VectorNode Class Reference

An E57 element containing ordered vector of child nodes. More...

List of all members.

Public Member Functions
	VectorNode (ImageFile destImageFile, bool allowHeteroChildren=false)
	Create a new empty Vector node.
bool	allowHeteroChildren () const
	Get whether child elements are allowed to be different types?
int64_t	childCount () const
	Get number of child elements in this VectorNode.
bool	isDefined (const ustring &pathName) const
	Is the given pathName defined relative to this node.
Node	get (int64_t index) const
	Get a child element by positional index.
Node	get (const ustring &pathName) const
	Get a child element by string path name.
void	append (Node n)
	Append a child element to end of VectorNode.
	operator Node () const
	Upcast a VectorNode handle to a generic Node handle.
	VectorNode (const Node &n)
	Downcast a generic Node handle to a VectorNode handle.
bool	isRoot () const
	Is this a root node.
Node	parent () const
	Return parent of node, or self if a root node.
ustring	pathName () const
	Get absolute pathname of node.
ustring	elementName () const
	Get elementName string, that identifies the node in its parent..
ImageFile	destImageFile () const
	Get the ImageFile that was declared as the destination for the node when it was created.
bool	isAttached () const
	Has node been attached into the tree of an ImageFile.
void	dump (int indent=0, std::ostream &os=std::cout) const
	Diagnostic function to print internal state of object to output stream in an indented format.
void	checkInvariant (bool doRecurse=true, bool doUpcast=true)
	Check whether VectorNode class invariant is true.

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Detailed Description

An E57 element containing ordered vector of child nodes.

A VectorNode is a container of ordered child nodes. The child nodes are automatically assigned an elementName, which is a string version of the positional index of the child starting at "0". Child nodes may only be appended onto the end of a VectorNode.

A VectorNode that is created with a restriction that its children must have the same type is called a "homogeneous VectorNode". A VectorNode without such a restriction is called a "heterogeneous VectorNode".

See Node class discussion for discussion of the common functions that StructureNode supports.

Class Invariant

A class invariant is a list of statements about an object that are always true before and after any operation on the object. An invariant is useful for testing correct operation of an implementation. Statements in an invariant can involve only externally visible state, or can refer to internal implementation-specific state that is not visible to the API user. The following C++ code checks externally visible state for consistency and throws an exception if the invariant is violated:

void VectorNode::checkInvariant(bool doRecurse, bool doUpcast) {
    // If destImageFile not open, can't test invariant (almost every call would throw)
    if (!destImageFile().isOpen())
        return;

    // If requested, call Node::checkInvariant
    if (doUpcast)
        static_cast<Node>(*this).checkInvariant(false, false);

    // Check each child
    for (int64_t i = 0; i < childCount(); i++) {
        Node child = get(i);

        // If requested, check children recursively
        if (doRecurse)
            child.checkInvariant(doRecurse, true);

        // Child's parent must be this
        if (static_cast<Node>(*this) != child.parent())
           throw E57_EXCEPTION1(E57_ERROR_INVARIANCE_VIOLATION);

        // Child's elementName must be defined
        if (!isDefined(child.elementName()))
           throw E57_EXCEPTION1(E57_ERROR_INVARIANCE_VIOLATION);

        // Getting child by element name must yield same child
        Node n = get(child.elementName());
        if (n != child)
           throw E57_EXCEPTION1(E57_ERROR_INVARIANCE_VIOLATION);
    }
} // end VectorNode::checkInvariant

See also:

Node