private LetterPostion SameLetterPostion(char letter, string format, int postion)
{
LetterPostion count = new LetterPostion();
int leftPostion = postion;
int rightPostion = postion;
while (leftPostion > 0)
{
leftPostion--;
if (format[leftPostion] == letter)
{
count.LeftCount++;
}
else
{
break;
}
}
while (rightPostion < format.Length - 1)
{
++rightPostion;
if (format[rightPostion] == letter)
{
count.RightCount++;
}
else
{
break;
}
}
return(count);
}
public DateTime Format(string format, int chengedPostion, bool isUp, DateTime baseTime)
{
string timeFormat = format;
DateTime time = baseTime;
// hh:mm:ss => !h!h!:!m!m!:!s!s! => 9! length= 8
//chengedPostion max= 8 min = 0
if (chengedPostion > timeFormat.Length)
{
throw new ArgumentOutOfRangeException("chengedPostion");
}
if (chengedPostion >= timeFormat.Length - 1)
{
chengedPostion = timeFormat.Length - 1;
}
if (chengedPostion < 0)
{
chengedPostion = 0;
}
int operand = isUp ? 1 : -1;
char positionchar = timeFormat[chengedPostion];
LetterPostion postion = SameLetterPostion(positionchar, timeFormat, chengedPostion);
switch (positionchar)
{
case ':':
return(Format(format, chengedPostion - 1, isUp, baseTime));
case '-':
return(Format(format, chengedPostion - 1, isUp, baseTime));
case 'h':
return(time.AddHours(operand));
case 'm':
operand = (int)Math.Pow(10, postion.RightCount) * operand;
return(time.AddMinutes(operand));
case 's':
operand = (int)Math.Pow(10, postion.RightCount) * operand;
return(time.AddSeconds(operand));
case 'd':
return(time.AddDays(operand));
case 'M':
return(time.AddMonths(operand));
case 'y':
operand = (int)Math.Pow(10, postion.RightCount) * operand;
if (time.Year + operand < 1 || time.Year + operand > 9999)
{
return(time);
}
return(time.AddYears(operand));
default:
throw new NotImplementedException();
}
}