function transliteration_process in Transliteration 6.2

Same name and namespace in other branches

1. 5.2 transliteration.inc \transliteration_process()
2. 6.3 transliteration.inc \transliteration_process()

Transliterate UTF-8 text to ASCII.

Based on Mediawiki's UtfNormal::quickIsNFCVerify().

Parameters

$string: UTF-8 text input.

$unknown: Replacement string for characters that do not have a suitable ASCII equivalent.

$source_langcode: Optional ISO 639 language code that denotes the language of the input. Used to apply language-specific variations and defaults to the current display language. If transliteration takes place during output (instead of creation) and the source language is not known at that time, it is recommended to set this argument to 'en' to produce consistent results for all enabled languages.

Return value

Transliterated text.

2 calls to transliteration_process()

transliteration_clean_filename in ./transliteration.inc

Sanitize a file name.

transliteration_get in ./transliteration.module

Transliterate UTF-8 text to ASCII.

File

./transliteration.inc, line 55

Code

function transliteration_process($string, $unknown = '?', $source_langcode = NULL) {

  // Screen out some characters that eg won't be allowed in XML.
  $string = preg_replace('/[\\x00-\\x08\\x0b\\x0c\\x0e-\\x1f]/', $unknown, $string);

  // ASCII is always valid NFC!
  // If we're only ever given plain ASCII, we can avoid the overhead
  // of initializing the decomposition tables by skipping out early.
  if (!preg_match('/[\\x80-\\xff]/', $string)) {
    return $string;
  }
  static $tailBytes;
  if (!isset($tailBytes)) {

    // Each UTF-8 head byte is followed by a certain
    // number of tail bytes.
    $tailBytes = array();
    for ($n = 0; $n < 256; $n++) {
      if ($n < 0xc0) {
        $remaining = 0;
      }
      elseif ($n < 0xe0) {
        $remaining = 1;
      }
      elseif ($n < 0xf0) {
        $remaining = 2;
      }
      elseif ($n < 0xf8) {
        $remaining = 3;
      }
      elseif ($n < 0xfc) {
        $remaining = 4;
      }
      elseif ($n < 0xfe) {
        $remaining = 5;
      }
      else {
        $remaining = 0;
      }
      $tailBytes[chr($n)] = $remaining;
    }
  }

  // Chop the text into pure-ASCII and non-ASCII areas;
  // large ASCII parts can be handled much more quickly.
  // Don't chop up Unicode areas for punctuation, though,
  // that wastes energy.
  preg_match_all('/[\\x00-\\x7f]+|[\\x80-\\xff][\\x00-\\x40\\x5b-\\x5f\\x7b-\\xff]*/', $string, $matches);
  $result = '';
  foreach ($matches[0] as $str) {
    if ($str[0] < "") {

      // ASCII chunk: guaranteed to be valid UTF-8
      // and in normal form C, so skip over it.
      $result .= $str;
      continue;
    }

    // We'll have to examine the chunk byte by byte to ensure
    // that it consists of valid UTF-8 sequences, and to see
    // if any of them might not be normalized.
    //
    // Since PHP is not the fastest language on earth, some of
    // this code is a little ugly with inner loop optimizations.
    $head = '';
    $chunk = strlen($str);

    // Counting down is faster. I'm *so* sorry.
    $len = $chunk + 1;
    for ($i = -1; --$len;) {
      $c = $str[++$i];
      if ($remaining = $tailBytes[$c]) {

        // UTF-8 head byte!
        $sequence = $head = $c;
        do {

          // Look for the defined number of tail bytes...
          if (--$len && ($c = $str[++$i]) >= "" && $c < "") {

            // Legal tail bytes are nice.
            $sequence .= $c;
          }
          else {
            if ($len == 0) {

              // Premature end of string!
              // Drop a replacement character into output to
              // represent the invalid UTF-8 sequence.
              $result .= $unknown;
              break 2;
            }
            else {

              // Illegal tail byte; abandon the sequence.
              $result .= $unknown;

              // Back up and reprocess this byte; it may itself
              // be a legal ASCII or UTF-8 sequence head.
              --$i;
              ++$len;
              continue 2;
            }
          }
        } while (--$remaining);
        $n = ord($head);
        if ($n <= 0xdf) {
          $ord = ($n - 192) * 64 + (ord($sequence[1]) - 128);
        }
        else {
          if ($n <= 0xef) {
            $ord = ($n - 224) * 4096 + (ord($sequence[1]) - 128) * 64 + (ord($sequence[2]) - 128);
          }
          else {
            if ($n <= 0xf7) {
              $ord = ($n - 240) * 262144 + (ord($sequence[1]) - 128) * 4096 + (ord($sequence[2]) - 128) * 64 + (ord($sequence[3]) - 128);
            }
            else {
              if ($n <= 0xfb) {
                $ord = ($n - 248) * 16777216 + (ord($sequence[1]) - 128) * 262144 + (ord($sequence[2]) - 128) * 4096 + (ord($sequence[3]) - 128) * 64 + (ord($sequence[4]) - 128);
              }
              else {
                if ($n <= 0xfd) {
                  $ord = ($n - 252) * 1073741824 + (ord($sequence[1]) - 128) * 16777216 + (ord($sequence[2]) - 128) * 262144 + (ord($sequence[3]) - 128) * 4096 + (ord($sequence[4]) - 128) * 64 + (ord($sequence[5]) - 128);
                }
              }
            }
          }
        }
        $result .= _transliteration_replace($ord, $unknown, $source_langcode);
        $head = '';
      }
      elseif ($c < "") {

        // ASCII byte.
        $result .= $c;
        $head = '';
      }
      elseif ($c < "") {

        // Illegal tail bytes.
        if ($head == '') {
          $result .= $unknown;
        }
      }
      else {

        // Miscellaneous freaks.
        $result .= $unknown;
        $head = '';
      }
    }
  }
  return $result;
}