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);
}
static IList <EbnfMessage> _TryParseExpression(ParseNode pn, out EbnfExpression result)
{
result = null;
Debug.Assert(EbnfParser.expression == pn.SymbolId, "Not positioned on expression");
var msgs = new List <EbnfMessage>();
if (1 == pn.Children.Count)
{
var c = pn.Children[0];
if (EbnfParser.symbol == c.SymbolId)
{
ParseContext pc;
var cc = c.Children[0];
//TODO: parse the regular expressions and literals to make sure they're valid.
switch (cc.SymbolId)
{
case EbnfParser.identifier:
result = new EbnfRefExpression(cc.Value);
return(msgs);
case EbnfParser.regex:
pc = ParseContext.Create(cc.Value);
pc.EnsureStarted();
pc.Advance();
pc.TryReadUntil('\'', '\\', false);
result = new EbnfRegexExpression(pc.GetCapture());
return(msgs);
case EbnfParser.literal:
pc = ParseContext.Create(cc.Value);
pc.EnsureStarted();
pc.Advance();
pc.TryReadUntil('\"', '\\', false);
result = new EbnfLiteralExpression(pc.GetCapture());
return(msgs);
case EbnfParser.lbrace:
msgs.AddRange(_TryParseExpressions(c, 1, out result));
result = new EbnfRepeatExpression(result);
if (EbnfParser.rbracePlus == c.Children[c.Children.Count - 1].SymbolId)
{
((EbnfRepeatExpression)result).IsOptional = false;
}
return(msgs);
case EbnfParser.lbracket:
msgs.AddRange(_TryParseExpressions(c, 1, out result));
result = new EbnfOptionalExpression(result);
return(msgs);
case EbnfParser.lparen:
msgs.AddRange(_TryParseExpressions(c, 1, out result));
return(msgs);
default:
break;
}
}
}
return(msgs);
}
