1  /*
  2   * Copyright (C) 2008 Apple Inc. All rights reserved.
  3   *
  4   * Redistribution and use in source and binary forms, with or without
  5   * modification, are permitted provided that the following conditions
  6   * are met:
  7   * 1. Redistributions of source code must retain the above copyright
  8   *    notice, this list of conditions and the following disclaimer.
  9   * 2. Redistributions in binary form must reproduce the above copyright
 10   *    notice, this list of conditions and the following disclaimer in the
 11   *    documentation and/or other materials provided with the distribution.
 12   *
 13   * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 14   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 15   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 16   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 17   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 18   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 19   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 20   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 21   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 22   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 23   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 24   */
 25  
 26  #ifndef OpaqueJSString_h
 27  #define OpaqueJSString_h
 28  
 29  #include <atomic>
 30  #include <wtf/ThreadSafeRefCounted.h>
 31  #include <wtf/text/WTFString.h>
 32  
 33  namespace JSC {
 34      class Identifier;
 35      class VM;
 36  }
 37  
 38  struct OpaqueJSString : public ThreadSafeRefCounted<OpaqueJSString> {
 39      static Ref<OpaqueJSString> create()
 40      {
 41          return adoptRef(*new OpaqueJSString);
 42      }
 43  
 44      static Ref<OpaqueJSString> create(const LChar* characters, unsigned length)
 45      {
 46          return adoptRef(*new OpaqueJSString(characters, length));
 47      }
 48  
 49      static Ref<OpaqueJSString> create(const UChar* characters, unsigned length)
 50      {
 51          return adoptRef(*new OpaqueJSString(characters, length));
 52      }
 53  
 54      JS_EXPORT_PRIVATE static RefPtr<OpaqueJSString> tryCreate(const String&);
 55      JS_EXPORT_PRIVATE static RefPtr<OpaqueJSString> tryCreate(String&&);
 56  
 57      JS_EXPORT_PRIVATE ~OpaqueJSString();
 58  
 59      bool is8Bit() { return m_string.is8Bit(); }
 60      const LChar* characters8() { return m_string.characters8(); }
 61      const UChar* characters16() { return m_string.characters16(); }
 62      unsigned length() { return m_string.length(); }
 63  
 64      const UChar* characters();
 65  
 66      JS_EXPORT_PRIVATE String string() const;
 67      JSC::Identifier identifier(JSC::VM*) const;
 68  
 69      static bool equal(const OpaqueJSString*, const OpaqueJSString*);
 70  
 71  private:
 72      friend class WTF::ThreadSafeRefCounted<OpaqueJSString>;
 73  
 74      OpaqueJSString()
 75          : m_characters(nullptr)
 76      {
 77      }
 78  
 79      OpaqueJSString(const String& string)
 80          : m_string(string.isolatedCopy())
 81          , m_characters(m_string.impl() && m_string.is8Bit() ? nullptr : const_cast<UChar*>(m_string.characters16()))
 82      {
 83      }
 84  
 85      explicit OpaqueJSString(String&& string)
 86          : m_string(WTFMove(string))
 87          , m_characters(m_string.impl() && m_string.is8Bit() ? nullptr : const_cast<UChar*>(m_string.characters16()))
 88      {
 89      }
 90  
 91      OpaqueJSString(const LChar* characters, unsigned length)
 92          : m_string(characters, length)
 93          , m_characters(nullptr)
 94      {
 95      }
 96  
 97      OpaqueJSString(const UChar* characters, unsigned length)
 98          : m_string(characters, length)
 99          , m_characters(m_string.impl() && m_string.is8Bit() ? nullptr : const_cast<UChar*>(m_string.characters16()))
100      {
101      }
102  
103      String m_string;
104  
105      // This will be initialized on demand when characters() is called if the string needs up-conversion.
106      std::atomic<UChar*> m_characters;
107  };
108  
109  #endif