public TokenTree replaceEquals()
{
List<Token> tokens = ReverseBFS();
foreach(Token t in tokens)
{
if(t is Operator && t.name == "EQUALS")
{
Token parent = t.parent;
Token left = t.getChild(0);
Token right = t.getChild(1);
Token n = new Operator(name: "AND");
Token newLeft = new Operator(name: "IMPLIES");
Token newRight = new Operator(name: "IMPLIES");
newLeft.setChild(0, left.Clone());
newLeft.setChild(1, right.Clone());
newRight.setChild(0, right.Clone());
newRight.setChild(1, left.Clone());
n.setChild(0, newLeft);
newLeft.parent = n;
n.setChild(1, newRight);
newRight.parent = n;
if (parent == null)
{
root = n;
}
else
{
parent.setChild(t.indexInParent, n);
}
}
}
return this;
}
public Token Clone()
{
Token n;
if (this is Operator)
{
n = new Operator(parent, name);
}
else if (this is Quantifier)
{
n = new Quantifier(parent, name);
}
else if(this is Function)
{
n = new Function(parent, name, childrenCount);
}
else
{
n = (Token)Activator.CreateInstance(GetType());
n.name = name;
n.priority = priority;
n.parent = parent;
n.childrenCount = childrenCount;
}
n.indexInParent = indexInParent;
for(int i=0;i<childrenCount;++i)
{
n.setChild(i, getChild(i));
}
return n;
}
public TokenTree convertAlternativeToConjunctions()
{
bool somethingDone;
do
{
somethingDone = false;
List<Token> tokens = ReverseBFS();
foreach (Token t in tokens)
{
if (t is Operator && t.name == "OR")
{
List<Token> left = new List<Token>();
List<Token> right = new List<Token>();
if(t.getChild(0) is Operator && t.getChild(0).name == "AND")
{
left.AddRange(getChildrenRecursively(t.getChild(0)));
}
else
{
left.Add(t.getChild(0));
}
if (t.getChild(1) is Operator && t.getChild(1).name == "AND")
{
right.AddRange(getChildrenRecursively(t.getChild(1)));
}
else
{
right.Add(t.getChild(1));
}
if (left.Count == 1 && right.Count == 1)
continue;
somethingDone = true;
List<Operator> alternatives = new List<Operator>();
foreach(Token l in left)
{
foreach(Token r in right)
{
Operator n = new Operator(name: "OR");
n.setChild(0, l);
n.setChild(1, r);
alternatives.Add(n);
}
}
Token mainAnd = new Operator(name: "AND");
Token current = mainAnd;
for(int i=0;i<alternatives.Count - 2;++i)
{
current.setChild(0, alternatives[i]);
current.setChild(1, new Operator(name:"AND"));
current = current.getChild(1);
}
current.setChild(0, alternatives[alternatives.Count - 2]);
current.setChild(1, alternatives[alternatives.Count - 1]);
if (t.parent == null)
root = mainAnd;
else
t.parent.setChild(t.indexInParent, mainAnd);
}
}
} while (somethingDone);
return this;
}
public TokenTree restrainNegation()
{
bool somethingDone;
do {
somethingDone = false;
List<Token> tokens = ReverseBFS();
foreach (Token t in tokens)
{
if (t is Negation && t.getChild(0).isFinal() == false)
{
Token t_parent = t.parent;
Token c = t.getChild(0);
if(c is Negation)
{
somethingDone = true;
if (t_parent == null)
root = c.getChild(0);
else
t_parent.setChild(t.indexInParent, c.getChild(0));
// Console.WriteLine(serialize());
}
else if(c is Operator)
{
somethingDone = true;
if (c.name == "AND")
{
Token n = new Operator(name: "OR");
Token left = c.getChild(0);
Token right = c.getChild(1);
Token newLeft = new Negation();
Token newRight = new Negation();
newLeft.setChild(0, left.Clone());
newRight.setChild(0, right.Clone());
n.setChild(0, newLeft);
n.setChild(1, newRight);
if (t_parent == null)
{
root = n;
}
else
{
t_parent.setChild(t.indexInParent, n);
}
//Console.WriteLine(serialize());
}
else if (c.name == "OR")
{
Token n = new Operator(name: "AND");
Token left = c.getChild(0);
Token right = c.getChild(1);
Token newLeft = new Negation();
Token newRight = new Negation();
newLeft.setChild(0, left.Clone());
newRight.setChild(0, right.Clone());
n.setChild(0, newLeft);
n.setChild(1, newRight);
if (t_parent == null)
{
root = n;
}
else
{
t_parent.setChild(t.indexInParent, n);
}
//Console.WriteLine(serialize());
}
}
else if(c is Quantifier)
{
somethingDone = true;
if (c.name == "FORALL")
{
Token n = new Quantifier(name: "EXISTS");
Token left = c.getChild(0);
Token right = c.getChild(1);
Token newRight = new Negation();
newRight.setChild(0, right.Clone());
n.setChild(0, left);
n.setChild(1, newRight);
if (t_parent == null)
{
root = n;
}
else
{
t_parent.setChild(t.indexInParent, n);
}
} else if (c.name == "EXISTS")
{
Token n = new Quantifier(name: "FORALL");
Token left = c.getChild(0);
Token right = c.getChild(1);
Token newRight = new Negation();
newRight.setChild(0, right.Clone());
n.setChild(0, left);
n.setChild(1, newRight);
if (t_parent == null)
{
root = n;
}
else
{
t_parent.setChild(t.indexInParent, n);
}
}
}
}
}
} while (somethingDone);
return this;
}