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qgsexpression.h
-------------------
begin : August 2011
copyright : (C) 2011 Martin Dobias
email : wonder.sk at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#ifndef QGSEXPRESSION_H
#define QGSEXPRESSION_H
#include <QMetaType>
#include <QStringList>
#include <QVariant>
#include <QList>
#include <QDomDocument>
#include <QCoreApplication>
#include "qgis.h"
#include "qgsunittypes.h"
class QgsFeature;
class QgsGeometry;
class QgsOgcUtils;
class QgsVectorLayer;
class QgsVectorDataProvider;
class QgsField;
class QgsFields;
class QgsDistanceArea;
class QDomElement;
class QgsExpressionContext;
class QgsExpressionPrivate;
/**
Class for parsing and evaluation of expressions (formerly called "search strings").
The expressions try to follow both syntax and semantics of SQL expressions.
Usage:
\code{.cpp}
QgsExpression exp("gid*2 > 10 and type not in ('D','F'));
if (exp.hasParserError())
{
// show error message with parserErrorString() and exit
}
QVariant result = exp.evaluate(feature, fields);
if (exp.hasEvalError())
{
// show error message with evalErrorString()
}
else
{
// examine the result
}
\endcode
Three Value Logic
=================
Similarly to SQL, this class supports three-value logic: true/false/unknown.
Unknown value may be a result of operations with missing data (NULL). Please note
that NULL is different value than zero or an empty string. For example
3 > NULL returns unknown.
There is no special (three-value) 'boolean' type: true/false is represented as
1/0 integer, unknown value is represented the same way as NULL values: invalid QVariant.
Performance
===========
For better performance with many evaluations you may first call prepare(fields) function
to find out indices of columns and then repeatedly call evaluate(feature).
Type conversion
===============
Operators and functions that expect arguments to be of a particular
type automatically convert the arguments to that type, e.g. sin('2.1') will convert
the argument to a double, length(123) will first convert the number to a string.
Explicit conversion can be achieved with to_int, to_real, to_string functions.
If implicit or explicit conversion is invalid, the evaluation returns an error.
Comparison operators do numeric comparison in case both operators are numeric (int/double)
or they can be converted to numeric types.
Implicit sharing
================
This class is implicitly shared, copying has a very low overhead.
It is normally preferable to call `QgsExpression( otherExpression )` instead of
`QgsExpression( otherExpression.expression() )`. A deep copy will only be made
when {@link prepare()} is called. For usage this means mainly, that you should
normally keep an unprepared master copy of a QgsExpression and whenever using it
with a particular QgsFeatureIterator copy it just before and prepare it using the
same context as the iterator.
Implicit sharing was added in 2.14
*/
Q_NOWARN_DEPRECATED_PUSH
class CORE_EXPORT QgsExpression
{
Q_DECLARE_TR_FUNCTIONS( QgsExpression )
public:
/**
* Creates a new expression based on the provided string.
* The string will immediately be parsed. For optimization
* {@link prepare()} should alwys be called before every
* loop in which this expression is used.
*/
QgsExpression( const QString& expr );
/**
* Create a copy of this expression. This is preferred
* over recreating an expression from a string since
* it does not need to be re-parsed.
*/
QgsExpression( const QgsExpression& other );
/**
* Create a copy of this expression. This is preferred
* over recreating an expression from a string since
* it does not need to be re-parsed.
*/
QgsExpression& operator=( const QgsExpression& other );
~QgsExpression();
//! Returns true if an error occurred when parsing the input expression
bool hasParserError() const;
//! Returns parser error
QString parserErrorString() const;
class Node;
//! Returns root node of the expression. Root node is null is parsing has failed
const Node* rootNode() const;
//! Get the expression ready for evaluation - find out column indexes.
//! @deprecated use prepare( const QgsExpressionContext *context ) instead
Q_DECL_DEPRECATED bool prepare( const QgsFields &fields );
/** Get the expression ready for evaluation - find out column indexes.
* @param context context for preparing expression
* @note added in QGIS 2.12
*/
bool prepare( const QgsExpressionContext *context );
/**
* Get list of columns referenced by the expression.
* @note if the returned list contains the QgsFeatureRequest::AllAttributes constant then
* all attributes from the layer are required for evaluation of the expression.
* QgsFeatureRequest::setSubsetOfAttributes automatically handles this case.
*
* TODO QGIS3: Return QSet<QString>
*/
QStringList referencedColumns() const;
//! Returns true if the expression uses feature geometry for some computation
bool needsGeometry() const;
// evaluation
//! Evaluate the feature and return the result
//! @note prepare() should be called before calling this method
//! @deprecated use evaluate( const QgsExpressionContext* context ) instead
Q_DECL_DEPRECATED QVariant evaluate( const QgsFeature* f );
//! Evaluate the feature and return the result
//! @note prepare() should be called before calling this method
//! @note available in python bindings as evaluatePrepared
//! @deprecated use evaluate( const QgsExpressionContext* context ) instead
Q_DECL_DEPRECATED QVariant evaluate( const QgsFeature& f );
//! Evaluate the feature and return the result
//! @note this method does not expect that prepare() has been called on this instance
//! @deprecated use evaluate( const QgsExpressionContext* context ) instead
Q_DECL_DEPRECATED QVariant evaluate( const QgsFeature* f, const QgsFields& fields );
//! Evaluate the feature and return the result
//! @note this method does not expect that prepare() has been called on this instance
//! @note not available in python bindings
//! @deprecated use evaluate( const QgsExpressionContext* context ) instead
Q_DECL_DEPRECATED QVariant evaluate( const QgsFeature& f, const QgsFields& fields );
/** Evaluate the feature and return the result.
* @note this method does not expect that prepare() has been called on this instance
* @note added in QGIS 2.12
*/
QVariant evaluate();
/** Evaluate the expression against the specified context and return the result.
* @param context context for evaluating expression
* @note prepare() should be called before calling this method.
* @note added in QGIS 2.12
*/
QVariant evaluate( const QgsExpressionContext* context );
//! Returns true if an error occurred when evaluating last input
bool hasEvalError() const;
//! Returns evaluation error
QString evalErrorString() const;
//! Set evaluation error (used internally by evaluation functions)
void setEvalErrorString( const QString& str );
//! Set the number for $rownum special column
//! @deprecated use QgsExpressionContext to set row number instead
Q_DECL_DEPRECATED void setCurrentRowNumber( int rowNumber );
//! Return the number used for $rownum special column
//! @deprecated use QgsExpressionContext to retrieve row number instead
Q_DECL_DEPRECATED int currentRowNumber(); //TODO QGIS 3.0: make the following methods private. They are still required for replaceExpressionText
//but should not be publicly used
/** Assign a special column
* @deprecated use global or project QgsExpressionContext variables instead
*/
Q_DECL_DEPRECATED static void setSpecialColumn( const QString& name, const QVariant& value );
/** Unset a special column
* @deprecated use global or project QgsExpressionContext variables instead
*/
Q_DECL_DEPRECATED static void unsetSpecialColumn( const QString& name );
/** Return the value of the given special column or a null QVariant if undefined
* @deprecated use global or project QgsExpressionContext variables instead
*/
Q_DECL_DEPRECATED static QVariant specialColumn( const QString& name );
/** Check whether a special column exists
* @note added in 2.2
*/
static bool hasSpecialColumn( const QString& name );
/** Checks whether an expression consists only of a single field reference
* @note added in 2.9
*/
bool isField() const { return rootNode() && dynamic_cast<const NodeColumnRef*>( rootNode() ) ;}
//! @deprecated use QgsExpressionContext variant instead
Q_DECL_DEPRECATED static bool isValid( const QString& text, const QgsFields& fields, QString &errorMessage );
/** Tests whether a string is a valid expression.
* @param text string to test
* @param context optional expression context
* @param errorMessage will be filled with any error message from the validation
* @returns true if string is a valid expression
* @note added in QGIS 2.12
*/
static bool isValid( const QString& text, const QgsExpressionContext* context, QString &errorMessage );
void setScale( double scale );
double scale();
//! Return the original, unmodified expression string.
//! If there was none supplied because it was constructed by sole
//! API calls, dump() will be used to create one instead.
QString expression() const;
//! Return an expression string, constructed from the internal
//! abstract syntax tree. This does not contain any nice whitespace
//! formatting or comments. In general it is preferrable to use
//! expression() instead.
QString dump() const;
/** Return calculator used for distance and area calculations
* (used by $length, $area and $perimeter functions only)
* @see setGeomCalculator()
* @see distanceUnits()
* @see areaUnits()
*/
QgsDistanceArea *geomCalculator();
/** Sets the geometry calculator used for distance and area calculations in expressions.
* (used by $length, $area and $perimeter functions only). By default, no geometry
* calculator is set and all distance and area calculations are performed using simple
* cartesian methods (ie no ellipsoidal calculations).
* @see geomCalculator()
*/
//TODO QGIS 3.0 change calc to a pointer, so that calculator can be cleared by passing nullptr
void setGeomCalculator( const QgsDistanceArea &calc );
/** Returns the desired distance units for calculations involving geomCalculator(), eg "$length" and "$perimeter".
* @note distances are only converted when a geomCalculator() has been set
* @note added in QGIS 2.14
* @see setDistanceUnits()
* @see areaUnits()
*/
QGis::UnitType distanceUnits() const;
/** Sets the desired distance units for calculations involving geomCalculator(), eg "$length" and "$perimeter".
* @note distances are only converted when a geomCalculator() has been set
* @note added in QGIS 2.14
* @see distanceUnits()
* @see setAreaUnits()
*/
void setDistanceUnits( QGis::UnitType unit );
/** Returns the desired areal units for calculations involving geomCalculator(), eg "$area".
* @note areas are only converted when a geomCalculator() has been set
* @note added in QGIS 2.14
* @see setAreaUnits()
* @see distanceUnits()
*/
QgsUnitTypes::AreaUnit areaUnits() const;
/** Sets the desired areal units for calculations involving geomCalculator(), eg "$area".
* @note areas are only converted when a geomCalculator() has been set
* @note added in QGIS 2.14
* @see areaUnits()
* @see setDistanceUnits()
*/
void setAreaUnits( QgsUnitTypes::AreaUnit unit );
/** This function currently replaces each expression between [% and %]
* in the string with the result of its evaluation on the feature
* passed as argument.
*
* Additional substitutions can be passed through the substitutionMap
* parameter
* @param action
* @param feat
* @param layer
* @param substitutionMap
* @param distanceArea optional QgsDistanceArea. If specified, the QgsDistanceArea is used for distance and area conversion
* @deprecated use QgsExpressionContext variant instead
*/
Q_DECL_DEPRECATED static QString replaceExpressionText( const QString &action, const QgsFeature *feat,
QgsVectorLayer *layer,
const QMap<QString, QVariant> *substitutionMap = nullptr,
const QgsDistanceArea* distanceArea = nullptr );
/** This function replaces each expression between [% and %]
* in the string with the result of its evaluation with the specified context
*
* Additional substitutions can be passed through the substitutionMap parameter
* @param action
* @param context expression context
* @param substitutionMap
* @param distanceArea optional QgsDistanceArea. If specified, the QgsDistanceArea is used for distance
* and area conversion
* @note added in QGIS 2.12
*/
static QString replaceExpressionText( const QString &action, const QgsExpressionContext* context,
const QMap<QString, QVariant> *substitutionMap = nullptr,
const QgsDistanceArea* distanceArea = nullptr );
/** Attempts to evaluate a text string as an expression to a resultant double
* value.
* @param text text to evaluate as expression
* @param fallbackValue value to return if text can not be evaluated as a double
* @returns evaluated double value, or fallback value
* @note added in QGIS 2.7
* @note this method is inefficient for bulk evaluation of expressions, it is intended
* for one-off evaluations only.
*/
static double evaluateToDouble( const QString& text, const double fallbackValue );
/**
* @brief list of unary operators
* @note if any change is made here, the definition of QgsExpression::UnaryOperatorText[] must be adapted.
*/
enum UnaryOperator
{
uoNot,
uoMinus,
};
/**
* @brief list of binary operators
* @note if any change is made here, the definition of QgsExpression::BinaryOperatorText[] must be adapted.
*/
enum BinaryOperator
{
// logical
boOr,
boAnd,
// comparison
boEQ, // =
boNE, // <>
boLE, // <=
boGE, // >=
boLT, // <
boGT, // >
boRegexp,
boLike,
boNotLike,
boILike,
boNotILike,
boIs,
boIsNot,
// math
boPlus,
boMinus,
boMul,
boDiv,
boIntDiv,
boMod,
boPow,
// strings
boConcat,
};
enum SpatialOperator
{
soBbox,
soIntersects,
soContains,
soCrosses,
soEquals,
soDisjoint,
soOverlaps,
soTouches,
soWithin,
};
//! @note not available in Python bindings
static const char* BinaryOperatorText[];
//! @note not available in Python bindings
static const char* UnaryOperatorText[];
typedef QVariant( *FcnEval )( const QVariantList& values, const QgsFeature* f, QgsExpression* parent );
/** Function definition for evaluation against an expression context
*/
typedef QVariant( *FcnEvalContext )( const QVariantList& values, const QgsExpressionContext* context, QgsExpression* parent );
/**
* A abstract base class for defining QgsExpression functions.
*/
class CORE_EXPORT Function
{
public:
Function( const QString& fnname,
int params,
const QString& group,
const QString& helpText = QString(),
bool usesGeometry = false,
const QStringList& referencedColumns = QStringList(),
bool lazyEval = false,
bool handlesNull = false,
bool isContextual = false )
: mName( fnname )
, mParams( params )
, mUsesGeometry( usesGeometry )
, mGroup( group )
, mHelpText( helpText )
, mReferencedColumns( referencedColumns )
, mLazyEval( lazyEval )
, mHandlesNull( handlesNull )
, mIsContextual( isContextual )
{}
virtual ~Function() {}
/** The name of the function. */
QString name() { return mName; }
/** The number of parameters this function takes. */
int params() { return mParams; }
/** Does this function use a geometry object. */
bool usesgeometry() { return mUsesGeometry; }
/** Returns a list of possible aliases for the function. These include
* other permissible names for the function, eg deprecated names.
* @return list of known aliases
* @note added in QGIS 2.9
*/
virtual QStringList aliases() const { return QStringList(); }
/** True if this function should use lazy evaluation. Lazy evaluation functions take QgsExpression::Node objects
* rather than the node results when called. You can use node->eval(parent, feature) to evaluate the node and return the result
* Functions are non lazy default and will be given the node return value when called **/
bool lazyEval() { return mLazyEval; }
virtual QStringList referencedColumns() const { return mReferencedColumns; }
/** Returns whether the function is only available if provided by a QgsExpressionContext object.
* @note added in QGIS 2.12
*/
bool isContextual() const { return mIsContextual; }
/** The group the function belongs to. */
QString group() { return mGroup; }
/** The help text for the function. */
const QString helptext() { return mHelpText.isEmpty() ? QgsExpression::helptext( mName ) : mHelpText; }
//! @deprecated Use QgsExpressionContext variant instead
Q_DECL_DEPRECATED virtual QVariant func( const QVariantList&, const QgsFeature*, QgsExpression* );
/** Returns result of evaluating the function.
* @param values list of values passed to the function
* @param context context expression is being evaluated against
* @param parent parent expression
* @returns result of function
* @note named funcV2 in Python bindings. Will be renamed to func to replace deprecated method in QGIS 3.0.
*/
//TODO QGIS 3.0 - rename python method
virtual QVariant func( const QVariantList& values, const QgsExpressionContext* context, QgsExpression* parent );
bool operator==( const Function& other ) const
{
if ( QString::compare( mName, other.mName, Qt::CaseInsensitive ) == 0 )
return true;
return false;
}
virtual bool handlesNull() const { return mHandlesNull; }
private:
QString mName;
int mParams;
bool mUsesGeometry;
QString mGroup;
QString mHelpText;
QStringList mReferencedColumns;
bool mLazyEval;
bool mHandlesNull;
bool mIsContextual; //if true function is only available through an expression context
};
/**
* c++ helper class for defining QgsExpression functions.
* \note not available in Python bindings
*/
class StaticFunction : public Function
{
public:
//! @deprecated use QgsExpressionContext variant instead
Q_DECL_DEPRECATED StaticFunction( const QString& fnname,
int params,
FcnEval fcn,
const QString& group,
const QString& helpText = QString(),
bool usesGeometry = false,
const QStringList& referencedColumns = QStringList(),
bool lazyEval = false,
const QStringList& aliases = QStringList(),
bool handlesNull = false )
: Function( fnname, params, group, helpText, usesGeometry, referencedColumns, lazyEval, handlesNull )
, mFnc( fcn )
, mContextFnc( nullptr )
, mAliases( aliases )
{}
virtual ~StaticFunction() {}
/** Static function for evaluation against a QgsExpressionContext
*/
StaticFunction( const QString& fnname,
int params,
FcnEvalContext fcn,
const QString& group,
const QString& helpText = QString(),
bool usesGeometry = false,
const QStringList& referencedColumns = QStringList(),
bool lazyEval = false,
const QStringList& aliases = QStringList(),
bool handlesNull = false )
: Function( fnname, params, group, helpText, usesGeometry, referencedColumns, lazyEval, handlesNull )
, mFnc( nullptr )
, mContextFnc( fcn )
, mAliases( aliases )
{}
//! @deprecated use QgsExpressionContext variant instead
Q_DECL_DEPRECATED virtual QVariant func( const QVariantList& values, const QgsFeature* f, QgsExpression* parent ) override;
/** Returns result of evaluating the function.
* @param values list of values passed to the function
* @param context context expression is being evaluated against
* @param parent parent expression
* @returns result of function
*/
virtual QVariant func( const QVariantList& values, const QgsExpressionContext* context, QgsExpression* parent ) override
{
return mContextFnc ? mContextFnc( values, context, parent ) : QVariant();
}
virtual QStringList aliases() const override { return mAliases; }
private:
FcnEval mFnc;
FcnEvalContext mContextFnc;
QStringList mAliases;
};
//! @note not available in Python bindings
static QList<Function*> gmFunctions;
static const QList<Function*>& Functions();
//! @note not available in Python bindings
static QStringList gmBuiltinFunctions;
static const QStringList& BuiltinFunctions();
/** Registers a function to the expression engine. This is required to allow expressions to utilise the function.
* @param function function to register
* @param transferOwnership set to true to transfer ownership of function to expression engine
* @returns true on successful registration
* @see unregisterFunction
*/
static bool registerFunction( Function* function, bool transferOwnership = false );
/** Unregisters a function from the expression engine. The function will no longer be usable in expressions.
* @param name function name
* @see registerFunction
*/
static bool unregisterFunction( const QString& name );
//! List of functions owned by the expression engine
//! @note not available in Python bindings
static QList<Function*> gmOwnedFunctions;
/** Deletes all registered functions whose ownership have been transferred to the expression engine.
* @note added in QGIS 2.12
*/
static void cleanRegisteredFunctions();
//! tells whether the identifier is a name of existing function
static bool isFunctionName( const QString& name );
//! return index of the function in Functions array
static int functionIndex( const QString& name );
/** Returns the number of functions defined in the parser
* @return The number of function defined in the parser.
*/
static int functionCount();
/**
* Returns a list of special Column definitions
*/
static QList<Function*> specialColumns();
/** Returns a quoted column reference (in double quotes)
* @see quotedString()
* @see quotedValue()
*/
static QString quotedColumnRef( QString name );
/** Returns a quoted version of a string (in single quotes)
* @see quotedValue()
* @see quotedColumnRef()
*/
static QString quotedString( QString text );
/** Returns a string representation of a literal value, including appropriate
* quotations where required.
* @param value value to convert to a string representation
* @note added in QGIS 2.14
* @see quotedString()
* @see quotedColumnRef()
*/
static QString quotedValue( const QVariant& value );
/** Returns a string representation of a literal value, including appropriate
* quotations where required.
* @param value value to convert to a string representation
* @param type value type
* @note added in QGIS 2.14
* @see quotedString()
* @see quotedColumnRef()
*/
static QString quotedValue( const QVariant& value, QVariant::Type type );
//////
class Visitor; // visitor interface is defined below
enum NodeType
{
ntUnaryOperator,
ntBinaryOperator,
ntInOperator,
ntFunction,
ntLiteral,
ntColumnRef,
ntCondition
};
class CORE_EXPORT Node
{
public:
virtual ~Node() {}
/**
* Abstract virtual that returns the type of this node.
*
* @return The type of this node
*/
virtual NodeType nodeType() const = 0;
/**
* Abstract virtual eval method
* Errors are reported to the parent
* @deprecated use QgsExpressionContext variant instead
*/
Q_DECL_DEPRECATED virtual QVariant eval( QgsExpression* parent, const QgsFeature* f );
/**
* Abstract virtual eval method
* Errors are reported to the parent
* @note added in QGIS 2.12
*/
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context );
/**
* Abstract virtual preparation method
* Errors are reported to the parent
* @deprecated use QgsExpressionContext variant instead
*/
Q_DECL_DEPRECATED virtual bool prepare( QgsExpression* parent, const QgsFields &fields );
/**
* Abstract virtual preparation method
* Errors are reported to the parent
* @note added in QGIS 2.12
*/
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context );
/**
* Abstract virtual dump method
*
* @return An expression which represents this node as string
*/
virtual QString dump() const = 0;
/**
* Generate a clone of this node.
* Make sure that the clone does not contain any information which is
* generated in prepare and context related.
* Ownership is transferred to the caller.
*
* @return a deep copy of this node.
*/
virtual Node* clone() const = 0;
/**
* Abstract virtual method which returns a list of columns required to
* evaluate this node.
*
* When reimplementing this, you need to return any column that is required to
* evaluate this node and in addition recursively collect all the columns required
* to evaluate child nodes.
*
* @return A list of columns required to evaluate this expression
*/
virtual QStringList referencedColumns() const = 0;
/**
* Abstract virtual method which returns if the geometry is required to evaluate
* this expression.
*
* This needs to call `needsGeometry()` recursively on any child nodes.
*
* @return true if a geometry is required to evaluate this expression
*/
virtual bool needsGeometry() const = 0;
/**
* Support the visitor pattern.
*
* For any implementation this should look like
*
* C++:
*
* v.visit( *this );
*
* Python:
*
* v.visit( self)
*
* @param v A visitor that visits this node.
*/
virtual void accept( Visitor& v ) const = 0;
};
class CORE_EXPORT NodeList
{
public:
NodeList() {}
virtual ~NodeList() { qDeleteAll( mList ); }
/** Takes ownership of the provided node */
void append( Node* node ) { mList.append( node ); }
int count() { return mList.count(); }
QList<Node*> list() { return mList; }
/** Creates a deep copy of this list. Ownership is transferred to the caller */
NodeList* clone() const;
virtual QString dump() const;
protected:
QList<Node*> mList;
};
class CORE_EXPORT Interval
{
// YEAR const value taken from postgres query
// SELECT EXTRACT(EPOCH FROM interval '1 year')
static const int YEARS = 31557600;
static const int MONTHS = 60 * 60 * 24 * 30;
static const int WEEKS = 60 * 60 * 24 * 7;
static const int DAY = 60 * 60 * 24;
static const int HOUR = 60 * 60;
static const int MINUTE = 60;
public:
Interval( double seconds = 0 ) : mSeconds( seconds ), mValid( true ) { }
//! interval length in years
double years() { return mSeconds / YEARS;}
//! interval length in months
double months() { return mSeconds / MONTHS; }
//! interval length in weeks
double weeks() { return mSeconds / WEEKS;}
//! interval length in days
double days() { return mSeconds / DAY;}
//! interval length in hours
double hours() { return mSeconds / HOUR;}
//! interval length in minutus
double minutes() { return mSeconds / MINUTE;}
//! interval length in seconds
double seconds() { return mSeconds; }
//! getter interval validity
bool isValid() { return mValid; }
//! setter interval validity
void setValid( bool valid ) { mValid = valid; }
//! compare two intervals
bool operator==( QgsExpression::Interval other ) const;
//! return an invalid interval
static QgsExpression::Interval invalidInterVal();
//! convert a string to an interval
static QgsExpression::Interval fromString( const QString& string );
private:
double mSeconds;
bool mValid;
};
class CORE_EXPORT NodeUnaryOperator : public Node
{
public:
NodeUnaryOperator( UnaryOperator op, Node* operand ) : mOp( op ), mOperand( operand ) {}
~NodeUnaryOperator() { delete mOperand; }
UnaryOperator op() const { return mOp; }
Node* operand() const { return mOperand; }
virtual NodeType nodeType() const override { return ntUnaryOperator; }
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QString dump() const override;
virtual QStringList referencedColumns() const override { return mOperand->referencedColumns(); }
virtual bool needsGeometry() const override { return mOperand->needsGeometry(); }
virtual void accept( Visitor& v ) const override { v.visit( *this ); }
virtual Node* clone() const override;
protected:
UnaryOperator mOp;
Node* mOperand;
};
class CORE_EXPORT NodeBinaryOperator : public Node
{
public:
NodeBinaryOperator( BinaryOperator op, Node* opLeft, Node* opRight ) : mOp( op ), mOpLeft( opLeft ), mOpRight( opRight ) {}
~NodeBinaryOperator() { delete mOpLeft; delete mOpRight; }
BinaryOperator op() const { return mOp; }
Node* opLeft() const { return mOpLeft; }
Node* opRight() const { return mOpRight; }
virtual NodeType nodeType() const override { return ntBinaryOperator; }
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QString dump() const override;
virtual QStringList referencedColumns() const override { return mOpLeft->referencedColumns() + mOpRight->referencedColumns(); }
virtual bool needsGeometry() const override { return mOpLeft->needsGeometry() || mOpRight->needsGeometry(); }
virtual void accept( Visitor& v ) const override { v.visit( *this ); }
virtual Node* clone() const override;
int precedence() const;
bool leftAssociative() const;
protected:
bool compare( double diff );
int computeInt( int x, int y );
double computeDouble( double x, double y );
QDateTime computeDateTimeFromInterval( const QDateTime& d, QgsExpression::Interval *i );
BinaryOperator mOp;
Node* mOpLeft;
Node* mOpRight;
};
class CORE_EXPORT NodeInOperator : public Node
{
public:
NodeInOperator( Node* node, NodeList* list, bool notin = false ) : mNode( node ), mList( list ), mNotIn( notin ) {}
virtual ~NodeInOperator() { delete mNode; delete mList; }
Node* node() const { return mNode; }
bool isNotIn() const { return mNotIn; }
NodeList* list() const { return mList; }
virtual NodeType nodeType() const override { return ntInOperator; }
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QString dump() const override;
virtual QStringList referencedColumns() const override { QStringList lst( mNode->referencedColumns() ); Q_FOREACH ( const Node* n, mList->list() ) lst.append( n->referencedColumns() ); return lst; }
virtual bool needsGeometry() const override { bool needs = false; Q_FOREACH ( Node* n, mList->list() ) needs |= n->needsGeometry(); return needs; }
virtual void accept( Visitor& v ) const override { v.visit( *this ); }
virtual Node* clone() const override;
protected:
Node* mNode;
NodeList* mList;
bool mNotIn;
};
class CORE_EXPORT NodeFunction : public Node
{
public:
NodeFunction( int fnIndex, NodeList* args ) : mFnIndex( fnIndex ), mArgs( args ) {}
//NodeFunction( QString name, NodeList* args ) : mName(name), mArgs(args) {}
virtual ~NodeFunction() { delete mArgs; }
int fnIndex() const { return mFnIndex; }
NodeList* args() const { return mArgs; }
virtual NodeType nodeType() const override { return ntFunction; }
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QString dump() const override;
virtual QStringList referencedColumns() const override;
virtual bool needsGeometry() const override { bool needs = Functions()[mFnIndex]->usesgeometry(); if ( mArgs ) { Q_FOREACH ( Node* n, mArgs->list() ) needs |= n->needsGeometry(); } return needs; }
virtual void accept( Visitor& v ) const override { v.visit( *this ); }
virtual Node* clone() const override;
protected:
int mFnIndex;
NodeList* mArgs;
private:
QgsExpression::Function* getFunc() const;
};
class CORE_EXPORT NodeLiteral : public Node
{
public:
NodeLiteral( const QVariant& value ) : mValue( value ) {}
/** The value of the literal. */
inline QVariant value() const { return mValue; }
virtual NodeType nodeType() const override { return ntLiteral; }
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QString dump() const override;
virtual QStringList referencedColumns() const override { return QStringList(); }
virtual bool needsGeometry() const override { return false; }
virtual void accept( Visitor& v ) const override { v.visit( *this ); }
virtual Node* clone() const override;
protected:
QVariant mValue;
};
class CORE_EXPORT NodeColumnRef : public Node
{
public:
NodeColumnRef( const QString& name ) : mName( name ), mIndex( -1 ) {}
/** The name of the column. */
QString name() const { return mName; }
virtual NodeType nodeType() const override { return ntColumnRef; }
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QString dump() const override;
virtual QStringList referencedColumns() const override { return QStringList( mName ); }
virtual bool needsGeometry() const override { return false; }
virtual void accept( Visitor& v ) const override { v.visit( *this ); }
virtual Node* clone() const override;
protected:
QString mName;
int mIndex;
};
class CORE_EXPORT WhenThen
{
public:
WhenThen( Node* whenExp, Node* thenExp ) : mWhenExp( whenExp ), mThenExp( thenExp ) {}
~WhenThen() { delete mWhenExp; delete mThenExp; }
// protected:
Node* mWhenExp;
Node* mThenExp;
private:
WhenThen( const WhenThen& rh );
WhenThen& operator=( const WhenThen& rh );
};
typedef QList<WhenThen*> WhenThenList;
class CORE_EXPORT NodeCondition : public Node
{
public:
NodeCondition( WhenThenList* conditions, Node* elseExp = nullptr ) : mConditions( *conditions ), mElseExp( elseExp ) { delete conditions; }
NodeCondition( const WhenThenList& conditions, Node* elseExp = nullptr ) : mConditions( conditions ), mElseExp( elseExp ) {}
~NodeCondition() { delete mElseExp; qDeleteAll( mConditions ); }
virtual NodeType nodeType() const override { return ntCondition; }
virtual QVariant eval( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual bool prepare( QgsExpression* parent, const QgsExpressionContext* context ) override;
virtual QString dump() const override;
virtual QStringList referencedColumns() const override;
virtual bool needsGeometry() const override;
virtual void accept( Visitor& v ) const override { v.visit( *this ); }
virtual Node* clone() const override;
protected:
WhenThenList mConditions;
Node* mElseExp;
};
//////
/** Support for visitor pattern - algorithms dealing with the expressions
may be implemented without modifying the Node classes */
class CORE_EXPORT Visitor
{
public:
virtual ~Visitor() {}
virtual void visit( const NodeUnaryOperator& n ) = 0;
virtual void visit( const NodeBinaryOperator& n ) = 0;
virtual void visit( const NodeInOperator& n ) = 0;
virtual void visit( const NodeFunction& n ) = 0;
virtual void visit( const NodeLiteral& n ) = 0;
virtual void visit( const NodeColumnRef& n ) = 0;
virtual void visit( const NodeCondition& n ) = 0;
};
/** Entry function for the visitor pattern */
void acceptVisitor( Visitor& v ) const;
/** Returns the help text for a specified function.
* @param name function name
* @see variableHelpText()
*/
static QString helptext( QString name );
/** Returns the help text for a specified variable.
* @param variableName name of variable
* @param showValue set to true to include current value of variable in help text
* @param value current value of variable to show in help text
* @see helptext()
* @note added in QGIS 2.12
*/
static QString variableHelpText( const QString& variableName, bool showValue = true, const QVariant& value = QVariant() );
/** Returns the translated name for a function group.
* @param group untranslated group name
*/
static QString group( const QString& group );
/** Formats an expression result for friendly display to the user. Truncates the result to a sensible
* length, and presents text representations of non numeric/text types (eg geometries and features).
* @param value expression result to format
* @returns formatted string, may contain HTML formatting characters
* @note added in QGIS 2.14
*/
static QString formatPreviewString( const QVariant& value );
protected:
/**
* Used by QgsOgcUtils to create an empty
*/
QgsExpression();
void initGeomCalculator();
static QMap<QString, QVariant> gmSpecialColumns;
static QMap<QString, QString> gmSpecialColumnGroups;
struct HelpArg
{
HelpArg( const QString& arg, const QString& desc, bool descOnly = false, bool syntaxOnly = false )
: mArg( arg )
, mDescription( desc )
, mDescOnly( descOnly )
, mSyntaxOnly( syntaxOnly )
{}
QString mArg;
QString mDescription;
bool mDescOnly;
bool mSyntaxOnly;
};
struct HelpExample
{
HelpExample( const QString& expression, const QString& returns, const QString& note = QString::null )
: mExpression( expression )
, mReturns( returns )
, mNote( note )
{}
QString mExpression;
QString mReturns;
QString mNote;
};
struct HelpVariant
{
HelpVariant( const QString& name, const QString& description,
const QList<HelpArg>& arguments = QList<HelpArg>(),
bool variableLenArguments = false,
const QList<HelpExample>& examples = QList<HelpExample>(),
const QString& notes = QString::null )
: mName( name )
, mDescription( description )
, mArguments( arguments )
, mVariableLenArguments( variableLenArguments )
, mExamples( examples )
, mNotes( notes )
{}
QString mName;
QString mDescription;
QList<HelpArg> mArguments;
bool mVariableLenArguments;
QList<HelpExample> mExamples;
QString mNotes;
};
struct Help
{
Help() {}
Help( const QString& name, const QString& type, const QString& description, const QList<HelpVariant>& variants )
: mName( name )
, mType( type )
, mDescription( description )
, mVariants( variants )
{}
QString mName;
QString mType;
QString mDescription;
QList<HelpVariant> mVariants;
};
/**
* Helper for implicit sharing. When called will create
* a new deep copy of this expression.
*
* @note not available in Python bindings
*/
void detach();
QgsExpressionPrivate* d;
static QHash<QString, Help> gFunctionHelpTexts;
static QHash<QString, QString> gVariableHelpTexts;
static QHash<QString, QString> gGroups;
//! @note not available in Python bindings
static void initFunctionHelp();
//! @note not available in Python bindings
static void initVariableHelp();
friend class QgsOgcUtils;
};
Q_NOWARN_DEPRECATED_POP
Q_DECLARE_METATYPE( QgsExpression::Interval )
Q_DECLARE_METATYPE( QgsExpression::Node* )
#endif // QGSEXPRESSION_H
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