static EbnfExpression _SeqToExpression(IList <EbnfExpression> seq)
{
EbnfExpression result;
switch (seq.Count)
{
case 0:
result = null;
break;
case 1:
result = seq[0];
break;
default:
var ce = new EbnfConcatExpression();
for (int jc = seq.Count, j = 0; j < jc; ++j)
{
if (null == ce.Left)
{
ce.Left = seq[j];
}
else if (null == ce.Right)
{
ce.Right = seq[j];
}
if (null != ce.Right)
{
ce = new EbnfConcatExpression(ce, null);
}
}
if (null == ce.Right)
{
result = ce.Left;
}
else
{
result = ce;
}
break;
}
return(result);
}
static EbnfExpression _ParseExpression(EbnfDocument doc, ParseContext pc)
{
EbnfExpression current = null;
EbnfExpression 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();
current = new EbnfOrExpression(current, _ParseExpression(doc, pc));
current.SetLocationInfo(line, column, position);
break;
case '(':
pc.Advance();
e = _ParseExpression(doc, pc);
current.SetLocationInfo(line, column, position);
pc.Expecting(')');
pc.Advance();
e.SetLocationInfo(line, column, position);
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
break;
case '[':
pc.Advance();
e = new EbnfOptionalExpression(_ParseExpression(doc, pc));
e.SetLocationInfo(line, column, position);
pc.TrySkipCCommentsAndWhiteSpace();
pc.Expecting(']');
pc.Advance();
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
break;
case '{':
pc.Advance();
e = new EbnfRepeatExpression(_ParseExpression(doc, pc));
e.SetLocationInfo(line, column, position);
pc.TrySkipCCommentsAndWhiteSpace();
pc.Expecting('}');
pc.Advance();
if ('+' == pc.Current)
{
pc.Advance();
((EbnfRepeatExpression)e).IsOptional = false;
}
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
break;
case '\"':
e = new EbnfLiteralExpression(pc.ParseJsonString());
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
e.SetLocationInfo(line, column, position);
break;
case '\'':
pc.Advance();
pc.ClearCapture();
pc.TryReadUntil('\'', '\\', false);
pc.Expecting('\'');
pc.Advance();
e = new EbnfRegexExpression(pc.Capture);
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
e.SetLocationInfo(line, column, position);
break;
case ';':
case ']':
case ')':
case '}':
return(current);
default:
e = new EbnfRefExpression(_ParseIdentifier(pc));
if (null == current)
{
current = e;
}
else
{
current = new EbnfConcatExpression(current, e);
}
e.SetLocationInfo(line, column, position);
break;
}
}
pc.TrySkipCCommentsAndWhiteSpace();
return(current);
}
