An element has (1) a tagword, (2) a map of (name,value) pairs called attributes, and (3) a list of child nodes. More...

#include <Xml.h>

Inheritance diagram for SimTK::Xml::Element:

Public Member Functions
Construction and destruction
As discussed elsewhere, elements come in two varieties: value elements and compound elements. New value elements can be created easily since they are essentially just a name,value pair. Compound elements require a series of method calls to create the Element node and then add child nodes to it. In either case you may want to add attributes also.
	Element ()
	Create an empty Element handle; this is suitable only for holding references to other Elements. More...

	Element (const String &tagWord, const String &value="")
	Create a value element that uses the given tag word but is not yet part of any XML document, and optionally give it an inital value. More...

template<class T >
	Element (const String &tagWord, const T &value)
	Create a new value element and set its initial value to the text equivalent of any type T for which a conversion construction String(T) is allowed (generally any type for which a stream insertion operator<<() exists). More...

Element	clone () const
	The clone() method makes a deep copy of this Element and its children and returns a new orphan Element with the same contents; ordinary assignment and copy construction are shallow. More...

const String &	getElementTag () const
	Get the element tag word. More...

void	setElementTag (const String &tag)
	Change the tag word that is used to bracket this element. More...

void	insertNodeBefore (const node_iterator &pos, Node node)
	Insert a node into the list of this Element's children, just before the node pointed to by the supplied iterator (or at the end if the iterator is node_end()). More...

void	insertNodeAfter (const node_iterator &pos, Node node)
	Insert a node into the list of this Element's children, just after the node pointed to by the supplied iterator (or at the end if the iterator is node_end()). More...

void	eraseNode (const node_iterator &deleteThis)
	Delete the indicated node, which must be a child of this element, and must not be node_end(). More...

Node	removeNode (const node_iterator &removeThis)
	Remove the indicated node from this element without erasing it, returning it as an orphan Node. More...

Value elements
As described elsewhere, value elements are those that have no child elements and only a single Text node, whose contents can be considered as the element's value. Methods in this section allow you to work conveniently with value elements, getting direct access to the value string or interpreting it as some other type. You can easily modify the value by obtaining a writable refence to the String object that holds it. We provide methods for working with this element's value (if it is a value element) and with an element's children's values (if this element is compound).
bool	isValueElement () const
	Determine whether this element qualifies as a "value element", defined as an element containing zero or one Text nodes and no child elements. More...

const String &	getValue () const
	Get the text value of this value element. More...

String &	updValue ()
	Obtain a writable reference to the String containing the value of this value element. More...

void	setValue (const String &value)
	Set the text value of this value element. More...

template<class T >
void	setValueAs (const T &value)
	Set the value of this value element to the text equivalent of any type T for which a conversion construction String(T) is allowed (generally any type for which a stream insertion operator<<() exists). More...

template<class T >
T	getValueAs () const
	Assuming this is a "value element", convert its text value to the type of the template argument T. More...

template<class T >
void	getValueAs (T &out) const
	Alternate form of getValueAs() that avoids unnecessary copying and heap allocation for reading in large container objects. More...

const String &	getRequiredElementValue (const String &tag) const
	Get the text value of a child value element that must be present in this element. More...

String	getOptionalElementValue (const String &tag, const String &def="") const
	Get the text value of a child value element that may be present in this element, otherwise return a default string. More...

template<class T >
T	getRequiredElementValueAs (const String &tag) const
	Convert the text value of a required child value element to the type of the template argument T. More...

template<class T >
T	getOptionalElementValueAs (const String &tag, const T &def) const
	Convert the text value of an optional child value element, if present, to the type of the template argument T. More...

Attributes
You can add, modify, and remove element attributes with the methods in this section. You can work directly with individual attributes by name, or you can iterate through the list of attributes.
bool	hasAttribute (const String &name) const
	Return true if this element has an attribute of this name. More...

void	setAttributeValue (const String &name, const String &value)
	Set the value of an attribute of this element, creating a new one if this is a new attribute name otherwise modifying an existing one. More...

void	eraseAttribute (const String &name)
	Erase an attribute of this element if it exists, otherwise do nothing. More...

const String &	getRequiredAttributeValue (const String &name) const
	Get the value of an attribute as a string and throw an error if that attribute is not present. More...

template<class T >
T	getRequiredAttributeValueAs (const String &name) const
	Convert the text value of a required attribute to the type of the template argument T. More...

String	getOptionalAttributeValue (const String &name, const String &def="") const
	Get the value of an attribute as a string if the attribute is present in this element, otherwise return a supplied default value. More...

template<class T >
T	getOptionalAttributeValueAs (const String &name, const T &def) const
	Convert the value of an optional attribute, if present, from a string to the type of the template argument T. More...

Attribute	getRequiredAttribute (const String &name)
	Obtain an Attribute handle referencing a particular attribute of this element; an error will be thrown if no such attribute is present. More...

Attribute	getOptionalAttribute (const String &name)
	Obtain an Attribute handle referencing a particular attribute of this element specified by name, or an empty handle if no such attribute is present. More...

Array_< Attribute >	getAllAttributes ()
	Return an array containing Attribute handles referencing all the attributes of this element. More...

attribute_iterator	attribute_begin ()
	For iterating through all the attributes of this element. More...

attribute_iterator	attribute_end () const
	This attribute_end() iterator indicates the end of a sequence of attributes. More...

Compound elements
Many elements contain child nodes, including other elements. When there is just a single child Text node and no child elements, we call the element a "value element" and it is easiest to work with using the methods in the "Value elements" section. When there are child elements and/or multiple Text nodes, the element is called a "compound element" and you need a way to iterate and recurse through its contents. The methods in this section support looking through all contained nodes, nodes of specified types, element nodes, or element nodes with a specified tags. You can obtain handles to child Nodes or Elements and then iterate through those recursively.
bool	hasElement (const String &tag) const
	Return true if this element has a child element with this tag. More...

bool	hasNode (NodeType allowed=AnyNodes) const
	See if this element has any child nodes, or any child nodes of the type(s) allowed by the NodeType filter if one is supplied. More...

Element	getRequiredElement (const String &tag)
	Get a reference to a child element that must be present in this element. More...

Element	getOptionalElement (const String &tag)
	Get a reference to a child element that may be present in this element; otherwise return an invalid Element handle. More...

Array_< Element >	getAllElements (const String &tag="")
	Return an array containing Element handles referencing all the immediate child elements contained in this element, or all the child elements of a particular type (that is, with a given tag word). More...

Array_< Node >	getAllNodes (NodeType allowed=AnyNodes)
	Return an array containing Node handles referencing all the immediate child nodes contained in this element, or all the child nodes of a particular type or types. More...

element_iterator	element_begin (const String &tag="")
	For iterating through the immediate child elements of this element, or the child elements that have the indicated tag if one is supplied. More...

element_iterator	element_end () const
	This element_end() iterator indicates the end of any sequence of elements regardless of the tag restriction on the iterator being used. More...

node_iterator	node_begin (NodeType allowed=AnyNodes)
	For iterating through the immediate child nodes of this element, or the child nodes of the type(s) allowed by the NodeType filter if one is supplied. More...

node_iterator	node_end () const
	This node_end() iterator indicates the end of any sequence of nodes regardless of the NodeType restriction on the iterator being used. More...

Public Member Functions inherited from SimTK::Xml::Node
bool	operator== (const Node &other) const
	Comparing Nodes for equality means asking if the two Node handles are referring to exactly the same object; two different nodes that happen to have the same properties will not test equal by this criteria. More...

bool	operator!= (const Node &other) const
	Inequality test using same criteria as operator==(). More...

	Node ()
	Create an empty Node handle that can be used to hold a reference to any kind of Node. More...

	Node (const Node &src)
	Copy constructor is shallow; that is, this handle will refer to the same node as the source. More...

Node &	operator= (const Node &src)
	Copy assignment is shallow; the handle is first cleared and then will refer to the same node as the source. More...

Node	clone () const
	The clone() method makes a deep copy of this Node and its children and returns a new orphan Node with the same contents; ordinary assignment and copy construction is shallow. More...

	~Node ()
	The Node handle destructor does not recover heap space so if you create orphan nodes and then don't put them in a document there will be a memory leak unless you explicitly destruct them first with clearOrphan(). More...

void	clear ()
	This method restores the Node handle to its default-constructed state but does not recover any heap space; use clearOrphan() if you know this node was never put into a document. More...

void	clearOrphan ()
	This method explictly frees the heap space for an orphan node that was created but never inserted into a document. More...

NodeType	getNodeType () const
	Get the Xml::NodeType of this node. More...

String	getNodeTypeAsString () const
	Get the Node type as a string; an empty handle returns "NoNode". More...

bool	isValid () const
	Return true if this Node handle is referencing some node, false if the Node handle is empty. More...

bool	isTopLevelNode () const
	Return true if this Node is owned by the top-level Xml document, false if the Node is owned by an Element or is an orphan, or if the Node handle is empty. More...

bool	isOrphan () const
	Return true if this Node is an orphan, meaning that it is not empty, but is not owned by any element or top-level document. More...

bool	hasParentElement () const
	Return true if this node has a parent, i.e. More...

Element	getParentElement ()
	Return a handle referencing this node's parent if it has one, otherwise throws an error; check first with hasParentElement() if you aren't sure. More...

const String &	getNodeText () const
	Return a text value associated with this Node (not including its child nodes if any); the behavior depends on the NodeType. More...

void	writeToString (String &out, bool compact=false) const
	Serialize this node (and everything it contains) to the given String. More...

Static Public Member Functions
Conversion to Element from Node
If you have a handle to a Node, such as would be returned by a node_iterator, you can check whether that Node is an Element and if so cast it to one.
static bool	isA (const Node &)
	Test whether a given Node is an element node. More...

static const Element &	getAs (const Node &node)
	Recast a Node to a const Element, throwing an error if the Node is not actually an element node. More...

static Element &	getAs (Node &node)
	Recast a writable Node to a writable Element, throwing an error if the Node is not actually an element node. More...

Friends
class	Xml::Node

class	Xml::element_iterator

Additional Inherited Members
Related Functions inherited from SimTK::Xml::Node
std::ostream &	operator<< (std::ostream &o, const Xml::Node &xmlNode)
	Output a "pretty printed" textual representation of the given XML node (and all its contents) to an std::ostream. More...

Detailed Description

An element has (1) a tagword, (2) a map of (name,value) pairs called attributes, and (3) a list of child nodes.

The tag word, which begins with an underscore or a letter, can serve as either the type or the name of the element depending on context. The nodes can be comments, unknowns, text, and child elements (recursively). It is common for "leaf" elements (elements with no child elements) to be supplied simply for their values, for example mass might be provided via an element "<mass> 29.3 </mass>". We call such elements "value elements" since they have a uniquely identifiable value similar to that of attributes. Value elements have no more than one text node. They may have attributes, and may also have comment and unknown nodes but they cannot have any child elements. This class provides a special set of methods for dealing with value nodes very conveniently; they will fail if you attempt to use them on an element that is not a value element.

Constructor & Destructor Documentation

SimTK::Xml::Element::Element ( )

inline

Create an empty Element handle; this is suitable only for holding references to other Elements.

SimTK::Xml::Element::Element	(	const String &	tagWord,
		const String &	value = `""`
	)

explicit

Create a value element that uses the given tag word but is not yet part of any XML document, and optionally give it an inital value.

Note that although you provide the initial value as a string, you can access it as any type T to which that string can be converted, using the getValueAs<T>() templatized method.

If no initial value is provided, then the element will be empty so would print as "<tagWord />". If you provide a value (say "contents") here or add one later, it will print as "<tagWord>contents</tagWord>". In general you can add child elements and other node types with subsequent method calls; that would change this element from a value element to a compound element.

See Also: getValue(), updValue(), setValue()

template<class T >

SimTK::Xml::Element::Element	(	const String &	tagWord,
		const T &	value
	)

inline

Create a new value element and set its initial value to the text equivalent of any type T for which a conversion construction String(T) is allowed (generally any type for which a stream insertion operator<<() exists).

See Also: getValueAs<T>(), setValueAs<T>()

Member Function Documentation

Element SimTK::Xml::Element::clone ( ) const

The clone() method makes a deep copy of this Element and its children and returns a new orphan Element with the same contents; ordinary assignment and copy construction are shallow.

const String& SimTK::Xml::Element::getElementTag ( ) const

Get the element tag word.

This may represent the name or type of the element depending on context.

void SimTK::Xml::Element::setElementTag ( const String & tag )

Change the tag word that is used to bracket this element.

void SimTK::Xml::Element::insertNodeBefore	(	const node_iterator &	pos,
		Node	node
	)

Insert a node into the list of this Element's children, just before the node pointed to by the supplied iterator (or at the end if the iterator is node_end()).

The iterator must refer to a node that is a child of this Element. This Element takes over ownership of the node which must not already have a parent.

void SimTK::Xml::Element::insertNodeAfter	(	const node_iterator &	pos,
		Node	node
	)

Insert a node into the list of this Element's children, just after the node pointed to by the supplied iterator (or at the end if the iterator is node_end()).

The iterator must refer to a node that is a child of this Element. This Element takes over ownership of the node which must not already have a parent.

void SimTK::Xml::Element::eraseNode ( const node_iterator & deleteThis )

Delete the indicated node, which must be a child of this element, and must not be node_end().

The node will be removed from this element and deleted. The iterator is invalid after this call; be sure not to use it again. Also, there must not be any handles referencing the now-deleted node.

Node SimTK::Xml::Element::removeNode ( const node_iterator & removeThis )

Remove the indicated node from this element without erasing it, returning it as an orphan Node.

The node must be a child of this element, and must not be node_end(). The node will be removed from this element and returned as an orphan. The iterator is invalid after this call; be sure not to use it again.

bool SimTK::Xml::Element::isValueElement ( ) const

Determine whether this element qualifies as a "value element", defined as an element containing zero or one Text nodes and no child elements.

You can treat a value element as you would an attribute – it can be viewed as having a single value, which is just the value of its lone Text node (or a null string if it doesn't have any text).

const String& SimTK::Xml::Element::getValue ( ) const

Get the text value of this value element.

An error will be thrown if this is not a "value element". See the comments for this class for the definition of a "value element".

Note: This does not return the same text as the base class method Node::getNodeText() does in the case of an element node; that returns the element tag word not its contents.

See Also: isValueElement(), setValue(), updValue()

String& SimTK::Xml::Element::updValue ( )

Obtain a writable reference to the String containing the value of this value element.

An error will be thrown if this is not a value element. If the element was initially empty and didn't contain a Text node, one will be added to it here with a null-string value so that we can return a reference to it.

See Also: isValueElement(), getValue()

void SimTK::Xml::Element::setValue ( const String & value )

Set the text value of this value element.

An error will be thrown if this is not a value element. If the element was initially empty and didn't contain a Text node, one will be added to it here so that we have a place to hold the value.

See Also: isValueElement(), setValueAs<T>()

template<class T >

void SimTK::Xml::Element::setValueAs ( const T & value )

inline

Set the value of this value element to the text equivalent of any type T for which a conversion construction String(T) is allowed (generally any type for which a stream insertion operator<<() exists).

template<class T >

T SimTK::Xml::Element::getValueAs ( ) const

inline

Assuming this is a "value element", convert its text value to the type of the template argument T.

It is an error if the text can not be converted, in its entirety, to a single object of type T. (But note that type T may be a container of some sort, like a Vector or Array.)

Template Parameters

T	A type that can be read from a stream using the ">>" operator.

template<class T >

void SimTK::Xml::Element::getValueAs ( T & out ) const

inline

Alternate form of getValueAs() that avoids unnecessary copying and heap allocation for reading in large container objects.

const String& SimTK::Xml::Element::getRequiredElementValue ( const String & tag ) const

inline

Get the text value of a child value element that must be present in this element.

The child is identified by its tag; if there is more than one this refers to the first one. Then the element is expected to contain either zero or one Text nodes; if none we'll return a null string, otherwise the value of the Text node. Thus an element like "<tag>stuff</tag>" will have the value "stuff". An error will be thrown if either the element is not found or it is not a "value element".

String SimTK::Xml::Element::getOptionalElementValue	(	const String &	tag,
		const String &	def = `""`
	)		const

inline

Get the text value of a child value element that may be present in this element, otherwise return a default string.

If the child element is found, it must be a "value element" as defined above.

template<class T >

T SimTK::Xml::Element::getRequiredElementValueAs ( const String & tag ) const

inline

Convert the text value of a required child value element to the type of the template argument T.

It is an error if the element is present but is not a value element, or if the text cannot be converted, in its entirety, to a single object of type T. (But note that type T may be a container of some sort, like a Vector or Array.)

Template Parameters

T	A type that can be read from a stream using the ">>" operator.

Parameters

[in] tag The tag of the required child text element.

Returns: The value of the text element, converted to an object of type T.

template<class T >

T SimTK::Xml::Element::getOptionalElementValueAs	(	const String &	tag,
		const T &	def
	)		const

inline

Convert the text value of an optional child value element, if present, to the type of the template argument T.

It is an error if the child element is present but is not a value element, or if the text cannot be converted, in its entirety, to a single object of type T. (But note that type T may be a container of some sort, like a Vector or Array.) If the child element is not present, then return a supplied default value of type T.

Template Parameters

T	A type that can be read from a stream with operator ">>".

Parameters

[in]	tag	The tag of the optional child element.
[in]	def	The value of type T to return if child element is missing.

Returns: The value of element tag if it is present, otherwise a copy of the supplied default value def.

bool SimTK::Xml::Element::hasAttribute ( const String & name ) const

Return true if this element has an attribute of this name.

void SimTK::Xml::Element::setAttributeValue	(	const String &	name,
		const String &	value
	)

Set the value of an attribute of this element, creating a new one if this is a new attribute name otherwise modifying an existing one.

void SimTK::Xml::Element::eraseAttribute ( const String & name )

Erase an attribute of this element if it exists, otherwise do nothing.

If you need to know if the attribute exists, use hasAttribute(). There is no removeAttribute() that orphans an existing Attribute, but you can easily recreate one with the same name and value.

const String& SimTK::Xml::Element::getRequiredAttributeValue ( const String & name ) const

inline

Get the value of an attribute as a string and throw an error if that attribute is not present.

template<class T >

T SimTK::Xml::Element::getRequiredAttributeValueAs ( const String & name ) const

inline

Convert the text value of a required attribute to the type of the template argument T.

It is an error if the text can not be converted, in its entirety, to a single object of type T. (But note that type T may be a container of some sort, like a Vec3.)

Template Parameters

T	A type that can be read from a stream using the ">>" operator.

String SimTK::Xml::Element::getOptionalAttributeValue	(	const String &	name,
		const String &	def = `""`
	)		const

inline

Get the value of an attribute as a string if the attribute is present in this element, otherwise return a supplied default value.

Parameters

[in]	name	The name of the optional attribute.
[in]	def	The string to return if the attribute is missing.

Returns: The value of attribute name if it is present, otherwise a copy of the supplied default string def.

template<class T >

T SimTK::Xml::Element::getOptionalAttributeValueAs	(	const String &	name,
		const T &	def
	)		const

inline

Convert the value of an optional attribute, if present, from a string to the type of the template argument T.

It is an error if the text can not be converted, in its entirety, to a single object of type T. (But note that type T may be a container of some sort, like a Vec3.) If the attribute is not present, then return a supplied default value of type T.

Template Parameters

T	A type that can be read from a stream with operator ">>".

Parameters

[in]	name	The name of the optional attribute.
[in]	def	The value of type T to return if the attribute is missing.

Returns: The value of attribute name if it is present, otherwise a copy of the supplied default value def.

Attribute SimTK::Xml::Element::getRequiredAttribute ( const String & name )

Obtain an Attribute handle referencing a particular attribute of this element; an error will be thrown if no such attribute is present.

Attribute SimTK::Xml::Element::getOptionalAttribute ( const String & name )

Obtain an Attribute handle referencing a particular attribute of this element specified by name, or an empty handle if no such attribute is present.

Array_<Attribute> SimTK::Xml::Element::getAllAttributes ( )

inline

Return an array containing Attribute handles referencing all the attributes of this element.

Attributes are returned in the order that they appear in the element tag. Attribute names within a tag are unique; if the source document had repeated attribute names only the last one to appear is retained and that's the only one we'll find here. This is just a shortcut for

Array_<Attribute>(attribute_begin(), attribute_end());

attribute_iterator SimTK::Xml::Element::attribute_begin ( )

For iterating through all the attributes of this element.

If there are no attributes then the returned attribute_iterator tests equal to attribute_end().

attribute_iterator SimTK::Xml::Element::attribute_end ( ) const

This attribute_end() iterator indicates the end of a sequence of attributes.

bool SimTK::Xml::Element::hasElement ( const String & tag ) const

Return true if this element has a child element with this tag.

bool SimTK::Xml::Element::hasNode ( NodeType allowed = AnyNodes ) const

See if this element has any child nodes, or any child nodes of the type(s) allowed by the NodeType filter if one is supplied.

Element SimTK::Xml::Element::getRequiredElement ( const String & tag )

Get a reference to a child element that must be present in this element.

The child is identified by its tag; if there is more than one only the first one is returned. If you want to see all children with this tag, use getAllElements() or use an element_iterator.

Element SimTK::Xml::Element::getOptionalElement ( const String & tag )

Get a reference to a child element that may be present in this element; otherwise return an invalid Element handle.

Test using the Element's isValid() method.

Array_<Element> SimTK::Xml::Element::getAllElements ( const String & tag = "" )

inline

Return an array containing Element handles referencing all the immediate child elements contained in this element, or all the child elements of a particular type (that is, with a given tag word).

Elements are returned in the order they are seen in the document. This is just a shortcut for

Array_<Element>(element_begin(tag), element_end());

Array_<Node> SimTK::Xml::Element::getAllNodes ( NodeType allowed = AnyNodes )

inline

Return an array containing Node handles referencing all the immediate child nodes contained in this element, or all the child nodes of a particular type or types.

Nodes are returned in the order they are seen in the document. This is just a shortcut for

Array_<Node>(node_begin(allowed), node_end());

element_iterator SimTK::Xml::Element::element_begin ( const String & tag = "" )

For iterating through the immediate child elements of this element, or the child elements that have the indicated tag if one is supplied.

If there are no children with the allowed tag then the returned element_iterator tests equal to element_end().

element_iterator SimTK::Xml::Element::element_end ( ) const

This element_end() iterator indicates the end of any sequence of elements regardless of the tag restriction on the iterator being used.

node_iterator SimTK::Xml::Element::node_begin ( NodeType allowed = AnyNodes )

For iterating through the immediate child nodes of this element, or the child nodes of the type(s) allowed by the NodeType filter if one is supplied.

If there are no children of the allowed types then the returned node_iterator tests equal to node_end().

node_iterator SimTK::Xml::Element::node_end ( ) const

This node_end() iterator indicates the end of any sequence of nodes regardless of the NodeType restriction on the iterator being used.

static bool SimTK::Xml::Element::isA ( const Node & )

static

Test whether a given Node is an element node.

static const Element& SimTK::Xml::Element::getAs ( const Node & node )

static

Recast a Node to a const Element, throwing an error if the Node is not actually an element node.

See Also: isA()

static Element& SimTK::Xml::Element::getAs ( Node & node )

static

Recast a writable Node to a writable Element, throwing an error if the Node is not actually an element node.

See Also: isA()

Friends And Related Function Documentation

friend class Xml::Node

friend

friend class Xml::element_iterator

friend

The documentation for this class was generated from the following file:

Xml.h

Public Member Functions

Static Public Member Functions

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation