private ExpressionTreeNode ParseOr()
{
var node = ParseAnd();
if (_tokenReader.Token != Token.Or)
{
return(node);
}
_tokenReader.NextToken();
ExpressionTreeNode root = ExpressionTreeNode.CreateOr(node, ParseAnd());
node = root;
while (true)
{
if (_tokenReader.Token != Token.Or)
{
return(root);
}
_tokenReader.NextToken();
var child1 = node.Child2;
node.Child2 = ExpressionTreeNode.CreateOr(child1, ParseAnd());
node = node.Child2;
}
}
/// <summary>
/// AND(NOT,NOT) -> NOT(OR)
/// </summary>
/// <param name="node"></param>
private static ExpressionTreeNode TwoNotInAndRule(ExpressionTreeNode node, ref int count)
{
if (node == null)
{
return(null);
}
if (node.Operation == "AND" && node.Child1.Operation == "NOT" && node.Child2.Operation == "NOT")
{
var andChild = ExpressionTreeNode.CreateOr(node.Child1.Child1, node.Child2.Child1);
node = ExpressionTreeNode.CreateNot(andChild);
count++;
}
return(node);
}