// SAX Attribute List Interface.
// No warranty; no copyright -- use this as you will.
// $Id: AttributeList.java,v 1.2 2004/09/13 21:00:18 damon Exp $
package ewesoft.xml.sax;
/**
* Interface for an element's attribute specifications.
*
* <p>The SAX parser implements this interface and passes an instance
* to the SAX application as the second argument of each startElement
* event.</p>
*
* <p>The instance provided will return valid results only during the
* scope of the startElement invocation (to save it for future
* use, the application must make a copy: the AttributeListImpl
* helper class provides a convenient constructor for doing so).</p>
*
* <p>An AttributeList includes only attributes that have been
* specified or defaulted: #IMPLIED attributes will not be included.</p>
*
* <p>There are two ways for the SAX application to obtain information
* from the AttributeList. First, it can iterate through the entire
* list:</p>
*
* <pre>
* public void startElement (String name, AttributeList atts) {
* for (int i = 0; i < atts.getLength(); i++) {
* String name = atts.getName(i);
* String type = atts.getType(i);
* String value = atts.getValue(i);
* [...]
* }
* }
* </pre>
*
* <p>(Note that the result of getLength() will be zero if there
* are no attributes.)
*
* <p>As an alternative, the application can request the value or
* type of specific attributes:</p>
*
* <pre>
* public void startElement (String name, AttributeList atts) {
* String identifier = atts.getValue("id");
* String label = atts.getValue("label");
* [...]
* }
* </pre>
*
* <p>The AttributeListImpl helper class provides a convenience
* implementation for use by parser or application writers.</p>
*
* @author David Megginson (ak117@freenet.carleton.ca)
* @version 1.0
* @see ewesoft.xml.sax.DocumentHandler#startElement
*/
public interface AttributeList {
/**
* Return the number of attributes in this list.
*
* <p>The SAX parser may provide attributes in any
* arbitrary order, regardless of the order in which they were
* declared or specified. The number of attributes may be
* zero.</p>
*
* @return The number of attributes in the list.
*/
public abstract int getLength ();
/**
* Return the name of an attribute in this list (by position).
*
* <p>The names must be unique: the SAX parser shall not include the
* same attribute twice. Attributes without values (those declared
* #IMPLIED without a value specified in the start tag) will be
* omitted from the list.</p>
*
* <p>If the attribute name has a namespace prefix, the prefix
* will still be attached.</p>
*
* @param i The index of the attribute in the list (starting at 0).
* @return The name of the indexed attribute, or null
* if the index is out of range.
* @see #getLength
*/
public abstract String getName (int i);
/**
* Return the type of an attribute in the list (by position).
*
* <p>The attribute type is one of the strings "CDATA", "ID",
* "IDREF", "IDREFS", "NMTOKEN", "NMTOKENS", "ENTITY", "ENTITIES",
* or "NOTATION" (always in upper case).</p>
*
* <p>If the parser has not read a declaration for the attribute,
* or if the parser does not report attribute types, then it must
* return the value "CDATA" as stated in the XML 1.0 Recommentation
* (clause 3.3.3, "Attribute-Value Normalization").</p>
*
* <p>For an enumerated attribute that is not a notation, the
* parser will report the type as "NMTOKEN".</p>
*
* @param i The index of the attribute in the list (starting at 0).
* @return The attribute type as a string, or
* null if the index is out of range.
* @see #getLength
* @see #getType(java.lang.String)
*/
public abstract String getType (int i);
/**
* Return the value of an attribute in the list (by position).
*
* <p>If the attribute value is a list of tokens (IDREFS,
* ENTITIES, or NMTOKENS), the tokens will be concatenated
* into a single string separated by whitespace.</p>
*
* @param i The index of the attribute in the list (starting at 0).
* @return The attribute value as a string, or
* null if the index is out of range.
* @see #getLength
* @see #getValue(java.lang.String)
*/
public abstract String getValue (int i);
/**
* Return the type of an attribute in the list (by name).
*
* <p>The return value is the same as the return value for
* getType(int).</p>
*
* <p>If the attribute name has a namespace prefix in the document,
* the application must include the prefix here.</p>
*
* @param name The name of the attribute.
* @return The attribute type as a string, or null if no
* such attribute exists.
* @see #getType(int)
*/
public abstract String getType (String name);
/**
* Return the value of an attribute in the list (by name).
*
* <p>The return value is the same as the return value for
* getValue(int).</p>
*
* <p>If the attribute name has a namespace prefix in the document,
* the application must include the prefix here.</p>
*
* @param name The name of the attribute.
* @return The attribute value as a string, or null if
* no such attribute exists.
* @see #getValue(int)
*/
public abstract String getValue (String name);
}