multimapnamesenumeration.java

Tomcat 4.1与WebServer集成组件的源代码包.

/*
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
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 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
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 * This software consists of voluntary contributions made by many
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 * [Additional notices, if required by prior licensing conditions]
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package org.apache.tomcat.util.collections;

import org.apache.tomcat.util.buf.MessageBytes;

import java.io.*;
import java.util.*;
import java.text.*;

/** Enumerate the distinct header names.
    Each nextElement() is O(n) ( a comparation is
    done with all previous elements ).

    This is less frequesnt than add() -
    we want to keep add O(1).
*/
public final class MultiMapNamesEnumeration implements Enumeration {
    int pos;
    int size;
    String next;
    MultiMap headers;

    // toString and unique options are not implemented -
    // we allways to toString and unique.
    
    /** Create a new multi-map enumeration.
     * @param  headers the collection to enumerate 
     * @param  toString convert each name to string 
     * @param  unique return only unique names
     */
    MultiMapNamesEnumeration(MultiMap headers, boolean toString,
			     boolean unique) {
	this.headers=headers;
	pos=0;
	size = headers.size();
	findNext();
    }

    private void findNext() {
	next=null;
	for(  ; pos< size; pos++ ) {
	    next=headers.getName( pos ).toString();
	    for( int j=0; j<pos ; j++ ) {
		if( headers.getName( j ).equalsIgnoreCase( next )) {
		    // duplicate.
		    next=null;
		    break;
		}
	    }
	    if( next!=null ) {
		// it's not a duplicate
		break;
	    }
	}
	// next time findNext is called it will try the
	// next element
	pos++;
    }
    
    public boolean hasMoreElements() {
	return next!=null;
    }

    public Object nextElement() {
	String current=next;
	findNext();
	return current;
    }
}