diff options
Diffstat (limited to 'src/corelib/serialization/qcborstream.cpp')
| -rw-r--r-- | src/corelib/serialization/qcborstream.cpp | 309 |
1 files changed, 30 insertions, 279 deletions
diff --git a/src/corelib/serialization/qcborstream.cpp b/src/corelib/serialization/qcborstream.cpp index aed286a11f..22286188b8 100644 --- a/src/corelib/serialization/qcborstream.cpp +++ b/src/corelib/serialization/qcborstream.cpp @@ -197,9 +197,7 @@ QDebug operator<<(QDebug dbg, QCborSimpleType st) For example, the following creates a QCborValue containing a byte array tagged with a tag 2. - \code - QCborValue(QCborTag(2), QByteArray("\x01\0\0\0\0\0\0\0\0", 9)); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 0 \sa QCborKnownTags, QCborStreamWriter::append(QCborTag), QCborStreamReader::isTag(), QCborStreamReader::toTag(), @@ -530,25 +528,7 @@ QString QCborError::toString() const } \enddiv - \code - writer.startMap(4); // 4 elements in the map - - writer.append(QLatin1String("label")); - writer.append(QLatin1String("journald")); - - writer.append(QLatin1String("autoDetect")); - writer.append(false); - - writer.append(QLatin1String("condition")); - writer.append(QLatin1String("libs.journald")); - - writer.append(QLatin1String("output")); - writer.startArray(1); - writer.append(QLatin1String("privateFeature")); - writer.endArray(); - - writer.endMap(); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 1 \section1 CBOR support @@ -731,12 +711,7 @@ static CborError qt_cbor_encoder_write_callback(void *self, const void *data, si The following example writes an empty map to a file: - \code - QFile f("output", QIODevice::WriteOnly); - QCborStreamWriter writer(&f); - writer.startMap(0); - writer.endMap(); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 2 QCborStreamWriter does not take ownership of \a device. @@ -755,15 +730,7 @@ QCborStreamWriter::QCborStreamWriter(QIODevice *device) The following example writes a number to a byte array then returns it. - \code - QByteArray encodedNumber(qint64 value) - { - QByteArray ba; - QCborStreamWriter writer(&ba); - writer.append(value); - return ba; - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 3 QCborStreamWriter does not take ownership of \a data. */ @@ -821,11 +788,7 @@ QIODevice *QCborStreamWriter::device() const Unsigned Integer value. In the following example, we write the values 0, 2\sup{32} and \c UINT64_MAX: - \code - writer.append(0U); - writer.append(Q_UINT64_C(4294967296)); - writer.append(std::numeric_limits<quint64>::max()); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 4 \sa QCborStreamReader::isUnsignedInteger(), QCborStreamReader::toUnsignedInteger() */ @@ -842,12 +805,7 @@ void QCborStreamWriter::append(quint64 u) sign of the parameter. In the following example, we write the values 0, -1, 2\sup{32} and \c INT64_MAX: - \code - writer.append(0); - writer.append(-1); - writer.append(Q_INT64_C(4294967296)); - writer.append(std::numeric_limits<qint64>::max()); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 5 \sa QCborStreamReader::isInteger(), QCborStreamReader::toInteger() */ @@ -865,11 +823,7 @@ void QCborStreamWriter::append(qint64 i) equivalent to 2\sup{64} (that is, -18,446,744,073,709,551,616). In the following example, we write the values -1, -2\sup{32} and INT64_MIN: - \code - writer.append(QCborNegativeInteger(1)); - writer.append(QCborNegativeInteger(Q_INT64_C(4294967296))); - writer.append(QCborNegativeInteger(-quint64(std::numeric_limits<qint64>::min()))); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 6 Note how this function can be used to encode numbers that cannot fit a standard computer's 64-bit signed integer like \l qint64. That is, if \a n @@ -895,14 +849,7 @@ void QCborStreamWriter::append(QCborNegativeInteger n) The following example will load and append the contents of a file to the stream: - \code - void writeFile(QCborStreamWriter &writer, const QString &fileName) - { - QFile f(fileName); - if (f.open(QIODevice::ReadOnly)) - writer.append(f.readAll()); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 7 As the example shows, unlike JSON, CBOR requires no escaping for binary content. @@ -920,9 +867,7 @@ void QCborStreamWriter::append(QCborNegativeInteger n) The following example appends a simple string to the stream: - \code - writer.append(QLatin1String("Hello, World")); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 8 \b{Performance note}: CBOR requires that all Text Strings be encoded in UTF-8, so this function will iterate over the characters in the string to @@ -955,12 +900,7 @@ void QCborStreamWriter::append(QLatin1String str) The following example writes an arbitrary QString to the stream: - \code - void writeString(QCborStreamWriter &writer, const QString &str) - { - writer.append(str); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 9 \sa QCborStreamReader::isString(), QCborStreamReader::readString() */ @@ -979,13 +919,7 @@ void QCborStreamWriter::append(QStringView str) In the following example, we append a CBOR Tag 36 (Regular Expression) and a QRegularExpression's pattern to the stream: - \code - void writeRxPattern(QCborStreamWriter &writer, const QRegularExpression &rx) - { - writer.append(QCborTag(36)); - writer.append(rx.pattern()); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 10 \sa QCborStreamReader::isTag(), QCborStreamReader::toTag() */ @@ -1005,13 +939,7 @@ void QCborStreamWriter::append(QCborTag tag) integer representing the current time to the stream, obtained using the \c time() function: - \code - void writeCurrentTime(QCborStreamWriter &writer) - { - writer.append(QCborKnownTags::UnixTime_t); - writer.append(time(nullptr)); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 11 \sa QCborStreamReader::isTag(), QCborStreamReader::toTag() */ @@ -1023,10 +951,7 @@ void QCborStreamWriter::append(QCborTag tag) Type value. In the following example, we write the simple type for Null as well as for type 32, which Qt has no support for. - \code - writer.append(QCborSimpleType::Null); - writer.append(QCborSimpleType(32)); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 12 \note Using Simple Types for which there is no specification can lead to validation errors by the remote receiver. In addition, simple type values 24 @@ -1047,16 +972,7 @@ void QCborStreamWriter::append(QCborSimpleType st) a C++ \tt float to \c qfloat16 if there's no loss of precision and append it, or instead append the \tt float. - \code - void writeFloat(QCborStreamWriter &writer, float f) - { - qfloat16 f16 = f; - if (qIsNaN(f) || f16 == f) - writer.append(f16); - else - writer.append(f); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 13 \sa QCborStreamReader::isFloat16(), QCborStreamReader::toFloat16() */ @@ -1073,16 +989,7 @@ void QCborStreamWriter::append(qfloat16 f) a C++ \tt double to \tt float if there's no loss of precision and append it, or instead append the \tt double. - \code - void writeFloat(QCborStreamWriter &writer, double d) - { - float f = d; - if (qIsNaN(d) || d == f) - writer.append(f); - else - writer.append(d); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 14 \sa QCborStreamReader::isFloat(), QCborStreamReader::toFloat() */ @@ -1104,25 +1011,7 @@ void QCborStreamWriter::append(float f) which is expected to be taken into account by the system FPU or floating point emulation directly. - \code - void writeDouble(QCborStreamWriter &writer, double d) - { - float f; - if (qIsNaN(d)) { - writer.append(qfloat16(qQNaN())); - } else if (qIsInf(d)) { - writer.append(d < 0 ? -qInf() : qInf()); - } else if ((f = d) == d) { - qfloat16 f16 = f; - if (f16 == f) - writer.append(f16); - else - writer.append(f); - } else { - writer.append(d); - } - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 15 Determining if a double can be converted to an integral with no loss of precision is left as an exercise to the reader. @@ -1200,9 +1089,7 @@ void QCborStreamWriter::appendTextString(const char *utf8, qsizetype len) value or a CBOR True value. This function is equivalent to (and implemented as): - \code - writer.append(b ? QCborSimpleType::True : QCborSimpleType::False); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 16 \sa appendNull(), appendUndefined(), QCborStreamReader::isBool(), QCborStreamReader::toBool() @@ -1215,9 +1102,7 @@ void QCborStreamWriter::appendTextString(const char *utf8, qsizetype len) Appends a CBOR Null value to the stream. This function is equivalent to (and implemented as): The parameter is ignored. - \code - writer.append(QCborSimpleType::Null); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 17 \sa appendNull(), append(QCborSimpleType), QCborStreamReader::isNull() */ @@ -1228,9 +1113,7 @@ void QCborStreamWriter::appendTextString(const char *utf8, qsizetype len) Appends a CBOR Null value to the stream. This function is equivalent to (and implemented as): - \code - writer.append(QCborSimpleType::Null); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 18 \sa append(std::nullptr_t), append(QCborSimpleType), QCborStreamReader::isNull() */ @@ -1241,9 +1124,7 @@ void QCborStreamWriter::appendTextString(const char *utf8, qsizetype len) Appends a CBOR Undefined value to the stream. This function is equivalent to (and implemented as): - \code - writer.append(QCborSimpleType::Undefined); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 19 \sa append(QCborSimpleType), QCborStreamReader::isUndefined() */ @@ -1260,15 +1141,7 @@ void QCborStreamWriter::appendTextString(const char *utf8, qsizetype len) The following example appends elements from the linked list of strings passed as input: - \code - void appendList(QCborStreamWriter &writer, const QLinkedList<QString> &list) - { - writer.startArray(); - for (const QString &s : list) - writer.append(s); - writer.endArray(); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 20 \sa startArray(quint64), endArray(), startMap(), QCborStreamReader::isArray(), QCborStreamReader::isLengthKnown() @@ -1293,15 +1166,7 @@ void QCborStreamWriter::startArray() The following example appends all strings found in the \l QStringList passed as input: - \code - void appendList(QCborStreamWriter &writer, const QStringList &list) - { - writer.startArray(list.size()); - for (const QString &s : list) - writer.append(s); - writer.endArray(); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 21 \b{Size limitations}: The parameter to this function is quint64, which would seem to allow up to 2\sup{64}-1 elements in the array. However, both @@ -1349,17 +1214,7 @@ bool QCborStreamWriter::endArray() The following example appends elements from the linked list of int and string pairs passed as input: - \code - void appendMap(QCborStreamWriter &writer, const QLinkedList<QPair<int, QString>> &list) - { - writer.startMap(); - for (const auto pair : list) { - writer.append(pair.first) - writer.append(pair.second); - } - writer.endMap(); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 22 \sa startMap(quint64), endMap(), startArray(), QCborStreamReader::isMap(), QCborStreamReader::isLengthKnown() @@ -1384,17 +1239,7 @@ void QCborStreamWriter::startMap() The following example appends all strings found in the \l QMap passed as input: - \code - void appendMap(QCborStreamWriter &writer, const QMap<int, QString> &map) - { - writer.startMap(map.size()); - for (auto it = map.begin(); it != map.end(); ++it) { - writer.append(it.key()); - writer.append(it.value()); - } - writer.endMap(); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 23 \b{Size limitations}: The parameter to this function is quint64, which would seem to allow up to 2\sup{64}-1 pairs in the map. However, both @@ -1475,33 +1320,7 @@ bool QCborStreamWriter::endMap() So a processor function typically looks like this: - \code - void handleStream(QCborStreamReader &reader) - { - switch (reader.type()) - case QCborStreamReader::UnsignedInteger: - case QCborStreamReader::NegativeInteger: - case QCborStreamReader::SimpleType: - case QCborStreamReader::Float16: - case QCborStreamReader::Float: - case QCborStreamReader::Double: - handleFixedWidth(reader); - reader.next(); - break; - case QCborStreamReader::ByteArray: - case QCborStreamReader::String: - handleString(reader); - break; - case QCborStreamReader::Array: - case QCborStreamReader::Map: - reader.enterContainer(); - while (reader.lastError() == QCborError::NoError) - handleStream(reader); - if (reader.lastError() == QCborError::NoError) - reader.leaveContainer(); - } - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 24 \section1 CBOR support @@ -1717,20 +1536,7 @@ bool QCborStreamWriter::endMap() The following example pre-allocates a QVariantList given the array's size for more efficient decoding: - \code - QVariantList populateFromCbor(QCborStreamReader &reader) - { - QVariantList list; - if (reader.isLengthKnown()) - list.reserve(reader.length()); - - reader.enterContainer(); - while (reader.lastError() == QCborError::NoError && reader.hasNext()) - list.append(readOneElement(reader)); - if (reader.lastError() == QCborError::NoError) - reader.leaveContainer(); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 25 \note The code above does not validate that the length is a sensible value. If the input stream reports that the length is 1 billion elements, the above @@ -1754,22 +1560,7 @@ bool QCborStreamWriter::endMap() The following example pre-allocates a QVariantMap given the map's size for more efficient decoding: - \code - QVariantMap populateFromCbor(QCborStreamReader &reader) - { - QVariantMap map; - if (reader.isLengthKnown()) - map.reserve(reader.length()); - - reader.enterContainer(); - while (reader.lastError() == QCborError::NoError && reader.hasNext()) { - QString key = readElementAsString(reader); - map.insert(key, readOneElement(reader)); - } - if (reader.lastError() == QCborError::NoError) - reader.leaveContainer(); - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 26 The example above uses a function called \c readElementAsString to read the map's keys and obtain a string. That is because CBOR maps may contain any @@ -2702,23 +2493,7 @@ bool QCborStreamReader::leaveContainer() always loop around calling this function, even if isLengthKnown() has is true. The typical use of this function is as follows: - \code - QString decodeString(QCborStreamReader &reader) - { - QString result; - auto r = reader.readString(); - while (r.code == QCborStreamReader::Ok) { - result += r.data; - r = reader.readString(); - } - - if (r.code == QCborStreamReader::Error) { - // handle error condition - result.clear(); - } - return result; - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 27 This function does not perform any type conversions, including from integers or from byte arrays. Therefore, it may only be called if isString() returned @@ -2754,23 +2529,7 @@ QCborStreamReader::StringResult<QString> QCborStreamReader::_readString_helper() always loop around calling this function, even if isLengthKnown() has is true. The typical use of this function is as follows: - \code - QBytearray decodeBytearray(QCborStreamReader &reader) - { - QBytearray result; - auto r = reader.readBytearray(); - while (r.code == QCborStreamReader::Ok) { - result += r.data; - r = reader.readByteArray(); - } - - if (r.code == QCborStreamReader::Error) { - // handle error condition - result.clear(); - } - return result; - } - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 28 This function does not perform any type conversions, including from integers or from strings. Therefore, it may only be called if isByteArray() is true; @@ -2840,15 +2599,7 @@ qsizetype QCborStreamReader::_currentStringChunkSize() const This function is usually used alongside currentStringChunkSize() in a loop. For example: - \code - QCborStreamReader<qsizetype> result; - do { - qsizetype size = reader.currentStringChunkSize(); - qsizetype oldsize = buffer.size(); - buffer.resize(oldsize + size); - result = reader.readStringChunk(buffer.data() + oldsize, size); - } while (result.status() == QCborStreamReader::Ok); - \endcode + \snippet code/src_corelib_serialization_qcborstream.cpp 29 Unlike readByteArray() and readString(), this function is not limited by implementation limits of QByteArray and QString. |