[Firebird-net-provider] FbCommand sql parser

[Gareth]

I have created a new sql parser method for the FbCommand.

It removes single line comments "-- " and block comments "/* */".
It replaces tabs, newlines, carriage returns and multiple spaces with
a single space.
It also extracts the parameter names.

Has anyone got any comments ?

-- 

Gareth

        private string ParseNamedParameters(string sql)
        {
          // Clear the current parameters.
          this.namedParameters.Clear();

          // Should we parse if there are no parameters. (comments ?
control characters ?)
          if (sql.IndexOf('@') == -1)
          {
              return sql;
          }

          bool          inParam       = false;
          bool          inSpace       = false;
          bool          inSingleQuote = false;
          bool          inDoubleQuote = false;
          char[]        crlf          = new char[] {'\r', '\n'};
          StringBuilder paramBuilder  = new StringBuilder(31);
          StringBuilder resultBuilder = new StringBuilder(sql.Length);

          for (int i = 0, j = sql.Length; i < j; i++)
          {

            // Are we busy with a parameter ?
            if (inParam == true)
            {
                if (Char.IsLetterOrDigit(sql[i]) || sql[i] == '_' ||
sql[i] == '$')
                {
                    paramBuilder.Append(sql[i]);
                    continue;
                }
                else
                {
                    this.namedParameters.Add(paramBuilder.ToString());
                    paramBuilder.Length = 0;
                    resultBuilder.Append('?');
                    inParam = false;
                    inSpace = false;
                }
            }

            // Are we busy with quoted text ?
            if ((inSingleQuote == true) || (inDoubleQuote == true))
            {
              resultBuilder.Append(sql[i]);

              if (sql[i] == '\'')
              {
                  inSingleQuote = false;
                  continue;
              }

              inDoubleQuote = false;
              continue;
            }

            switch (sql[i])
            {
              // We are starting to read a parameter ?
              case '@':
                inParam = true;
                paramBuilder.Append('@');
                continue;

              // Are we starting a single line comment ?
              case '-':
                if ((i < j - 1) && (sql[i + 1] == '-'))
                {
                  int index = sql.IndexOfAny(crlf, i + 2);

                  i = index > i ?index - 1 :j;
                  continue;
                }

                break;

              // Are we starting a block comment ?
              case '/':
                if ((i < j - 1) && (sql[i + 1] == '*'))
                {
                  int index = sql.IndexOf("*/", i + 2);

                  i = index > i ? index + 1 : j;
                  continue;
                }

                break;

              // We are starting single quoted text ?
              case '\'':
                inSingleQuote = true;
                resultBuilder.Append('\'');
                continue;

              // We are starting double quoted text ?
              case '\"':
                inDoubleQuote = true;
                resultBuilder.Append('\"');
                continue;

              // Add a space in place of control characters.
              // Do not combine more than one space at a time.
              case ' ':
              case '\t':
              case '\r':
              case '\n':
                if (inSpace == false)
                {
                  inSpace = true;
                  resultBuilder.Append(' ');
                }

                continue;
            }

            inSpace = false;
            resultBuilder.Append(sql[i]);
          }

          if (inParam == true)
          {
              this.namedParameters.Add(paramBuilder.ToString());
              resultBuilder.Append('?');
          }

          return resultBuilder.ToString();
        }

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