Castle Game Engine: X3DNodes: Class TMFNode

# Class TMFNode
Description | Hierarchy | Fields | Methods | Properties
## Unit X3DNodes ## Declaration `type TMFNode = class(TX3DMultField)` ## Description VRML/X3D field holding a list of nodes. Just like SFNode, it's defined in this unit, as it uses TX3DNode. Note that items of MFNode cannot be nil (i.e. VRML/X3D doesn't allow to use NULL inside MFNode), contrary to SFNode. Note that `TMFNode` implementation doesn't use TX3DSimpleMultField. One reason is that we don't want to parse MFNode items by SFNode parser, because MFNode doesn't allow NULL items. (In the past, another argument was that we want to use TX3DNodeList and it wasn't compatible with TX3DSimpleMultField. But now TX3DNodeList descends from TFPSList, so it isn't a problem.) Just like for TSFNode: Note that we store AllowedChildren list, which is a list of classes allowed as Items. But this is used only to produce warnings for a user. You should never assert that every item actually is one the requested classes. ## Hierarchy TPersistent TNonRefCountedInterfacedPersistent TX3DFileItem TX3DFieldOrEvent TX3DField TX3DMultField TMFNode ## Overview ### Methods
| `procedure SaveToStreamValue(Writer: TX3DWriter); override;`
| `function SaveToXmlValue: TSaveToXmlMethod; override;`
| `function GetCount: Integer; override;`
| `procedure SetCount(const Value: Integer); override;`
| `constructor CreateUndefined(AParentNode: TX3DFileItem; const AName: string; const AExposed: boolean); override;`
| `constructor Create(AParentNode: TX3DNode; const AName: string; const AAllowedChildrenClasses: array of TX3DNodeClass); overload;`
| `constructor Create(AParentNode: TX3DNode; const AName: string; AAllowedChildrenClasses: TX3DNodeClassesList); overload;`
| `constructor Create(AParentNode: TX3DNode; const AName: string; AnAllowedChildrenInterface: TGUID); overload;`
| `destructor Destroy; override;`
| `procedure Add(Node: TX3DNode); overload;`
| `procedure Add(Position: Integer; Node: TX3DNode); overload;`
| `procedure Delete(Index: Integer);`
| `function Remove(const Node: TX3DNode): Integer;`
| `function Extract(Index: Integer): TX3DNode;`
| `procedure Clear;`
| `procedure AssignItems(SourceItems: TX3DNodeList);`
| `procedure Replace(Index: Integer; Node: TX3DNode);`
| `procedure ParseValue(Lexer: TX3DLexer; Reader: TX3DReader); override;`
| `procedure ParseXMLAttribute(const AttributeValue: string; Reader: TX3DReader); override;`
| `procedure ParseXMLElement(Element: TDOMElement; Reader: TX3DReader); override;`
| `function EqualsDefaultValue: boolean; override;`
| `function Equals(SecondValue: TX3DField; const EqualityEpsilon: Double): boolean; override;`
| `procedure Assign(Source: TPersistent); override;`
| `procedure AssignValue(Source: TX3DField); override;`
| `procedure AssignDefaultValueFromValue; override;`
| `class function TypeName: string; override;`
| `class function CreateEvent(const AParentNode: TX3DFileItem; const AName: string; const AInEvent: boolean): TX3DEvent; override;`
| `procedure WarningIfChildNotAllowed(Child: TX3DNode);`
| `function ChildAllowed(Child: TX3DNode): boolean;`
| `procedure AssignDefaultItems(SourceItems: TX3DNodeList);`
| `procedure ClearDefault;`
| `procedure EnumerateValid(Func: TEnumerateChildrenFunction);`
### Properties
| `property Items: TX3DNodeList read FItems;`
| `property ItemsArray[Index:Integer]: TX3DNode read GetItems;`
| `property ParentNode: TX3DNode read FParentNode;`
| `property DefaultItems: TX3DNodeList read FDefaultItems;`
| `property DefaultValueExists: boolean read FDefaultValueExists write FDefaultValueExists default false;`
## Description ### Methods
| `procedure SaveToStreamValue(Writer: TX3DWriter); override;`
| `function SaveToXmlValue: TSaveToXmlMethod; override;`
| `function GetCount: Integer; override;`
Get or set the number of items. When increasing this, remember that new items of TMFNode will be `Nil`. You must immediately initialize them to something else then `Nil` by the Replace method. Other TMFNode methods, and outside code working with MFNodes, usually assumes that all MFNode children are non-nil. (As VRML/X3D spec don't really allow NULL items inside MFNode fields.)
| `procedure SetCount(const Value: Integer); override;`
| `constructor CreateUndefined(AParentNode: TX3DFileItem; const AName: string; const AExposed: boolean); override;`
Construct a field allowing any children class. Suitable only for special cases. For example, in instantiated prototypes, we must initially just allow all children, otherwise valid prototypes with SFNode/MFNode would cause warnings when parsing.
| `constructor Create(AParentNode: TX3DNode; const AName: string; const AAllowedChildrenClasses: array of TX3DNodeClass); overload;`
| `constructor Create(AParentNode: TX3DNode; const AName: string; AAllowedChildrenClasses: TX3DNodeClassesList); overload;`
Constructor that takes a list of allowed children classes. Note that we copy the contents of AAllowedChildrenClasses, not the reference.
| `constructor Create(AParentNode: TX3DNode; const AName: string; AnAllowedChildrenInterface: TGUID); overload;`
Constructor that allows as children any implementor of given interface.
| `destructor Destroy; override;`
| `procedure Add(Node: TX3DNode); overload;`
| `procedure Add(Position: Integer; Node: TX3DNode); overload;`
| `procedure Delete(Index: Integer);`
| `function Remove(const Node: TX3DNode): Integer;`
Search list for given node, and, if found, remove it. Returns the index of removed item, or -1 if not found.
| `function Extract(Index: Integer): TX3DNode;`
Remove child with given Index, and return it, never freeing it. This is analogous to TX3DNode.ExtractChild, see there for more explanation.
| `procedure Clear;`
| `procedure AssignItems(SourceItems: TX3DNodeList);`
| `procedure Replace(Index: Integer; Node: TX3DNode);`
| `procedure ParseValue(Lexer: TX3DLexer; Reader: TX3DReader); override;`
| `procedure ParseXMLAttribute(const AttributeValue: string; Reader: TX3DReader); override;`
| `procedure ParseXMLElement(Element: TDOMElement; Reader: TX3DReader); override;`
| `function EqualsDefaultValue: boolean; override;`
| `function Equals(SecondValue: TX3DField; const EqualityEpsilon: Double): boolean; override;`
| `procedure Assign(Source: TPersistent); override;`
| `procedure AssignValue(Source: TX3DField); override;`
| `procedure AssignDefaultValueFromValue; override;`
| `class function TypeName: string; override;`
| `class function CreateEvent(const AParentNode: TX3DFileItem; const AName: string; const AInEvent: boolean): TX3DEvent; override;`
| `procedure WarningIfChildNotAllowed(Child: TX3DNode);`
Checks is Child allowed on the list of nodes of this MFNode, and makes OnWarning if not. Check is allowed is done looking at AllowedChildrenAll and AllowedChildren properties. Child must not be `Nil`. OnWarning message will suggest that this Child is added to this node. In other words, you should only pass as Child a node that you want to add (e.g. by Add) to this field, otherwise OnWarning message will be a little unsensible.
| `function ChildAllowed(Child: TX3DNode): boolean;`
| `procedure AssignDefaultItems(SourceItems: TX3DNodeList);`
Operate on DefaultItems, just like analogous AssignItems and Clear.
| `procedure ClearDefault;`
| `procedure EnumerateValid(Func: TEnumerateChildrenFunction);`
Calls Func for all current children that are valid (allowed by ChildAllowed). The main use for this is to simplify implementation of TX3DNode.DirectEnumerateActive overrides in TX3DNode descendants.
### Properties
| `property Items: TX3DNodeList read FItems;`
Lists items of this field. Do not modify this list explicitly. Use only methods in this class like Add. They take care of calling appropriate AddParentField / RemoveParentField, otherwise you could break reference-counting of nodes by ParentFields.
| `property ItemsArray[Index:Integer]: TX3DNode read GetItems;`
| `property ParentNode: TX3DNode read FParentNode;`
| `property DefaultItems: TX3DNodeList read FDefaultItems;`
Lists default items of this field. Do not modify this list explicitly. Use only methods in this class like AssignDefaultItems (they take care of calling appropriate AddParentField / RemoveParentField, otherwise you could break reference-counting of nodes by ParentFields).
| `property DefaultValueExists: boolean read FDefaultValueExists write FDefaultValueExists default false;`
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