static void SetCurrentSelector(ref Selector root, ref Selector workingRoot, ref Operator workingRootParent, Operator op, Selector sel)
{
var updateRoot = root == workingRoot;
op.Left = workingRoot;
op.Right = sel;
workingRoot = op;
if (workingRootParent != null)
{
workingRootParent.Right = workingRoot;
}
if (updateRoot)
{
root = workingRoot;
}
if (workingRoot is Or)
{
workingRootParent = (Operator)workingRoot;
workingRoot = sel;
}
}
public static Selector Parse(CssReader reader, char stopChar = '\0')
{
Selector root = All, workingRoot = All;
Operator workingRootParent = null;
Action <Operator, Selector> setCurrentSelector = (op, sel) => SetCurrentSelector(ref root, ref workingRoot, ref workingRootParent, op, sel);
int p;
reader.SkipWhiteSpaces();
while ((p = reader.Peek()) > 0)
{
switch (unchecked ((char)p))
{
case '*':
setCurrentSelector(new And(), All);
reader.Read();
break;
case '.':
reader.Read();
var className = reader.ReadIdent();
if (className == null)
{
return(Invalid);
}
setCurrentSelector(new And(), new Class(className));
break;
case '#':
reader.Read();
var id = reader.ReadName();
if (id == null)
{
return(Invalid);
}
setCurrentSelector(new And(), new Id(id));
break;
case '[':
throw new NotImplementedException("Attributes not implemented");
case ',':
reader.Read();
setCurrentSelector(new Or(), All);
reader.SkipWhiteSpaces();
break;
case '+':
reader.Read();
setCurrentSelector(new Adjacent(), All);
reader.SkipWhiteSpaces();
break;
case '~':
reader.Read();
setCurrentSelector(new Sibling(), All);
reader.SkipWhiteSpaces();
break;
case '>':
reader.Read();
setCurrentSelector(new Child(), All);
reader.SkipWhiteSpaces();
break;
case '^': //not in CSS spec
reader.Read();
var element = reader.ReadIdent();
if (element == null)
{
return(Invalid);
}
setCurrentSelector(new And(), new Base(element));
break;
case ' ':
case '\t':
case '\n':
case '\r':
case '\f':
reader.Read();
bool processWs = false;
while ((p = reader.Peek()) > 0)
{
var c = unchecked ((char)p);
if (char.IsWhiteSpace(c))
{
reader.Read();
continue;
}
processWs = (c != '+' &&
c != '>' &&
c != ',' &&
c != '~' &&
c != stopChar);
break;
}
if (!processWs)
{
break;
}
setCurrentSelector(new Descendent(), All);
reader.SkipWhiteSpaces();
break;
default:
if (unchecked ((char)p) == stopChar)
{
return(root);
}
var elementName = reader.ReadIdent();
if (elementName == null)
{
return(Invalid);
}
setCurrentSelector(new And(), new Element(elementName));
break;
}
}
return(root);
}