poslookuplist.cs

英语句子自然语言处理统计分析例子 Statistical parsing of English sentences Shows how to generate parse trees for

//Copyright (C) 2005 Richard J. Northedge
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

//This file is based on the POSDictionary.java source file found in the
//original java implementation of OpenNLP.  That source file contains the following header:

//Copyright (C) 2004 Thomas Morton
// 
//This library is free software; you can redistribute it and/or
//modify it under the terms of the GNU Lesser General Public
//License as published by the Free Software Foundation; either
//version 2.1 of the License, or (at your option) any later version.
// 
//This library is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//GNU Lesser General Public License for more details.
// 
//You should have received a copy of the GNU Lesser General Public
//License along with this program; if not, write to the Free Software
//Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

using System;
using System.Collections;

namespace OpenNLP.Tools.PosTagger
{
	/// <summary>
	/// Provides a means of determining which tags are valid for a particular word based on a tag dictionary read from a file.
	/// </summary>
	public class PosLookupList
	{
		private Hashtable mDictionary;
		private bool mIsCaseSensitive;
		
		public PosLookupList(string file) : this(file, true)
		{
		}
		
		/// <summary>
		/// Create tag dictionary object with contents of specified file and using specified case to determine how to access entries in the tag dictionary.
		/// </summary>
		/// <param name="file">
		/// The file name for the tag dictionary.
		/// </param>
		/// <param name="caseSensitive">
		/// Specifies whether the tag dictionary is case sensitive or not.
		/// </param>
		public PosLookupList(string file, bool caseSensitive) : this(new System.IO.StreamReader(file, System.Text.Encoding.UTF7), caseSensitive)
		{
		}
		
		/// <summary>
		/// Create tag dictionary object with contents of specified file and using specified case to determine how to access entries in the tag dictionary.
		/// </summary>
		/// <param name="reader">
		/// A reader for the tag dictionary.
		/// </param>
		/// <param name="caseSensitive">
		/// Specifies whether the tag dictionary is case sensitive or not.
		/// </param>
		public PosLookupList(System.IO.StreamReader reader, bool caseSensitive)
		{
			mDictionary = new Hashtable();
			mIsCaseSensitive = caseSensitive;
			for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())
			{
				string[] parts = line.Split(' ');
				string[] tags = new string[parts.Length - 1];
				for (int currentTag = 0, tagCount = parts.Length - 1; currentTag < tagCount; currentTag++)
				{
					tags[currentTag] = parts[currentTag + 1];
				}
				mDictionary[parts[0]] = tags;
			}
		}
		
		/// <summary>
		/// Returns a list of valid tags for the specified word. </summary>
		/// <param name="word">
		/// The word.
		/// </param>
		/// <returns>
		/// A list of valid tags for the specified word or null if no information is available for that word.
		/// </returns>
		public virtual string[] GetTags(string word)
		{
			if (mIsCaseSensitive)
			{
				return (string[]) mDictionary[word];
			}
			else
			{
				return (string[]) mDictionary[word.ToLower(System.Globalization.CultureInfo.InvariantCulture)];
			}
		}
	}
}