return 0x80;
        } else if (userFriendly.matches("(?i)(?:French|Latin|Western.*European)")) {
          // Mostly 1-byte UTF-8 sequences, mixed with occasional 2-byte
          // sequences - "Western European" text
          return 0x90;
        } else if (userFriendly.matches("(?i)(?:Branch.*Prediction.*Hostile)")) {
          // Defeat branch predictor for: c < 0x80 ; branch taken 50% of the time.
          return 0x100;

          return 0x80;
        } else if (userFriendly.matches("(?i)(?:French|Latin|Western.*European)")) {
          // Mostly 1-byte UTF-8 sequences, mixed with occasional 2-byte
          // sequences - "Western European" text
          return 0x90;
        } else if (userFriendly.matches("(?i)(?:Branch.*Prediction.*Hostile)")) {
          // Defeat branch predictor for: c < 0x80 ; branch taken 50% of the time.
          return 0x100;

      // should never reach here!
      throw new UnsupportedOperationException();
    }

    @Override
    public Entry<K, V> belowSamplesGreater() {
      // should never reach here!
      throw new UnsupportedOperationException();
    }

    @Override
    public Entry<K, V> aboveSamplesLesser() {
      // should never reach here!
      throw new UnsupportedOperationException();

      i++;
    }

    // This loop optimizes for chars less than 0x800.
    for (; i < utf16Length; i++) {
      char c = sequence.charAt(i);
      if (c < 0x800) {
        utf8Length += ((0x7f - c) >>> 31); // branch free!
      } else {
        utf8Length += encodedLengthGeneral(sequence, i);
        break;
      }
    }

    if (utf8Length < utf16Length) {

    return x > 0 & (x & (x - 1)) == 0;
  }

  /**
   * Returns 1 if {@code x < y} as unsigned integers, and 0 otherwise. Assumes that x - y fits into
   * a signed int. The implementation is branch-free, and benchmarks suggest it is measurably (if
   * narrowly) faster than the straightforward ternary expression.
   */
  @VisibleForTesting
  static int lessThanBranchFree(int x, int y) {

    return Platform.stringIsNullOrEmpty(string);
  }

  /**
   * Returns a string, of length at least {@code minLength}, consisting of {@code string} prepended
   * with as many copies of {@code padChar} as are necessary to reach that length. For example,
   *
   * <ul>
   *   <li>{@code padStart("7", 3, '0')} returns {@code "007"}
   *   <li>{@code padStart("2010", 3, '0')} returns {@code "2010"}
   * </ul>
   *

          } else if (endOfInput) { // (b)
            doneEncoding = true;
          } else { // (c)
            readMoreChars();
          }
        } else if (result.isError()) {
          // Only reach here if a CharsetEncoder with non-REPLACE settings is used.
          result.throwException();
          return 0; // Not called.
        }
      }
    }
  }

  @CheckForNull
  public abstract C previous(C value);

  /**
   * Returns a signed value indicating how many nested invocations of {@link #next} (if positive) or
   * {@link #previous} (if negative) are needed to reach {@code end} starting from {@code start}.
   * For example, if {@code end = next(next(next(start)))}, then {@code distance(start, end) == 3}
   * and {@code distance(end, start) == -3}. As well, {@code distance(a, a)} is always zero.

   * than CPUs, supposing that each thread were bound to a CPU,
   * there would exist a perfect hash function mapping threads to
   * slots that eliminates collisions. When we reach capacity, we
   * search for this mapping by randomly varying the hash codes of
   * colliding threads.  Because search is random, and collisions
   * only become known via CAS failures, convergence can be slow,

  @CheckForNull
  public abstract C previous(C value);

  /**
   * Returns a signed value indicating how many nested invocations of {@link #next} (if positive) or
   * {@link #previous} (if negative) are needed to reach {@code end} starting from {@code start}.
   * For example, if {@code end = next(next(next(start)))}, then {@code distance(start, end) == 3}
   * and {@code distance(end, start) == -3}. As well, {@code distance(a, a)} is always zero.