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); }