/* 
 * 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.
 */

using System;

using AttributeSource = Lucene.Net.Util.AttributeSource;

namespace Lucene.Net.Analysis
{
	
	/// <summary> A Tokenizer is a TokenStream whose input is a Reader.
	/// <p/>
	/// This is an abstract class; subclasses must override {@link #IncrementToken()}
	/// <p/>
	/// NOTE: Subclasses overriding {@link #IncrementToken()} must call
	/// {@link AttributeSource#ClearAttributes()} before setting attributes.
	/// Subclasses overriding {@link #IncrementToken()} must call
	/// {@link Token#Clear()} before setting Token attributes.
	/// </summary>
	
	public abstract class Tokenizer:TokenStream
	{
		/// <summary>The text source for this Tokenizer. </summary>
		protected internal System.IO.TextReader input;
		
		/// <summary>Construct a tokenizer with null input. </summary>
		protected internal Tokenizer()
		{
		}
		
		/// <summary>Construct a token stream processing the given input. </summary>
		protected internal Tokenizer(System.IO.TextReader input)
		{
			this.input = CharReader.Get(input);
		}
		
		/// <summary>Construct a tokenizer with null input using the given AttributeFactory. </summary>
		protected internal Tokenizer(AttributeFactory factory):base(factory)
		{
		}
		
		/// <summary>Construct a token stream processing the given input using the given AttributeFactory. </summary>
		protected internal Tokenizer(AttributeFactory factory, System.IO.TextReader input):base(factory)
		{
			this.input = CharReader.Get(input);
		}
		
		/// <summary>Construct a token stream processing the given input using the given AttributeSource. </summary>
		protected internal Tokenizer(AttributeSource source):base(source)
		{
		}
		
		/// <summary>Construct a token stream processing the given input using the given AttributeSource. </summary>
		protected internal Tokenizer(AttributeSource source, System.IO.TextReader input):base(source)
		{
			this.input = CharReader.Get(input);
		}
		
		/// <summary>By default, closes the input Reader. </summary>
		public override void  Close()
		{
			input.Close();
		}
  
		/// <summary>Return the corrected offset. If {@link #input} is a {@link CharStream} subclass
		/// this method calls {@link CharStream#CorrectOffset}, else returns <code>currentOff</code>.
		/// </summary>
		/// <param name="currentOff">offset as seen in the output
		/// </param>
		/// <returns> corrected offset based on the input
		/// </returns>
		/// <seealso cref="CharStream.CorrectOffset">
		/// </seealso>
		protected internal int CorrectOffset(int currentOff)
		{
			return (input is CharStream)?((CharStream) input).CorrectOffset(currentOff):currentOff;
		}
		
		/// <summary>Expert: Reset the tokenizer to a new reader.  Typically, an
		/// analyzer (in its reusableTokenStream method) will use
		/// this to re-use a previously created tokenizer. 
		/// </summary>
		public virtual void  Reset(System.IO.TextReader input)
		{
			this.input = input;
		}
	}
}