public BinaryExpression(BinaryOperator @operator, CssExpression left, CssExpression right)
{
_operator = @operator;
_left = left;
_right = right;
}
public static CssExpression State(CssExpression expression, string state) => new StateExpression(expression, state);
private static CssExpression Combine(CssExpression left, CssExpression right, CssExpression.BinaryOperator op) => left == null ? right : CssExpression.Binary(op, left, right);
public static CssExpression Binary(BinaryOperator op, CssExpression left, CssExpression right) => new BinaryExpression(op, left, right);
public static CssExpression Parse(TextReader reader)
{
var ors = new List <CssExpression>();
CssExpression current = null;
var currentOp = CssExpression.BinaryOperator.And;
int code;
while ((code = reader.Read()) >= 0)
{
var c = (char)code;
switch (c)
{
case '*': current = Combine(current, CssExpression.All, currentOp);; break;
case '.': current = Combine(current, CssExpression.Class(ReadText(reader)), currentOp); break;
case '#': current = Combine(current, CssExpression.Id(ReadText(reader)), currentOp); break;
case ':': current = CssExpression.State(current, ReadText(reader)); break;
case '~':
while (reader.Peek() == ' ')
{
reader.Read();
}
currentOp = CssExpression.BinaryOperator.Prev;
break;
case '+':
while (reader.Peek() == ' ')
{
reader.Read();
}
currentOp = CssExpression.BinaryOperator.PrevSibling;
break;
case ',':
while (reader.Peek() == ' ')
{
reader.Read();
}
ors.Add(current);
current = null;
break;
case '>':
while (reader.Peek() == ' ')
{
reader.Read();
}
currentOp = CssExpression.BinaryOperator.Parent;
break;
case ' ':
currentOp = ReadOperator(reader);
break;
case '[':
{
var attrValue = ReadText(reader, true).Split('=');
reader.Read();
var attr = attrValue[0];
if (attr.Length == 0)
{
break;
}
if (attrValue.Length == 1)
{
current = Combine(current,
CssExpression.Attr(CssExpression.AttributeOperator.Exists, attrValue[0], null),
currentOp);
break;
}
var opChar = attr.Last();
var attrOp = CssExpression.AttributeOperator.Equals;
switch (opChar)
{
case '~': attrOp = CssExpression.AttributeOperator.DelimitedContains; break;
case '|': attrOp = CssExpression.AttributeOperator.DelimitedStartWith; break;
case '^': attrOp = CssExpression.AttributeOperator.StartWith; break;
case '$': attrOp = CssExpression.AttributeOperator.EndWith; break;
case '*': attrOp = CssExpression.AttributeOperator.Contains; break;
}
var val = attrValue[1];
if (val.StartsWith("\""))
{
val = val.Trim('"');
}
else if (val.StartsWith("'"))
{
val = val.Trim('\'');
}
current = Combine(current, CssExpression.Attr(
attrOp,
attrOp == CssExpression.AttributeOperator.Equals ? attr : attr.Substring(0, attr.Length - 1),
val),
currentOp);
break;
}
case '\r':
case '\n':
case '\t':
break;
default:
current = Combine(current, CssExpression.Tag(c + ReadText(reader)), currentOp);
break;
}
}
if (ors.Count > 0)
{
ors.Add(current);
return(CssExpression.Or(ors));
}
return(current ?? CssExpression.None);
}
