StructureNode Class Reference

An E57 element containing named child nodes. More...

List of all members.

Public Member Functions
	StructureNode (ImageFile destImageFile)
	Create an empty StructureNode.
int64_t	childCount () const
	Return number of child nodes contained by this StructureNode.
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 by path name.
void	set (const ustring &pathName, Node n)
	Add a new child at a given path.
	operator Node () const
	Upcast a StructureNode handle to a generic Node handle.
	StructureNode (const Node &n)
	Downcast a generic Node handle to a StructureNode 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 StructureNode class invariant is true.

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Detailed Description

An E57 element containing named child nodes.

A StructureNode is a container of named child nodes, which may be any of the eight node types. The children of a structure node must have unique elementNames. Once a child node is set with a particular elementName, it may not be modified.

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 consistancy and throws an exception if the invariant is violated:

void StructureNode::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 StructureNode::checkInvariant

See also:

Node