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39
40#ifndef QBYTEARRAYMATCHER_H
41#define QBYTEARRAYMATCHER_H
42
43#include <QtCore/qbytearray.h>
44
45QT_BEGIN_NAMESPACE
46
47
48class QByteArrayMatcherPrivate;
49
50class Q_CORE_EXPORT QByteArrayMatcher
51{
52public:
53 QByteArrayMatcher();
54 explicit QByteArrayMatcher(const QByteArray &pattern);
55 explicit QByteArrayMatcher(const char *pattern, int length);
56 QByteArrayMatcher(const QByteArrayMatcher &other);
57 ~QByteArrayMatcher();
58
59 QByteArrayMatcher &operator=(const QByteArrayMatcher &other);
60
61 void setPattern(const QByteArray &pattern);
62
63 int indexIn(const QByteArray &ba, int from = 0) const;
64 int indexIn(const char *str, int len, int from = 0) const;
65 inline QByteArray pattern() const
66 {
67 if (q_pattern.isNull())
68 return QByteArray(reinterpret_cast<const char*>(p.p), p.l);
69 return q_pattern;
70 }
71
72private:
73 QByteArrayMatcherPrivate *d;
74 QByteArray q_pattern;
75 struct Data {
76 uchar q_skiptable[256];
77 const uchar *p;
78 int l;
79 };
80 union {
81 uint dummy[256];
82 Data p;
83 };
84};
85
86class QStaticByteArrayMatcherBase
87{
88 Q_DECL_ALIGN(16)
89 struct Skiptable {
90 uchar data[256];
91 } m_skiptable;
92protected:
93 explicit Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcherBase(const char *pattern, uint n) noexcept
94 : m_skiptable(generate(pattern, n)) {}
95 // compiler-generated copy/more ctors/assignment operators are ok!
96 // compiler-generated dtor is ok!
97
98 Q_CORE_EXPORT int indexOfIn(const char *needle, uint nlen, const char *haystack, int hlen, int from) const noexcept;
99
100private:
101 static Q_DECL_RELAXED_CONSTEXPR Skiptable generate(const char *pattern, uint n) noexcept
102 {
103 const auto uchar_max = (std::numeric_limits<uchar>::max)();
104 uchar max = n > uchar_max ? uchar_max : n;
105 Skiptable table = {
106 // this verbose initialization code aims to avoid some opaque error messages
107 // even on powerful compilers such as GCC 5.3. Even though for GCC a loop
108 // format can be found that v5.3 groks, it's probably better to go with this
109 // for the time being:
110 {
111 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
112 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
113 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
114 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
115 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
116 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
117 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
118 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
119
120 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
121 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
122 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
123 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
124 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
125 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
126 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
127 max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max,
128 }
129 };
130 pattern += n - max;
131 while (max--)
132 table.data[uchar(*pattern++)] = max;
133 return table;
134 }
135};
136
137template <uint N>
138class QStaticByteArrayMatcher : QStaticByteArrayMatcherBase
139{
140 char m_pattern[N];
141 Q_STATIC_ASSERT_X(N > 2, "QStaticByteArrayMatcher makes no sense for finding a single-char pattern");
142public:
143 explicit Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcher(const char (&patternToMatch)[N]) noexcept
144 : QStaticByteArrayMatcherBase(patternToMatch, N - 1), m_pattern()
145 {
146 for (uint i = 0; i < N; ++i)
147 m_pattern[i] = patternToMatch[i];
148 }
149
150 int indexIn(const QByteArray &haystack, int from = 0) const noexcept
151 { return this->indexOfIn(m_pattern, N - 1, haystack.data(), haystack.size(), from); }
152 int indexIn(const char *haystack, int hlen, int from = 0) const noexcept
153 { return this->indexOfIn(m_pattern, N - 1, haystack, hlen, from); }
154
155 QByteArray pattern() const { return QByteArray(m_pattern, int(N - 1)); }
156};
157
158template <uint N>
159Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcher<N> qMakeStaticByteArrayMatcher(const char (&pattern)[N]) noexcept
160{ return QStaticByteArrayMatcher<N>(pattern); }
161
162QT_END_NAMESPACE
163
164#endif // QBYTEARRAYMATCHER_H
165