QGIS API Documentation
2.14.0-Essen
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Single scope for storing variables and functions for use within a QgsExpressionContext. More...
#include <qgsexpressioncontext.h>
Classes | |
struct | StaticVariable |
Single variable definition for use within a QgsExpressionContextScope. More... | |
Public Member Functions | |
QgsExpressionContextScope (const QString &name=QString()) | |
Constructor for QgsExpressionContextScope. More... | |
QgsExpressionContextScope (const QgsExpressionContextScope &other) | |
Copy constructor. More... | |
~QgsExpressionContextScope () | |
void | addFunction (const QString &name, QgsScopedExpressionFunction *function) |
Adds a function to the scope. More... | |
void | addVariable (const QgsExpressionContextScope::StaticVariable &variable) |
Adds a variable into the context scope. More... | |
QStringList | filteredVariableNames () const |
Returns a fitlered and sorted list of variable names contained within the scope. More... | |
QgsExpression::Function * | function (const QString &name) const |
Retrieves a function from the scope. More... | |
QStringList | functionNames () const |
Retrieves a list of names of functions contained in the scope. More... | |
bool | hasFunction (const QString &name) const |
Tests whether a function with the specified name exists in the scope. More... | |
bool | hasVariable (const QString &name) const |
Tests whether a variable with the specified name exists in the scope. More... | |
bool | isReadOnly (const QString &name) const |
Tests whether the specified variable is read only and should not be editable by users. More... | |
QString | name () const |
Returns the friendly display name of the context scope. More... | |
QgsExpressionContextScope & | operator= (const QgsExpressionContextScope &other) |
bool | removeVariable (const QString &name) |
Removes a variable from the context scope, if found. More... | |
void | setFeature (const QgsFeature &feature) |
Convenience function for setting a feature for the scope. More... | |
void | setFields (const QgsFields &fields) |
Convenience function for setting a fields for the scope. More... | |
void | setVariable (const QString &name, const QVariant &value) |
Convenience method for setting a variable in the context scope by name and value. More... | |
QVariant | variable (const QString &name) const |
Retrieves a variable's value from the scope. More... | |
int | variableCount () const |
Returns the count of variables contained within the scope. More... | |
QStringList | variableNames () const |
Returns a list of variable names contained within the scope. More... | |
Single scope for storing variables and functions for use within a QgsExpressionContext.
Examples include a project's scope, which could contain information about the current project such as the project file's location. QgsExpressionContextScope can encapsulate both variables (static values) and functions(which are calculated only when an expression is evaluated).
Definition at line 76 of file qgsexpressioncontext.h.
Constructor for QgsExpressionContextScope.
name | friendly display name for the context scope |
Definition at line 45 of file qgsexpressioncontext.cpp.
QgsExpressionContextScope::QgsExpressionContextScope | ( | const QgsExpressionContextScope & | other | ) |
Copy constructor.
Definition at line 51 of file qgsexpressioncontext.cpp.
QgsExpressionContextScope::~QgsExpressionContextScope | ( | ) |
Definition at line 78 of file qgsexpressioncontext.cpp.
void QgsExpressionContextScope::addFunction | ( | const QString & | name, |
QgsScopedExpressionFunction * | function | ||
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Adds a function to the scope.
name | function name |
function | function to insert. Ownership is transferred to the scope. |
Definition at line 187 of file qgsexpressioncontext.cpp.
void QgsExpressionContextScope::addVariable | ( | const QgsExpressionContextScope::StaticVariable & | variable | ) |
Adds a variable into the context scope.
If a variable with the same name is already set then its value is overwritten, otherwise a new variable is added to the scope.
variable | definition of variable to insert |
Definition at line 97 of file qgsexpressioncontext.cpp.
QStringList QgsExpressionContextScope::filteredVariableNames | ( | ) | const |
Returns a fitlered and sorted list of variable names contained within the scope.
Hidden variable names will be excluded, and the list will be sorted so that read only variables are listed first.
Definition at line 150 of file qgsexpressioncontext.cpp.
QgsExpression::Function * QgsExpressionContextScope::function | ( | const QString & | name | ) | const |
Retrieves a function from the scope.
name | function name |
Definition at line 177 of file qgsexpressioncontext.cpp.
QStringList QgsExpressionContextScope::functionNames | ( | ) | const |
Retrieves a list of names of functions contained in the scope.
Definition at line 182 of file qgsexpressioncontext.cpp.
bool QgsExpressionContextScope::hasFunction | ( | const QString & | name | ) | const |
Tests whether a function with the specified name exists in the scope.
name | function name |
Definition at line 172 of file qgsexpressioncontext.cpp.
bool QgsExpressionContextScope::hasVariable | ( | const QString & | name | ) | const |
Tests whether a variable with the specified name exists in the scope.
name | variable name |
Definition at line 107 of file qgsexpressioncontext.cpp.
bool QgsExpressionContextScope::isReadOnly | ( | const QString & | name | ) | const |
Tests whether the specified variable is read only and should not be editable by users.
name | variable name |
Definition at line 167 of file qgsexpressioncontext.cpp.
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inline |
Returns the friendly display name of the context scope.
Definition at line 116 of file qgsexpressioncontext.h.
QgsExpressionContextScope & QgsExpressionContextScope::operator= | ( | const QgsExpressionContextScope & | other | ) |
Definition at line 62 of file qgsexpressioncontext.cpp.
bool QgsExpressionContextScope::removeVariable | ( | const QString & | name | ) |
Removes a variable from the context scope, if found.
name | name of variable to remove |
Definition at line 102 of file qgsexpressioncontext.cpp.
void QgsExpressionContextScope::setFeature | ( | const QgsFeature & | feature | ) |
Convenience function for setting a feature for the scope.
Any existing feature set by the scope will be overwritten.
feature | feature for scope |
Definition at line 192 of file qgsexpressioncontext.cpp.
void QgsExpressionContextScope::setFields | ( | const QgsFields & | fields | ) |
Convenience function for setting a fields for the scope.
Any existing fields set by the scope will be overwritten.
fields | fields for scope |
Definition at line 197 of file qgsexpressioncontext.cpp.
Convenience method for setting a variable in the context scope by name and value.
If a variable with the same name is already set then its value is overwritten, otherwise a new variable is added to the scope.
name | variable name |
value | variable value |
Definition at line 83 of file qgsexpressioncontext.cpp.
Retrieves a variable's value from the scope.
name | variable name |
Definition at line 112 of file qgsexpressioncontext.cpp.
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inline |
Returns the count of variables contained within the scope.
Definition at line 179 of file qgsexpressioncontext.h.
QStringList QgsExpressionContextScope::variableNames | ( | ) | const |
Returns a list of variable names contained within the scope.
Definition at line 117 of file qgsexpressioncontext.cpp.