qt5base-lts/examples/corelib/serialization/convert/datastreamconverter.cpp
Thiago Macieira 9be00330af Examples: add an example that converts between different file formats
This example converts to and from:
 - Binary JSON
 - CBOR
 - CBOR Diagnostic notation (output only)
 - JSON
 - Null (output only)
 - QDataStream
 - QVariant dump (output only)
 - Text
 - XML

Change-Id: Ibab69e0efefb40bdbf94fffd150b59f8c0da3174
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
2018-07-04 03:03:47 +00:00

274 lines
8.4 KiB
C++

/****************************************************************************
**
** Copyright (C) 2018 Intel Corporation.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
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** information use the contact form at https://www.qt.io/contact-us.
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** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
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** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
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#include "datastreamconverter.h"
#include <QDataStream>
#include <QDebug>
#include <QTextStream>
static const char optionHelp[] =
"byteorder=host|big|little Byte order to use.\n"
"version=<n> QDataStream version (default: Qt 5.0).\n"
;
static const char signature[] = "qds";
static DataStreamDumper dataStreamDumper;
static DataStreamConverter DataStreamConverter;
QDataStream &operator<<(QDataStream &ds, const VariantOrderedMap &map)
{
ds << qint64(map.size());
for (const auto &pair : map)
ds << pair.first << pair.second;
return ds;
}
QDataStream &operator>>(QDataStream &ds, VariantOrderedMap &map)
{
map.clear();
qint64 size;
ds >> size;
map.reserve(size);
while (size-- > 0) {
VariantOrderedMap::value_type pair;
ds >> pair.first >> pair.second;
map.append(pair);
}
return ds;
}
static QString dumpVariant(const QVariant &v, const QString &indent = QLatin1String("\n"))
{
QString result;
QString indented = indent + QLatin1String(" ");
int type = v.userType();
if (type == qMetaTypeId<VariantOrderedMap>() || type == QVariant::Map) {
const auto map = (type == QVariant::Map) ?
VariantOrderedMap(v.toMap()) : v.value<VariantOrderedMap>();
result = QLatin1String("Map {");
for (const auto &pair : map) {
result += indented + dumpVariant(pair.first, indented);
result.chop(1); // remove comma
result += QLatin1String(" => ") + dumpVariant(pair.second, indented);
}
result.chop(1); // remove comma
result += indent + QLatin1String("},");
} else if (type == QVariant::List) {
const QVariantList list = v.toList();
result = QLatin1String("List [");
for (const auto &item : list)
result += indented + dumpVariant(item, indented);
result.chop(1); // remove comma
result += indent + QLatin1String("],");
} else {
QDebug debug(&result);
debug.nospace() << v << ',';
}
return result;
}
QString DataStreamDumper::name()
{
return QStringLiteral("datastream-dump");
}
Converter::Direction DataStreamDumper::directions()
{
return Out;
}
Converter::Options DataStreamDumper::outputOptions()
{
return SupportsArbitraryMapKeys;
}
const char *DataStreamDumper::optionsHelp()
{
return nullptr;
}
bool DataStreamDumper::probeFile(QIODevice *f)
{
Q_UNUSED(f);
return false;
}
QVariant DataStreamDumper::loadFile(QIODevice *f, Converter *&outputConverter)
{
Q_UNREACHABLE();
Q_UNUSED(f);
Q_UNUSED(outputConverter);
return QVariant();
}
void DataStreamDumper::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
{
Q_UNUSED(options);
QString s = dumpVariant(contents);
s[s.size() - 1] = QLatin1Char('\n'); // replace the comma with newline
QTextStream out(f);
out << s;
}
DataStreamConverter::DataStreamConverter()
{
qRegisterMetaType<VariantOrderedMap>();
qRegisterMetaTypeStreamOperators<VariantOrderedMap>();
}
QString DataStreamConverter::name()
{
return QStringLiteral("datastream");
}
Converter::Direction DataStreamConverter::directions()
{
return InOut;
}
Converter::Options DataStreamConverter::outputOptions()
{
return SupportsArbitraryMapKeys;
}
const char *DataStreamConverter::optionsHelp()
{
return optionHelp;
}
bool DataStreamConverter::probeFile(QIODevice *f)
{
return f->isReadable() && f->peek(sizeof(signature) - 1) == signature;
}
QVariant DataStreamConverter::loadFile(QIODevice *f, Converter *&outputConverter)
{
if (!outputConverter)
outputConverter = &dataStreamDumper;
char c;
if (f->read(sizeof(signature) -1) != signature ||
!f->getChar(&c) || (c != 'l' && c != 'B')) {
fprintf(stderr, "Could not load QDataStream file: invalid signature.\n");
exit(EXIT_FAILURE);
}
QDataStream ds(f);
ds.setByteOrder(c == 'l' ? QDataStream::LittleEndian : QDataStream::BigEndian);
std::underlying_type<QDataStream::Version>::type version;
ds >> version;
ds.setVersion(QDataStream::Version(version));
QVariant result;
ds >> result;
return result;
}
void DataStreamConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
{
QDataStream::Version version = QDataStream::Qt_5_0;
auto order = QDataStream::ByteOrder(QSysInfo::ByteOrder);
for (const QString &option : options) {
const QStringList pair = option.split('=');
if (pair.size() == 2) {
if (pair.first() == "byteorder") {
if (pair.last() == "little") {
order = QDataStream::LittleEndian;
continue;
} else if (pair.last() == "big") {
order = QDataStream::BigEndian;
continue;
} else if (pair.last() == "host") {
order = QDataStream::ByteOrder(QSysInfo::ByteOrder);
continue;
}
}
if (pair.first() == "version") {
bool ok;
int n = pair.last().toInt(&ok);
if (ok) {
version = QDataStream::Version(n);
continue;
}
fprintf(stderr, "Invalid version number '%s': must be a number from 1 to %d.\n",
qPrintable(pair.last()), QDataStream::Qt_DefaultCompiledVersion);
exit(EXIT_FAILURE);
}
}
fprintf(stderr, "Unknown QDataStream formatting option '%s'. Available options are:\n%s",
qPrintable(option), optionHelp);
exit(EXIT_FAILURE);
}
char c = order == QDataStream::LittleEndian ? 'l' : 'B';
f->write(signature);
f->write(&c, 1);
QDataStream ds(f);
ds.setVersion(version);
ds.setByteOrder(order);
ds << std::underlying_type<decltype(version)>::type(version);
ds << contents;
}