src/share/classes/java/lang/AbstractStringBuilder.java

rev 6546 : 7197183: Alternate implementation of String.subSequence which uses shared backing array.
Reviewed-by: duke

*** 497,508 ****
              throw new IndexOutOfBoundsException(
                  "start " + start + ", end " + end + ", s.length() "
                  + s.length());
          int len = end - start;
          ensureCapacityInternal(count + len);
!         for (int i = start, j = count; i < end; i++, j++)
              value[j] = s.charAt(i);
          count += len;
          return this;
      }
  
      /**
--- 497,517 ----
              throw new IndexOutOfBoundsException(
                  "start " + start + ", end " + end + ", s.length() "
                  + s.length());
          int len = end - start;
          ensureCapacityInternal(count + len);
!         if (s instanceof String) {
!             System.arraycopy(((String)s).value, start, value, count, len);
!         } else if ((s instanceof StringBuilder) || (s instanceof StringBuffer)) {
!             // two instanceof on leaf class is faster than instanceof check on AbstractStringBuilder.
!             System.arraycopy(((AbstractStringBuilder)s).value, start, value, count, len);
!         } else {
!             // unspecialized path
!             for (int i = start, j = count; i < end; i++, j++) {
                  value[j] = s.charAt(i);
+             }
+         }
          count += len;
          return this;
      }
  
      /**
*** 1120,1131 ****
--- 1129,1148 ----
                  + s.length());
          int len = end - start;
          ensureCapacityInternal(count + len);
          System.arraycopy(value, dstOffset, value, dstOffset + len,
                           count - dstOffset);
+         if (s instanceof String) {
+             System.arraycopy(((String)s).value, start, value, dstOffset, len);
+         } else if ((s instanceof StringBuilder) || (s instanceof StringBuffer)) {
+             // two instanceof on leaf class is faster than instanceof check on AbstractStringBuilder.
+             System.arraycopy(((AbstractStringBuilder)s).value, start, value, dstOffset, len);
+         } else {
+             // unspecialized path
              for (int i=start; i<end; i++)
                  value[dstOffset++] = s.charAt(i);
+         }
          count += len;
          return this;
      }
  
      /**