cscの作法 その564

概要

cscの作法、調べてみた。
grep見つけたので、やってみた。

参考にしたページ

サンプルコード

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

public class Searcher {
	protected readonly string[] Words;
	public Searcher(string[] words) {
		Words = words;
	}
	public virtual bool Search(string line) {
		return Words.Any(x => line.Contains(x));
	}
}
public class RegexSearcher: Searcher {
	private readonly Regex pattern;
	public RegexSearcher(string[] words): base(words) {
		Array.Sort(words);
		var p = string.Join("|", words.Select(Regex.Escape));
		pattern = new Regex(p, RegexOptions.Compiled);
	}
	public override bool Search(string line) {
		return pattern.IsMatch(line);
	}
}
public class KmpSearcher: Searcher {
	private readonly Kmp[] matchers;
	public KmpSearcher(string[] words): base(words) {
		matchers = words.Select(x => new Kmp(x)).ToArray();
	}
	public override bool Search(string line) {
		foreach (var m in matchers)
			m.Reset();
		return line.Any(c => matchers.Any(m => m.Match(c)));
	}
	private class Kmp {
		private string pattern;
		private int[] table;
		private int matchingLength = 0;
		public Kmp(string p) {
			pattern = p;
			table = new int[p.Length];
			if (p.Length < 1)
				return;
			table[0] = -1;
			if (p.Length < 2)
				return;
			table[1] = 0;
			int i = 2;
			int length = 0;
			while (i < p.Length)
			{
				if (p[i - 1] == p[length])
				{
					length++;
					table[i] = length;
					i++;
				}
				else if (length > 0)
				{
					length = table[length];
				}
				else
				{
					table[i] = 0;
					i++;
				}
			}
		}
		public bool Match(char c) {
			if (pattern.Length <= matchingLength)
			{
				return true;
			}
			while (pattern[matchingLength] != c)
			{
				matchingLength = table[matchingLength];
				if (matchingLength < 0)
				{
					matchingLength = 0;
					return false;
				}
			}
			matchingLength++;
			return (pattern.Length <= matchingLength);
		}
		public void Reset() {
			matchingLength = 0;
		}
	}
}
public static class GrepUtil {
	public static Func<string[], Searcher> SearcherFactory = words => new Searcher(words);
	public static IEnumerable<String> Grep(TextReader reader, params string[] words) {
		var searcher = SearcherFactory(words);
		string line;
		for (var i = 1; (line = reader.ReadLine()) != null; i++)
			if (searcher.Search(line))
				yield return i + ": " + line;
	}
}
public class Program {
	public static void Main(string[] args) {
		string input = @"Java 1 is nice.
Java 2 is fine.
Java 3 is good.
Java 4 is good.
Java 5 is fine.
Java 6 is good.
Java 7 is good.
Java 8 is marvelous.";
		using (var sr = new StringReader(input))
		{
			List<string> result = GrepUtil.Grep(sr, "fine", "marvelous").ToList();
			foreach (var item in result)
				Console.WriteLine(item);
		}
	}
}

実行結果

>grep0
2: Java 2 is fine.
5: Java 5 is fine.
8: Java 8 is marvelous.

以上。