third_party/WebKit/Source/wtf/text/StringView.h

   1 /*
   2  * Copyright (C) 2013 Google 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 are
   6  * met:
   7  *
   8  *     * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *     * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  *     * Neither the name of Google Inc. nor the names of its
  15  * contributors may be used to endorse or promote products derived from
  16  * this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #ifndef WTF_StringView_h
  32 #define WTF_StringView_h
  33
  34 #include "wtf/text/StringImpl.h"
  35
  36 namespace WTF {
  37
  38 class WTF_EXPORT StringView {
  39 public:
  40     StringView()
  41         : m_offset(0)
  42         , m_length(0)
  43     {
  44     }
  45
  46     explicit StringView(PassRefPtr<StringImpl> impl)
  47         : m_impl(impl)
  48         , m_offset(0)
  49         , m_length(m_impl->length())
  50     {
  51     }
  52
  53     StringView(PassRefPtr<StringImpl> impl, unsigned offset, unsigned length)
  54         : m_impl(impl)
  55         , m_offset(offset)
  56         , m_length(length)
  57     {
  58         ASSERT_WITH_SECURITY_IMPLICATION(offset + length <= m_impl->length());
  59     }
  60
  61     void narrow(unsigned offset, unsigned length)
  62     {
  63         ASSERT_WITH_SECURITY_IMPLICATION(offset + length <= m_length);
  64         m_offset += offset;
  65         m_length = length;
  66     }
  67
  68     bool isEmpty() const { return !m_length; }
  69     unsigned length() const { return m_length; }
  70
  71     bool is8Bit() const { return m_impl->is8Bit(); }
  72
  73     const LChar* characters8() const
  74     {
  75         if (!m_impl)
  76             return 0;
  77         ASSERT(is8Bit());
  78         return m_impl->characters8() + m_offset;
  79     }
  80
  81     const UChar* characters16() const
  82     {
  83         if (!m_impl)
  84             return 0;
  85         ASSERT(!is8Bit());
  86         return m_impl->characters16() + m_offset;
  87     }
  88
  89     PassRefPtr<StringImpl> toString() const
  90     {
  91         if (!m_impl)
  92             return m_impl;
  93         if (m_impl->is8Bit())
  94             return StringImpl::create(characters8(), m_length);
  95         return StringImpl::create(characters16(), m_length);
  96     }
  97
  98 private:
  99     RefPtr<StringImpl> m_impl;
 100     unsigned m_offset;
 101     unsigned m_length;
 102 };
 103
 104 }
 105
 106 using WTF::StringView;
 107
 108 #endif