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
36namespace WTF {
37
38class WTF_EXPORT StringView {
39public:
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
98private:
99    RefPtr<StringImpl> m_impl;
100    unsigned m_offset;
101    unsigned m_length;
102};
103
104}
105
106using WTF::StringView;
107
108#endif
109