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Expression context creation for processing improvements

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Hiding away the implementation directly in QgsProcessingFeatureSource

See discussion ec97102bc6 (r152903378)
This commit is contained in:
Matthias Kuhn 2017-11-24 11:01:41 +01:00
parent fd127ee6a4
commit abe1a9b661
4 changed files with 30 additions and 22 deletions
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7
python/core/processing/qgsprocessingutils.sip
View File

@ -274,10 +274,11 @@ class QgsProcessingFeatureSource : QgsFeatureSource
virtual QVariant maximumValue( int fieldIndex ) const;
QgsFeatureSource *source() const;
QgsExpressionContext createExpressionContext( const QgsProcessingContext &context ) const;
%Docstring
Access the underlying original ``source``.
:rtype: QgsFeatureSource
Returns an expression context scope suitable for this source or a default global/project
context if nothing more specific can be created.
:rtype: QgsExpressionContext
%End
};

24
src/core/processing/qgsprocessingalgorithm.cpp
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@ -132,22 +132,16 @@ QgsExpressionContext QgsProcessingAlgorithm::createExpressionContext( const QVar
// If there's a source capable of generating a context scope, use it
if ( source )
{
QgsExpressionContextGenerator *generator = dynamic_cast<QgsExpressionContextGenerator *>( source->source() );
if ( generator )
{
const auto &scopes = generator->createExpressionContext().takeScopes();
for ( QgsExpressionContextScope *scope : scopes )
c << scope;
}
const auto &scopes = source->createExpressionContext( context ).takeScopes();
for ( QgsExpressionContextScope *scope : scopes )
c << scope;
}
else if ( c.scopeCount() == 0 )
{
//empty scope, populate with initial scopes
c << QgsExpressionContextUtils::globalScope()
<< QgsExpressionContextUtils::projectScope( context.project() );
}
else
if ( c.scopeCount() == 0 )
{
//empty scope, populate with initial scopes
c << QgsExpressionContextUtils::globalScope()
<< QgsExpressionContextUtils::projectScope( context.project() );
}
c << QgsExpressionContextUtils::processingAlgorithmScope( this, parameters, context );
return c;

16
src/core/processing/qgsprocessingutils.cpp
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@ -721,7 +721,19 @@ QVariant QgsProcessingFeatureSource::maximumValue( int fieldIndex ) const
return mSource->maximumValue( fieldIndex );
}
QgsFeatureSource *QgsProcessingFeatureSource::source() const
QgsExpressionContext QgsProcessingFeatureSource::createExpressionContext( const QgsProcessingContext &context ) const
{
return mSource;
QgsExpressionContext expressionContext;
QgsExpressionContextGenerator *generator = dynamic_cast<QgsExpressionContextGenerator *>( mSource );
if ( generator )
{
expressionContext = generator->createExpressionContext();
}
else
{
expressionContext
<< QgsExpressionContextUtils::globalScope()
<< QgsExpressionContextUtils::projectScope( context.project() );
}
return expressionContext;
}

5
src/core/processing/qgsprocessingutils.h
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@ -320,9 +320,10 @@ class CORE_EXPORT QgsProcessingFeatureSource : public QgsFeatureSource
QVariant maximumValue( int fieldIndex ) const override;
/**
* Access the underlying original \a source.
* Returns an expression context scope suitable for this source or a default global/project
* context if nothing more specific can be created.
*/
QgsFeatureSource *source() const;
QgsExpressionContext createExpressionContext( const QgsProcessingContext &context ) const;
private: