File	Doc	Category	Size	Date	Package
HTMLCollectionImpl.java	API Doc	Apache Xerces 3.0.1	19148	Fri Sep 14 20:33:54 BST 2007	org.apache.html.dom

HTMLCollectionImpl

• java.lang.Object

Fields Summary
static final short	ANCHOR Request collection of all anchors in document: <A> elements that have a name attribute.
static final short	FORM Request collection of all forms in document: <FORM> elements.
static final short	IMAGE Request collection of all images in document: <IMAGE> elements.
static final short	APPLET Request collection of all Applets in document: <APPLET> and <OBJECT> elements (<OBJECT> must contain an Applet).
static final short	LINK Request collection of all links in document: <A> and <AREA> elements (must have a href attribute).
static final short	OPTION Request collection of all options in selection: <OPTION> elments in <SELECT> or <OPTGROUP>.
static final short	ROW Request collection of all rows in table: <TR> elements in table or table section.
static final short	ELEMENT Request collection of all form elements: <INPUT>, <BUTTON>, <SELECT>, <TEXT> and <TEXTAREA> elements inside form <FORM>.
static final short	AREA Request collection of all areas in map: <AREA> element in <MAP> (non recursive).
static final short	TBODY Request collection of all table bodies in table: <TBODY> element in table <TABLE> (non recursive).
static final short	CELL Request collection of all cells in row: <TD> elements in <TR> (non recursive).
private short	_lookingFor Indicates what this collection is looking for. Holds one of the enumerated values and used by {@link #collectionMatch}. Set by the constructor and determine the collection's use for its life time.
private Element	_topLevel This is the top level element underneath which the collection exists.

Constructors Summary

HTMLCollectionImpl(HTMLElement topLevel, short lookingFor) Construct a new collection that retrieves element of the specific type (lookingFor) from the specific document portion (topLevel). param topLevel The element underneath which the collection exists param lookingFor Code indicating what elements to look for if ( topLevel == null ) throw new NullPointerException( "HTM011 Argument 'topLevel' is null." ); _topLevel = topLevel; _lookingFor = lookingFor;

Methods Summary
protected boolean	collectionMatch(org.w3c.dom.Element elem, java.lang.String name) Determines if current element matches based on what we're looking for. The element is passed along with an optional identifier name. If the element is the one we're looking for, return true. If the name is also specified, the name must match the id attribute (match name first for anchors). param elem The current element param name The identifier name or null return The element matches what we're looking for boolean match; synchronized ( elem ) { // Begin with no matching. Depending on what we're looking for, // attempt to match based on the element type. This is the quickest // way to match involving only a cast. Do the expensive string // comparison later on. match = false; switch ( _lookingFor ) { case ANCHOR: // Anchor is an <A> element with a 'name' attribute. Otherwise, it's // just a link. match = ( elem instanceof HTMLAnchorElement ) && elem.getAttribute( "name" ).length() > 0; break; case FORM: // Any <FORM> element. match = ( elem instanceof HTMLFormElement ); break; case IMAGE: // Any <IMG> element. <OBJECT> elements with images are not returned. match = ( elem instanceof HTMLImageElement ); break; case APPLET: // Any <APPLET> element, and any <OBJECT> element which represents an // Applet. This is determined by 'codetype' attribute being // 'application/java' or 'classid' attribute starting with 'java:'. match = ( elem instanceof HTMLAppletElement ) || ( elem instanceof HTMLObjectElement && ( "application/java".equals( elem.getAttribute( "codetype" ) ) || elem.getAttribute( "classid" ).startsWith( "java:" ) ) ); break; case ELEMENT: // All form elements implement HTMLFormControl for easy identification. match = ( elem instanceof HTMLFormControl ); break; case LINK: // Any <A> element, and any <AREA> elements with an 'href' attribute. match = ( ( elem instanceof HTMLAnchorElement || elem instanceof HTMLAreaElement ) && elem.getAttribute( "href" ).length() > 0 ); break; case AREA: // Any <AREA> element. match = ( elem instanceof HTMLAreaElement ); break; case OPTION: // Any <OPTION> element. match = ( elem instanceof HTMLOptionElement ); break; case ROW: // Any <TR> element. match = ( elem instanceof HTMLTableRowElement ); break; case TBODY: // Any <TBODY> element (one of three table section types). match = ( elem instanceof HTMLTableSectionElement && elem.getTagName().equals( "TBODY" ) ); break; case CELL: // Any <TD> element. match = ( elem instanceof HTMLTableCellElement ); break; } // If element type was matched and a name was specified, must also match // the name against either the 'id' or the 'name' attribute. The 'name' // attribute is relevant only for <A> elements for backward compatibility. if ( match && name != null ) { // If an anchor and 'name' attribute matches, return true. Otherwise, // try 'id' attribute. if ( elem instanceof HTMLAnchorElement && name.equals( elem.getAttribute( "name" ) ) ) return true; match = name.equals( elem.getAttribute( "id" ) ); } } return match;
public final int	getLength() Returns the length of the collection. This method might traverse the entire document tree. return Length of the collection // Call recursive function on top-level element. return getLength( _topLevel );
private int	getLength(org.w3c.dom.Element topLevel) Recursive function returns the number of elements of a particular type that exist under the top level element. This is a recursive function and the top level element is passed along. param topLevel Top level element from which to scan return Number of elements int length; Node node; synchronized ( topLevel ) { // Always count from zero and traverse all the childs of the // current element in the order they appear. length = 0; node = topLevel.getFirstChild(); while ( node != null ) { // If a particular node is an element (could be HTML or XML), // do two things: if it's the one we're looking for, count // another matched element; at any rate, traverse it's // children as well. if ( node instanceof Element ) { if ( collectionMatch( (Element) node, null ) ) ++ length; else if ( recurse() ) length += getLength( (Element) node ); } node = node.getNextSibling(); } } return length;
public final org.w3c.dom.Node	item(int index) Retrieves the indexed node from the collection. Nodes are numbered in tree order - depth-first traversal order. This method might traverse the entire document tree. param index The index of the node to return return The specified node or null if no such node found if ( index < 0 ) throw new IllegalArgumentException( "HTM012 Argument 'index' is negative." ); // Call recursive function on top-level element. return item( _topLevel, new CollectionIndex( index ) );
private org.w3c.dom.Node	item(org.w3c.dom.Element topLevel, org.apache.html.dom.CollectionIndex index) Recursive function returns the numbered element of a particular type that exist under the top level element. This is a recursive function and the top level element is passed along. Note that this function must call itself with an index and get back both the element (if one was found) and the new index which is decremeneted for any like element found. Since integers are only passed by value, this function makes use of a separate class ({@link CollectionIndex}) to hold that index. param topLevel Top level element from which to scan param index The index of the item to retreive return Number of elements see CollectionIndex Node node; Node result; synchronized ( topLevel ) { // Traverse all the childs of the current element in the order // they appear. Count from the index backwards until you reach // matching element with an index of zero. Return that element. node = topLevel.getFirstChild(); while ( node != null ) { // If a particular node is an element (could be HTML or XML), // do two things: if it's the one we're looking for, decrease // the index and if zero, return this node; at any rate, // traverse it's children as well. if ( node instanceof Element ) { if ( collectionMatch( (Element) node, null ) ) { if ( index.isZero() ) return node; index.decrement(); } else if ( recurse() ) { result = item( (Element) node, index ); if ( result != null ) return result; } } node = node.getNextSibling(); } } return null;
public final org.w3c.dom.Node	namedItem(java.lang.String name) Retrieves the named node from the collection. The name is matched case sensitive against the id attribute of each element in the collection, returning the first match. The tree is traversed in depth-first order. This method might traverse the entire document tree. param name The name of the node to return return The specified node or null if no such node found if ( name == null ) throw new NullPointerException( "HTM013 Argument 'name' is null." ); // Call recursive function on top-level element. return namedItem( _topLevel, name );
private org.w3c.dom.Node	namedItem(org.w3c.dom.Element topLevel, java.lang.String name) Recursive function returns an element of a particular type with the specified name (id attribute). param topLevel Top level element from which to scan param name The named element to look for return The first named element found Node node; Node result; synchronized ( topLevel ) { // Traverse all the childs of the current element in the order // they appear. node = topLevel.getFirstChild(); while ( node != null ) { // If a particular node is an element (could be HTML or XML), // do two things: if it's the one we're looking for, and the // name (id attribute) attribute is the one we're looking for, // return this element; otherwise, traverse it's children. if ( node instanceof Element ) { if ( collectionMatch( (Element) node, name ) ) return node; else if ( recurse() ) { result = namedItem( (Element) node, name ); if ( result != null ) return result; } } node = node.getNextSibling(); } return node; }
protected boolean	recurse() Returns true if scanning methods should iterate through the collection. When looking for elements in the document, recursing is needed to traverse the full document tree. When looking inside a specific element (e.g. for a cell inside a row), recursing can lead to erroneous results. return True if methods should recurse to traverse entire tree return _lookingFor > 0;