/*
 Copyright (c) 2006 - 2008  Eric J. Feminella  <eric@ericfeminella.com>
 All rights reserved.

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is 
 furnished to do so, subject to the following conditions:

 The above copyright notice and this permission notice shall be included in 
 all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
 THE SOFTWARE.

 @internal
 */

package com.ericfeminella.collections
{
    import flash.errors.IllegalOperationError;
    
    /**
     *
     * StringTokenizer provides a simple API from which Strings can be
     * split into individual tokens based on a specific delimiter.
     *
     * <p>
     * <code>StringTokenizer</code> provides an <code>Iterator</code>
     * and <code>IEnumeration</code> implementation, thus making it
     * easy to implement as either interface.
     * </p>
     *
     * <p>
     * Additionally, <code>StringTokenizer</code> provides two static
     * factory methods for creating an instance as either implementaton
     * These convenience factory methods are <code>createIterator</code>
     * and <code>createEnumeration</code>
     * </p>
     *
     * @example
     * 
     * <listing version="3.0">
     *
     * var tokens:StringTokenizer = StringTokenizer("hello world", " ");
     *
     * while ( tokens.hasMoreTokens() )
     * {
     *     trace( tokens.nextToken() );
     * }
     * // outputs:
     * // hello
     * // world
     *
     * </listing>
     *
     * @see com.ericfeminella.collections.Iterator
     * @see com.ericfeminella.collections.IEnumeration
     *
     */
    public class StringTokenizer implements Iterator, IEnumeration
    {
        /**
         *
         * The source <code>String</code> from which tokens are extracted
         * from based on the specified delimiter
         *
         */
        protected var source:String;

        /**
         *
         * Defines the delimiter from which the <code>source</code> String
         * tokens are to be extracted
         *
         */
        protected var delimiter:String;

        /**
         *
         * Defines the token <code>Array</code> which contains each token
         * String extracted by the <code>StringTokenizer</code> instance
         *
         */
        protected var tokens:Array;

        /**
         *
         * Stores the current position (cursor) in the tokens array from
         * which calls to <code>nextToken();</code> are based on
         *
         */
        protected var cursor:int;

        /**
         *
         * Creates a new instance of <code>StringTokenizer</code> and
         * processes the source String into an array of tokens based
         * on the specified delimiter
         *
         * @example
         * <listing version="3.0">
         *
         * var tokens:StringTokenizer = new StringTokenizer("This is a test", " ");
         *
         * trace( tokens.countTokens() );
         *
         * </listing>
         *
         * @param the source String from which the tokens are to be extracted
         * @param the delimiter on which the tokens are extracted
         *
         */
        public function StringTokenizer(source:String, delimiter:String)
        {
            this.source = source;
            this.delimiter = delimiter;

            this.tokens = source.split( delimiter );
        }

        /**
         *
         * Static Factory method which creates a new <code>Iterator</code>
         * StringTokenizer implementation
         *
         * @example
         * <listing version="3.0">
         *
         * var tokens:Iterator = StringTokenizer.createIterator("This is a test", " ");
         *
         * while ( tokens.hasNext() )
         * {
         *     trace( tokens.next() );
         * }
         *
         * </listing>
         *
         * @param  the source String from which the tokens are to be extracted
         * @param  the delimiter on which the tokens are extracted
         * @return a new <code>StringTokenizer</code> as an <code>Iterator</code>
         *
         */
        public static function createIterator(source:String, delimiter:String) : Iterator
        {
            return new StringTokenizer( source, delimiter );
        }

        /**
         *
         * Static Factory method which creates a new <code>IEnumeration</code>
         * StringTokenizer implementation
         *
         * @example
         * <listing version="3.0">
         *
         * var tokens:IEnumeration = StringTokenizer.createEnumeration("This is a test", " ");
         *
         * while ( tokens.hasMoreElements() )
         * {
         *     trace( tokens.nextElement() );
         * }
         *
         * </listing>
         *
         * @param  the source String from which the tokens are to be extracted
         * @param  the delimiter on which the tokens are extracted
         * @return a new <code>StringTokenizer</code> as an <code>IEnumeration</code>
         *
         */
        public static function createEnumeration(source:String, delimiter:String) : IEnumeration
        {
            return new StringTokenizer( source, delimiter );
        }

        /**
         *
         * Retrieves the length of tokens extracted from the source
         * String
         *
         * @return the length of tokens in the source
         *
         */
        public function countTokens() : int
        {
            return tokens.length;
        }

        /**
         *
         * Determines if there are more tokens which have yet to be
         * retrieved via calls to <code>nextToken</code>
         *
         * @return true if more tokens remain, otherwise false
         *
         */
        public function hasMoreTokens() : Boolean
        {
            return cursor < tokens.length;
        }

        /**
         *
         * Retrieves the next token in the <code>StringTokenizer</code>
         * instance.
         *
         * <p>
         * If the current position of the <code>StringTokenizer</code>
         * instance is greater than or equal to the length of the source
         * a null value is returned
         * </p>
         *
         * @return the next token in the source String
         *
         */
        public function nextToken() : String
        {
            var token:String;

            if ( hasMoreTokens() )
            {
                token = tokens[cursor];
                cursor++;
            }

            return token;
        }

        /**
         *
         * <code>Iterator</code> implementation which determines if
         * there are more tokens which have yet to be retrieved via
         * calls to <code>nextToken</code>
         *
         * @return true if more tokens remain, otherwise false
         *
         */
        public function hasNext() : Boolean
        {
            return hasMoreTokens();
        }

        /**
         *
         * Retrieves the next element in the <code>StringTokenizer</code>
         * instance
         *
         * @return the next token based on the current position
         *
         */
        public function next() : *
        {
            return nextToken();
        }

       /**
        *
        * Resets the position of the <code>StringTokenizer</code> to
        * zero
        *
        */
        public function reset() : void
        {
            cursor = 0;
        }


        /**
         *
         * Determines the current position within the token
         *
         * @return the current index of the token
         *
         */
        public function position() : int
        {
            return cursor;
        }

        /**
         *
         * Remove must be implemented to provide a standard iterator
         * implementation.
         *
         * <p>
         * Typically this method would not provide an actual implementation
         * as a concrete iterator is not to perform modifications, but rather
         * simply provide a mechanism for iterating the object, thus being
         * considered as read-only. Therefore concrete implementationx should
         * throw an Exception
         * </p>
         *
         * @throws flash.errors.IllegalOperationError
         *
         */
        public function remove() : void
        {
            throw new IllegalOperationError("IllegalOperationError: remove is not supported");
        }

        /**
         *
         * <code>IEnumeration</code> implementation which determines if
         * there are more tokens which have yet to be retrieved via calls
         * to <code>nextToken</code>
         *
         * @return true if more tokens remain, otherwise false
         *
         */
        public function hasMoreElements() : Boolean
        {
            return hasMoreTokens();
        }

        /**
         *
         * Retrieves the next token in the <code>StringTokenizer</code>
         * instance
         *
         * @return the next token in the source String
         *
         */
        public function nextElement() : *
        {
            return nextToken();
        }
    }
}