Introduce QByteArrayView

Created a QByteArrayView in symmetry with QStringView.
Added the basic tests symmetrical to QStringView tests.

Moved the implementations of non-modifying methods of QByteArray to
namespace QtPrivate, to be reused inline from both QByteArray and
QByteArrayView. Changed QByteArray's counterparts of those methods to
take QByteArrayView as argument instead of QByteArray. Removed
QByteArray's operator QNoImplicitBoolCast(), because it was causing
ambiguity when calling those methods with QByteArray argument (it was
there to perevnt if(!ba)/if(ba) from compiling, but currently that would
be ambiguous and won't compile anyway).

[ChangeLog][QtCore][QByteArrayView] New class.

Task-number: QTBUG-84321
Change-Id: I05f92e654cf65c95f2bb31b9c9018746ac110426
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 137 insertions, 251 deletions

diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 375c64a90c..c498aa30a6 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -408,47 +408,16 @@ int qstrnicmp(const char *str1, qsizetype len1, const char *str2, qsizetype len2
 
 /*!
     \internal
-    ### Qt6: replace the QByteArray parameter with [pointer,len] pair
  */
-int qstrcmp(const QByteArray &str1, const char *str2)
-{
-    if (!str2)
-        return str1.isEmpty() ? 0 : +1;
-
-    const char *str1data = str1.constData();
-    const char *str1end = str1data + str1.length();
-    for ( ; str1data < str1end && *str2; ++str1data, ++str2) {
-        int diff = int(uchar(*str1data)) - uchar(*str2);
-        if (diff)
-            // found a difference
-            return diff;
-    }
-
-    // Why did we stop?
-    if (*str2 != '\0')
-        // not the null, so we stopped because str1 is shorter
-        return -1;
-    if (str1data < str1end)
-        // we haven't reached the end, so str1 must be longer
-        return +1;
-    return 0;
-}
-
-/*!
-    \internal
-    ### Qt6: replace the QByteArray parameter with [pointer,len] pair
- */
-int qstrcmp(const QByteArray &str1, const QByteArray &str2)
+int QtPrivate::compareMemory(QByteArrayView lhs, QByteArrayView rhs)
 {
-    int l1 = str1.length();
-    int l2 = str2.length();
-    int ret = memcmp(str1.constData(), str2.constData(), qMin(l1, l2));
+    int ret = memcmp(lhs.data(), rhs.data(), qMin(lhs.size(), rhs.size()));
     if (ret != 0)
         return ret;
 
     // they matched qMin(l1, l2) bytes
     // so the longer one is lexically after the shorter one
-    return l1 - l2;
+    return lhs.size() == rhs.size() ? 0 : lhs.size() > rhs.size() ? 1 : -1;
 }
 
 // the CRC table below is created by the following piece of code
@@ -911,7 +880,7 @@ QByteArray qUncompress(const uchar* data, int nbytes)
     This issue does not apply to \l{QString}s since they represent characters
     using Unicode.
 
-    \sa QString, QBitArray
+    \sa  QByteArrayView, QString, QBitArray
 */
 
 /*!
@@ -1446,22 +1415,15 @@ QByteArray &QByteArray::operator=(const char *str)
     \sa front(), at(), operator[]()
 */
 
-/*! \fn bool QByteArray::contains(const QByteArray &ba) const
+/*! \fn bool QByteArray::contains(QByteArrayView bv) const
+    \since 6.0
 
-    Returns \c true if the byte array contains an occurrence of the byte
-    array \a ba; otherwise returns \c false.
+    Returns \c true if this byte array contains an occurrence of the
+    sequence of bytes viewed by \a bv; otherwise returns \c false.
 
     \sa indexOf(), count()
 */
 
-/*! \fn bool QByteArray::contains(const char *str) const
-
-    \overload
-
-    Returns \c true if the byte array contains the '\\0'-terminated string \a
-    str; otherwise returns \c false.
-*/
-
 /*! \fn bool QByteArray::contains(char ch) const
 
     \overload
@@ -2388,61 +2350,54 @@ QByteArray QByteArray::repeated(int times) const
         hashHaystack -= (a) << ol_minus_1; \
     hashHaystack <<= 1
 
-/*!
-    Returns the index position of the first occurrence of the byte
-    array \a ba in this byte array, searching forward from index
-    position \a from. Returns -1 if \a ba could not be found.
-
-    Example:
-    \snippet code/src_corelib_text_qbytearray.cpp 21
-
-    \sa lastIndexOf(), contains(), count()
-*/
+static inline qsizetype findCharHelper(QByteArrayView haystack, qsizetype from, char needle) noexcept
+{
+    if (from < 0)
+        from = qMax(from + haystack.size(), qsizetype(0));
+    if (from < haystack.size()) {
+        const char *const b = haystack.data();
+        if (const auto n = static_cast<const char *>(
+                    memchr(b + from, needle, static_cast<size_t>(haystack.size() - from)))) {
+            return n - b;
+        }
+    }
+    return -1;
+}
 
-int QByteArray::indexOf(const QByteArray &ba, int from) const
+qsizetype QtPrivate::findByteArray(QByteArrayView haystack, qsizetype from, QByteArrayView needle) noexcept
 {
-    const int ol = ba.size();
+    const auto ol = needle.size();
     if (ol == 0)
         return from;
     if (ol == 1)
-        return indexOf(ba[0], from);
+        return findCharHelper(haystack, from, needle.front());
 
-    const int l = size();
+    const auto l = haystack.size();
     if (from > l || ol + from > l)
         return -1;
 
-    return static_cast<int>(qFindByteArray(data(), size(), from, ba.data(), ol));
+    return qFindByteArray(haystack.data(), haystack.size(), from, needle.data(), ol);
 }
 
-/*! \fn int QByteArray::indexOf(const char *str, int from) const
-
-    \overload
+/*! \fn int QByteArray::indexOf(QByteArrayView bv, int from) const
+    \since 6.0
 
-    Returns the index position of the first occurrence of the '\\0'-terminated
-    string \a str in the byte array, searching forward from index position \a
-    from. Returns -1 if \a str could not be found.
-*/
-int QByteArray::indexOf(const char *c, int from) const
-{
-    const int ol = qstrlen(c);
-    if (ol == 1)
-        return indexOf(*c, from);
+    Returns the index position of the start of the first occurrence of the
+    sequence of bytes viewed by \a bv in this byte array, searching forward
+    from index position \a from. Returns -1 if no match is found.
 
-    const int l = size();
-    if (from > l || ol + from > l)
-        return -1;
-    if (ol == 0)
-        return from;
+    Example:
+    \snippet code/src_corelib_text_qbytearray.cpp 21
 
-    return static_cast<int>(qFindByteArray(data(), size(), from, c, ol));
-}
+    \sa lastIndexOf(), contains(), count()
+*/
 
 /*!
     \overload
 
-    Returns the index position of the first occurrence of the byte \a ch in the
-    byte array, searching forward from index position \a from. Returns -1 if \a
-    ch could not be found.
+    Returns the index position of the start of the first occurrence of the
+    byte \a ch in this byte array, searching forward from index position \a from.
+    Returns -1 if no match is found.
 
     Example:
     \snippet code/src_corelib_text_qbytearray.cpp 22
@@ -2452,16 +2407,7 @@ int QByteArray::indexOf(const char *c, int from) const
 
 int QByteArray::indexOf(char ch, int from) const
 {
-    if (from < 0)
-        from = qMax(from + size(), 0);
-    if (from < size()) {
-        const char *n = data() + from - 1;
-        const char *e = end();
-        while (++n != e)
-        if (*n == ch)
-            return  n - data();
-    }
-    return -1;
+    return static_cast<int>(findCharHelper(*this, from, ch));
 }
 
 static qsizetype lastIndexOfHelper(const char *haystack, qsizetype l, const char *needle,
@@ -2498,57 +2444,55 @@ static qsizetype lastIndexOfHelper(const char *haystack, qsizetype l, const char
 
 }
 
-/*!
-    \fn int QByteArray::lastIndexOf(const QByteArray &ba, int from) const
-
-    Returns the index position of the last occurrence of the byte array \a ba in
-    this byte array, searching backward from index position \a from. If \a from
-    is -1 (the default), the search starts at the last byte (at index size() -
-    1). Returns -1 if \a ba could not be found.
-
-    Example:
-    \snippet code/src_corelib_text_qbytearray.cpp 23
-
-    \sa indexOf(), contains(), count()
-*/
+static inline qsizetype lastIndexOfCharHelper(QByteArrayView haystack, qsizetype from, char needle) noexcept
+{
+    if (from < 0)
+        from += haystack.size();
+    else if (from > haystack.size())
+        from = haystack.size() - 1;
+    if (from >= 0) {
+        const char *b = haystack.data();
+        const char *n = b + from + 1;
+        while (n-- != b) {
+            if (*n == needle)
+                return n - b;
+        }
+    }
+    return -1;
+}
 
-int QByteArray::lastIndexOf(const QByteArray &ba, int from) const
+qsizetype QtPrivate::lastIndexOf(QByteArrayView haystack, qsizetype from, QByteArrayView needle) noexcept
 {
-    if (isEmpty())
-        return !ba.size() ? 0 : -1;
-    const int ol = ba.size();
+    if (haystack.isEmpty())
+        return !needle.size() ? 0 : -1;
+    const auto ol = needle.size();
     if (ol == 1)
-        return lastIndexOf(ba[0], from);
+        return lastIndexOfCharHelper(haystack, from, needle.front());
 
-    return lastIndexOfHelper(data(), size(), ba.data(), ol, from);
+    return lastIndexOfHelper(haystack.data(), haystack.size(), needle.data(), ol, from);
 }
 
-/*! \fn int QByteArray::lastIndexOf(const char *str, int from) const
-    \overload
+/*! \fn int QByteArray::lastIndexOf(QByteArrayView bv, int from) const
+    \since 6.0
 
-    Returns the index position of the last occurrence of the '\\0'-terminated
-    string \a str in the byte array, searching backward from index position \a
-    from. If \a from is -1 (the default), the search starts at the last byte (at
-    index size() - 1). Returns -1 if \a str could not be found.
-*/
-int QByteArray::lastIndexOf(const char *str, int from) const
-{
-    if (isEmpty())
-        return (str && *str) ? -1 : 0;
-    const int ol = qstrlen(str);
-    if (ol == 1)
-        return lastIndexOf(*str, from);
+    Returns the index position of the start of the last occurrence of the sequence
+    of bytes viewed by \a bv in this byte array, searching backward from index
+    position \a from. If \a from is -1 (the default), the search starts from the
+    end of the byte array. Returns -1 if no match is found.
 
-    return lastIndexOfHelper(data(), size(), str, ol, from);
-}
+    Example:
+    \snippet code/src_corelib_text_qbytearray.cpp 23
+
+    \sa indexOf(), contains(), count()
+*/
 
 /*!
     \overload
 
-    Returns the index position of the last occurrence of byte \a ch in the byte
-    array, searching backward from index position \a from. If \a from is -1 (the
-    default), the search starts at the last byte (at index size() - 1). Returns
-    -1 if \a ch could not be found.
+    Returns the index position of the start of the last occurrence of byte \a ch in
+    this byte array, searching backward from index position \a from. If \a from is -1
+    (the default), the search starts at the last byte (at index size() - 1). Returns
+    -1 if no match is found.
 
     Example:
     \snippet code/src_corelib_text_qbytearray.cpp 24
@@ -2558,53 +2502,45 @@ int QByteArray::lastIndexOf(const char *str, int from) const
 
 int QByteArray::lastIndexOf(char ch, int from) const
 {
-    if (from < 0)
-        from += size();
-    else if (from > size())
-        from = size()-1;
-    if (from >= 0) {
-        const char *b = data();
-        const char *n = b + from + 1;
-        while (n-- != b)
-            if (*n == ch)
-                return  n - b;
-    }
-    return -1;
+    return static_cast<int>(lastIndexOfCharHelper(*this, from, ch));
 }
 
-/*!
-    Returns the number of (potentially overlapping) occurrences of
-    byte array \a ba in this byte array.
-
-    \sa contains(), indexOf()
-*/
+static inline qsizetype countCharHelper(QByteArrayView haystack, char needle) noexcept
+{
+    qsizetype num = 0;
+    for (char ch : haystack) {
+        if (ch == needle)
+            ++num;
+    }
+    return num;
+}
 
-int QByteArray::count(const QByteArray &ba) const
+qsizetype QtPrivate::count(QByteArrayView haystack, QByteArrayView needle) noexcept
 {
-    int num = 0;
-    int i = -1;
-    if (size() > 500 && ba.size() > 5) {
-        QByteArrayMatcher matcher(ba);
-        while ((i = matcher.indexIn(*this, i + 1)) != -1)
+    if (needle.size() == 1)
+        return countCharHelper(haystack, needle[0]);
+
+    qsizetype num = 0;
+    qsizetype i = -1;
+    if (haystack.size() > 500 && needle.size() > 5) {
+        QByteArrayMatcher matcher(needle.data());
+        while ((i = matcher.indexIn(haystack.data(), i + 1)) != -1)
             ++num;
     } else {
-        while ((i = indexOf(ba, i + 1)) != -1)
+        while ((i = haystack.indexOf(needle, i + 1)) != -1)
             ++num;
     }
     return num;
 }
 
-/*!
-    \overload
+/*! \fn int QByteArray::count(QByteArrayView &bv) const
+    \since 6.0
 
-    Returns the number of (potentially overlapping) occurrences of
-    '\\0'-terminated string \a str in the byte array.
-*/
+    Returns the number of (potentially overlapping) occurrences of the
+    sequence of bytes viewed by \a bv in this byte array.
 
-int QByteArray::count(const char *str) const
-{
-    return count(fromRawData(str, qstrlen(str)));
-}
+    \sa contains(), indexOf()
+*/
 
 /*!
     \overload
@@ -2616,13 +2552,7 @@ int QByteArray::count(const char *str) const
 
 int QByteArray::count(char ch) const
 {
-    int num = 0;
-    const char *i = end();
-    const char *b = begin();
-    while (i != b)
-        if (*--i == ch)
-            ++num;
-    return num;
+    return static_cast<int>(countCharHelper(*this, ch));
 }
 
 /*! \fn int QByteArray::count() const
@@ -2633,119 +2563,75 @@ int QByteArray::count(char ch) const
 */
 
 /*!
-    \fn int QByteArray::compare(const char *c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const
-    \since 5.12
-
-    Returns an integer less than, equal to, or greater than zero depending on
-    whether this QByteArray sorts before, at the same position as, or after the
-    '\\0'-terminated string \a c. The comparison is performed according to case
-    sensitivity \a cs.
-
-    \sa operator==
-*/
-
-/*!
-    \fn int QByteArray::compare(const QByteArray &a, Qt::CaseSensitivity cs = Qt::CaseSensitive) const
-    \overload
-    \since 5.12
+    \fn int QByteArray::compare(const QByteArrayView &bv, Qt::CaseSensitivity cs = Qt::CaseSensitive) const
+    \since 6.0
 
     Returns an integer less than, equal to, or greater than zero depending on
     whether this QByteArray sorts before, at the same position as, or after the
-    QByteArray \a a. The comparison is performed according to case sensitivity
+    QByteArrayView \a bv. The comparison is performed according to case sensitivity
     \a cs.
 
-    \sa operator==
+    \sa operator==, {Character Case}
 */
 
-/*!
-    Returns \c true if this byte array starts with byte array \a ba;
-    otherwise returns \c false.
-
-    Example:
-    \snippet code/src_corelib_text_qbytearray.cpp 25
-
-    \sa endsWith(), left()
-*/
-bool QByteArray::startsWith(const QByteArray &ba) const
+bool QtPrivate::startsWith(QByteArrayView haystack, QByteArrayView needle) noexcept
 {
-    if (size() < ba.size())
+    if (haystack.size() < needle.size())
         return false;
-    if (data() == ba.data() || ba.size() == 0)
+    if (haystack.data() == needle.data() || needle.size() == 0)
         return true;
-    return memcmp(data(), ba.data(), ba.size()) == 0;
+    return memcmp(haystack.data(), needle.data(), needle.size()) == 0;
 }
 
-/*! \overload
+/*! \fn bool QByteArray::startsWith(QByteArrayView bv) const
+    \since 6.0
+
+    Returns \c true if this byte array starts with the sequence of bytes
+    viewed by \a bv; otherwise returns \c false.
 
-    Returns \c true if this byte array starts with '\\0'-terminated string \a
-    str; otherwise returns \c false.
+    Example:
+    \snippet code/src_corelib_text_qbytearray.cpp 25
+
+    \sa endsWith(), left()
 */
-bool QByteArray::startsWith(const char *str) const
-{
-    if (!str || !*str)
-        return true;
-    const int len = int(strlen(str));
-    if (size() < len)
-        return false;
-    return qstrncmp(data(), str, len) == 0;
-}
 
-/*! \overload
+/*!
+    \fn bool QByteArray::startsWith(char ch) const
+    \overload
 
     Returns \c true if this byte array starts with byte \a ch; otherwise returns
     \c false.
 */
-bool QByteArray::startsWith(char ch) const
+
+bool QtPrivate::endsWith(QByteArrayView haystack, QByteArrayView needle) noexcept
 {
-    if (size() == 0)
+    if (haystack.size() < needle.size())
         return false;
-    return data()[0] == ch;
+    if (haystack.end() == needle.end() || needle.size() == 0)
+        return true;
+    return memcmp(haystack.end() - needle.size(), needle.data(), needle.size()) == 0;
 }
 
 /*!
-    Returns \c true if this byte array ends with byte array \a ba;
-    otherwise returns \c false.
+    \fn bool QByteArray::endsWith(QByteArrayView bv) const
+    \since 6.0
+
+    Returns \c true if this byte array ends with the sequence of bytes
+    viewed by \a bv; otherwise returns \c false.
 
     Example:
     \snippet code/src_corelib_text_qbytearray.cpp 26
 
     \sa startsWith(), right()
 */
-bool QByteArray::endsWith(const QByteArray &ba) const
-{
-    if (size() < ba.size())
-        return false;
-    if (end() == ba.end() || ba.size() == 0)
-        return true;
-    return memcmp(end() - ba.size(), ba.data(), ba.size()) == 0;
-}
-
-/*! \overload
 
-    Returns \c true if this byte array ends with '\\0'-terminated string \a str;
-    otherwise returns \c false.
-*/
-bool QByteArray::endsWith(const char *str) const
-{
-    if (!str || !*str)
-        return true;
-    const int len = int(strlen(str));
-    if (size() < len)
-        return false;
-    return qstrncmp(end() - len, str, len) == 0;
-}
-
-/*! \overload
+/*!
+    \fn bool QByteArray::endsWith(char ch) const
+    \overload
 
     Returns \c true if this byte array ends with byte \a ch;
     otherwise returns \c false.
 */
-bool QByteArray::endsWith(char ch) const
-{
-    if (size() == 0)
-        return false;
-    return data()[size() - 1] == ch;
-}
 
 /*
     Returns true if \a c is an uppercase ASCII letter.