2023년 8월 — [S.T.RE] 정규표현식 기초 배워보기

public bool IsValidPhoneNumber(string phoneNumber)
{
    string[] areaCodes = new string[] { "070", "02", "031", "032", "033", "041", "042", "043", "051", "052", "053", "054", "055", "061", "062", "063", "064" };

    string[] parts = phoneNumber.Split('-');
    if (parts.Length != 3)
    {
        return false; // 번호는 반드시 3 부분으로 나뉘어야 합니다.
    }

    if (!areaCodes.Contains(parts[0]))
    {
        return false; // 첫 번째 부분은 지역 코드 중 하나여야 합니다.
    }

    if (parts[1].Length < 3 || parts[1].Length > 4 || !IsAllDigits(parts[1]))
    {
        return false; // 두 번째 부분은 3자리 또는 4자리 숫자여야 합니다.
    }

    if (parts[2].Length != 4 || !IsAllDigits(parts[2]))
    {
        return false; // 세 번째 부분은 4자리 숫자여야 합니다.
    }

    return true;
}

private bool IsAllDigits(string s)
{
    foreach (char c in s)
    {
        if (!char.IsDigit(c))
        {
            return false;
        }
    }

    return true;
}

@"^(070|02|031|032|033|041|042|043|051|052|053|054|055|061|062|063|064)-(\d{3,4})-(\d{4})$"

var client = new HttpClient();
var content = await client.GetStringAsync("https://www.nasa.gov/rss/dyn/breaking_news.rss");
var matches = Regex.Matches(content, @"<link[^>]*>(?<LinkUrl>[^<]*)", RegexOptions.Compiled);
var links = matches
	.Select(x => Uri.TryCreate(x.Groups["LinkUrl"].Value, UriKind.Absolute, out Uri result) ? result : null)
	.Where(x => x != null)
	.ToList();
links.Dump();

var mySimpleDomLang = @"
ADD 1 4.0
DIV 1 0
SUB 6 1.9
MUL 4.1 8
DIV 2 2.3
MOD 3.5 3
HLO 4 6
Z A A
";

var matches = Regex.Matches(
	mySimpleDomLang,
	@"(?<Instruction>[^\s]+)\s+(?<Op1>[^\s]+)\s+(?<Op2>[^\s]+)",
	RegexOptions.Compiled);

// 행을 나누는 Split 메서드를 쓰지 않아도 자동으로 그룹핑이 이루어집니다.
//matches.Dump();

for (var i = 0; i < matches.Count; i++)
{
	var currentLine = matches[i].Groups.AsReadOnly();

	// Index 0은 전체 문자열을 반환합니다.
	//currentLine.Skip(1).Dump();

	var instruction = currentLine.ElementAtOrDefault(1)?.Value;
	var firstOp = currentLine.ElementAtOrDefault(2)?.Value;
	var secondOp = currentLine.ElementAtOrDefault(3)?.Value;

	switch (instruction)
	{
		case "ADD":
			if (decimal.TryParse(firstOp, out decimal addArg1) &&
				decimal.TryParse(secondOp, out decimal addArg2))
				Console.Out.WriteLine(
					$"{firstOp} + {secondOp} = {addArg1 + addArg2:#,##0.00}");
			else
				Console.Out.WriteLine($"Cannot process ADD instruction. (Line {i + 1})");
			break;
		case "SUB":
			if (decimal.TryParse(firstOp, out decimal subArg1) &&
				decimal.TryParse(secondOp, out decimal subArg2))
				Console.Out.WriteLine(
					$"{firstOp} - {secondOp} = {subArg1 - subArg2:#,##0.00}");
			else
				Console.Out.WriteLine($"Cannot process SUB instruction. (Line {i + 1})");
			break;
		case "MUL":
			if (decimal.TryParse(firstOp, out decimal mulArg1) &&
				decimal.TryParse(secondOp, out decimal mulArg2))
				Console.Out.WriteLine(
					$"{firstOp} * {secondOp} = {mulArg1 * mulArg2:#,##0.00}");
			else
				Console.Out.WriteLine($"Cannot process MUL instruction. (Line {i + 1})");
			break;
		case "DIV":
			if (decimal.TryParse(firstOp, out decimal divArg1) &&
				decimal.TryParse(secondOp, out decimal divArg2) &&
				divArg2 != decimal.Zero)
				Console.Out.WriteLine(
					$"{firstOp} / {secondOp} = {divArg1 / divArg2:#,##0.00}");
			else
				Console.Out.WriteLine($"Cannot process DIV instruction. (Line {i + 1})");
			break;
		case "MOD":
			if (decimal.TryParse(firstOp, out decimal modArg1) &&
				decimal.TryParse(secondOp, out decimal modArg2))
				Console.Out.WriteLine(
					$"{firstOp} % {secondOp} = {modArg1 % modArg2:#,##0.00}");
			else
				Console.Out.WriteLine($"Cannot process MOD instruction. (Line {i + 1})");
			break;
		default:
			Console.Out.WriteLine($"Cannot process '{instruction}' instruction. (Line {i + 1})");
			break;
	}
}

using var host = new SimpleAsyncHost();
host.ListenAsync().Wait();

// https://gist.github.com/stanroze/11008822
public sealed class SimpleAsyncHost : IDisposable
{
	private HttpListener _httpListener;
	private Lazy<HttpClient> _httpClientFactory;
	private bool _disposed;

	public SimpleAsyncHost(string prefix = "http://localhost:10090/")
	{
		Console.Out.WriteLine($"Prefix: {prefix}");
		_httpListener = new HttpListener();
		_httpListener.Prefixes.Add(prefix);
		_httpClientFactory = new Lazy<HttpClient>();
	}

	public async Task ListenAsync()
	{
		_httpListener.Start();

		while (!_disposed)
		{
			HttpListenerContext ctx = null;
			try
			{
				ctx = await _httpListener.GetContextAsync();
			}
			catch (HttpListenerException ex)
			{
				if (ex.ErrorCode == 995) return;
			}

			if (ctx == null) continue;
			
			var client = _httpClientFactory.Value;
			var content = await client.GetStringAsync("http://www.example.com/");
			content = Regex.Replace(content, @"<a[^>]*>[^<]*</a>", "<p>링크 치환됨</p>", RegexOptions.Compiled);

			var response = ctx.Response;
			response.Headers.Add(HttpResponseHeader.CacheControl, "private, no-store");
			response.ContentType = "text/html";
			response.StatusCode = (int)HttpStatusCode.OK;

			var messageBytes = Encoding.UTF8.GetBytes(content);
			response.ContentLength64 = messageBytes.Length;
			await response.OutputStream.WriteAsync(messageBytes, 0, messageBytes.Length);
			response.OutputStream.Close();
			response.Close();
		}
	}

	public void Dispose()
	{
		if (_disposed)
			return;
			
		if (_httpListener.IsListening)
			_httpListener.Stop();
			
		_disposed = true;
	}
}