/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.xerces.util;

import java.util.Enumeration;
import java.util.NoSuchElementException;

import org.apache.xerces.xni.NamespaceContext;

Namespace support for XML document handlers. This class doesn't 
perform any error checking and assumes that all strings passed
as arguments to methods are unique symbols. The SymbolTable class
can be used for this purpose.
Author:
Andy Clark, IBM
Version:
$Id: NamespaceSupport.java 965250 2010-07-18 16:04:58Z mrglavas $/**
 * Namespace support for XML document handlers. This class doesn't 
 * perform any error checking and assumes that all strings passed
 * as arguments to methods are unique symbols. The SymbolTable class
 * can be used for this purpose.
 *
 * @author Andy Clark, IBM
 *
 * @version $Id: NamespaceSupport.java 965250 2010-07-18 16:04:58Z mrglavas $
 */
public class NamespaceSupport implements NamespaceContext {

    //
    // Data
    //

    
Namespace binding information. This array is composed of a
series of tuples containing the namespace binding information:
<prefix, uri>. The default size can be set to anything
as long as it is a power of 2 greater than 1.
See Also:
fNamespaceSize
fContext/** 
     * Namespace binding information. This array is composed of a
     * series of tuples containing the namespace binding information:
     * &lt;prefix, uri&gt;. The default size can be set to anything
     * as long as it is a power of 2 greater than 1.
     *
     * @see #fNamespaceSize
     * @see #fContext
     */
    protected String[] fNamespace = new String[16 * 2];

    
The top of the namespace information array. /** The top of the namespace information array. */
    protected int fNamespaceSize;

    // NOTE: The constructor depends on the initial context size 
    //       being at least 1. -Ac

    
Context indexes. This array contains indexes into the namespace
information array. The index at the current context is the start
index of declared namespace bindings and runs to the size of the
namespace information array.
See Also:
fNamespaceSize/** 
     * Context indexes. This array contains indexes into the namespace
     * information array. The index at the current context is the start
     * index of declared namespace bindings and runs to the size of the
     * namespace information array.
     *
     * @see #fNamespaceSize
     */
    protected int[] fContext = new int[8];

    
The current context. /** The current context. */
    protected int fCurrentContext;
    
    protected String[] fPrefixes = new String[16];
    
    //
    // Constructors
    //

    
Default constructor. /** Default constructor. */
    public NamespaceSupport() {
    } // <init>()

    
Constructs a namespace context object and initializes it with
the prefixes declared in the specified context.
/** 
     * Constructs a namespace context object and initializes it with
     * the prefixes declared in the specified context.
     */
    public NamespaceSupport(NamespaceContext context) {
        pushContext();
        // copy declaration in the context
        Enumeration prefixes = context.getAllPrefixes();
        while (prefixes.hasMoreElements()){
            String prefix = (String)prefixes.nextElement();
            String uri = context.getURI(prefix);
            declarePrefix(prefix, uri);
        }
      } // <init>(NamespaceContext)


    //
    // Public methods
    //
    
	
See Also:
reset.reset()/**
	 * @see org.apache.xerces.xni.NamespaceContext#reset()
	 */
    public void reset() {

        // reset namespace and context info
        fNamespaceSize = 0;
        fCurrentContext = 0;
        fContext[fCurrentContext] = fNamespaceSize;

        // bind "xml" prefix to the XML uri
        fNamespace[fNamespaceSize++] = XMLSymbols.PREFIX_XML;
        fNamespace[fNamespaceSize++] = NamespaceContext.XML_URI;
        // bind "xmlns" prefix to the XMLNS uri
        fNamespace[fNamespaceSize++] = XMLSymbols.PREFIX_XMLNS;
        fNamespace[fNamespaceSize++] = NamespaceContext.XMLNS_URI;
        ++fCurrentContext;

    } // reset(SymbolTable)


	
See Also:
pushContext.pushContext()/**
	 * @see org.apache.xerces.xni.NamespaceContext#pushContext()
	 */
    public void pushContext() {

        // extend the array, if necessary
        if (fCurrentContext + 1 == fContext.length) {
            int[] contextarray = new int[fContext.length * 2];
            System.arraycopy(fContext, 0, contextarray, 0, fContext.length);
            fContext = contextarray;
        }

        // push context
        fContext[++fCurrentContext] = fNamespaceSize;

    } // pushContext()


	
See Also:
popContext.popContext()/**
	 * @see org.apache.xerces.xni.NamespaceContext#popContext()
	 */
    public void popContext() {
        fNamespaceSize = fContext[fCurrentContext--];
    } // popContext()

	
See Also:
declarePrefix.declarePrefix(String, String)/**
	 * @see org.apache.xerces.xni.NamespaceContext#declarePrefix(String, String)
	 */
    public boolean declarePrefix(String prefix, String uri) {
        // ignore "xml" and "xmlns" prefixes
        if (prefix == XMLSymbols.PREFIX_XML || prefix == XMLSymbols.PREFIX_XMLNS) {
            return false;
        }

        // see if prefix already exists in current context
        for (int i = fNamespaceSize; i > fContext[fCurrentContext]; i -= 2) {
            if (fNamespace[i - 2] == prefix) {
                // REVISIT: [Q] Should the new binding override the
                //          previously declared binding or should it
                //          it be ignored? -Ac
                // NOTE:    The SAX2 "NamespaceSupport" helper allows
                //          re-bindings with the new binding overwriting
                //          the previous binding. -Ac
                fNamespace[i - 1] = uri;
                return true;
            }
        }

        // resize array, if needed
        if (fNamespaceSize == fNamespace.length) {
            String[] namespacearray = new String[fNamespaceSize * 2];
            System.arraycopy(fNamespace, 0, namespacearray, 0, fNamespaceSize);
            fNamespace = namespacearray;
        }

        // bind prefix to uri in current context
        fNamespace[fNamespaceSize++] = prefix;
        fNamespace[fNamespaceSize++] = uri;

        return true;

    } // declarePrefix(String,String):boolean

	
See Also:
getURI.getURI(String)/**
	 * @see org.apache.xerces.xni.NamespaceContext#getURI(String)
	 */
    public String getURI(String prefix) {
        
        // find prefix in current context
        for (int i = fNamespaceSize; i > 0; i -= 2) {
            if (fNamespace[i - 2] == prefix) {
                return fNamespace[i - 1];
            }
        }

        // prefix not found
        return null;

    } // getURI(String):String


	
See Also:
getPrefix.getPrefix(String)/**
	 * @see org.apache.xerces.xni.NamespaceContext#getPrefix(String)
	 */
    public String getPrefix(String uri) {

        // find uri in current context
        for (int i = fNamespaceSize; i > 0; i -= 2) {
            if (fNamespace[i - 1] == uri) {
                if (getURI(fNamespace[i - 2]) == uri)
                    return fNamespace[i - 2];
            }
        }

        // uri not found
        return null;

    } // getPrefix(String):String


	
See Also:
getDeclaredPrefixCount.getDeclaredPrefixCount()/**
	 * @see org.apache.xerces.xni.NamespaceContext#getDeclaredPrefixCount()
	 */
    public int getDeclaredPrefixCount() {
        return (fNamespaceSize - fContext[fCurrentContext]) / 2;
    } // getDeclaredPrefixCount():int

	
See Also:
getDeclaredPrefixAt.getDeclaredPrefixAt(int)/**
	 * @see org.apache.xerces.xni.NamespaceContext#getDeclaredPrefixAt(int)
	 */
    public String getDeclaredPrefixAt(int index) {
        return fNamespace[fContext[fCurrentContext] + index * 2];
    } // getDeclaredPrefixAt(int):String

	
See Also:
getAllPrefixes.getAllPrefixes()/**
	 * @see org.apache.xerces.xni.NamespaceContext#getAllPrefixes()
	 */
	public Enumeration getAllPrefixes() {
        int count = 0;
        if (fPrefixes.length < (fNamespace.length/2)) {
            // resize prefix array          
            String[] prefixes = new String[fNamespaceSize];
            fPrefixes = prefixes;
        }
        String prefix = null;
        boolean unique = true;
        for (int i = 2; i < (fNamespaceSize-2); i += 2) {
            prefix = fNamespace[i + 2];            
            for (int k=0;k<count;k++){
                if (fPrefixes[k]==prefix){
                    unique = false;
                    break;
                }               
            }
            if (unique){
                fPrefixes[count++] = prefix;
            }
            unique = true;
        }
		return new Prefixes(fPrefixes, count);
	}
    
    /*
     * non-NamespaceContext methods
     */
    
    
Checks whether a binding or unbinding for
the given prefix exists in the context.
Params:
prefix – The prefix to look up.
Returns:
true if the given prefix exists in the context/** 
     * Checks whether a binding or unbinding for
     * the given prefix exists in the context.
     * 
     * @param prefix The prefix to look up. 
     * 
     * @return true if the given prefix exists in the context
     */
    public boolean containsPrefix(String prefix) {

        // find prefix in current context
        for (int i = fNamespaceSize; i > 0; i -= 2) {
            if (fNamespace[i - 2] == prefix) {
                return true;
            }
        }
        
        // prefix not found
        return false;
    }
    
    protected final class Prefixes implements Enumeration {
        private String[] prefixes;
        private int counter = 0;
        private int size = 0;
               
		
Constructor for Prefixes.
/**
		 * Constructor for Prefixes.
		 */
		public Prefixes(String [] prefixes, int size) {
			this.prefixes = prefixes;
            this.size = size;
		}

       
See Also:
hasMoreElements.hasMoreElements()/**
		 * @see java.util.Enumeration#hasMoreElements()
		 */
		public boolean hasMoreElements() {           
			return (counter< size);
		}

		
See Also:
nextElement.nextElement()/**
		 * @see java.util.Enumeration#nextElement()
		 */
		public Object nextElement() {
            if (counter< size){
                return fPrefixes[counter++];
            }
			throw new NoSuchElementException("Illegal access to Namespace prefixes enumeration.");
		}
        
        public String toString(){
            StringBuffer buf = new StringBuffer();
            for (int i=0;i<size;i++){
                buf.append(prefixes[i]);
                buf.append(' ');
            }
                
            return buf.toString(); 
        }

}

} // class NamespaceSupport