QLatin1String: add iterators

[ChangeLog][QtCore][QLatin1String] Added iterators, {c,}{r,}{begin,end}().

Change-Id: I0222a3ff44f2aa827c737e2fa3cfbb8aad69b5a7
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Anton Kudryavtsev <antkudr@mail.ru>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qstring.cpp

@@ -8313,6 +8313,76 @@ QString &QString::setRawData(const QChar *unicode, int size)
     \sa QString, QLatin1Char, {QStringLiteral()}{QStringLiteral}
 */
 
+/*!
+    \typedef QLatin1String::value_type
+    \since 5.10
+
+    Alias for \c{const char}. Provided for compatibility with the STL.
+*/
+
+/*!
+    \typedef QLatin1String::difference_type
+    \since 5.10
+
+    Alias for \c{int}. Provided for compatibility with the STL.
+*/
+
+/*!
+    \typedef QLatin1String::size_type
+    \since 5.10
+
+    Alias for \c{int}. Provided for compatibility with the STL.
+*/
+
+/*!
+    \typedef QLatin1String::reference
+    \since 5.10
+
+    Alias for \c{value_type &}. Provided for compatibility with the STL.
+*/
+
+/*!
+    \typedef QLatin1String::iterator
+    \since 5.10
+
+    This typedef provides an STL-style const iterator for QLatin1String.
+
+    QLatin1String does not support mutable iterators, so this is the same
+    as const_iterator.
+
+    \sa const_iterator, reverse_iterator
+*/
+
+/*!
+    \typedef QLatin1String::const_iterator
+    \since 5.10
+
+    This typedef provides an STL-style const iterator for QLatin1String.
+
+    \sa iterator, const_reverse_iterator
+*/
+
+/*!
+    \typedef QLatin1String::reverse_iterator
+    \since 5.10
+
+    This typedef provides an STL-style const reverse iterator for QLatin1String.
+
+    QLatin1String does not support mutable reverse iterators, so this is the
+    same as const_reverse_iterator.
+
+    \sa const_reverse_iterator, iterator
+*/
+
+/*!
+    \typedef QLatin1String::const_reverse_iterator
+    \since 5.10
+
+    This typedef provides an STL-style const reverse iterator for QLatin1String.
+
+    \sa reverse_iterator, const_iterator
+*/
+
 /*! \fn QLatin1String::QLatin1String()
     \since 5.6
 
@@ -8407,6 +8477,97 @@ QString &QString::setRawData(const QChar *unicode, int size)
     \sa at()
 */
 
+/*!
+    \fn QLatin1String::const_iterator QLatin1String::begin() const
+    \since 5.10
+
+    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first character in
+    the string.
+
+    This function is provided for STL compatibility.
+
+    \sa end(), cbegin(), rbegin(), data()
+*/
+
+/*!
+    \fn QLatin1String::const_iterator QLatin1String::cbegin() const
+    \since 5.10
+
+    Same as begin().
+
+    This function is provided for STL compatibility.
+
+    \sa cend(), begin(), crbegin(), data()
+*/
+
+/*!
+    \fn QLatin1String::const_iterator QLatin1String::end() const
+    \since 5.10
+
+    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
+    character after the last character in the list.
+
+    This function is provided for STL compatibility.
+
+    \sa begin(), cend(), rend()
+*/
+
+/*! \fn QLatin1String::const_iterator QLatin1String::cend() const
+    \since 5.10
+
+    Same as end().
+
+    This function is provided for STL compatibility.
+
+    \sa cbegin(), end(), crend()
+*/
+
+/*!
+    \fn QLatin1String::const_reverse_iterator QLatin1String::rbegin() const
+    \since 5.10
+
+    Returns a const \l{STL-style iterators}{STL-style} reverse iterator pointing to the first
+    character in the string, in reverse order.
+
+    This function is provided for STL compatibility.
+
+    \sa rend(), crbegin(), begin()
+*/
+
+/*!
+    \fn QLatin1String::const_reverse_iterator QLatin1String::crbegin() const
+    \since 5.10
+
+    Same as rbegin().
+
+    This function is provided for STL compatibility.
+
+    \sa crend(), rbegin(), cbegin()
+*/
+
+/*!
+    \fn QLatin1String::const_reverse_iterator QLatin1String::rend() const
+    \since 5.10
+
+    Returns a \l{STL-style iterators}{STL-style} reverse iterator pointing to one past
+    the last character in the string, in reverse order.
+
+    This function is provided for STL compatibility.
+
+    \sa rbegin(), crend(), end()
+*/
+
+/*!
+    \fn QLatin1String::const_reverse_iterator QLatin1String::crend() const
+    \since 5.10
+
+    Same as rend().
+
+    This function is provided for STL compatibility.
+
+    \sa crbegin(), rend(), cend()
+*/
+
 /*! \fn QLatin1String QLatin1String::mid(int start) const
     \since 5.8
 

src/corelib/tools/qstring.h

@@ -103,6 +103,27 @@ public:
     Q_DECL_CONSTEXPR QLatin1Char at(int i) const { return QLatin1Char(m_data[i]); }
     Q_DECL_CONSTEXPR QLatin1Char operator[](int i) const { return at(i); }
 
+    using value_type = const char;
+    using reference = value_type&;
+    using const_reference = reference;
+    using iterator = value_type*;
+    using const_iterator = iterator;
+    using difference_type = int; // violates Container concept requirements
+    using size_type = int;       // violates Container concept requirements
+
+    Q_DECL_CONSTEXPR const_iterator begin() const Q_DECL_NOTHROW { return data(); }
+    Q_DECL_CONSTEXPR const_iterator cbegin() const Q_DECL_NOTHROW { return data(); }
+    Q_DECL_CONSTEXPR const_iterator end() const Q_DECL_NOTHROW { return data() + size(); }
+    Q_DECL_CONSTEXPR const_iterator cend() const Q_DECL_NOTHROW { return data() + size(); }
+
+    using reverse_iterator = std::reverse_iterator<iterator>;
+    using const_reverse_iterator = reverse_iterator;
+
+    const_reverse_iterator rbegin() const Q_DECL_NOTHROW { return const_reverse_iterator(end()); }
+    const_reverse_iterator crbegin() const Q_DECL_NOTHROW { return const_reverse_iterator(end()); }
+    const_reverse_iterator rend() const Q_DECL_NOTHROW { return const_reverse_iterator(begin()); }
+    const_reverse_iterator crend() const Q_DECL_NOTHROW { return const_reverse_iterator(begin()); }
+
     Q_DECL_CONSTEXPR QLatin1String mid(int pos) const
     { return QLatin1String(m_data + pos, m_size - pos); }
     Q_DECL_CONSTEXPR QLatin1String mid(int pos, int n) const

tests/auto/corelib/tools/qlatin1string/tst_qlatin1string.cpp

@@ -48,6 +48,7 @@ private Q_SLOTS:
     void midLeftRight();
     void nullString();
     void emptyString();
+    void iterators();
     void relationalOperators_data();
     void relationalOperators();
 };
@@ -155,6 +156,22 @@ void tst_QLatin1String::emptyString()
     }
 }
 
+void tst_QLatin1String::iterators()
+{
+    QLatin1String hello("hello");
+    QLatin1String olleh("olleh");
+
+    QVERIFY(std::equal(hello.begin(), hello.end(),
+                       olleh.rbegin()));
+    QVERIFY(std::equal(hello.rbegin(), hello.rend(),
+                       QT_MAKE_CHECKED_ARRAY_ITERATOR(olleh.begin(), olleh.size())));
+
+    QVERIFY(std::equal(hello.cbegin(), hello.cend(),
+                       olleh.rbegin()));
+    QVERIFY(std::equal(hello.crbegin(), hello.crend(),
+                       QT_MAKE_CHECKED_ARRAY_ITERATOR(olleh.begin(), olleh.size())));
+}
+
 void tst_QLatin1String::relationalOperators_data()
 {
     QTest::addColumn<QLatin1StringContainer>("lhs");