XmlGraphNode IExprVisitor <XmlGraphNode> .VisitChars(CharsExpr charsExpr)
{
return(this.Graph.CreateNode());
}
Expr ParseImpl(Token[] tokens, int from, int to)
{
var items = new LinkedList <Expr>();
var makeOr = false;
var makeCheck = false;
var makeCheckNot = false;
for (int i = from; i <= to; i++)
{
var t = tokens[i];
switch (t.kind)
{
case TokenKind.openGroup:
var nextPos = this.SkipBraces(tokens, i + 1, to);
var groupNode = this.ParseImpl(tokens, i + 1, nextPos - 1);
if (groupNode == null)
{
return(null);
}
i = nextPos;
items.AddLast(groupNode);
break;
case TokenKind.closeGroup:
return(null);
case TokenKind.checkOp:
makeCheck = true;
continue;
case TokenKind.checkNotOp:
makeCheckNot = true;
continue;
case TokenKind.orOp:
makeOr = true;
continue;
case TokenKind.quantor:
int minNum = -1, maxNum = -1;
this.ParseQuantifier(t.str, ref minNum, ref maxNum);
Expr lastExprPart;
if (items.Last.Value is CharsExpr chars)
{
lastExprPart = new CharsExpr(chars.Chars.Last().ToString());
items.RemoveLast();
items.AddLast(new CharsExpr(chars.Chars.Substring(0, chars.Chars.Length - 1)));
}
else
{
lastExprPart = items.Last.Value;
items.RemoveLast();
}
items.AddLast(Expr.Number(lastExprPart, minNum, maxNum));
break;
case TokenKind.charClass:
var classAlts = this.ParseCharClass(tokens, ref i);
items.AddLast(classAlts);
break;
case TokenKind.anyChar:
items.AddLast(Expr.AnyChar());
break;
case TokenKind.ch:
items.AddLast(Expr.Characters(t.str));
break;
case TokenKind.escapedChar:
items.AddLast(GiveEscape(t));
break;
case TokenKind.rangeOp:
return(null);
default:
throw new NotImplementedException("");
}
if (makeOr)
{
if (makeCheck || makeCheckNot)
{
return(null);
}
if (items.Count < 2)
{
return(null);
}
var nextPos = i + 1;
if (nextPos <= to)
{
if (tokens[nextPos].Check(TokenKind.quantor))
{
continue;
}
}
var lastItemIfAlts = items.Last.Previous.Value as AlternativesExpr;
var newAltesChildren = lastItemIfAlts == null ? new[] { items.Last.Previous.Value, items.Last.Value }
: lastItemIfAlts.Items.Concat(new[] { items.Last.Value }).ToArray();
var newAltsNode = Expr.Alternatives(newAltesChildren);
items.RemoveLast();
items.RemoveLast();
items.AddLast(newAltsNode);
makeOr = false;
}
else if (makeCheck)
{
if (makeOr || makeCheckNot)
{
return(null);
}
var lastExprPart = items.Last.Value;
items.RemoveLast();
items.AddLast(Expr.Check(lastExprPart));
makeCheck = false;
}
else if (makeCheckNot)
{
if (makeCheck || makeOr)
{
return(null);
}
var lastExprPart = items.Last.Value;
items.RemoveLast();
items.AddLast(Expr.CheckNot(lastExprPart));
makeCheckNot = false;
}
}
return(Expr.Sequence(items.ToArray()));
}
