private NFA parseParenthesis(string str, ref int loc)
{
//str[loc] == '('
loc++;
NFA totalNFA = null;
NFA builtNFA = null;
while (str[loc] != ')')
{
if (loc >= str.Length)
{
throw new RegexException("Regex has a ( without a matching )");
}
if (str[loc] == '|')
{
if (totalNFA == null)
{
totalNFA = builtNFA;
}
else
{
totalNFA = totalNFA.or(builtNFA);
}
builtNFA = null;
loc++;
}
NFA nextNFA = parseOne(str, ref loc);
if (builtNFA == null)
{
builtNFA = nextNFA;
}
else
{
builtNFA = builtNFA.conc(nextNFA);
}
}
if (totalNFA == null)
{
totalNFA = builtNFA;
}
else
{
totalNFA = totalNFA.or(builtNFA);
}
loc++;
//loc is first character after )
return(totalNFA);
}
private NFA parseAlternates(String str, ref int loc)
{
//str[loc] == '['
loc++;
bool exclusion = false;
if (str[loc] == '^')
{
exclusion = true;
loc++;
}
NFA builtNFA = null;
while (str[loc] != ']')
{
if (loc >= str.Length)
{
throw new RegexException("Regex has a [ without a matching ]");
}
NFA nextNFA;
if (str[loc] == '\\')
{
nextNFA = parseSpecial(str, ref loc);
}
else if (loc < str.Length - 1 && str[loc + 1] == '-')
{
char start = str[loc];
loc += 2;
char end = str[loc];
HashSet <char> chars = new HashSet <char>();
for (char ch = start; ch <= end; ch++)
{
chars.Add(ch);
}
nextNFA = new NFA(chars);
loc++;
}
else
{
nextNFA = new NFA(str.Substring(loc, 1));
loc++;
}
if (builtNFA == null)
{
builtNFA = nextNFA;
}
else
{
builtNFA = builtNFA.or(nextNFA);
}
}
if (exclusion)
{
builtNFA = builtNFA.complement();
}
builtNFA = builtNFA.complement().or(new NFA(1).complement()).complement();
loc++;
//loc is first character after ]
return(builtNFA);
}