TFPExprFunction class

In unit fpExprPars

Internally used class for representing function calls in expression trees

Declaration

pascal

TFPExprFunction = class(TFPExprIdentifierNode)

Inheritance

Descends from it: TAggregateExpr TFPFunctionCallBack TFPFunctionEventHandler

Description

The TFPExprFunction class represents a function call node in the expression tree. It serves as the base class for all function implementations that can be called from within expressions, including mathematical functions, string functions, date/time functions, and user-defined functions.

The class manages function parameters, validates argument types and counts, and provides the framework for function evaluation. It handles the common aspects of function calls such as parameter management and type checking.

Derived classes implement specific functions by overriding the evaluation methods and providing function-specific logic. The class supports functions with varying numbers of parameters and different return types.

This class is used internally by the TFPExpressionParser class to construct an AST (Abstract Syntax Tree). There is normally no need for you to use or instantiate this class directly.

Properties

`ArgumentNodes`	public	The argument nodes for the function
`ArgumentParams`	public	The argument parameters for the function

Methods

`CalcParams`	protected
`ConvertArgument`	protected
`Check`	public	Validate the function expression
`CreateFunction`	public	Create function with identifier and arguments
`Destroy`	public	Destroy function expression and free resources
`InitAggregate`	public	Initialize aggregate processing for function
`UpdateAggregate`	public	Update aggregate calculations for function
`HasAggregate`	public	Check if function contains aggregates
`AsString`	public	Get string representation of function expression

Inherited

From TFPExprIdentifierNode (4)

CreateIdentifier GetNodeValue Identifier NodeType

From TFPExprNode (3)

CheckNodeType IsAggregate NodeValue

From TObject (41)

AfterConstruction BeforeDestruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance Create DefaultHandler DefaultHandlerStr Dispatch DispatchStr Disposed DisposeOf Equals FieldAddress Free FreeInstance GetDisposed GetHashCode GetInterface GetInterfaceByStr GetInterfaceEntry GetInterfaceEntryByStr GetInterfaceTable GetInterfaceWeak GetLastCastErrorInfo InheritsFrom InitInstance InstanceSize MethodAddress MethodName newinstance QualifiedClassName SafeCallException StringMessageTable SystemHasExtendedRTTI ToString UnitName

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.