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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QBYTEARRAYMATCHER_H
#define QBYTEARRAYMATCHER_H
#include <QtCore/qbytearray.h>
#include <limits>
QT_BEGIN_NAMESPACE
class QByteArrayMatcherPrivate;
class Q_CORE_EXPORT QByteArrayMatcher
{
public:
QByteArrayMatcher();
explicit QByteArrayMatcher(const QByteArray &pattern);
explicit QByteArrayMatcher(QByteArrayView pattern)
: QByteArrayMatcher(pattern.data(), pattern.size())
{}
explicit QByteArrayMatcher(const char *pattern, qsizetype length = -1);
QByteArrayMatcher(const QByteArrayMatcher &other);
~QByteArrayMatcher();
QByteArrayMatcher &operator=(const QByteArrayMatcher &other);
void setPattern(const QByteArray &pattern);
#if QT_CORE_REMOVED_SINCE(6, 3)
qsizetype indexIn(const QByteArray &ba, qsizetype from = 0) const;
#else
Q_WEAK_OVERLOAD
qsizetype indexIn(const QByteArray &ba, qsizetype from = 0) const
{ return indexIn(QByteArrayView{ba}, from); }
#endif
qsizetype indexIn(const char *str, qsizetype len, qsizetype from = 0) const;
qsizetype indexIn(QByteArrayView data, qsizetype 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;
qsizetype l;
};
union {
uint dummy[256];
Data p;
};
};
class QStaticByteArrayMatcherBase
{
alignas(16)
struct Skiptable {
uchar data[256];
} m_skiptable;
protected:
explicit constexpr QStaticByteArrayMatcherBase(const char *pattern, size_t n) noexcept
: m_skiptable(generate(pattern, n)) {}
// compiler-generated copy/more ctors/assignment operators are ok!
~QStaticByteArrayMatcherBase() = default;
#if QT_CORE_REMOVED_SINCE(6, 3) && QT_POINTER_SIZE != 4
Q_CORE_EXPORT int indexOfIn(const char *needle, uint nlen, const char *haystack, int hlen, int from) const noexcept;
#endif
Q_CORE_EXPORT qsizetype indexOfIn(const char *needle, size_t nlen,
const char *haystack, qsizetype hlen,
qsizetype from) const noexcept;
private:
static constexpr Skiptable generate(const char *pattern, size_t n) noexcept
{
const auto uchar_max = (std::numeric_limits<uchar>::max)();
uchar max = n > uchar_max ? uchar_max : uchar(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 <size_t N>
class QStaticByteArrayMatcher : QStaticByteArrayMatcherBase
{
char m_pattern[N];
// N includes the terminating '\0'!
static_assert(N > 2, "QStaticByteArrayMatcher makes no sense for finding a single-char pattern");
public:
explicit constexpr QStaticByteArrayMatcher(const char (&patternToMatch)[N]) noexcept
: QStaticByteArrayMatcherBase(patternToMatch, N - 1), m_pattern()
{
for (size_t i = 0; i < N; ++i)
m_pattern[i] = patternToMatch[i];
}
Q_WEAK_OVERLOAD
qsizetype indexIn(const QByteArray &haystack, qsizetype from = 0) const noexcept
{ return this->indexOfIn(m_pattern, N - 1, haystack.data(), haystack.size(), from); }
qsizetype indexIn(const char *haystack, qsizetype hlen, qsizetype from = 0) const noexcept
{ return this->indexOfIn(m_pattern, N - 1, haystack, hlen, from); }
qsizetype indexIn(QByteArrayView haystack, qsizetype from = 0) const noexcept
{ return this->indexOfIn(m_pattern, N - 1, haystack.data(), haystack.size(), from); }
QByteArray pattern() const { return QByteArray(m_pattern, qsizetype(N - 1)); }
};
template <size_t N>
constexpr QStaticByteArrayMatcher<N> qMakeStaticByteArrayMatcher(const char (&pattern)[N]) noexcept
{ return QStaticByteArrayMatcher<N>(pattern); }
QT_END_NAMESPACE
#endif // QBYTEARRAYMATCHER_H
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