);
+            moveGapTo(end);
+
+            if (mGapLength < 2)
+                resizeFor(length() + 1);
 
-        change(start, end, tb, tbstart, tbend);
+            for (int i = mSpanCount - 1; i >= 0; i--) {
+                if (mSpanStarts[i] == mGapStart)
+                    mSpanStarts[i]++;
+
+                if (mSpanEnds[i] == mGapStart)
+                    mSpanEnds[i]++;
+            }
+
+            mText[mGapStart] = ' ';
+            mGapStart++;
+            mGapLength--;
+
+            if (mGapLength < 1) {
+                new Exception("mGapLength < 1").printStackTrace();
+            }
 
-        if (adjustSelection) {
+            change(start + 1, start + 1, tb, tbstart, tbend);
+            change(start, start + 1, "", 0, 0);
+            change(start + newLen, start + newLen + origLen, "", 0, 0);
+
+            /*
+             * Special case to keep the cursor in the same position
+             * if it was somewhere in the middle of the replaced region.
+             * If it was at the start or the end or crossing the whole
+             * replacement, it should already be where it belongs.
+             * TODO: Is there some more general mechanism that could
+             * accomplish this?
+             */
             if (selstart > start && selstart < end) {
                 long off = selstart - start;
 
-                off = off * newLen / origLen;
+                off = off * newLen / (end - start);
                 selstart = (int) off + start;
 
                 setSpan(false, Selection.SELECTION_START, selstart, selstart,
@@ -449,7 +474,7 @@ public SpannableStringBuilder replace(final int start, final int end,
             if (selend > start && selend < end) {
                 long off = selend - start;
 
-                off = off * newLen / origLen;
+                off = off * newLen / (end - start);
                 selend = (int) off + start;
 
                 setSpan(false, Selection.SELECTION_END, selend, selend, Spanned.SPAN_POINT_POINT);