TFPExpressionParser class

In unit fpExprPars

Class for parsing and evaluating mathematical expressions

Declaration

pascal

TFPExpressionParser = class(TComponent)

Inheritance

TFPExpressionParser
TComponent
TPersistent
TObject

Description

This is the main expression parser class that provides comprehensive functionality for parsing and evaluating mathematical expressions.

The parser handles the complete expression evaluation pipeline from tokenization through parsing to evaluation, supporting complex expressions with proper operator precedence, parentheses, function calls, and variable references.

Key features include built-in mathematical functions, string operations, date/time handling, boolean logic, comparison operations, and extensibility through custom functions and variables.

Properties

`Scanner`	protected
`ExprNode`	protected
`Dirty`	protected
`ExtractingIdentifiers`	protected
`AsFloat`	public	Expression result as floating point value
`AsCurrency`	public	Expression result as currency value
`AsInteger`	public	Expression result as integer value
`AsString`	public	Expression result as string value
`AsBoolean`	public	Expression result as boolean value
`AsDateTime`	public	Expression result as date/time value
`Expression`	published	Expression string to be evaluated
`Identifiers`	published	Collection of identifiers and their values
`BuiltIns`	published	Manager for built-in functions and constants

Methods

`ParserError`	protected
`SetExpression`	protected
`CheckResultType`	protected
`CheckResultTypes`	protected
`ConvertNode`	protected
`BuiltinsManager`	protected
`Level1`	protected
`Level2`	protected
`Level3`	protected
`Level4`	protected
`Level5`	protected
`Level6`	protected
`Level7`	protected
`Primitive`	protected
`GetToken`	protected
`TokenType`	protected
`CurrentToken`	protected
`CreateHashList`	protected
`Create`	public	Create expression parser instance
`Destroy`	public	Destroy expression parser and free resources
`IdentifierByName`	public	Get identifier definition by name
`Clear`	public	Clear the current expression
`EvaluateExpression`	public	Evaluate the expression and return result
`ExtractIdentifierNames`	public
`ExtractNode`	public	Extract expression node from result
`Evaluate`	public	Evaluate the current expression
`ResultType`	public	Get the result type of the expression
`HasAggregate`	public	Check if expression contains aggregates
`InitAggregate`	public	Initialize aggregate calculation
`UpdateAggregate`	public	Update aggregate calculation with value

Inherited

From TComponent (74)

_AddRef _Release BeforeDestruction CanObserve ChangeName ComObject ComponentCount ComponentIndex Components ComponentState ComponentStyle DefineProperties DesignInfo DestroyComponents Destroying ExecuteAction FindComponent FreeNotification FreeOnRelease GetChildOwner GetChildParent GetChildren GetDeltaStreams GetEnumerator GetIDsOfNames GetNamePath GetObservers GetOwner GetParentComponent GetTypeInfo GetTypeInfoCount HasParent iicrGetComponent InsertComponent Invoke IsImplementorOf Loaded Loading Name Notification ObserverAdded Observers OnGetDeltaStreams Owner PaletteCreated QueryInterface ReadDeltaState ReadDeltaStream ReadState ReferenceInterface RemoveComponent RemoveFreeNotification RemoveFreeNotifications SafeCallException SetAncestor SetChildOrder SetDesigning SetDesignInstance SetInline SetName SetParentComponent SetSubComponent Tag ToString TToStringNameMode UpdateAction Updated UpdateRegistry Updating ValidateContainer ValidateInsert ValidateRename VCLComObject WriteState

From TPersistent (5)

Assign AssignTo FPOAttachObserver FPODetachObserver FPONotifyObservers

From TObject (37)

AfterConstruction CheckDisposed ClassInfo ClassName ClassNameIs ClassParent ClassType CleanupInstance 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 StringMessageTable SystemHasExtendedRTTI UnitName

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