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39 | |
40 | #ifndef QBYTEARRAYMATCHER_H |
41 | #define QBYTEARRAYMATCHER_H |
42 | |
43 | #include <QtCore/qbytearray.h> |
44 | |
45 | #include <limits> |
46 | |
47 | QT_BEGIN_NAMESPACE |
48 | |
49 | |
50 | class QByteArrayMatcherPrivate; |
51 | |
52 | class Q_CORE_EXPORT QByteArrayMatcher |
53 | { |
54 | public: |
55 | QByteArrayMatcher(); |
56 | explicit QByteArrayMatcher(const QByteArray &pattern); |
57 | explicit QByteArrayMatcher(const char *pattern, int length); |
58 | QByteArrayMatcher(const QByteArrayMatcher &other); |
59 | ~QByteArrayMatcher(); |
60 | |
61 | QByteArrayMatcher &operator=(const QByteArrayMatcher &other); |
62 | |
63 | void setPattern(const QByteArray &pattern); |
64 | |
65 | int indexIn(const QByteArray &ba, int from = 0) const; |
66 | int indexIn(const char *str, int len, int from = 0) const; |
67 | inline QByteArray pattern() const |
68 | { |
69 | if (q_pattern.isNull()) |
70 | return QByteArray(reinterpret_cast<const char*>(p.p), p.l); |
71 | return q_pattern; |
72 | } |
73 | |
74 | private: |
75 | QByteArrayMatcherPrivate *d; |
76 | QByteArray q_pattern; |
77 | struct Data { |
78 | uchar q_skiptable[256]; |
79 | const uchar *p; |
80 | int l; |
81 | }; |
82 | union { |
83 | uint dummy[256]; |
84 | Data p; |
85 | }; |
86 | }; |
87 | |
88 | class QStaticByteArrayMatcherBase |
89 | { |
90 | Q_DECL_ALIGN(16) |
91 | struct Skiptable { |
92 | uchar data[256]; |
93 | } m_skiptable; |
94 | protected: |
95 | explicit Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcherBase(const char *pattern, uint n) noexcept |
96 | : m_skiptable(generate(pattern, n)) {} |
97 | // compiler-generated copy/more ctors/assignment operators are ok! |
98 | // compiler-generated dtor is ok! |
99 | |
100 | Q_CORE_EXPORT int indexOfIn(const char *needle, uint nlen, const char *haystack, int hlen, int from) const noexcept; |
101 | |
102 | private: |
103 | static Q_DECL_RELAXED_CONSTEXPR Skiptable generate(const char *pattern, uint n) noexcept |
104 | { |
105 | const auto uchar_max = (std::numeric_limits<uchar>::max)(); |
106 | uchar max = n > uchar_max ? uchar_max : n; |
107 | Skiptable table = { |
108 | // this verbose initialization code aims to avoid some opaque error messages |
109 | // even on powerful compilers such as GCC 5.3. Even though for GCC a loop |
110 | // format can be found that v5.3 groks, it's probably better to go with this |
111 | // for the time being: |
112 | .data: { |
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 | max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, |
120 | max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, |
121 | |
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 | max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, |
129 | max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, |
130 | } |
131 | }; |
132 | pattern += n - max; |
133 | while (max--) |
134 | table.data[uchar(*pattern++)] = max; |
135 | return table; |
136 | } |
137 | }; |
138 | |
139 | template <uint N> |
140 | class QStaticByteArrayMatcher : QStaticByteArrayMatcherBase |
141 | { |
142 | char m_pattern[N]; |
143 | // N includes the terminating '\0'! |
144 | Q_STATIC_ASSERT_X(N > 2, "QStaticByteArrayMatcher makes no sense for finding a single-char pattern" ); |
145 | public: |
146 | explicit Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcher(const char (&patternToMatch)[N]) noexcept |
147 | : QStaticByteArrayMatcherBase(patternToMatch, N - 1), m_pattern() |
148 | { |
149 | for (uint i = 0; i < N; ++i) |
150 | m_pattern[i] = patternToMatch[i]; |
151 | } |
152 | |
153 | int indexIn(const QByteArray &haystack, int from = 0) const noexcept |
154 | { return this->indexOfIn(m_pattern, N - 1, haystack.data(), haystack.size(), from); } |
155 | int indexIn(const char *haystack, int hlen, int from = 0) const noexcept |
156 | { return this->indexOfIn(m_pattern, N - 1, haystack, hlen, from); } |
157 | |
158 | QByteArray pattern() const { return QByteArray(m_pattern, int(N - 1)); } |
159 | }; |
160 | |
161 | template <uint N> |
162 | Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcher<N> qMakeStaticByteArrayMatcher(const char (&pattern)[N]) noexcept |
163 | { return QStaticByteArrayMatcher<N>(pattern); } |
164 | |
165 | QT_END_NAMESPACE |
166 | |
167 | #endif // QBYTEARRAYMATCHER_H |
168 | |