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-rw-r--r--src/corelib/io/qtextstream.cpp53
-rw-r--r--src/corelib/io/qtextstream.h1
-rw-r--r--tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp121
3 files changed, 155 insertions, 20 deletions
diff --git a/src/corelib/io/qtextstream.cpp b/src/corelib/io/qtextstream.cpp
index 771067fa14..ff3b007b21 100644
--- a/src/corelib/io/qtextstream.cpp
+++ b/src/corelib/io/qtextstream.cpp
@@ -1581,17 +1581,60 @@ QString QTextStream::readAll()
*/
QString QTextStream::readLine(qint64 maxlen)
{
+ QString line;
+
+ readLine(&line, maxlen);
+ return line;
+}
+
+/*!
+ \since 5.5
+
+ Reads one line of text from the stream into \a line.
+ If \a line is 0, the read line is not stored.
+
+ The maximum allowed line length is set to \a maxlen. If
+ the stream contains lines longer than this, then the lines will be
+ split after \a maxlen characters and returned in parts.
+
+ If \a maxlen is 0, the lines can be of any length.
+
+ The resulting line has no trailing end-of-line characters ("\\n"
+ or "\\r\\n"), so calling QString::trimmed() can be unnecessary.
+
+ If \a line has sufficient capacity for the data that is about to be
+ read, this function may not need to allocate new memory. Because of
+ this, it can be faster than the other readLine() overload.
+
+ Returns \c false if the stream has read to the end of the file or
+ an error has occurred; otherwise returns \c true. The contents in
+ \a line before the call are discarded in any case.
+
+ \sa readAll(), QIODevice::readLine()
+*/
+bool QTextStream::readLine(QString *line, qint64 maxlen)
+{
Q_D(QTextStream);
- CHECK_VALID_STREAM(QString());
+ // keep in sync with CHECK_VALID_STREAM
+ if (!d->string && !d->device) {
+ qWarning("QTextStream: No device");
+ if (line && !line->isNull())
+ line->resize(0);
+ return false;
+ }
const QChar *readPtr;
int length;
- if (!d->scan(&readPtr, &length, int(maxlen), QTextStreamPrivate::EndOfLine))
- return QString();
+ if (!d->scan(&readPtr, &length, int(maxlen), QTextStreamPrivate::EndOfLine)) {
+ if (line && !line->isNull())
+ line->resize(0);
+ return false;
+ }
- QString tmp = QString(readPtr, length);
+ if (Q_LIKELY(line))
+ line->setUnicode(readPtr, length);
d->consumeLastToken();
- return tmp;
+ return true;
}
/*!
diff --git a/src/corelib/io/qtextstream.h b/src/corelib/io/qtextstream.h
index b15e7772e2..6f5e2473e4 100644
--- a/src/corelib/io/qtextstream.h
+++ b/src/corelib/io/qtextstream.h
@@ -124,6 +124,7 @@ public:
void skipWhiteSpace();
QString readLine(qint64 maxlen = 0);
+ bool readLine(QString *line, qint64 maxlen = 0);
QString readAll();
QString read(qint64 maxlen);
diff --git a/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp b/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp
index faa635fa96..84f9c53b21 100644
--- a/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp
+++ b/tests/auto/corelib/io/qtextstream/tst_qtextstream.cpp
@@ -81,6 +81,7 @@ private slots:
void readLineMaxlen_data();
void readLineMaxlen();
void readLinesFromBufferCRCR();
+ void readLineOverload();
// all
void readAllFromDevice_data();
@@ -593,6 +594,63 @@ void tst_QTextStream::readLinesFromBufferCRCR()
}
}
+class ErrorDevice : public QIODevice
+{
+protected:
+ qint64 readData(char *data, qint64 maxlen) Q_DECL_OVERRIDE
+ {
+ Q_UNUSED(data)
+ Q_UNUSED(maxlen)
+ return -1;
+ }
+
+ qint64 writeData(const char *data, qint64 len) Q_DECL_OVERRIDE
+ {
+ Q_UNUSED(data)
+ Q_UNUSED(len)
+ return -1;
+ }
+};
+
+void tst_QTextStream::readLineOverload()
+{
+ QByteArray data = "1\n2\n3";
+
+ QTextStream ts(&data);
+ QString line;
+
+ ts.readLine(&line);
+ QCOMPARE(line, QStringLiteral("1"));
+
+ ts.readLine(Q_NULLPTR, 0); // read the second line, but don't store it
+
+ ts.readLine(&line);
+ QCOMPARE(line, QStringLiteral("3"));
+
+ QVERIFY(!ts.readLine(&line));
+ QVERIFY(line.isEmpty());
+
+ QFile file(m_rfc3261FilePath);
+ QVERIFY(file.open(QFile::ReadOnly));
+
+ ts.setDevice(&file);
+ line.reserve(1);
+ int maxLineCapacity = line.capacity();
+
+ while (ts.readLine(&line)) {
+ QVERIFY(line.capacity() >= maxLineCapacity);
+ maxLineCapacity = line.capacity();
+ }
+
+ line = "Test string";
+ ErrorDevice errorDevice;
+ QVERIFY(errorDevice.open(QIODevice::ReadOnly));
+ ts.setDevice(&errorDevice);
+
+ QVERIFY(!ts.readLine(&line));
+ QVERIFY(line.isEmpty());
+}
+
// ------------------------------------------------------------------------------
void tst_QTextStream::readLineFromString_data()
{
@@ -912,13 +970,28 @@ void tst_QTextStream::lineCount()
}
// ------------------------------------------------------------------------------
+struct CompareIndicesForArray
+{
+ int *array;
+ CompareIndicesForArray(int *array) : array(array) {}
+ bool operator() (const int i1, const int i2)
+ {
+ return array[i1] < array[i2];
+ }
+};
+
void tst_QTextStream::performance()
{
// Phase #1 - test speed of reading a huge text file with QFile.
QTime stopWatch;
- int elapsed1 = 0;
- int elapsed2 = 0;
+ const int N = 3;
+ const char * readMethods[N] = {
+ "QFile::readLine()",
+ "QTextStream::readLine()",
+ "QTextStream::readLine(QString *)"
+ };
+ int elapsed[N] = {0, 0, 0};
stopWatch.restart();
int nlines1 = 0;
@@ -930,7 +1003,7 @@ void tst_QTextStream::performance()
file.readLine();
}
- elapsed1 += stopWatch.elapsed();
+ elapsed[0] = stopWatch.elapsed();
stopWatch.restart();
int nlines2 = 0;
@@ -943,20 +1016,38 @@ void tst_QTextStream::performance()
stream.readLine();
}
- elapsed2 += stopWatch.elapsed();
+ elapsed[1] = stopWatch.elapsed();
+ stopWatch.restart();
+
+ int nlines3 = 0;
+ QFile file3(m_rfc3261FilePath);
+ QVERIFY(file3.open(QFile::ReadOnly));
+
+ QTextStream stream2(&file3);
+ QString line;
+ while (stream2.readLine(&line))
+ ++nlines3;
+
+ elapsed[2] = stopWatch.elapsed();
+
QCOMPARE(nlines1, nlines2);
+ QCOMPARE(nlines2, nlines3);
+
+ for (int i = 0; i < N; i++) {
+ qDebug("%s used %.3f seconds to read the file", readMethods[i],
+ elapsed[i] / 1000.0);
+ }
+
+ int idx[N] = {0, 1, 2};
+ std::sort(idx, idx + N, CompareIndicesForArray(elapsed));
- qDebug("QFile used %.2f seconds to read the file",
- elapsed1 / 1000.0);
-
- qDebug("QTextStream used %.2f seconds to read the file",
- elapsed2 / 1000.0);
- if (elapsed2 > elapsed1) {
- qDebug("QFile is %.2fx faster than QTextStream",
- double(elapsed2) / double(elapsed1));
- } else {
- qDebug("QTextStream is %.2fx faster than QFile",
- double(elapsed1) / double(elapsed2));
+ for (int i = 0; i < N-1; i++) {
+ int i1 = idx[i];
+ int i2 = idx[i+1];
+ qDebug("Reading by %s is %.2fx faster than by %s",
+ readMethods[i1],
+ double(elapsed[i2]) / double(elapsed[i1]),
+ readMethods[i2]);
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-26 02:56:48 +0000