QGIS API Documentation 3.35.0-Master (f6e073f0eed)
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qgsexpressioncontext.h
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1/***************************************************************************
2 qgsexpressioncontext.h
3 ----------------------
4 Date : April 2015
5 Copyright : (C) 2015 by Nyall Dawson
6 Email : nyall dot dawson at gmail dot com
7 ***************************************************************************
8 * *
9 * This program is free software; you can redistribute it and/or modify *
10 * it under the terms of the GNU General Public License as published by *
11 * the Free Software Foundation; either version 2 of the License, or *
12 * (at your option) any later version. *
13 * *
14 ***************************************************************************/
15#ifndef QGSEXPRESSIONCONTEXT_H
16#define QGSEXPRESSIONCONTEXT_H
17
18#include "qgis_core.h"
19#include "qgis_sip.h"
20#include <QVariant>
21#include <QHash>
22#include <QString>
23#include <QStringList>
24#include <QSet>
25#include <QPointer>
26
28#include "qgsfeature.h"
29
32class LoadLayerFunction;
33
43{
44 public:
45
50 QgsScopedExpressionFunction( const QString &fnname,
51 int params,
52 const QString &group,
53 const QString &helpText = QString(),
54 bool usesGeometry = false,
55 const QSet<QString> &referencedColumns = QSet<QString>(),
56 bool lazyEval = false,
57 bool handlesNull = false,
58 bool isContextual = true )
59 : QgsExpressionFunction( fnname, params, group, helpText, lazyEval, handlesNull, isContextual )
60 , mUsesGeometry( usesGeometry )
61 , mReferencedColumns( referencedColumns )
62 {}
63
68 QgsScopedExpressionFunction( const QString &fnname,
70 const QString &group,
71 const QString &helpText = QString(),
72 bool usesGeometry = false,
73 const QSet<QString> &referencedColumns = QSet<QString>(),
74 bool lazyEval = false,
75 bool handlesNull = false,
76 bool isContextual = true )
77 : QgsExpressionFunction( fnname, params, group, helpText, lazyEval, handlesNull, isContextual )
78 , mUsesGeometry( usesGeometry )
79 , mReferencedColumns( referencedColumns )
80 {}
81
82 QVariant func( const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override = 0;
83
88
89 bool usesGeometry( const QgsExpressionNodeFunction *node ) const override;
90
91 QSet<QString> referencedColumns( const QgsExpressionNodeFunction *node ) const override;
92
93 bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
94
95 private:
96 bool mUsesGeometry;
97 QSet<QString> mReferencedColumns;
98};
99
100
114{
115 public:
116
121 {
122
131 StaticVariable( const QString &name = QString(), const QVariant &value = QVariant(), bool readOnly = false, bool isStatic = false, const QString &description = QString() )
132 : name( name )
133 , value( value )
134 , readOnly( readOnly )
135 , isStatic( isStatic )
136 , description( description )
137 {}
138
140 QString name;
141
143 QVariant value;
144
147
150
152 QString description;
153 };
154
159 QgsExpressionContextScope( const QString &name = QString() );
160
165
166 QgsExpressionContextScope &operator=( const QgsExpressionContextScope &other );
167
169
173 QString name() const { return mName; }
174
182 void setVariable( const QString &name, const QVariant &value, bool isStatic = false );
183
191 void addVariable( const QgsExpressionContextScope::StaticVariable &variable );
192
199 bool removeVariable( const QString &name );
200
208 bool hasVariable( const QString &name ) const;
209
217 QVariant variable( const QString &name ) const;
218
224 QStringList variableNames() const;
225
232 QStringList filteredVariableNames() const;
233
240 bool isReadOnly( const QString &name ) const;
241
247 bool isStatic( const QString &name ) const;
248
254 QString description( const QString &name ) const;
255
259 int variableCount() const { return mVariables.count(); }
260
268 bool hasFunction( const QString &name ) const;
269
278 QgsExpressionFunction *function( const QString &name ) const;
279
285 QStringList functionNames() const;
286
293 void addFunction( const QString &name, QgsScopedExpressionFunction *function SIP_TRANSFER );
294
299 bool hasFeature() const { return mHasFeature; }
300
306 QgsFeature feature() const { return mFeature; }
307
315 void setFeature( const QgsFeature &feature ) { mHasFeature = true; mFeature = feature; }
316
322 void removeFeature() { mHasFeature = false; mFeature = QgsFeature(); }
323
329 bool hasGeometry() const { return mHasGeometry; }
330
337 QgsGeometry geometry() const { return mGeometry; }
338
347 void setGeometry( const QgsGeometry &geometry ) { mHasGeometry = true; mGeometry = geometry; }
348
355 void removeGeometry() { mHasGeometry = false; mGeometry = QgsGeometry(); }
356
362 void setFields( const QgsFields &fields );
363
369 void readXml( const QDomElement &element, const QgsReadWriteContext &context );
370
376 bool writeXml( QDomElement &element, QDomDocument &document, const QgsReadWriteContext &context ) const;
377
378
387 QStringList hiddenVariables() const;
388
399 void setHiddenVariables( const QStringList &hiddenVariables );
400
401
412 void addHiddenVariable( const QString &hiddenVariable );
413
423 void removeHiddenVariable( const QString &hiddenVariable );
424
435 void addLayerStore( QgsMapLayerStore *store );
436
443 QList< QgsMapLayerStore * > layerStores() const;
444
445 private:
446 QString mName;
447 QHash<QString, StaticVariable> mVariables;
448 QHash<QString, QgsScopedExpressionFunction * > mFunctions;
449 bool mHasFeature = false;
450 QgsFeature mFeature;
451 bool mHasGeometry = false;
452 QgsGeometry mGeometry;
453 QStringList mHiddenVariables;
454
455 QList< QPointer< QgsMapLayerStore > > mLayerStores;
456};
457
470class CORE_EXPORT QgsExpressionContext
471{
472 public:
473
476
481 explicit QgsExpressionContext( const QList<QgsExpressionContextScope *> &scopes SIP_TRANSFER );
482
487
488 QgsExpressionContext &operator=( const QgsExpressionContext &other ) SIP_SKIP;
489
490 QgsExpressionContext &operator=( QgsExpressionContext &&other ) noexcept SIP_SKIP;
491
493
501 bool hasVariable( const QString &name ) const;
502
512 QVariant variable( const QString &name ) const;
513
518 QVariantMap variablesToMap() const;
519
527 bool isHighlightedVariable( const QString &name ) const;
528
535 QStringList highlightedVariables() const;
536
544 void setHighlightedVariables( const QStringList &variableNames );
545
554 bool isHighlightedFunction( const QString &name ) const;
555
567 void setHighlightedFunctions( const QStringList &names );
568
576 QgsExpressionContextScope *activeScopeForVariable( const QString &name );
577
586 const QgsExpressionContextScope *activeScopeForVariable( const QString &name ) const SIP_SKIP;
587
594 QgsExpressionContextScope *scope( int index );
595
600 QgsExpressionContextScope *lastScope();
601
606 QList< QgsExpressionContextScope * > scopes() { return mStack; }
607
613 int indexOfScope( QgsExpressionContextScope *scope ) const;
614
620 int indexOfScope( const QString &scopeName ) const;
621
630 QStringList variableNames() const;
631
638 QStringList filteredVariableNames() const;
639
646 bool isReadOnly( const QString &name ) const;
647
655 QString description( const QString &name ) const;
656
663 bool hasFunction( const QString &name ) const;
664
670 QStringList functionNames() const;
671
680 QgsExpressionFunction *function( const QString &name ) const;
681
685 int scopeCount() const;
686
693 void appendScope( QgsExpressionContextScope *scope SIP_TRANSFER );
694
701 void appendScopes( const QList<QgsExpressionContextScope *> &scopes SIP_TRANSFER );
702
706 QgsExpressionContextScope *popScope();
707
715 QList<QgsExpressionContextScope *> takeScopes() SIP_SKIP;
716
723
731 void setFeature( const QgsFeature &feature );
732
737 bool hasFeature() const;
738
743 QgsFeature feature() const;
744
753 void setGeometry( const QgsGeometry &geometry );
754
760 bool hasGeometry() const;
761
767 QgsGeometry geometry() const;
768
776 void setFields( const QgsFields &fields );
777
782 QgsFields fields() const;
783
789 void setOriginalValueVariable( const QVariant &value );
790
801 void setCachedValue( const QString &key, const QVariant &value ) const;
802
810 bool hasCachedValue( const QString &key ) const;
811
821 QVariant cachedValue( const QString &key ) const;
822
829 void clearCachedValues() const;
830
836 QList< QgsMapLayerStore * > layerStores() const;
837
849 void setLoadedLayerStore( QgsMapLayerStore *store );
850
858 QgsMapLayerStore *loadedLayerStore() const;
859
871 void setFeedback( QgsFeedback *feedback );
872
881 QgsFeedback *feedback() const;
882
884 static const QString EXPR_FIELDS;
886 static const QString EXPR_ORIGINAL_VALUE;
888 static const QString EXPR_SYMBOL_COLOR;
890 static const QString EXPR_SYMBOL_ANGLE;
892 static const QString EXPR_GEOMETRY_PART_COUNT;
894 static const QString EXPR_GEOMETRY_PART_NUM;
895
900 static const QString EXPR_GEOMETRY_RING_NUM;
902 static const QString EXPR_GEOMETRY_POINT_COUNT;
904 static const QString EXPR_GEOMETRY_POINT_NUM;
906 static const QString EXPR_CLUSTER_SIZE;
908 static const QString EXPR_CLUSTER_COLOR;
909
910 private:
911
912 QList< QgsExpressionContextScope * > mStack;
913 QStringList mHighlightedVariables;
914 QStringList mHighlightedFunctions;
915
916 QgsFeedback *mFeedback = nullptr;
917
918 std::unique_ptr< LoadLayerFunction > mLoadLayerFunction;
919 QPointer< QgsMapLayerStore > mDestinationStore;
920
921 // Cache is mutable because we want to be able to add cached values to const contexts
922 mutable QMap< QString, QVariant > mCachedValues;
923
924};
925
926#endif // QGSEXPRESSIONCONTEXT_H
Single scope for storing variables and functions for use within a QgsExpressionContext.
void removeGeometry()
Removes any geometry associated with the scope.
void removeFeature()
Removes any feature associated with the scope.
void setFeature(const QgsFeature &feature)
Convenience function for setting a feature for the scope.
bool hasFeature() const
Returns true if the scope has a feature associated with it.
QgsGeometry geometry() const
Sets the geometry associated with the scope.
QString name() const
Returns the friendly display name of the context scope.
int variableCount() const
Returns the count of variables contained within the scope.
bool hasGeometry() const
Returns true if the scope has a geometry associated with it.
void setGeometry(const QgsGeometry &geometry)
Convenience function for setting a geometry for the scope.
QgsFeature feature() const
Sets the feature associated with the scope.
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
QList< QgsExpressionContextScope * > scopes()
Returns a list of scopes contained within the stack.
A abstract base class for defining QgsExpression functions.
QList< QgsExpressionFunction::Parameter > ParameterList
List of parameters, used for function definition.
virtual bool isStatic(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const
Will be called during prepare to determine if the function is static.
virtual QSet< QString > referencedColumns(const QgsExpressionNodeFunction *node) const
Returns a set of field names which are required for this function.
virtual bool usesGeometry(const QgsExpressionNodeFunction *node) const
Does this function use a geometry object.
An expression node for expression functions.
Class for parsing and evaluation of expressions (formerly called "search strings").
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:56
Base class for feedback objects to be used for cancellation of something running in a worker thread.
Definition qgsfeedback.h:44
Container of fields for a vector layer.
Definition qgsfields.h:45
A geometry is the spatial representation of a feature.
A storage object for map layers, in which the layers are owned by the store and have their lifetime b...
The class is used as a container of context for various read/write operations on other objects.
Expression function for use within a QgsExpressionContextScope.
virtual QgsScopedExpressionFunction * clone() const =0
Returns a clone of the function.
QgsScopedExpressionFunction(const QString &fnname, int params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QSet< QString > &referencedColumns=QSet< QString >(), bool lazyEval=false, bool handlesNull=false, bool isContextual=true)
Create a new QgsScopedExpressionFunction.
QgsScopedExpressionFunction(const QString &fnname, const QgsExpressionFunction::ParameterList &params, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QSet< QString > &referencedColumns=QSet< QString >(), bool lazyEval=false, bool handlesNull=false, bool isContextual=true)
Create a new QgsScopedExpressionFunction using named parameters.
QVariant func(const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override=0
Returns result of evaluating the function.
#define SIP_SKIP
Definition qgis_sip.h:126
#define SIP_TRANSFER
Definition qgis_sip.h:36
#define SIP_FACTORY
Definition qgis_sip.h:76
Single variable definition for use within a QgsExpressionContextScope.
bool readOnly
True if variable should not be editable by users.
StaticVariable(const QString &name=QString(), const QVariant &value=QVariant(), bool readOnly=false, bool isStatic=false, const QString &description=QString())
Constructor for StaticVariable.
bool isStatic
A static variable can be cached for the lifetime of a context.
QString description
Translated description of variable, for use within expression builder widgets.