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Optimise expression context storage/retrieval of features

Shaves ~10% rendering time off a 1 million point layer
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nyalldawson committed Feb 22, 2017
1 parent bde4ff9 commit abc6129b607b7aff40e93d84a824702efcf254f4
@@ -992,6 +992,12 @@ QgsExpressionItem {#qgis_api_break_3_0_QgsExpressionItem}
- CustomSortRole was renamed to CUSTOM_SORT_ROLE
- ItemTypeRole was renamed to ITEM_TYPE_ROLE

QgsExpressionContext {#qgis_api_break_3_0_QgsExpressionContext}
--------------------

- EXPR_FEATURE was removed. Use the direct feature manipulation methods feature(), hasFeature() and setFeature() instead


QgsExpressionContextUtils {#qgis_api_break_3_0_QgsExpressionContextUtils}
-------------------------

@@ -189,17 +189,12 @@ class QgsExpressionContextScope
*/
QStringList functionNames() const;

/** Adds a function to the scope.
* @param name function name
* @param function function to insert. Ownership is transferred to the scope.
* @see addVariable()
*/
void addFunction( const QString& name, QgsScopedExpressionFunction* function /Transfer/ );

/** Convenience function for setting a feature for the scope. Any existing
* feature set by the scope will be overwritten.
* @param feature feature for scope
*/
bool hasFeature() const;

QgsFeature feature() const;

void setFeature( const QgsFeature& feature );

/** Convenience function for setting a fields for the scope. Any existing
@@ -414,9 +409,7 @@ class QgsExpressionContext
*/
void setFeature( const QgsFeature& feature );

/** Convenience function for retrieving the feature for the context, if set.
* @see setFeature
*/
bool hasFeature() const;
QgsFeature feature() const;

/** Convenience function for setting a fields for the context. The fields
@@ -481,8 +474,6 @@ class QgsExpressionContext

//! Inbuilt variable name for fields storage
static const QString EXPR_FIELDS;
//! Inbuilt variable name for feature storage
static const QString EXPR_FEATURE;
//! Inbuilt variable name for value original value variable
static const QString EXPR_ORIGINAL_VALUE;
//! Inbuilt variable name for symbol color variable
@@ -318,8 +318,8 @@ static QgsFeature getFeature( const QVariant& value, QgsExpression* parent )
return 0;
}

#define FEAT_FROM_CONTEXT(c, f) if (!(c) || !(c)->hasVariable(QgsExpressionContext::EXPR_FEATURE)) return QVariant(); \
QgsFeature f = qvariant_cast<QgsFeature>( (c)->variable( QgsExpressionContext::EXPR_FEATURE ) );
#define FEAT_FROM_CONTEXT(c, f) if (!(c) || !(c)->hasFeature() ) return QVariant(); \
QgsFeature f = ( c )->feature();

static QgsExpression::Node* getNode( const QVariant& value, QgsExpression* parent )
{
@@ -5495,7 +5495,7 @@ QVariant QgsExpression::NodeColumnRef::eval( QgsExpression *parent, const QgsExp
}
}

if ( context && context->hasVariable( QgsExpressionContext::EXPR_FEATURE ) )
if ( context && context->hasFeature() )
{
QgsFeature feature = context->feature();
if ( index >= 0 )
@@ -34,7 +34,6 @@


const QString QgsExpressionContext::EXPR_FIELDS( QStringLiteral( "_fields_" ) );
const QString QgsExpressionContext::EXPR_FEATURE( QStringLiteral( "_feature_" ) );
const QString QgsExpressionContext::EXPR_ORIGINAL_VALUE( QStringLiteral( "value" ) );
const QString QgsExpressionContext::EXPR_SYMBOL_COLOR( QStringLiteral( "symbol_color" ) );
const QString QgsExpressionContext::EXPR_SYMBOL_ANGLE( QStringLiteral( "symbol_angle" ) );
@@ -58,6 +57,8 @@ QgsExpressionContextScope::QgsExpressionContextScope( const QString& name )
QgsExpressionContextScope::QgsExpressionContextScope( const QgsExpressionContextScope& other )
: mName( other.mName )
, mVariables( other.mVariables )
, mHasFeature( other.mHasFeature )
, mFeature( other.mFeature )
{
QHash<QString, QgsScopedExpressionFunction* >::const_iterator it = other.mFunctions.constBegin();
for ( ; it != other.mFunctions.constEnd(); ++it )
@@ -70,6 +71,8 @@ QgsExpressionContextScope& QgsExpressionContextScope::operator=( const QgsExpres
{
mName = other.mName;
mVariables = other.mVariables;
mHasFeature = other.mHasFeature;
mFeature = other.mFeature;

qDeleteAll( mFunctions );
mFunctions.clear();
@@ -196,10 +199,6 @@ void QgsExpressionContextScope::addFunction( const QString& name, QgsScopedExpre
mFunctions.insert( name, function );
}

void QgsExpressionContextScope::setFeature( const QgsFeature &feature )
{
addVariable( StaticVariable( QgsExpressionContext::EXPR_FEATURE, QVariant::fromValue( feature ), true ) );
}

void QgsExpressionContextScope::setFields( const QgsFields &fields )
{
@@ -468,9 +467,27 @@ void QgsExpressionContext::setFeature( const QgsFeature &feature )
mStack.last()->setFeature( feature );
}

bool QgsExpressionContext::hasFeature() const
{
Q_FOREACH ( const QgsExpressionContextScope* scope, mStack )
{
if ( scope->hasFeature() )
return true;
}
return false;
}

QgsFeature QgsExpressionContext::feature() const
{
return qvariant_cast<QgsFeature>( variable( QgsExpressionContext::EXPR_FEATURE ) );
//iterate through stack backwards, so that higher priority variables take precedence
QList< QgsExpressionContextScope* >::const_iterator it = mStack.constEnd();
while ( it != mStack.constBegin() )
{
--it;
if (( *it )->hasFeature() )
return ( *it )->feature();
}
return QgsFeature();
}

void QgsExpressionContext::setFields( const QgsFields &fields )
@@ -21,6 +21,7 @@
#include <QString>
#include <QStringList>
#include <QSet>
#include "qgsfeature.h"
#include "qgsexpression.h"

class QgsExpression;
@@ -250,11 +251,26 @@ class CORE_EXPORT QgsExpressionContextScope
*/
void addFunction( const QString& name, QgsScopedExpressionFunction* function );

/**
* Returns true if the scope has a feature associated with it.
* @note added in QGIS 3.0
* @see feature()
*/
bool hasFeature() const { return mHasFeature; }

/**
* Sets the feature associated with the scope.
* @see setFeature()
* @see hasFeature()
* @note added in QGIS 3.0
*/
QgsFeature feature() const { return mFeature; }

/** Convenience function for setting a feature for the scope. Any existing
* feature set by the scope will be overwritten.
* @param feature feature for scope
*/
void setFeature( const QgsFeature& feature );
void setFeature( const QgsFeature& feature ) { mHasFeature = true; mFeature = feature; }

/** Convenience function for setting a fields for the scope. Any existing
* fields set by the scope will be overwritten.
@@ -266,6 +282,8 @@ class CORE_EXPORT QgsExpressionContextScope
QString mName;
QHash<QString, StaticVariable> mVariables;
QHash<QString, QgsScopedExpressionFunction* > mFunctions;
bool mHasFeature = false;
QgsFeature mFeature;

bool variableNameSort( const QString &a, const QString &b );
};
@@ -474,6 +492,13 @@ class CORE_EXPORT QgsExpressionContext
*/
void setFeature( const QgsFeature& feature );

/**
* Returns true if the context has a feature associated with it.
* @note added in QGIS 3.0
* @see feature()
*/
bool hasFeature() const;

/** Convenience function for retrieving the feature for the context, if set.
* @see setFeature
*/
@@ -541,8 +566,6 @@ class CORE_EXPORT QgsExpressionContext

//! Inbuilt variable name for fields storage
static const QString EXPR_FIELDS;
//! Inbuilt variable name for feature storage
static const QString EXPR_FEATURE;
//! Inbuilt variable name for value original value variable
static const QString EXPR_ORIGINAL_VALUE;
//! Inbuilt variable name for symbol color variable
@@ -432,27 +432,28 @@ void TestQgsExpressionContext::evaluate()
void TestQgsExpressionContext::setFeature()
{
QgsFeature feature( 50LL );
feature.setValid( true );
QgsExpressionContextScope scope;
scope.setFeature( feature );
QVERIFY( scope.hasVariable( QgsExpressionContext::EXPR_FEATURE ) );
QCOMPARE(( qvariant_cast<QgsFeature>( scope.variable( QgsExpressionContext::EXPR_FEATURE ) ) ).id(), 50LL );
QVERIFY( scope.hasFeature() );
QCOMPARE( scope.feature().id(), 50LL );

//test setting a feature in a context with no scopes
QgsExpressionContext emptyContext;
QVERIFY( !emptyContext.feature().isValid() );
emptyContext.setFeature( feature );
//setFeature should have created a scope
QCOMPARE( emptyContext.scopeCount(), 1 );
QVERIFY( emptyContext.hasVariable( QgsExpressionContext::EXPR_FEATURE ) );
QCOMPARE(( qvariant_cast<QgsFeature>( emptyContext.variable( QgsExpressionContext::EXPR_FEATURE ) ) ).id(), 50LL );
QVERIFY( emptyContext.feature().isValid() );
QCOMPARE( emptyContext.feature().id(), 50LL );
QCOMPARE( emptyContext.feature().id(), 50LL );

QgsExpressionContext contextWithScope;
contextWithScope << new QgsExpressionContextScope();
contextWithScope.setFeature( feature );
QCOMPARE( contextWithScope.scopeCount(), 1 );
QVERIFY( contextWithScope.hasVariable( QgsExpressionContext::EXPR_FEATURE ) );
QCOMPARE(( qvariant_cast<QgsFeature>( contextWithScope.variable( QgsExpressionContext::EXPR_FEATURE ) ) ).id(), 50LL );
QVERIFY( contextWithScope.feature().isValid() );
QCOMPARE( contextWithScope.feature().id(), 50LL );
QCOMPARE( contextWithScope.feature().id(), 50LL );
}

@@ -652,7 +653,7 @@ void TestQgsExpressionContext::featureBasedContext()

QgsExpressionContext context = QgsExpressionContextUtils::createFeatureBasedContext( f, fields );

QgsFeature evalFeature = qvariant_cast<QgsFeature>( context.variable( QStringLiteral( "_feature_" ) ) );
QgsFeature evalFeature = context.feature();
QgsFields evalFields = qvariant_cast<QgsFields>( context.variable( QStringLiteral( "_fields_" ) ) );
QCOMPARE( evalFeature.attributes(), f.attributes() );
QCOMPARE( evalFields, fields );

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