IDN Data
========

In order to implement Nameprep (RFC 3491), OkHttp uses Unicode tables specified in Stringprep
(RFC 3454). Fragments of this RFC are dumped into the files in this directory and parsed by
`StringprepTablesReader` into a model that can be used at runtime.

This format is chosen to make it easy to validate that these tables are consistent with the RFC.

```
cd okhttp/src/test/resources/okhttp3/internal/idn/

import kotlin.test.assertEquals
import okio.Buffer
import okio.FileSystem
import okio.Path.Companion.toPath

class StringprepTablesReaderTest {
  @Test fun readRfc3491FromResources() {
    val reader = StringprepTablesReader(FileSystem.RESOURCES)
    val nameprep = reader.readNameprep("/okhttp3/internal/idn".toPath())
    assertThat((nameprep.unassigned as RangeListCodePointSet).ranges).hasSize(396)

import okio.Buffer
import okio.ByteString.Companion.decodeHex
import okio.FileSystem
import okio.Path.Companion.toPath
import org.junit.Test

class StringprepTest {
  private val reader = StringprepTablesReader(FileSystem.RESOURCES)
  private val rfc3491 = reader.readNameprep("/okhttp3/internal/idn".toPath())
  private val stringPrep =
    Stringprep(
      unassigned = RangeListCodePointSet(listOf()),

import okio.BufferedSource
import okio.ByteString.Companion.encodeUtf8
import okio.FileSystem
import okio.IOException
import okio.Options
import okio.Path
import okio.buffer
import okio.use

class StringprepTablesReader(
  private val fileSystem: FileSystem,
) {
  /**
   * Returns a [Stringprep] that uses the tables of Nameprep ([RFC 3491]).
   *
   * [RFC 3491]: https://datatracker.ietf.org/doc/html/rfc3491
   */