private void Parse()

in src/Elastic.Apm/Model/SignatureParser.cs [73:192]
115 lines of code
31 McCabe index (conditional complexity)

		private void Parse(Scanner scanner, string query, StringBuilder signature, StringBuilder dbLink)
		{
			var firstToken = scanner.ScanWhile(Scanner.Token.Comment);
			switch (firstToken)
			{
				case Scanner.Token.Call:
					signature.Append("CALL");
					if (scanner.ScanUntil(Scanner.Token.Ident))
						AppendIdentifiers(scanner, signature, dbLink);
					return;
				case Scanner.Token.Delete:
					signature.Append("DELETE");
					if (scanner.ScanUntil(Scanner.Token.From) && scanner.ScanUntil(Scanner.Token.Ident))
					{
						signature.Append(" FROM");
						AppendIdentifiers(scanner, signature, dbLink);
					}
					return;
				case Scanner.Token.Insert:
				case Scanner.Token.Replace:
					signature.Append(firstToken.ToString().ToUpperInvariant());
					if (scanner.ScanUntil(Scanner.Token.Into) && scanner.ScanUntil(Scanner.Token.Ident))
					{
						signature.Append(" INTO");
						AppendIdentifiers(scanner, signature, dbLink);
					}
					return;
				case Scanner.Token.Select:
					signature.Append("SELECT");
					var level = 0;
					for (var t = scanner.Scan(); t != Scanner.Token.Eof; t = scanner.Scan())
					{
						if (t == Scanner.Token.Lparen)
							level++;
						else if (t == Scanner.Token.Rparen)
							level--;
						else if (t == Scanner.Token.From)
						{
							if (level == 0)
							{
								if (scanner.ScanToken(Scanner.Token.Ident))
								{
									signature.Append(" FROM");
									AppendIdentifiers(scanner, signature, dbLink);
								}
								else
									return;
							}
						}
					}
					return;
				case Scanner.Token.Update:
					signature.Append("UPDATE");
					// Scan for the table name
					var hasPeriod = false;
					var hasFirstPeriod = false;
					var isDbLink = false;
					if (scanner.ScanToken(Scanner.Token.Ident))
					{
						signature.Append(' ');
						scanner.AppendCurrentTokenText(signature);
						for (var t = scanner.Scan(); t != Scanner.Token.Eof; t = scanner.Scan())
						{
							switch (t)
							{
								case Scanner.Token.Ident:
									if (hasPeriod)
									{
										scanner.AppendCurrentTokenText(signature);
										hasPeriod = false;
									}
									if (!hasFirstPeriod)
									{
										// Some dialects allow option keywords before the table name
										// example: UPDATE IGNORE foo.bar
										signature.Length = 0;
										signature.Append("UPDATE ");
										scanner.AppendCurrentTokenText(signature);
									}
									else if (isDbLink)
									{
										if (dbLink != null)
											scanner.AppendCurrentTokenText(dbLink);
										isDbLink = false;
									}
									// Two adjacent identifiers found after the first period.
									// Ignore the secondary ones, in case they are unknown keywords.
									break;
								case Scanner.Token.Period:
									hasFirstPeriod = true;
									hasPeriod = true;
									signature.Append('.');
									break;
								default:
									if ("@".Equals(scanner.ToString()))
									{
										isDbLink = true;
										break;
									}
									else
										return;
							}
						}
					}
					return;
				case Scanner.Token.Merge:
					signature.Append("MERGE");
					if (scanner.ScanToken(Scanner.Token.Into) && scanner.ScanUntil(Scanner.Token.Ident))
					{
						signature.Append(" INTO");
						AppendIdentifiers(scanner, signature, dbLink);
					}
					return;
				default:
					query = query.Trim();
					var indexOfWhitespace = query.IndexOf(' ');
					signature.Append(query, 0, indexOfWhitespace > 0 ? indexOfWhitespace : query.Length);
					break;
			}
		}