OffsetAttribute.cs

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/* 
 * 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 Attribute = Lucene.Net.Util.Attribute;

namespace Lucene.Net.Analysis.Tokenattributes
{
    
    /// <summary> The start and end character offset of a Token. </summary>
    [Serializable]
    public class OffsetAttribute:Attribute, IOffsetAttribute, System.ICloneable
    {
        private int startOffset;
        private int endOffset;

        /// <summary>Returns this Token's starting offset, the position of the first character
        /// corresponding to this token in the source text.
        /// Note that the difference between endOffset() and startOffset() may not be
        /// equal to termText.length(), as the term text may have been altered by a
        /// stemmer or some other filter. 
        /// </summary>
        public virtual int StartOffset
        {
            get { return startOffset; }
        }


        /// <summary>Set the starting and ending offset.
        /// See StartOffset() and EndOffset()
        /// </summary>
        public virtual void  SetOffset(int startOffset, int endOffset)
        {
            this.startOffset = startOffset;
            this.endOffset = endOffset;
        }


        /// <summary>Returns this Token's ending offset, one greater than the position of the
        /// last character corresponding to this token in the source text. The length
        /// of the token in the source text is (endOffset - startOffset). 
        /// </summary>
        public virtual int EndOffset
        {
            get { return endOffset; }
        }


        public override void  Clear()
        {
            startOffset = 0;
            endOffset = 0;
        }
        
        public  override bool Equals(System.Object other)
        {
            if (other == this)
            {
                return true;
            }
            
            if (other is OffsetAttribute)
            {
                OffsetAttribute o = (OffsetAttribute) other;
                return o.startOffset == startOffset && o.endOffset == endOffset;
            }
            
            return false;
        }
        
        public override int GetHashCode()
        {
            int code = startOffset;
            code = code * 31 + endOffset;
            return code;
        }
        
        public override void  CopyTo(Attribute target)
        {
            IOffsetAttribute t = (IOffsetAttribute) target;
            t.SetOffset(startOffset, endOffset);
        }
        
        override public System.Object Clone()
        {
            OffsetAttribute impl = new OffsetAttribute();
            impl.endOffset = endOffset;
            impl.startOffset = startOffset;
            return impl;
        }
    }
}