text: /*
   * Copyright (C) 2004, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
   * Copyright (C) 2006 Alexey Proskuryakov <ap@nypop.com>
   * Copyright (C) 2007-2009 Torch Mobile, Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include "sky/engine/wtf/text/TextEncoding.h"
  
  #include <unicode/unorm.h>
  #include "sky/engine/wtf/OwnPtr.h"
  #include "sky/engine/wtf/StdLibExtras.h"
  #include "sky/engine/wtf/text/CString.h"
  #include "sky/engine/wtf/text/TextEncodingRegistry.h"
  #include "sky/engine/wtf/text/WTFString.h"
  
  namespace WTF {
  
  static const TextEncoding& UTF7Encoding()
  {
      static TextEncoding globalUTF7Encoding("UTF-7");
      return globalUTF7Encoding;
  }
  
  TextEncoding::TextEncoding(const char* name)
      : m_name(atomicCanonicalTextEncodingName(name))
  {
      // Aliases are valid, but not "replacement" itself.
      if (m_name && isReplacementEncoding(name))
          m_name = 0;
  }
  
  TextEncoding::TextEncoding(const String& name)
      : m_name(atomicCanonicalTextEncodingName(name))
  {
      // Aliases are valid, but not "replacement" itself.
      if (m_name && isReplacementEncoding(name))
          m_name = 0;
  }
  
  String TextEncoding::decode(const char* data, size_t length, bool stopOnError, bool& sawError) const
  {
      if (!m_name)
          return String();
  
      return newTextCodec(*this)->decode(data, length, DataEOF, stopOnError, sawError);
  }
  
  CString TextEncoding::encode(const String& string, UnencodableHandling handling) const
  {
      if (!m_name)
          return CString();
  
      if (string.isEmpty())
          return "";
  
      OwnPtr<TextCodec> textCodec = newTextCodec(*this);
      CString encodedString;
      if (string.is8Bit())
          encodedString = textCodec->encode(string.characters8(), string.length(), handling);
      else
          encodedString = textCodec->encode(string.characters16(), string.length(), handling);
      return encodedString;
  }
  
  CString TextEncoding::normalizeAndEncode(const String& string, UnencodableHandling handling) const
  {
      if (!m_name)
          return CString();
  
      if (string.isEmpty())
          return "";
  
      // Text exclusively containing Latin-1 characters (U+0000..U+00FF) is left
      // unaffected by NFC. This is effectively the same as saying that all
      // Latin-1 text is already normalized to NFC.
      // Source: http://unicode.org/reports/tr15/
      if (string.is8Bit())
          return newTextCodec(*this)->encode(string.characters8(), string.length(), handling);
  
      const UChar* source = string.characters16();
      size_t length = string.length();
  
      Vector<UChar> normalizedCharacters;
  
      UErrorCode err = U_ZERO_ERROR;
      if (unorm_quickCheck(source, length, UNORM_NFC, &err) != UNORM_YES) {
          // First try using the length of the original string, since normalization to NFC rarely increases length.
          normalizedCharacters.grow(length);
          int32_t normalizedLength = unorm_normalize(source, length, UNORM_NFC, 0, normalizedCharacters.data(), length, &err);
          if (err == U_BUFFER_OVERFLOW_ERROR) {
              err = U_ZERO_ERROR;
              normalizedCharacters.resize(normalizedLength);
              normalizedLength = unorm_normalize(source, length, UNORM_NFC, 0, normalizedCharacters.data(), normalizedLength, &err);
          }
          ASSERT(U_SUCCESS(err));
  
          source = normalizedCharacters.data();
          length = normalizedLength;
      }
  
      return newTextCodec(*this)->encode(source, length, handling);
  }
  
  bool TextEncoding::usesVisualOrdering() const
  {
      if (noExtendedTextEncodingNameUsed())
          return false;
  
      static const char* const a = atomicCanonicalTextEncodingName("ISO-8859-8");
      return m_name == a;
  }
  
  bool TextEncoding::isNonByteBasedEncoding() const
  {
      if (noExtendedTextEncodingNameUsed()) {
          return *this == UTF16LittleEndianEncoding()
              || *this == UTF16BigEndianEncoding();
      }
  
      return *this == UTF16LittleEndianEncoding()
          || *this == UTF16BigEndianEncoding()
          || *this == UTF32BigEndianEncoding()
          || *this == UTF32LittleEndianEncoding();
  }
  
  bool TextEncoding::isUTF7Encoding() const
  {
      if (noExtendedTextEncodingNameUsed())
          return false;
  
      return *this == UTF7Encoding();
  }
  
  const TextEncoding& TextEncoding::closestByteBasedEquivalent() const
  {
      if (isNonByteBasedEncoding())
          return UTF8Encoding();
      return *this;
  }
  
  // HTML5 specifies that UTF-8 be used in form submission when a form is
  // is a part of a document in UTF-16 probably because UTF-16 is not a
  // byte-based encoding and can contain 0x00. By extension, the same
  // should be done for UTF-32. In case of UTF-7, it is a byte-based encoding,
  // but it's fraught with problems and we'd rather steer clear of it.
  const TextEncoding& TextEncoding::encodingForFormSubmission() const
  {
      if (isNonByteBasedEncoding() || isUTF7Encoding())
          return UTF8Encoding();
      return *this;
  }
  
  const TextEncoding& ASCIIEncoding()
  {
      static TextEncoding globalASCIIEncoding("ASCII");
      return globalASCIIEncoding;
  }
  
  const TextEncoding& Latin1Encoding()
  {
      static TextEncoding globalLatin1Encoding("latin1");
      return globalLatin1Encoding;
  }
  
  const TextEncoding& UTF16BigEndianEncoding()
  {
      static TextEncoding globalUTF16BigEndianEncoding("UTF-16BE");
      return globalUTF16BigEndianEncoding;
  }
  
  const TextEncoding& UTF16LittleEndianEncoding()
  {
      static TextEncoding globalUTF16LittleEndianEncoding("UTF-16LE");
      return globalUTF16LittleEndianEncoding;
  }
  
  const TextEncoding& UTF32BigEndianEncoding()
  {
      static TextEncoding globalUTF32BigEndianEncoding("UTF-32BE");
      return globalUTF32BigEndianEncoding;
  }
  
  const TextEncoding& UTF32LittleEndianEncoding()
  {
      static TextEncoding globalUTF32LittleEndianEncoding("UTF-32LE");
      return globalUTF32LittleEndianEncoding;
  }
  
  const TextEncoding& UTF8Encoding()
  {
      static TextEncoding globalUTF8Encoding("UTF-8");
      ASSERT(globalUTF8Encoding.isValid());
      return globalUTF8Encoding;
  }
  
  const TextEncoding& WindowsLatin1Encoding()
  {
      static TextEncoding globalWindowsLatin1Encoding("WinLatin1");
      return globalWindowsLatin1Encoding;
  }
  
  } // namespace WTF
  