QGIS API Documentation  3.14.0-Pi (9f7028fd23)
qgsexpressionfunction.h
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1 /***************************************************************************
2  qgsexpressionfunction.h
3  -------------------
4  begin : May 2017
5  copyright : (C) 2017 Matthias Kuhn
6  email : [email protected]
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 
16 #ifndef QGSEXPRESSIONFUNCTION_H
17 #define QGSEXPRESSIONFUNCTION_H
18 
19 #include <functional>
20 
21 #include <QString>
22 #include <QVariant>
23 #include <QSet>
24 #include <QJsonDocument>
25 #include <QJsonObject>
26 
27 #include "qgis.h"
28 #include "qgis_core.h"
29 #include "qgsexpressionnode.h"
30 
32 class QgsExpression;
35 
40 class CORE_EXPORT QgsExpressionFunction
41 {
42  public:
43 
47  typedef QVariant( *FcnEval )( const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) SIP_SKIP;
48 
54  class CORE_EXPORT Parameter
55  {
56  public:
57 
65  Parameter( const QString &name,
66  bool optional = false,
67  const QVariant &defaultValue = QVariant(),
68  bool isSubExpression = false )
69  : mName( name )
70  , mOptional( optional )
71  , mDefaultValue( defaultValue )
72  , mIsSubExpression( isSubExpression )
73  {}
74 
76  QString name() const { return mName; }
77 
79  bool optional() const { return mOptional; }
80 
82  QVariant defaultValue() const { return mDefaultValue; }
83 
89  bool isSubExpression() const { return mIsSubExpression; }
90 
91  bool operator==( const QgsExpressionFunction::Parameter &other ) const
92  {
93  return ( QString::compare( mName, other.mName, Qt::CaseInsensitive ) == 0 );
94  }
95 
96  private:
97  QString mName;
98  bool mOptional = false;
99  QVariant mDefaultValue;
100  bool mIsSubExpression = false;
101  };
102 
104  typedef QList< QgsExpressionFunction::Parameter > ParameterList;
105 
107  QgsExpressionFunction( const QString &fnname,
108  int params,
109  const QString &group,
110  const QString &helpText = QString(),
111  bool lazyEval = false,
112  bool handlesNull = false,
113  bool isContextual = false )
114  : mName( fnname )
115  , mParams( params )
116  , mGroups( group.isEmpty() ? QStringList() : QStringList() << group )
117  , mHelpText( helpText )
118  , mLazyEval( lazyEval )
119  , mHandlesNull( handlesNull )
120  , mIsContextual( isContextual )
121  {
122  }
123 
128  QgsExpressionFunction( const QString &fnname,
129  int params,
130  const QStringList &groups,
131  const QString &helpText = QString(),
132  bool lazyEval = false,
133  bool handlesNull = false,
134  bool isContextual = false )
135  : mName( fnname )
136  , mParams( params )
137  , mGroups( groups )
138  , mHelpText( helpText )
139  , mLazyEval( lazyEval )
140  , mHandlesNull( handlesNull )
141  , mIsContextual( isContextual )
142  {
143  }
144 
149  QgsExpressionFunction( const QString &fnname,
151  const QString &group,
152  const QString &helpText = QString(),
153  bool lazyEval = false,
154  bool handlesNull = false,
155  bool isContextual = false )
156  : mName( fnname )
157  , mParams( 0 )
158  , mParameterList( params )
159  , mGroups( group.isEmpty() ? QStringList() : QStringList() << group )
160  , mHelpText( helpText )
161  , mLazyEval( lazyEval )
162  , mHandlesNull( handlesNull )
163  , mIsContextual( isContextual )
164  {}
165 
170  QgsExpressionFunction( const QString &fnname,
172  const QStringList &groups,
173  const QString &helpText = QString(),
174  bool lazyEval = false,
175  bool handlesNull = false,
176  bool isContextual = false )
177  : mName( fnname )
178  , mParams( 0 )
179  , mParameterList( params )
180  , mGroups( groups )
181  , mHelpText( helpText )
182  , mLazyEval( lazyEval )
183  , mHandlesNull( handlesNull )
184  , mIsContextual( isContextual )
185  {}
186 
187  virtual ~QgsExpressionFunction() = default;
188 
190  QString name() const { return mName; }
191 
193  int params() const { return mParameterList.isEmpty() ? mParams : mParameterList.count(); }
194 
196  int minParams() const
197  {
198  if ( mParameterList.isEmpty() )
199  return mParams;
200 
201  int min = 0;
202  for ( const Parameter &param : mParameterList )
203  {
204  if ( !param.optional() )
205  min++;
206  }
207  return min;
208  }
209 
214  const QgsExpressionFunction::ParameterList &parameters() const { return mParameterList; }
215 
217  virtual bool usesGeometry( const QgsExpressionNodeFunction *node ) const;
218 
225  virtual QStringList aliases() const;
226 
232  bool lazyEval() const { return mLazyEval; }
233 
244  virtual bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const;
245 
254  virtual bool prepare( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const;
255 
264  virtual QSet<QString> referencedColumns( const QgsExpressionNodeFunction *node ) const;
265 
270  bool isContextual() const { return mIsContextual; }
271 
277  virtual bool isDeprecated() const;
278 
283  QString group() const { return mGroups.isEmpty() ? QString() : mGroups.at( 0 ); }
284 
290  QStringList groups() const { return mGroups; }
291 
293  const QString helpText() const;
294 
303  virtual QVariant func( const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) = 0;
304 
309  virtual QVariant run( QgsExpressionNode::NodeList *args, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node );
310 
311  bool operator==( const QgsExpressionFunction &other ) const;
312 
317  virtual bool handlesNull() const;
318 
319  protected:
320 
330  static bool allParamsStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context );
331 
332  private:
333  QString mName;
334  int mParams;
336  QStringList mGroups;
337  QString mHelpText;
338  bool mLazyEval;
339  bool mHandlesNull;
340  bool mIsContextual; //if true function is only available through an expression context
341 };
342 
348 #ifndef SIP_RUN
350 {
351  public:
352 
356  QgsStaticExpressionFunction( const QString &fnname,
357  int params,
358  FcnEval fcn,
359  const QString &group,
360  const QString &helpText = QString(),
361  bool usesGeometry = false,
362  const QSet<QString> &referencedColumns = QSet<QString>(),
363  bool lazyEval = false,
364  const QStringList &aliases = QStringList(),
365  bool handlesNull = false )
367  , mFnc( fcn )
368  , mAliases( aliases )
369  , mUsesGeometry( usesGeometry )
370  , mReferencedColumns( referencedColumns )
371  {
372  }
373 
377  QgsStaticExpressionFunction( const QString &fnname,
379  FcnEval fcn,
380  const QString &group,
381  const QString &helpText = QString(),
382  bool usesGeometry = false,
383  const QSet<QString> &referencedColumns = QSet<QString>(),
384  bool lazyEval = false,
385  const QStringList &aliases = QStringList(),
386  bool handlesNull = false )
388  , mFnc( fcn )
389  , mAliases( aliases )
390  , mUsesGeometry( usesGeometry )
391  , mReferencedColumns( referencedColumns )
392  {}
393 
405  QgsStaticExpressionFunction( const QString &fnname,
407  FcnEval fcn,
408  const QString &group,
409  const QString &helpText,
410  const std::function< bool( const QgsExpressionNodeFunction *node )> &usesGeometry,
411  const std::function< QSet<QString>( const QgsExpressionNodeFunction *node )> &referencedColumns,
412  bool lazyEval = false,
413  const QStringList &aliases = QStringList(),
414  bool handlesNull = false );
415 
420  QgsStaticExpressionFunction( const QString &fnname,
422  FcnEval fcn,
423  const QStringList &groups,
424  const QString &helpText = QString(),
425  bool usesGeometry = false,
426  const QSet<QString> &referencedColumns = QSet<QString>(),
427  bool lazyEval = false,
428  const QStringList &aliases = QStringList(),
429  bool handlesNull = false )
431  , mFnc( fcn )
432  , mAliases( aliases )
433  , mUsesGeometry( usesGeometry )
434  , mReferencedColumns( referencedColumns )
435  {}
436 
445  QVariant func( const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override
446  {
447  return mFnc ? mFnc( values, context, parent, node ) : QVariant();
448  }
449 
450  QStringList aliases() const override;
451 
452  bool usesGeometry( const QgsExpressionNodeFunction *node ) const override;
453 
454  QSet<QString> referencedColumns( const QgsExpressionNodeFunction *node ) const override;
455 
456  bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
457 
458  bool prepare( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
459 
466  void setIsStaticFunction( const std::function< bool ( const QgsExpressionNodeFunction *, QgsExpression *, const QgsExpressionContext * ) > &isStatic );
467 
475  void setIsStatic( bool isStatic );
476 
483  void setPrepareFunction( const std::function< bool( const QgsExpressionNodeFunction *, QgsExpression *, const QgsExpressionContext * )> &prepareFunc );
484 
488  static const QList<QgsExpressionFunction *> &functions();
489 
490  private:
491  FcnEval mFnc;
492  QStringList mAliases;
493  bool mUsesGeometry;
494  std::function < bool( const QgsExpressionNodeFunction *node ) > mUsesGeometryFunc;
495  std::function < QSet<QString>( const QgsExpressionNodeFunction *node ) > mReferencedColumnsFunc;
496  std::function < bool( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) > mIsStaticFunc = allParamsStatic;
497  std::function < bool( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) > mPrepareFunc;
498  QSet<QString> mReferencedColumns;
499  bool mIsStatic = false;
500 };
501 
511 {
512  public:
514 
515  bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
516 
517  QVariant run( QgsExpressionNode::NodeList *args, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override;
518 
519  QVariant func( const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override;
520 
521  bool prepare( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
522 
523 };
524 
534 {
535  public:
537 
538  bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
539 
540  QVariant run( QgsExpressionNode::NodeList *args, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override;
541 
542  QVariant func( const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override;
543 
544  bool prepare( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
545 
546 };
547 
558 {
559  public:
561 
562  bool isStatic( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
563 
564  QVariant run( QgsExpressionNode::NodeList *args, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override;
565 
566  QVariant func( const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node ) override;
567 
568  bool prepare( const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context ) const override;
569 
570  private:
571 
575  void appendTemporaryVariable( const QgsExpressionContext *context, const QString &name, const QVariant &value ) const;
576 
580  void popTemporaryVariable( const QgsExpressionContext *context ) const;
581 };
582 
583 #endif
584 
585 #endif // QGSEXPRESSIONFUNCTION_H
QgsExpressionContext
Expression contexts are used to encapsulate the parameters around which a QgsExpression should be eva...
Definition: qgsexpressioncontext.h:369
QgsExpressionFunction::helpText
const QString helpText() const
The help text for the function.
Definition: qgsexpressionfunction.cpp:68
QgsStaticExpressionFunction::aliases
QStringList aliases() const override
Returns a list of possible aliases for the function.
Definition: qgsexpressionfunction.cpp:175
QgsExpressionFunction::Parameter::isSubExpression
bool isSubExpression() const
Returns true if parameter argument is a separate sub-expression, and should not be checked while dete...
Definition: qgsexpressionfunction.h:89
QgsWithVariableExpressionFunction
Handles the with_variable(name, value, node) expression function.
Definition: qgsexpressionfunction.h:557
operator==
bool operator==(const QgsFeatureIterator &fi1, const QgsFeatureIterator &fi2)
Definition: qgsfeatureiterator.h:399
QgsStaticExpressionFunction::setPrepareFunction
void setPrepareFunction(const std::function< bool(const QgsExpressionNodeFunction *, QgsExpression *, const QgsExpressionContext *)> &prepareFunc)
Set a function that will be called in the prepare step to determine if the function is static or not.
Definition: qgsexpressionfunction.cpp:223
QgsExpressionFunction::Parameter::name
QString name() const
Returns the name of the parameter.
Definition: qgsexpressionfunction.h:76
QgsArrayFilterExpressionFunction
Handles the array_filter(array, expression) expression function.
Definition: qgsexpressionfunction.h:533
QgsArrayFilterExpressionFunction::prepare
bool prepare(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
This will be called during the prepare step() of an expression if it is not static.
Definition: qgsexpressionfunction.cpp:6779
qgis.h
QgsExpressionFunction::groups
QStringList groups() const
Returns a list of the groups the function belongs to.
Definition: qgsexpressionfunction.h:290
QgsWithVariableExpressionFunction::func
QVariant func(const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override
Returns result of evaluating the function.
Definition: qgsexpressionfunction.cpp:6865
QgsExpressionFunction::isContextual
bool isContextual() const
Returns whether the function is only available if provided by a QgsExpressionContext object.
Definition: qgsexpressionfunction.h:270
QgsStaticExpressionFunction::functions
static const QList< QgsExpressionFunction * > & functions()
Returns a list of all registered expression functions.
QgsStaticExpressionFunction::func
QVariant func(const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override
Returns result of evaluating the function.
Definition: qgsexpressionfunction.h:445
QgsExpressionFunction::Parameter::operator==
bool operator==(const QgsExpressionFunction::Parameter &other) const
Definition: qgsexpressionfunction.h:91
QgsExpressionFunction::QgsExpressionFunction
QgsExpressionFunction(const QString &fnname, int params, const QString &group, const QString &helpText=QString(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
Constructor for function which uses unnamed parameters.
Definition: qgsexpressionfunction.h:107
QgsArrayForeachExpressionFunction::prepare
bool prepare(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
This will be called during the prepare step() of an expression if it is not static.
Definition: qgsexpressionfunction.cpp:6684
QgsExpressionFunction::handlesNull
virtual bool handlesNull() const
Returns true if the function handles NULL values in arguments by itself, and the default NULL value h...
Definition: qgsexpressionfunction.cpp:149
QgsArrayForeachExpressionFunction::isStatic
bool isStatic(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
Will be called during prepare to determine if the function is static.
Definition: qgsexpressionfunction.cpp:6622
QgsArrayFilterExpressionFunction::isStatic
bool isStatic(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
Will be called during prepare to determine if the function is static.
Definition: qgsexpressionfunction.cpp:6716
SIP_SKIP
#define SIP_SKIP
Definition: qgis_sip.h:126
QgsStaticExpressionFunction::isStatic
bool isStatic(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
Will be called during prepare to determine if the function is static.
Definition: qgsexpressionfunction.cpp:196
QgsWithVariableExpressionFunction::run
QVariant run(QgsExpressionNode::NodeList *args, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override
Evaluates the function, first evaluating all required arguments before passing them to the function's...
Definition: qgsexpressionfunction.cpp:6836
QgsArrayForeachExpressionFunction::func
QVariant func(const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override
Returns result of evaluating the function.
Definition: qgsexpressionfunction.cpp:6672
QgsExpressionFunction::params
int params() const
The number of parameters this function takes.
Definition: qgsexpressionfunction.h:193
QgsExpressionFunction::Parameter
Definition: qgsexpressionfunction.h:54
QgsExpressionFunction::ParameterList
QList< QgsExpressionFunction::Parameter > ParameterList
List of parameters, used for function definition.
Definition: qgsexpressionfunction.h:104
QgsExpressionFunction::QgsExpressionFunction
QgsExpressionFunction(const QString &fnname, const QgsExpressionFunction::ParameterList &params, const QString &group, const QString &helpText=QString(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
Constructor for function which uses named parameter list.
Definition: qgsexpressionfunction.h:149
QgsStaticExpressionFunction::setIsStaticFunction
void setIsStaticFunction(const std::function< bool(const QgsExpressionNodeFunction *, QgsExpression *, const QgsExpressionContext *) > &isStatic)
Set a function that will be called in the prepare step to determine if the function is static or not.
Definition: qgsexpressionfunction.cpp:212
QgsStaticExpressionFunction::referencedColumns
QSet< QString > referencedColumns(const QgsExpressionNodeFunction *node) const override
Returns a set of field names which are required for this function.
Definition: qgsexpressionfunction.cpp:188
qgsexpressionnode.h
QgsStaticExpressionFunction::QgsStaticExpressionFunction
QgsStaticExpressionFunction(const QString &fnname, const QgsExpressionFunction::ParameterList &params, FcnEval fcn, const QStringList &groups, const QString &helpText=QString(), bool usesGeometry=false, const QSet< QString > &referencedColumns=QSet< QString >(), bool lazyEval=false, const QStringList &aliases=QStringList(), bool handlesNull=false)
Static function for evaluation against a QgsExpressionContext, using a named list of parameter values...
Definition: qgsexpressionfunction.h:420
QgsWithVariableExpressionFunction::QgsWithVariableExpressionFunction
QgsWithVariableExpressionFunction()
Definition: qgsexpressionfunction.cpp:6801
QgsArrayForeachExpressionFunction
Handles the array_foreach(array, expression) expression function.
Definition: qgsexpressionfunction.h:510
QgsStaticExpressionFunction
Definition: qgsexpressionfunction.h:349
QgsExpressionFunction::Parameter::optional
bool optional() const
Returns true if the parameter is optional.
Definition: qgsexpressionfunction.h:79
QgsExpressionNodeFunction
An expression node for expression functions.
Definition: qgsexpressionnodeimpl.h:316
QgsExpressionContextScope
Single scope for storing variables and functions for use within a QgsExpressionContext....
Definition: qgsexpressioncontext.h:111
QgsStaticExpressionFunction::usesGeometry
bool usesGeometry(const QgsExpressionNodeFunction *node) const override
Does this function use a geometry object.
Definition: qgsexpressionfunction.cpp:180
QgsExpressionFunction::FcnEval
QVariant(* FcnEval)(const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node)
Function definition for evaluation against an expression context, using a list of values as parameter...
Definition: qgsexpressionfunction.h:47
QgsExpressionFunction::Parameter::defaultValue
QVariant defaultValue() const
Returns the default value for the parameter.
Definition: qgsexpressionfunction.h:82
QgsExpressionFunction::lazyEval
bool lazyEval() const
true if this function should use lazy evaluation.
Definition: qgsexpressionfunction.h:232
QgsExpressionFunction::group
QString group() const
Returns the first group which the function belongs to.
Definition: qgsexpressionfunction.h:283
QgsExpressionFunction
Definition: qgsexpressionfunction.h:40
QgsStaticExpressionFunction::prepare
bool prepare(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
This will be called during the prepare step() of an expression if it is not static.
Definition: qgsexpressionfunction.cpp:204
QgsArrayForeachExpressionFunction::run
QVariant run(QgsExpressionNode::NodeList *args, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override
Evaluates the function, first evaluating all required arguments before passing them to the function's...
Definition: qgsexpressionfunction.cpp:6638
QgsStaticExpressionFunction::QgsStaticExpressionFunction
QgsStaticExpressionFunction(const QString &fnname, const QgsExpressionFunction::ParameterList &params, FcnEval fcn, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QSet< QString > &referencedColumns=QSet< QString >(), bool lazyEval=false, const QStringList &aliases=QStringList(), bool handlesNull=false)
Static function for evaluation against a QgsExpressionContext, using a named list of parameter values...
Definition: qgsexpressionfunction.h:377
QgsExpressionFunction::name
QString name() const
The name of the function.
Definition: qgsexpressionfunction.h:190
QgsExpressionFunction::parameters
const QgsExpressionFunction::ParameterList & parameters() const
Returns the list of named parameters for the function, if set.
Definition: qgsexpressionfunction.h:214
QgsExpressionFunction::minParams
int minParams() const
The minimum number of parameters this function takes.
Definition: qgsexpressionfunction.h:196
QgsExpressionFunction::allParamsStatic
static bool allParamsStatic(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context)
This will return true if all the params for the provided function node are static within the constrai...
Definition: qgsexpressionfunction.cpp:228
QgsArrayFilterExpressionFunction::run
QVariant run(QgsExpressionNode::NodeList *args, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override
Evaluates the function, first evaluating all required arguments before passing them to the function's...
Definition: qgsexpressionfunction.cpp:6732
QgsArrayForeachExpressionFunction::QgsArrayForeachExpressionFunction
QgsArrayForeachExpressionFunction()
Definition: qgsexpressionfunction.cpp:6613
QgsExpressionFunction::Parameter::Parameter
Parameter(const QString &name, bool optional=false, const QVariant &defaultValue=QVariant(), bool isSubExpression=false)
Constructor for Parameter.
Definition: qgsexpressionfunction.h:65
QgsArrayFilterExpressionFunction::func
QVariant func(const QVariantList &values, const QgsExpressionContext *context, QgsExpression *parent, const QgsExpressionNodeFunction *node) override
Returns result of evaluating the function.
Definition: qgsexpressionfunction.cpp:6767
QgsExpressionFunction::QgsExpressionFunction
QgsExpressionFunction(const QString &fnname, const QgsExpressionFunction::ParameterList &params, const QStringList &groups, const QString &helpText=QString(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
Constructor for function which uses named parameter list and group list.
Definition: qgsexpressionfunction.h:170
QgsExpression
Definition: qgsexpression.h:113
QgsArrayFilterExpressionFunction::QgsArrayFilterExpressionFunction
QgsArrayFilterExpressionFunction()
Definition: qgsexpressionfunction.cpp:6707
QgsWithVariableExpressionFunction::prepare
bool prepare(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
This will be called during the prepare step() of an expression if it is not static.
Definition: qgsexpressionfunction.cpp:6877
QgsStaticExpressionFunction::setIsStatic
void setIsStatic(bool isStatic)
Tag this function as either static or not static.
Definition: qgsexpressionfunction.cpp:217
QgsStaticExpressionFunction::QgsStaticExpressionFunction
QgsStaticExpressionFunction(const QString &fnname, int params, FcnEval fcn, const QString &group, const QString &helpText=QString(), bool usesGeometry=false, const QSet< QString > &referencedColumns=QSet< QString >(), bool lazyEval=false, const QStringList &aliases=QStringList(), bool handlesNull=false)
Static function for evaluation against a QgsExpressionContext, using an unnamed list of parameter val...
Definition: qgsexpressionfunction.h:356
QgsExpressionNode::NodeList
A list of expression nodes.
Definition: qgsexpressionnode.h:117
QgsWithVariableExpressionFunction::isStatic
bool isStatic(const QgsExpressionNodeFunction *node, QgsExpression *parent, const QgsExpressionContext *context) const override
Will be called during prepare to determine if the function is static.
Definition: qgsexpressionfunction.cpp:6811
QgsExpressionFunction::QgsExpressionFunction
QgsExpressionFunction(const QString &fnname, int params, const QStringList &groups, const QString &helpText=QString(), bool lazyEval=false, bool handlesNull=false, bool isContextual=false)
Constructor for function which uses unnamed parameters and group list.
Definition: qgsexpressionfunction.h:128