API/OpaqueJSString.cpp

   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 #include "config.h"
  27 #include "OpaqueJSString.h"
  28
  29 #include "CallFrame.h"
  30 #include "Identifier.h"
  31 #include "JSGlobalObject.h"
  32 #include <wtf/text/StringView.h>
  33
  34 using namespace JSC;
  35
  36 PassRefPtr<OpaqueJSString> OpaqueJSString::create(const String& string)
  37 {
  38     if (string.isNull())
  39         return nullptr;
  40
  41     return adoptRef(new OpaqueJSString(string));
  42 }
  43
  44 OpaqueJSString::~OpaqueJSString()
  45 {
  46     // m_characters is put in a local here to avoid an extra atomic load.
  47     UChar* characters = m_characters;
  48     if (!characters)
  49         return;
  50
  51     if (!m_string.is8Bit() && m_string.characters16() == characters)
  52         return;
  53
  54     fastFree(characters);
  55 }
  56
  57 String OpaqueJSString::string() const
  58 {
  59     if (!this)
  60         return String();
  61
  62     // Return a copy of the wrapped string, because the caller may make it an Identifier.
  63     return m_string.isolatedCopy();
  64 }
  65
  66 Identifier OpaqueJSString::identifier(VM* vm) const
  67 {
  68     if (!this || m_string.isNull())
  69         return Identifier();
  70
  71     if (m_string.isEmpty())
  72         return Identifier(Identifier::EmptyIdentifier);
  73
  74     if (m_string.is8Bit())
  75         return Identifier(vm, m_string.characters8(), m_string.length());
  76
  77     return Identifier(vm, m_string.characters16(), m_string.length());
  78 }
  79
  80 const UChar* OpaqueJSString::characters()
  81 {
  82     if (!this)
  83         return nullptr;
  84
  85     // m_characters is put in a local here to avoid an extra atomic load.
  86     UChar* characters = m_characters;
  87     if (characters)
  88         return characters;
  89
  90     if (m_string.isNull())
  91         return nullptr;
  92
  93     unsigned length = m_string.length();
  94     UChar* newCharacters = static_cast<UChar*>(fastMalloc(length * sizeof(UChar)));
  95     StringView(m_string).getCharactersWithUpconvert(newCharacters);
  96
  97     if (!m_characters.compare_exchange_strong(characters, newCharacters)) {
  98         fastFree(newCharacters);
  99         return characters;
 100     }
 101
 102     return newCharacters;
 103 }
 104
 105 bool OpaqueJSString::equal(const OpaqueJSString* a, const OpaqueJSString* b)
 106 {
 107     if (a == b)
 108         return true;
 109
 110     if (!a || !b)
 111         return false;
 112
 113     return a->m_string == b->m_string;
 114 }