* href="https://github.com/google/guava/wiki/StringsExplained#charsets">{@code Charsets}</a>.
 *
 * @author Mike Bostock
 * @since 1.0
 */
@GwtCompatible
public final class Charsets {

  /**
   * US-ASCII: seven-bit ASCII, the Basic Latin block of the Unicode character set (ISO646-US).
   *
   * @deprecated Use {@link StandardCharsets#US_ASCII} instead.
   */
  @Deprecated @J2ktIncompatible @GwtIncompatible // Charset not supported by GWT

 *
 * Mappings may overlap.
 *
 * ASCII-Only
 * ==========
 *
 * Neither the section index nor the ranges data use bit 0x80 anywhere. That means the data is
 * strictly ASCII. This is intended to make it efficient to encode this data as a string, and to
 * index into it as a string.
 *
 * The mappings data contains non-ASCII characters.
 */
internal class IdnaMappingTable internal constructor(

        try {
            this.service = new String(buffer, bufferIndex, len, "ASCII");
        } catch (final UnsupportedEncodingException uee) {
            return 0;
        }
        bufferIndex += len + 1;
        // win98 observed not returning nativeFileSystem
        // Problems here with iSeries returning ASCII even though useUnicode = true
        // Fortunately we don't really need nativeFileSystem for anything.

        buf.enc_ndr_small(5); /* RPC version */
        buf.enc_ndr_small(0); /* minor version */
        buf.enc_ndr_small(ptype);
        buf.enc_ndr_small(flags);
        buf.enc_ndr_long(0x00000010); /* Little-endian / ASCII / IEEE */
        buf.enc_ndr_short(length);
        buf.enc_ndr_short(0); /* length of auth_value */
        buf.enc_ndr_long(call_id);
    }

    void decode_header(final NdrBuffer buf) throws NdrException {

    assertThat(
            deletingEscaper.escape(
                "\tEverything\0 outside the\uD800\uDC00 "
                    + "printable ASCII \uFFFFrange is \u007Fdeleted.\n"))
        .isEqualTo("Everything outside the printable ASCII range is deleted.");
  }

  public void testReplacementPriority() throws IOException {
    UnicodeEscaper replacingEscaper =

 *
 *  * In queries, ' ' is encoded to '+' and '+' is encoded to "%2B".
 *
 *  * Characters in `encodeSet` are percent-encoded.
 *
 *  * Control characters and non-ASCII characters are percent-encoded.
 *
 *  * All other characters are copied without transformation.
 *
 * @param alreadyEncoded true to leave '%' as-is; false to convert it to '%25'.

    "output": null
  },
  {
    "input": "xn--a.ß",
    "output": null
  },
  {
    "input": "xn--ls8h=",
    "output": null
  },
  {
    "comment": "Invalid Punycode (contains non-ASCII character)",
    "input": "xn--tešla",
    "output": null
  },
  {
    "comment": "Valid Punycode",
    "input": "xn--zca.xn--zca",
    "output": "xn--zca.xn--zca"
  },
  {
    "comment": "Mixed",

    assertThat(
            deletingEscaper.escape(
                "\tEverything\0 outside the\uD800\uDC00 "
                    + "printable ASCII \uFFFFrange is \u007Fdeleted.\n"))
        .isEqualTo("Everything outside the printable ASCII range is deleted.");
  }

  public void testReplacementPriority() throws IOException {
    CharEscaper replacingEscaper =

  }

  /** Sample CharMatcher instances for benchmarking. */
  public enum SampleMatcherConfig {
    WHITESPACE(CharMatcher.whitespace(), WHITESPACE_CHARACTERS),
    HASH(CharMatcher.is('#'), "#"),
    ASCII(CharMatcher.ascii(), ASCII_CHARACTERS),
    WESTERN_DIGIT("0123456789"),
    ALL_DIGIT(CharMatcher.digit(), ALL_DIGITS),
    OPS_5("+-*/%"),
    HEX_16(CharMatcher.inRange('0', '9').or(CharMatcher.inRange('A', 'F')), "0123456789ABCDEF"),

internal fun Array<String>.concat(value: String): Array<String> {
  val result = copyOf(size + 1)
  result[result.lastIndex] = value
  return result as Array<String>
}

/** Increments [startIndex] until this string is not ASCII whitespace. Stops at [endIndex]. */
internal fun String.indexOfFirstNonAsciiWhitespace(
  startIndex: Int = 0,
  endIndex: Int = length,
): Int {
  for (i in startIndex until endIndex) {
    when (this[i]) {