csharp/EPAM.Deltix.HdTime/FormatString.cs

/*
  Copyright 2021 EPAM Systems, Inc

  See the NOTICE file distributed with this work for additional information
  regarding copyright ownership. Licensed under the Apache License,
  Version 2.0 (the "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
  License for the specific language governing permissions and limitations under
  the License.
 */

using System;
using System.Text;

namespace EPAM.Deltix.HdTime
{
	internal class FormatString
	{
		internal interface ITarget
		{
			/**
			 * Return max field length for the specified char. <= 0 if not a field
			 * @param fieldChar field identifier character
			 * @return maximum field length before padding is applied, returns value <= 0 if not a field identifier
			 */

			int FieldLength(char fieldChar);

			/**
			 * Return padding character for the field
			 * Only called if fieldLength(fieldChar) > 0 && encountered length > fieldLength(fieldChar)
			 * @param fieldChar field identifier character
			 * @return
			 */
			char PaddingForField(char fieldChar);
			void AddField(char fieldChar, int length);
			void AddString(String str, int ofs, int n);
			void AddString(String str);
		}

		internal static void Parse(String fmt, ITarget target)
		{
			int fmtLength = fmt.Length;
			StringBuilder sb = new StringBuilder(fmtLength);
			bool literalMode = false, wasQuote = false;

			for (int i = 0; i < fmtLength;)
			{
				char c = fmt[i++];
				if ('\'' == c)
				{
					literalMode ^= true;
					if (false == (wasQuote ^= true))
						sb.Append('\'');

					continue;
				}

				wasQuote = false;
				int maxLen;
				if (!literalMode && (maxLen = target.FieldLength(c)) > 0)
				{
					int n = i;
					for (; n < fmtLength && fmt[n] == c; ++n) { }
					n -= i;
					i += n++;
					if (n > maxLen)
					{
						char padding = target.PaddingForField(c);
						for (int j = 0; j < n - maxLen; j++)
							sb.Append(padding);

						n = maxLen;
					}

					if (sb.Length > 0)
					{
						target.AddString(sb.ToString());
						sb.Length = 0;
					}

					target.AddField(c, n);
				}
				else
				{
					sb.Append(c);
				}
			}

			if (sb.Length > 0)
				target.AddString(sb.ToString());
		}
	}
}