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Replace std::variant with tagged union in QJSPrimitiveValue 

Pick-to: 6.1
Fixes: QTBUG-91717
Change-Id: Id19e08589206253b96c76bc40a799ccd95b0e0bf
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
This commit is contained in:
Ulf Hermann 2021-03-10 15:32:27 +01:00
parent 5e280b8792
commit 9970ebb277
2 changed files with 176 additions and 35 deletions
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209
src/qml/jsapi/qjsprimitivevalue.h
View File

@ -144,7 +144,7 @@ class QJSPrimitiveValue
};
public:
enum Type {
enum Type : quint8 {
Undefined,
Null,
Boolean,
@ -153,16 +153,16 @@ public:
String
};
constexpr Type type() const { return Type(d.index()); }
constexpr Type type() const { return Type(d.type()); }
constexpr QJSPrimitiveValue() = default;
constexpr QJSPrimitiveValue(QJSPrimitiveUndefined undefined) : d(undefined) {}
constexpr QJSPrimitiveValue(QJSPrimitiveNull null) : d(null) {}
constexpr QJSPrimitiveValue(bool value) : d(value) {}
constexpr QJSPrimitiveValue(int value) : d(value) {}
constexpr QJSPrimitiveValue(double value) : d(value) {}
QJSPrimitiveValue(QString string) : d(std::move(string)) {}
QJSPrimitiveValue(const QVariant &variant)
Q_IMPLICIT constexpr QJSPrimitiveValue() noexcept = default;
Q_IMPLICIT constexpr QJSPrimitiveValue(QJSPrimitiveUndefined undefined) noexcept : d(undefined) {}
Q_IMPLICIT constexpr QJSPrimitiveValue(QJSPrimitiveNull null) noexcept : d(null) {}
Q_IMPLICIT constexpr QJSPrimitiveValue(bool value) noexcept : d(value) {}
Q_IMPLICIT constexpr QJSPrimitiveValue(int value) noexcept : d(value) {}
Q_IMPLICIT constexpr QJSPrimitiveValue(double value) noexcept : d(value) {}
Q_IMPLICIT QJSPrimitiveValue(QString string) noexcept : d(std::move(string)) {}
explicit QJSPrimitiveValue(const QVariant &variant) noexcept
{
switch (variant.typeId()) {
case QMetaType::UnknownType:
@ -194,13 +194,14 @@ public:
switch (type()) {
case Undefined: return false;
case Null: return false;
case Boolean: return std::get<bool>(d);
case Integer: return std::get<int>(d) != 0;
case Boolean: return asBoolean();
case Integer: return asInteger() != 0;
case Double: {
const double v = std::get<double>(d);
const double v = asDouble();
return !QJSNumberCoercion::equals(v, 0) && !std::isnan(v);
}
case String: return !std::get<QString>(d).isEmpty();
case String: return !asString().isEmpty();
default: Q_UNREACHABLE();
}
return false;
@ -211,10 +212,11 @@ public:
switch (type()) {
case Undefined: return 0;
case Null: return 0;
case Boolean: return std::get<bool>(d);
case Integer: return std::get<int>(d);
case Double: return QJSNumberCoercion::toInteger(std::get<double>(d));
case String: return fromString(std::get<String>(d)).toInteger();
case Boolean: return asBoolean();
case Integer: return asInteger();
case Double: return QJSNumberCoercion::toInteger(asDouble());
case String: return fromString(asString()).toInteger();
default: Q_UNREACHABLE();
}
return 0;
@ -225,13 +227,14 @@ public:
switch (type()) {
case Undefined: return std::numeric_limits<double>::quiet_NaN();
case Null: return 0;
case Boolean: return std::get<bool>(d);
case Integer: return std::get<int>(d);
case Double: return std::get<double>(d);
case String: return fromString(std::get<String>(d)).toDouble();
case Boolean: return asBoolean();
case Integer: return asInteger();
case Double: return asDouble();
case String: return fromString(asString()).toDouble();
default: Q_UNREACHABLE();
}
return std::numeric_limits<double>::quiet_NaN();
return {};
}
QString toString() const
@ -239,10 +242,10 @@ public:
switch (type()) {
case Undefined: return QStringLiteral("undefined");
case Null: return QStringLiteral("null");
case Boolean: return std::get<bool>(d) ? QStringLiteral("true") : QStringLiteral("false");
case Integer: return QString::number(std::get<int>(d));
case Boolean: return asBoolean() ? QStringLiteral("true") : QStringLiteral("false");
case Integer: return QString::number(asInteger());
case Double: {
const double result = std::get<double>(d);
const double result = asDouble();
if (std::isnan(result))
return QStringLiteral("NaN");
if (std::isfinite(result))
@ -251,7 +254,7 @@ public:
return QStringLiteral("Infinity");
return QStringLiteral("-Infinity");
}
case String: return std::get<QString>(d);
case String: return asString();
}
Q_UNREACHABLE();
@ -512,10 +515,10 @@ private:
friend class QJSManagedValue;
friend class QJSValue;
constexpr bool asBoolean() const { return std::get<bool>(d); }
constexpr int asInteger() const { return std::get<int>(d); }
constexpr double asDouble() const { return std::get<double>(d); }
QString asString() const { return std::get<QString>(d); }
constexpr bool asBoolean() const { return d.getBool(); }
constexpr int asInteger() const { return d.getInt(); }
constexpr double asDouble() const { return d.getDouble(); }
QString asString() const { return d.getString(); }
constexpr bool parsedEquals(const QJSPrimitiveValue &other) const
{
@ -548,8 +551,8 @@ private:
const QJSPrimitiveValue &rhs)
{
int result;
if (Operators::opOverflow(std::get<Lhs>(lhs.d), std::get<Rhs>(rhs.d), &result))
return Operators::op(std::get<Lhs>(lhs.d), std::get<Rhs>(rhs.d));
if (Operators::opOverflow(lhs.d.get<Lhs>(), rhs.d.get<Rhs>(), &result))
return Operators::op(lhs.d.get<Lhs>(), rhs.d.get<Rhs>());
return result;
}
@ -632,7 +635,145 @@ private:
}
}
std::variant<QJSPrimitiveUndefined, QJSPrimitiveNull, bool, int, double, QString> d;
struct QJSPrimitiveValuePrivate
{
// Can't be default because QString has a non-trivial ctor.
constexpr QJSPrimitiveValuePrivate() noexcept {}
Q_IMPLICIT constexpr QJSPrimitiveValuePrivate(QJSPrimitiveUndefined) noexcept {}
Q_IMPLICIT constexpr QJSPrimitiveValuePrivate(QJSPrimitiveNull) noexcept
: m_type(Null) {}
Q_IMPLICIT constexpr QJSPrimitiveValuePrivate(bool b) noexcept
: m_bool(b), m_type(Boolean) {}
Q_IMPLICIT constexpr QJSPrimitiveValuePrivate(int i) noexcept
: m_int(i), m_type(Integer) {}
Q_IMPLICIT constexpr QJSPrimitiveValuePrivate(double d) noexcept
: m_double(d), m_type(Double) {}
Q_IMPLICIT QJSPrimitiveValuePrivate(QString s) noexcept
: m_string(std::move(s)), m_type(String) {}
constexpr QJSPrimitiveValuePrivate(const QJSPrimitiveValuePrivate &other) noexcept
: m_type(other.m_type)
{
// Not copy-and-swap since swap() would be much more complicated.
if (!assignSimple(other))
new (&m_string) QString(other.m_string);
}
constexpr QJSPrimitiveValuePrivate(QJSPrimitiveValuePrivate &&other) noexcept
: m_type(other.m_type)
{
// Not move-and-swap since swap() would be much more complicated.
if (!assignSimple(other))
new (&m_string) QString(std::move(other.m_string));
}
constexpr QJSPrimitiveValuePrivate &operator=(const QJSPrimitiveValuePrivate &other) noexcept
{
if (this == &other)
return *this;
if (m_type == String) {
if (other.m_type == String) {
m_type = other.m_type;
m_string = other.m_string;
return *this;
}
m_string.~QString();
}
m_type = other.m_type;
if (!assignSimple(other))
new (&m_string) QString(other.m_string);
return *this;
}
constexpr QJSPrimitiveValuePrivate &operator=(QJSPrimitiveValuePrivate &&other) noexcept
{
if (this == &other)
return *this;
if (m_type == String) {
if (other.m_type == String) {
m_type = other.m_type;
m_string = std::move(other.m_string);
return *this;
}
m_string.~QString();
}
m_type = other.m_type;
if (!assignSimple(other))
new (&m_string) QString(std::move(other.m_string));
return *this;
}
~QJSPrimitiveValuePrivate()
{
if (m_type == String)
m_string.~QString();
}
constexpr Type type() const noexcept { return m_type; }
constexpr bool getBool() const noexcept { return m_bool; }
constexpr int getInt() const noexcept { return m_int; }
constexpr double getDouble() const noexcept { return m_double; }
QString getString() const noexcept { return m_string; }
template<typename T>
constexpr T get() const noexcept {
if constexpr (std::is_same_v<T, QJSPrimitiveUndefined>)
return QJSPrimitiveUndefined();
else if constexpr (std::is_same_v<T, QJSPrimitiveNull>)
return QJSPrimitiveNull();
else if constexpr (std::is_same_v<T, bool>)
return getBool();
else if constexpr (std::is_same_v<T, int>)
return getInt();
else if constexpr (std::is_same_v<T, double>)
return getDouble();
else if constexpr (std::is_same_v<T, QString>)
return getString();
Q_UNREACHABLE();
return T();
}
private:
constexpr bool assignSimple(const QJSPrimitiveValuePrivate &other) noexcept
{
switch (other.m_type) {
case Undefined:
case Null:
return true;
case Boolean:
m_bool = other.m_bool;
return true;
case Integer:
m_int = other.m_int;
return true;
case Double:
m_double = other.m_double;
return true;
case String:
return false;
default:
Q_UNREACHABLE();
}
return false;
}
union {
bool m_bool = false;
int m_int;
double m_double;
QString m_string;
};
Type m_type = Undefined;
};
QJSPrimitiveValuePrivate d;
};
QT_END_NAMESPACE

2
src/qml/jsapi/qjsvalue.cpp
View File

@ -911,7 +911,7 @@ QJSValue::QJSValue(QJSPrimitiveValue &&value)
d = QV4::Encode(value.asDouble());
return;
case QJSPrimitiveValue::String:
QJSValuePrivate::setString(this, std::move(std::get<QString>(value.d)));
QJSValuePrivate::setString(this, value.asString());
return;
}