79 lines
2.4 KiB
C#
79 lines
2.4 KiB
C#
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Text.RegularExpressions;
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namespace BotSharp.NLP.Tokenize
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{
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/// <summary>
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/// Regular-Expression Tokenizers
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/// </summary>
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public class RegexTokenizer : ITokenizer
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{
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/// <summary>
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/// Tokenize a text into a sequence of alphabetic and non-alphabetic characters
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/// </summary>
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public const string WORD_PUNC = @"\w+|[^\w\s]+";
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/// <summary>
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/// Tokenize a string, treating any sequence of blank lines as a delimiter.
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/// Blank lines are defined as lines containing no characters, except for space or tab characters.
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/// options.IsGap = true
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/// </summary>
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public const string BLANK_LINE = @"\s*\n\s*\n\s*";
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/// <summary>
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/// Tokenize a string on whitespace (space, tab, newline).
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/// In general, users should use the string ``split()`` method instead.
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/// options.IsGap = true
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/// </summary>
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public const string WHITE_SPACE = @"\s+";
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private Regex _regex;
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public List<Token> Tokenize(string sentence, TokenizationOptions options)
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{
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_regex = new Regex(options.Pattern);
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var matches = _regex.Matches(sentence).Cast<Match>().ToArray();
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options.IsGap = new string[] { WHITE_SPACE, BLANK_LINE }.Contains(options.Pattern);
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if (options.IsGap)
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{
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int pos = 0;
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var tokens = new Token[matches.Length + 1];
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for (int span = 0; span <= matches.Length; span++)
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{
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var token = new Token
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{
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Text = (span == matches.Length) ? sentence.Substring(pos) : sentence.Substring(pos, matches[span].Index - pos),
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Start = pos
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};
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token.Text = token.Text.Trim();
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tokens[span] = token;
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if (span < matches.Length)
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{
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pos = matches[span].Index + 1;
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}
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}
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return tokens.ToList();
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}
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else
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{
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return matches.Select(x => new Token
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{
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Text = x.Value,
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Start = x.Index
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}).ToList();
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}
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}
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}
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}
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