// Maps a token of alphanumeric characters to a numbering format ID and a
// minimum length bound. Tokens specify the character(s) that begins a Unicode
// numbering sequence. For example, "i" specifies lower case roman numeral
// numbering. Leading "zeros" specify a minimum length to be maintained by
// padding, if necessary.
public static TokenInfo CreateFormat(string formatString, int startIdx, int tokLen)
{
Debug.Assert(startIdx >= 0 && tokLen > 0);
TokenInfo token = new TokenInfo();
token.formatString = null;
token.length = 1;
bool useDefault = false;
char ch = formatString[startIdx];
switch (ch)
{
case '1':
case 'A':
case 'I':
case 'a':
case 'i':
break;
default:
// NOTE: We do not support Tamil and Ethiopic numbering systems having no zeros
if (CharUtil.IsDecimalDigitOne(ch))
{
break;
}
if (CharUtil.IsDecimalDigitOne((char)(ch + 1)))
{
// Leading zeros request padding. Track how much.
int idx = startIdx;
do
{
token.length++;
} while (--tokLen > 0 && ch == formatString[++idx]);
// Recognize the token only if the next character is "one"
if (formatString[idx] == ++ch)
{
break;
}
}
useDefault = true;
break;
}
if (tokLen != 1)
{
// If remaining token length is not 1, do not recognize the token
useDefault = true;
}
if (useDefault)
{
// Default to Arabic numbering with no zero padding
token.startChar = NumberFormatter.DefaultStartChar;
token.length = 1;
}
else
{
token.startChar = ch;
}
return(token);
}
