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      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 <= 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 private:
     90     RefPtr<StringImpl> m_impl;
     91     unsigned m_offset;
     92     unsigned m_length;
     93 };
     94 
     95 }
     96 
     97 using WTF::StringView;
     98 
     99 #endif
    100