internal static XbnfExpression Parse(ParseContext pc)
{
XbnfExpression current = null;
XbnfExpression e;
long position;
int line;
int column;
pc.TrySkipCCommentsAndWhiteSpace();
position = pc.Position; line = pc.Line; column = pc.Column;
while (-1 != pc.Current && ']' != pc.Current && ')' != pc.Current && '}' != pc.Current && ';' != pc.Current)
{
pc.TrySkipCCommentsAndWhiteSpace();
position = pc.Position; line = pc.Line; column = pc.Column;
switch (pc.Current)
{
case '|':
pc.Advance();
position = pc.Position; line = pc.Line; column = pc.Column;
current = new XbnfOrExpression(current, Parse(pc));
current.SetLocation(line, column, position);
break;
case '(':
pc.Advance();
position = pc.Position; line = pc.Line; column = pc.Column;
e = Parse(pc);
current.SetLocation(line, column, position);
pc.Expecting(')');
pc.Advance();
e.SetLocation(line, column, position);
if (null == current)
{
current = e;
}
else
{
current = new XbnfConcatExpression(current, e);
}
break;
case '[':
pc.Advance();
e = new XbnfOptionalExpression(Parse(pc));
e.SetLocation(line, column, position);
pc.TrySkipCCommentsAndWhiteSpace();
pc.Expecting(']');
pc.Advance();
if (null == current)
{
current = e;
}
else
{
current = new XbnfConcatExpression(current, e);
}
break;
case '{':
pc.Advance();
e = new XbnfRepeatExpression(Parse(pc));
e.SetLocation(line, column, position);
pc.TrySkipCCommentsAndWhiteSpace();
pc.Expecting('}');
pc.Advance();
if ('+' == pc.Current)
{
pc.Advance();
((XbnfRepeatExpression)e).IsOptional = false;
}
if (null == current)
{
current = e;
}
else
{
current = new XbnfConcatExpression(current, e);
}
break;
case '\"':
e = new XbnfLiteralExpression(pc.ParseJsonString());
if (null == current)
{
current = e;
}
else
{
current = new XbnfConcatExpression(current, e);
}
e.SetLocation(line, column, position);
break;
case '\'':
pc.Advance();
pc.ClearCapture();
pc.TryReadUntil('\'', '\\', false);
pc.Expecting('\'');
pc.Advance();
e = new XbnfRegexExpression(pc.GetCapture());
if (null == current)
{
current = e;
}
else
{
current = new XbnfConcatExpression(current, e);
}
e.SetLocation(line, column, position);
break;
case ';':
case ']':
case ')':
case '}':
return(current);
default:
e = new XbnfRefExpression(ParseIdentifier(pc));
if (null == current)
{
current = e;
}
else
{
current = new XbnfConcatExpression(current, e);
}
e.SetLocation(line, column, position);
break;
}
}
pc.TrySkipCCommentsAndWhiteSpace();
return(current);
}
