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Simplify signature of untyped property bindings

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Instead of requiring the implementation to do the compare dance, let's
do this in the library. This reduces the amount of duplicated code
slightly and makes it easier to generate binding code from qml files.

Change-Id: Ia3b16cf9769e74d076b669efe4119ab84af3cdf0
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
This commit is contained in:
Simon Hausmann 2020-04-14 11:03:11 +02:00
parent 4857f0ebd7
commit f395cedc5b
3 changed files with 31 additions and 29 deletions
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12
src/corelib/kernel/qproperty.h
View File

@ -117,10 +117,8 @@ private:
class Q_CORE_EXPORT QUntypedPropertyBinding
{
public:
// Returns either a boolean to indicate value change or an error.
using BindingEvaluationResult = std::variant<bool, QPropertyBindingError>;
// returns true if value changed, false if the binding evaluation lead to the same value as the property
// already has.
using BindingEvaluationResult = QPropertyBindingError;
// writes binding result into dataPtr
using BindingEvaluationFunction = std::function<BindingEvaluationResult(const QMetaType &metaType, void *dataPtr)>;
QUntypedPropertyBinding();
@ -160,13 +158,11 @@ class QPropertyBinding : public QUntypedPropertyBinding
if (auto valuePtr = std::get_if<PropertyType>(&result)) {
PropertyType *propertyPtr = reinterpret_cast<PropertyType *>(dataPtr);
if (*propertyPtr == *valuePtr)
return false;
*propertyPtr = std::move(*valuePtr);
return true;
return {};
}
return false;
return {};
}
};

32
src/corelib/kernel/qpropertybinding.cpp
View File

@ -41,6 +41,7 @@
#include "qproperty_p.h"
#include <QScopedValueRollback>
#include <QVariant>
QT_BEGIN_NAMESPACE
@ -80,25 +81,34 @@ bool QPropertyBindingPrivate::evaluateIfDirtyAndReturnTrueIfValueChanged()
BindingEvaluationState evaluationFrame(this);
QPropertyBindingError evalError;
QUntypedPropertyBinding::BindingEvaluationResult result;
bool changed = false;
if (metaType.id() == QMetaType::Bool) {
auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
bool temp = propertyPtr->extraBit();
result = evaluationFunction(metaType, &temp);
if (auto changedPtr = std::get_if<bool>(&result)) {
changed = *changedPtr;
if (changed)
propertyPtr->setExtraBit(temp);
bool newValue = false;
evalError = evaluationFunction(metaType, &newValue);
if (evalError.type() == QPropertyBindingError::NoError) {
if (propertyPtr->extraBit() != newValue) {
propertyPtr->setExtraBit(newValue);
changed = true;
}
}
} else {
result = evaluationFunction(metaType, propertyDataPtr);
if (auto changedPtr = std::get_if<bool>(&result))
changed = *changedPtr;
QVariant resultVariant(metaType.id(), nullptr);
evalError = evaluationFunction(metaType, resultVariant.data());
if (evalError.type() == QPropertyBindingError::NoError) {
int compareResult = 0;
if (!QMetaType::compare(propertyDataPtr, resultVariant.constData(), metaType.id(), &compareResult) || compareResult != 0) {
changed = true;
metaType.destruct(propertyDataPtr);
metaType.construct(propertyDataPtr, resultVariant.constData());
}
}
}
if (auto errorPtr = std::get_if<QPropertyBindingError>(&result))
error = std::move(*errorPtr);
if (evalError.type() != QPropertyBindingError::NoError)
error = evalError;
dirty = false;
return changed;

16
tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
View File

@ -617,22 +617,20 @@ void tst_QProperty::genericPropertyBinding()
{
QUntypedPropertyBinding doubleBinding(QMetaType::fromType<double>(),
[](const QMetaType &, void *) -> bool {
[](const QMetaType &, void *) -> QUntypedPropertyBinding::BindingEvaluationResult {
Q_ASSERT(false);
return false;
return QPropertyBindingError::NoError;
}, QPropertyBindingSourceLocation());
QVERIFY(!property.setBinding(doubleBinding));
}
QUntypedPropertyBinding intBinding(QMetaType::fromType<int>(),
[](const QMetaType &metaType, void *dataPtr) -> bool {
[](const QMetaType &metaType, void *dataPtr) -> QUntypedPropertyBinding::BindingEvaluationResult {
Q_ASSERT(metaType.id() == qMetaTypeId<int>());
int *intPtr = reinterpret_cast<int*>(dataPtr);
if (*intPtr == 100)
return false;
*intPtr = 100;
return true;
return QPropertyBindingError::NoError;
}, QPropertyBindingSourceLocation());
QVERIFY(property.setBinding(intBinding));
@ -647,12 +645,10 @@ void tst_QProperty::genericPropertyBindingBool()
QVERIFY(!property.value());
QUntypedPropertyBinding boolBinding(QMetaType::fromType<bool>(),
[](const QMetaType &, void *dataPtr) -> bool {
[](const QMetaType &, void *dataPtr) -> QUntypedPropertyBinding::BindingEvaluationResult {
auto boolPtr = reinterpret_cast<bool *>(dataPtr);
if (*boolPtr)
return false;
*boolPtr = true;
return true;
return {};
}, QPropertyBindingSourceLocation());
QVERIFY(property.setBinding(boolBinding));