internal fun Regex.matchAtPolyfill(
  input: CharSequence,
  index: Int,
): MatchResult? {
  val candidate = find(input, index) ?: return null
  if (candidate.range.first != index) return null // Didn't match where it should have.
  return candidate
}

@JvmField
val EMPTY_BYTE_ARRAY: ByteArray = ByteArray(0)

/** Byte order marks. */
internal val UNICODE_BOMS =
  Options.of(
    // UTF-8.
    "efbbbf".decodeHex(),

There may be many routes for a single address. For example, a webserver that is hosted in multiple datacenters may yield multiple IP addresses in its DNS response.

In limited situations OkHttp will retry a route if connecting fails:

    }
  }

  /**
   * Returns an immediately-executable task for the calling thread to execute, sleeping as necessary
   * until one is ready. If there are no ready queues, or if other threads have everything under
   * control this will return null. If there is more than a single task ready to execute immediately
   * this will start another thread to handle that work.
   */
  fun awaitTaskToRun(): Task? {

          "\r\n".encodeUtf8(),
          // 1.  "--"    No more parts.
          "--".encodeUtf8(),
          // 2.  " "     Optional whitespace. Only used if there are more parts.
          " ".encodeUtf8(),
          // 3.  "\t"    Optional whitespace. Only used if there are more parts.
          "\t".encodeUtf8(),
        )
    }

    var sendRequestException: IOException? = null
    try {
      exchange.writeRequestHeaders(request)

      if (HttpMethod.permitsRequestBody(request.method) && requestBody != null) {
        // If there's a "Expect: 100-continue" header on the request, wait for a "HTTP/1.1 100
        // Continue" response before transmitting the request body. If we don't get that, return

  // State for negotiating failed routes
  private val postponedRoutes = mutableListOf<Route>()

  init {
    resetNextProxy(address.url, address.proxy)
  }

  /**
   * Returns true if there's another set of routes to attempt. Every address has at least one route.
   */
  operator fun hasNext(): Boolean = hasNextProxy() || postponedRoutes.isNotEmpty()

  @Throws(IOException::class)

  }

  @Test
  fun encodeMultiplePairs() {
    val body =
      FormBody.Builder()
        .add("sim", "ple")
        .add("hey", "there")
        .add("help", "me")
        .build()
    val expected = "sim=ple&hey=there&help=me"
    assertThat(body.contentLength()).isEqualTo(expected.length.toLong())
    val buffer = Buffer()
    body.writeTo(buffer)

      arrayOf(
        TlsVersion.TLS_1_2,
        TlsVersion.TLS_1_1,
        TlsVersion.TLS_1_0,
      )
    var socket = createSocketWithEnabledProtocols(*enabledSocketTlsVersions)

    // MODERN_TLS is used here.
    val attempt0 =
      routePlanner.planConnectToRoute(route)
        .planWithCurrentOrInitialConnectionSpec(connectionSpecs, socket)
    assertThat(attempt0.isTlsFallback).isFalse()

      factory.newConnectionPool(
        maxIdleConnections = 2,
      )
    val c1 = factory.newConnection(pool, routeA1, 50L)
    val c2 = factory.newConnection(pool, routeB1, 75L)

    // With 2 connections, there's no need to evict until the connections time out.
    assertThat(pool.closeConnections(100L)).isEqualTo(50L)
    assertThat(pool.connectionCount()).isEqualTo(2)
    assertThat(c1.socket().isClosed).isFalse()

  fun execute(): Response

  /**
   * Schedules the request to be executed at some point in the future.
   *
   * The [dispatcher][OkHttpClient.dispatcher] defines when the request will run: usually
   * immediately unless there are several other requests currently being executed.
   *
   * This client will later call back `responseCallback` with either an HTTP response or a failure
   * exception.
   *