TReader

[Properties (by Name)][Methods (by Name)][Events (by Name)]

Generic reader object which reads component data from any given source.

Declaration

Source position: classesh.inc line 1499

Type
  TReader = class (TFiler)
  private
    FDriver : TAbstractObjectReader;
    FOwner : TComponent;
    FParent : TComponent;
    FFixups : TObject;
    FLoaded : TFPList;
    FLock : TRTLCRITICALSECTION;
    FOnFindMethod : TFindMethodEvent;
    FOnSetMethodProperty : TSetMethodPropertyEvent;
    FOnSetName : TSetNameEvent;
    FOnReferenceName : TReferenceNameEvent;
    FOnAncestorNotFound : TAncestorNotFoundEvent;
    FOnError : TReaderError;
    FOnPropertyNotFound : TPropertyNotFoundEvent;
    FOnFindComponentClass : TFindComponentClassEvent;
    FOnCreateComponent : TCreateComponentEvent;
    FPropName : string;
    FCanHandleExcepts : Boolean;
    FOnReadStringProperty : TReadWriteStringPropertyEvent;
    procedure DoFixupReferences;
    function FindComponentClass(const AClassName: string) : TComponentClass;
    procedure Lock;
    procedure Unlock;
  protected
    function Error(const Message: string) : Boolean;  Virtual;
    function FindMethod(ARoot: TComponent; const AMethodName: string)
                        : CodePointer;  Virtual;
    procedure ReadProperty(AInstance: TPersistent);
    procedure ReadPropValue(Instance: TPersistent; PropInfo: Pointer);
    procedure PropertyError;
    procedure ReadData(Instance: TComponent);
    PropName : string;
    CanHandleExceptions : Boolean;
    function CreateDriver(Stream: TStream; BufSize: Integer)
                          : TAbstractObjectReader;  Virtual;
  public
    constructor Create(Stream: TStream; BufSize: Integer);
    destructor Destroy;  Override;
    procedure FlushBuffer;  Override;
    procedure BeginReferences;
    procedure CheckValue(Value: TValueType);
    procedure DefineProperty(const Name: string; AReadData: TReaderProc; 
                            WriteData: TWriterProc; HasData: Boolean)
                            ;  Override;
    procedure DefineBinaryProperty(const Name: string; 
                                  AReadData: TStreamProc; 
                                  WriteData: TStreamProc; HasData: Boolean)
                                  ;  Override;
    function EndOfList : Boolean;
    procedure EndReferences;
    procedure FixupReferences;
    function NextValue : TValueType;
    procedure Read(var Buf; Count: LongInt);  Virtual;
    function ReadBoolean : Boolean;
    function ReadChar : Char;
    function ReadWideChar : WideChar;
    function ReadUnicodeChar : UnicodeChar;
    procedure ReadCollection(Collection: TCollection);
    function ReadComponent(Component: TComponent) : TComponent;
    procedure ReadComponents(AOwner: TComponent; AParent: TComponent; 
                            Proc: TReadComponentsProc);
    function ReadFloat : Extended;
    function ReadSingle : Single;
    function ReadDate : TDateTime;
    function ReadCurrency : Currency;
    function ReadIdent : string;
    function ReadInteger : LongInt;
    function ReadInt64 : Int64;
    function ReadSet(EnumType: Pointer) : Integer;
    procedure ReadListBegin;
    procedure ReadListEnd;
    function ReadRootComponent(ARoot: TComponent) : TComponent;
    function ReadVariant : Variant;
    procedure ReadSignature;
    function ReadString : string;
    function ReadWideString : WideString;
    function ReadUnicodeString : UnicodeString;
    function ReadValue : TValueType;
    procedure CopyValue(Writer: TWriter);
    Driver : TAbstractObjectReader;
    Owner : TComponent;
    Parent : TComponent;
    OnError : TReaderError;
    OnPropertyNotFound : TPropertyNotFoundEvent;
    OnFindMethod : TFindMethodEvent;
    OnSetMethodProperty : TSetMethodPropertyEvent;
    OnSetName : TSetNameEvent;
    OnReferenceName : TReferenceNameEvent;
    OnAncestorNotFound : TAncestorNotFoundEvent;
    OnCreateComponent : TCreateComponentEvent;
    OnFindComponentClass : TFindComponentClassEvent;
    OnReadStringProperty : TReadWriteStringPropertyEvent;
  end
  ;

Description

The TReader class is a reader class that implements generic component streaming capabilities, independent of the format of the data in the stream. It uses a driver class TAbstractObjectReader to do the actual reading of data. The interface of the TReader class should be identical to the interface in Delphi.

Note that the TReader design is such that it can read a single component from a stream. It will read all children of this component, but it is not designed to read multiple components in succession from one stream.

It should never be necessary to create an instance of this class directly. Instead, the TStream.ReadComponent call should be used.

Members

Member	Type	Visibility	Description
BeginReferences	Method	public	Initializes the component referencing mechanism.
CanHandleExceptions	Property	protected	Indicates whether the reader is handling exceptions at this stage.
CheckValue	Method	public	Raises an exception if the next value in the stream is not of type Value
CopyValue	Method	public	Copy a value to a writer.
Create	Method	public	Creates a new reader class
CreateDriver	Method	protected
DefineBinaryProperty	Method	public	Reads a user-defined binary property from the stream.
DefineProperty	Method	public	Reads a user-defined property from the stream.
Destroy	Method	public	Destroys a reader class.
DoFixupReferences	Method	private
Driver	Property	public	The driver in use for streaming the data.
EndOfList	Method	public	Returns true if the stream contains an end-of-list marker.
EndReferences	Method	public	Finalizes the component referencing mechanism.
Error	Method	protected	Calls an installed error handler and passes it Message
FCanHandleExcepts	Field	private
FDriver	Field	private
FFixups	Field	private
FindComponentClass	Method	private
FindMethod	Method	protected	Return the address of a published method.
FixupReferences	Method	public	Tries to resolve all unresolved component references.
FLoaded	Field	private
FLock	Field	private
FlushBuffer	Method	public	Flush the buffer
FOnAncestorNotFound	Field	private
FOnCreateComponent	Field	private
FOnError	Field	private
FOnFindComponentClass	Field	private
FOnFindMethod	Field	private
FOnPropertyNotFound	Field	private
FOnReadStringProperty	Field	private
FOnReferenceName	Field	private
FOnSetMethodProperty	Field	private
FOnSetName	Field	private
FOwner	Field	private
FParent	Field	private
FPropName	Field	private
Lock	Method	private
NextValue	Method	public	Returns the type of the next value.
OnAncestorNotFound	Property	public	Handler called when the ancestor component cannot be found.
OnCreateComponent	Property	public	Handler called when a component needs to be created.
OnError	Property	public	Handler called when an error occurs.
OnFindComponentClass	Property	public	Handler called when a component class reference needs to be found.
OnFindMethod	Property	public	Handler to find or change a method address.
OnPropertyNotFound	Property	public	Handler for treating missing properties.
OnReadStringProperty	Property	public	Handler for translating strings when read from the stream.
OnReferenceName	Property	public	Handler called when another component is referenced.
OnSetMethodProperty	Property	public	Handler for setting method properties.
OnSetName	Property	public	Handler called when setting a component name.
Owner	Property	public	Owner of the component being read
Parent	Property	public	Parent of the component being read.
PropertyError	Method	protected	Skips a property value and raises an exception.
PropName	Property	protected	Name of the property being read at this moment.
Read	Method	public	Read raw data from stream
ReadBoolean	Method	public	Reads a boolean from the stream.
ReadChar	Method	public	Reads a character from the stream.
ReadCollection	Method	public	Reads a collection from the stream.
ReadComponent	Method	public	Starts reading a component from the stream.
ReadComponents	Method	public	Starts reading child components from the stream.
ReadCurrency	Method	public	Read a currency value from the stream.
ReadData	Method	protected	Reads the components data after it has been created.
ReadDate	Method	public	Reads a date from the stream
ReadFloat	Method	public	Reads a float from the stream.
ReadIdent	Method	public	Reads an identifier from the stream.
ReadInt64	Method	public	Reads a 64-bit integer from the stream.
ReadInteger	Method	public	Reads an integer from the stream
ReadListBegin	Method	public	Checks for the beginning of a list.
ReadListEnd	Method	public	Checks for the end of a list.
ReadProperty	Method	protected	Read and process a property name
ReadPropValue	Method	protected	Reads a property value for PropInfo.
ReadRootComponent	Method	public	Starts reading a root component.
ReadSet	Method	public	Read a set value from the stream
ReadSignature	Method	public	Read stream signature from the stream
ReadSingle	Method	public	Reads a single-type real from the stream.
ReadString	Method	public	Reads a string from the stream.
ReadUnicodeChar	Method	public	Read Unicode character
ReadUnicodeString	Method	public	Read a UnicodeString value from the stream
ReadValue	Method	public	Reads the next value type from the stream.
ReadVariant	Method	public	Read a variant from the stream
ReadWideChar	Method	public	Read widechar from the stream
ReadWideString	Method	public	Read a WideString value from the stream.
Unlock	Method	private

Inheritance

Class	Description
TReader	Generic reader object which reads component data from any given source.

See also

Name	Description
TAbstractObjectReader	Abstract driver class to read stored component data.
TAbstractObjectReader	Abstract driver class to read stored component data.
TAbstractObjectReader	Abstract driver class to read stored component data.
TAncestorNotFoundEvent	This event occurs when an ancestor component cannot be found.
TAncestorNotFoundEvent	This event occurs when an ancestor component cannot be found.
TComponent	Base class for all components that need owner-owned functionality.
TComponent	Base class for all components that need owner-owned functionality.
TComponent	Base class for all components that need owner-owned functionality.
TComponent	Base class for all components that need owner-owned functionality.
TCreateComponentEvent	Event handler type, occurs when a component instance must be created when a component is read from a stream.
TCreateComponentEvent	Event handler type, occurs when a component instance must be created when a component is read from a stream.
TFiler	Class responsible for streaming of components.
TFindComponentClassEvent	Event handler type, occurs when a component class pointer must be found when reading a component from a stream.
TFindComponentClassEvent	Event handler type, occurs when a component class pointer must be found when reading a component from a stream.
TFindMethodEvent	Occurs when the streaming process needs to locate a method
TFindMethodEvent	Occurs when the streaming process needs to locate a method
TFPList	Class to manage collections of pointers.
TObject	Base class of all classes.
TPropertyNotFoundEvent	Callback for the TReader.OnPropertyNotFound event.
TPropertyNotFoundEvent	Callback for the TReader.OnPropertyNotFound event.
TReaderError	Event handler type, called when an error occurs during the streaming.
TReaderError	Event handler type, called when an error occurs during the streaming.
TReadWriteStringPropertyEvent	Callback for the TReader.OnReadStringProperty event handler
TReadWriteStringPropertyEvent	Callback for the TReader.OnReadStringProperty event handler
TReferenceNameEvent	Occurs when a named object needs to be looked up.
TReferenceNameEvent	Occurs when a named object needs to be looked up.
TRTLCRITICALSECTION	A class for managing multiple threads
TSetMethodPropertyEvent	Callback for the TReader.OnSetMethodProperty event.
TSetMethodPropertyEvent	Callback for the TReader.OnSetMethodProperty event.
TSetNameEvent	Occurs when the reader needs to set a component's name.
TSetNameEvent	Occurs when the reader needs to set a component's name.
TWriter	Object to write component data to an arbitrary format.

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