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Unify and fix number to string conversion with radix 

Previously, the loop that generated the string could fail to terminate
with certain numbers as input. Also, the algorithm was duplicated in two
places.

Change-Id: Ie2075148d931e7cfcedb5bcd23af61e2e8afc232
Fixes: QTBUG-73999
Reviewed-by: Robert Loehning <robert.loehning@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Ulf Hermann 2019-02-22 17:13:36 +01:00
parent cdb8eb988e
commit b959074afb
3 changed files with 32 additions and 39 deletions
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38
src/qml/jsruntime/qv4numberobject.cpp
View File

@ -223,41 +223,9 @@ ReturnedValue NumberPrototype::method_toString(const FunctionObject *b, const Va
return v4->throwError(QStringLiteral("Number.prototype.toString: %0 is not a valid radix").arg(radix));
}
if (std::isnan(num)) {
return Encode(v4->newString(QStringLiteral("NaN")));
} else if (qt_is_inf(num)) {
return Encode(v4->newString(QLatin1String(num < 0 ? "-Infinity" : "Infinity")));
}
if (radix != 10) {
QString str;
bool negative = false;
if (num < 0) {
negative = true;
num = -num;
}
double frac = num - std::floor(num);
num = Value::toInteger(num);
do {
char c = (char)std::fmod(num, radix);
c = (c < 10) ? (c + '0') : (c - 10 + 'a');
str.prepend(QLatin1Char(c));
num = std::floor(num / radix);
} while (num != 0);
if (frac != 0) {
str.append(QLatin1Char('.'));
do {
frac = frac * radix;
char c = (char)std::floor(frac);
c = (c < 10) ? (c + '0') : (c - 10 + 'a');
str.append(QLatin1Char(c));
frac = frac - std::floor(frac);
} while (frac != 0);
}
if (negative)
str.prepend(QLatin1Char('-'));
return Encode(v4->newString(str));
}
QString str;
RuntimeHelpers::numberToString(&str, num, radix);
return Encode(v4->newString(str));
}
return Encode(Value::fromDouble(num).toString(v4));

17
src/qml/jsruntime/qv4runtime.cpp
View File

@ -298,13 +298,22 @@ void RuntimeHelpers::numberToString(QString *result, double num, int radix)
if (frac != 0) {
result->append(QLatin1Char('.'));
double magnitude = 1;
double next = frac;
do {
frac = frac * radix;
char c = (char)::floor(frac);
next *= radix;
const int floored = ::floor(next);
char c = char(floored);
c = (c < 10) ? (c + '0') : (c - 10 + 'a');
result->append(QLatin1Char(c));
frac = frac - ::floor(frac);
} while (frac != 0);
magnitude /= radix;
frac -= double(floored) * magnitude;
next -= double(floored);
// The next digit still makes a difference
// if a value of "radix" for it would change frac.
// Otherwise we've reached the limit of numerical precision.
} while (frac > 0 && frac - magnitude != frac);
}
if (negative)

16
tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
View File

@ -362,6 +362,7 @@ private slots:
void hugeObject();
void templateStringTerminator();
void arrayAndException();
void numberToStringWithRadix();
private:
// static void propertyVarWeakRefCallback(v8::Persistent<v8::Value> object, void* parameter);
@ -8878,6 +8879,21 @@ void tst_qqmlecmascript::arrayAndException()
QVERIFY(value.isError());
}
void tst_qqmlecmascript::numberToStringWithRadix()
{
QJSEngine engine;
{
const QJSValue value = engine.evaluate(".5.toString(5)");
QVERIFY(!value.isError());
QVERIFY(value.toString().startsWith("0.2222222222"));
}
{
const QJSValue value = engine.evaluate(".05.toString(5)");
QVERIFY(!value.isError());
QVERIFY(value.toString().startsWith("0.01111111111"));
}
}
QTEST_MAIN(tst_qqmlecmascript)
#include "tst_qqmlecmascript.moc"