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Diffstat (limited to 'src/corelib/text/qbytearraymatcher.h')
-rw-r--r-- | src/corelib/text/qbytearraymatcher.h | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/src/corelib/text/qbytearraymatcher.h b/src/corelib/text/qbytearraymatcher.h new file mode 100644 index 0000000000..0eedfc1d20 --- /dev/null +++ b/src/corelib/text/qbytearraymatcher.h @@ -0,0 +1,164 @@ +/**************************************************************************** +** +** Copyright (C) 2016 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the QtCore module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#ifndef QBYTEARRAYMATCHER_H +#define QBYTEARRAYMATCHER_H + +#include <QtCore/qbytearray.h> + +QT_BEGIN_NAMESPACE + + +class QByteArrayMatcherPrivate; + +class Q_CORE_EXPORT QByteArrayMatcher +{ +public: + QByteArrayMatcher(); + explicit QByteArrayMatcher(const QByteArray &pattern); + explicit QByteArrayMatcher(const char *pattern, int length); + QByteArrayMatcher(const QByteArrayMatcher &other); + ~QByteArrayMatcher(); + + QByteArrayMatcher &operator=(const QByteArrayMatcher &other); + + void setPattern(const QByteArray &pattern); + + int indexIn(const QByteArray &ba, int from = 0) const; + int indexIn(const char *str, int len, int from = 0) const; + inline QByteArray pattern() const + { + if (q_pattern.isNull()) + return QByteArray(reinterpret_cast<const char*>(p.p), p.l); + return q_pattern; + } + +private: + QByteArrayMatcherPrivate *d; + QByteArray q_pattern; + struct Data { + uchar q_skiptable[256]; + const uchar *p; + int l; + }; + union { + uint dummy[256]; + Data p; + }; +}; + +class QStaticByteArrayMatcherBase +{ + Q_DECL_ALIGN(16) + struct Skiptable { + uchar data[256]; + } m_skiptable; +protected: + explicit Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcherBase(const char *pattern, uint n) noexcept + : m_skiptable(generate(pattern, n)) {} + // compiler-generated copy/more ctors/assignment operators are ok! + // compiler-generated dtor is ok! + + Q_CORE_EXPORT int indexOfIn(const char *needle, uint nlen, const char *haystack, int hlen, int from) const noexcept; + +private: + static Q_DECL_RELAXED_CONSTEXPR Skiptable generate(const char *pattern, uint n) noexcept + { + const auto uchar_max = (std::numeric_limits<uchar>::max)(); + uchar max = n > uchar_max ? uchar_max : n; + Skiptable table = { + // this verbose initialization code aims to avoid some opaque error messages + // even on powerful compilers such as GCC 5.3. Even though for GCC a loop + // format can be found that v5.3 groks, it's probably better to go with this + // for the time being: + { + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, max, + } + }; + pattern += n - max; + while (max--) + table.data[uchar(*pattern++)] = max; + return table; + } +}; + +template <uint N> +class QStaticByteArrayMatcher : QStaticByteArrayMatcherBase +{ + char m_pattern[N]; + Q_STATIC_ASSERT_X(N > 2, "QStaticByteArrayMatcher makes no sense for finding a single-char pattern"); +public: + explicit Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcher(const char (&patternToMatch)[N]) noexcept + : QStaticByteArrayMatcherBase(patternToMatch, N - 1), m_pattern() + { + for (uint i = 0; i < N; ++i) + m_pattern[i] = patternToMatch[i]; + } + + int indexIn(const QByteArray &haystack, int from = 0) const noexcept + { return this->indexOfIn(m_pattern, N - 1, haystack.data(), haystack.size(), from); } + int indexIn(const char *haystack, int hlen, int from = 0) const noexcept + { return this->indexOfIn(m_pattern, N - 1, haystack, hlen, from); } + + QByteArray pattern() const { return QByteArray(m_pattern, int(N - 1)); } +}; + +template <uint N> +Q_DECL_RELAXED_CONSTEXPR QStaticByteArrayMatcher<N> qMakeStaticByteArrayMatcher(const char (&pattern)[N]) noexcept +{ return QStaticByteArrayMatcher<N>(pattern); } + +QT_END_NAMESPACE + +#endif // QBYTEARRAYMATCHER_H |