/**
* Returns the Calendar for a given COS string containing a date,
* or {@code null} if it cannot be parsed.
*
* The returned value will have 0 for DST_OFFSET.
*
* @param text A COS string containing a date.
* @return The Calendar that the text string represents, or {@code null} if it cannot be parsed.
*/
public static DateTime?toCalendar(CosString text)
{
if (text == null)
{
return(null);
}
return(toCalendar(text.GetString()));
}
/// <summary>
/// This will parse a PDF HEX string with fail fast semantic meaning that we stop if a not allowed character is found.
/// This is necessary in order to detect malformed input and be able to skip to next object start.
/// We assume starting '<' was already read.
/// </summary>
private static CosString ParseHexString(IRandomAccessRead reader)
{
var sBuf = new StringBuilder();
while (true)
{
int c = reader.Read();
if (ReadHelper.IsHexDigit((char)c))
{
sBuf.Append((char)c);
}
else if (c == '>')
{
break;
}
else if (c < 0)
{
throw new IOException("Missing closing bracket for hex string. Reached EOS.");
}
else if (c == ' ' || c == '\n' || c == '\t' || c == '\r' || c == '\b' || c == '\f')
{
}
else
{
// if invalid chars was found: discard last
// hex character if it is not part of a pair
if (sBuf.Length % 2 != 0)
{
sBuf.Remove(sBuf.Length - 1, 1);
}
// read till the closing bracket was found
do
{
c = reader.Read();
}while (c != '>' && c >= 0);
// might have reached EOF while looking for the closing bracket
// this can happen for malformed PDFs only. Make sure that there is
// no endless loop.
if (c < 0)
{
throw new IOException("Missing closing bracket for hex string. Reached EOS.");
}
// exit loop
break;
}
}
return(CosString.ParseHex(sBuf.ToString()));
}