static MuFormula RewriteBoxDia(MuFormula form)
{
// We extended our grammar from the assignment by allowing regular formulas instead of single-letter actions.
// Here, we rewrite such extended formulas to their more primitive versions for which we impemented evaluators.
if (form is Diamond) {
var dia = form as Diamond;
if (dia.RegularFormula.Multiplier == "+") {
// <R+>f = <R><R*>f
var rf2 = dia.RegularFormula.Clone();
rf2.Multiplier = "*";
dia.RegularFormula.Multiplier = "";
dia.Formula = new Diamond(dia.RegularFormula, new Diamond(rf2, dia.Formula));
}
else if (dia.RegularFormula.Multiplier == "*") {
// <R*>f = mu X . (<R> X || f)
var var = new Variable(GetFreeVar());
dia.RegularFormula.Multiplier = "";
return Rewrite(new Mu(var, new Disjunction(new Diamond(dia.RegularFormula, var), dia.Formula)));
}
dia.Formula = Rewrite(dia.Formula);
}
else if (form is Box) {
var box = form as Box;
if (box.RegularFormula.Multiplier == "+") {
// [R+]f = [R][R*]f
var rf2 = box.RegularFormula.Clone();
rf2.Multiplier = "*";
box.RegularFormula.Multiplier = "";
return new Box(box.RegularFormula, new Box(rf2, box.Formula));
}
else if (box.RegularFormula.Multiplier == "*") {
// [R*]f = nu X . ([R] X && f)
var var = new Variable(GetFreeVar());
box.RegularFormula.Multiplier = "";
return Rewrite(new Nu(var, new Disjunction(new Box(box.RegularFormula, var), box.Formula)));
}
box.Formula = Rewrite(box.Formula);
}
// we also need to perform this on all subformulas
else if (form is Disjunction) form = new Disjunction(Rewrite(((Disjunction)form).Left), Rewrite(((Disjunction)form).Right));
else if (form is Conjunction) form = new Conjunction(Rewrite(((Conjunction)form).Left), Rewrite(((Conjunction)form).Right));
else if (form is Mu) form = new Mu(((Mu)form).Variable, Rewrite(((Mu)form).Formula));
else if (form is Nu) form = new Nu(((Nu)form).Variable, Rewrite(((Nu)form).Formula));
else if (form is Negation) form = new Negation(Rewrite(((Negation)form).Formula));
return form;
}
private object CreateNewObject(GOLD.Reduction r)
{
object result = null;
switch ((ProductionIndex)r.Parent.TableIndex()) {
case ProductionIndex.Nl_Newline:
// <nl> ::= NewLine <nl>
break;
case ProductionIndex.Nl_Newline2:
// <nl> ::= NewLine
break;
case ProductionIndex.Regform_Pipepipe:
// <regForm> ::= <regForm> '||' <regFormSeq>
result = new UnionFormula((RegularFormula)r[0].Data, (RegularFormula)r[2].Data);
break;
case ProductionIndex.Regform:
// <regForm> ::= <regFormSeq>
result = r[0].Data;
break;
case ProductionIndex.Regformseq_Dot:
// <regFormSeq> ::= <regFormSeq> '.' <regFormValue>
result = new SequenceFormula((RegularFormula)r[0].Data, (RegularFormula)r[2].Data);
break;
case ProductionIndex.Regformseq:
// <regFormSeq> ::= <regFormValue>
result = r[0].Data;
break;
case ProductionIndex.Regformvalue_Identifier:
// <regFormValue> ::= Identifier <Multiplier>
result = new SingleAction((string)r[0].Data, (string)r[1].Data);
break;
case ProductionIndex.Regformvalue_Not:
// <regFormValue> ::= not <regForm>
result = new NegateAction((RegularFormula)r[1].Data);
break;
case ProductionIndex.Regformvalue_Lparen_Rparen:
// <regFormValue> ::= '(' <regForm> ')' <Multiplier>
if ((string)r[3].Data != "")
return new NestedFormula((RegularFormula)r[1].Data, (string)r[3].Data);
else // small optimization
result = r[1].Data;
break;
case ProductionIndex.Multiplier_Plus:
// <Multiplier> ::= '+'
result = "+";
break;
case ProductionIndex.Multiplier_Times:
// <Multiplier> ::= '*'
result = "*";
break;
case ProductionIndex.Multiplier:
// <Multiplier> ::=
result = "";
break;
case ProductionIndex.Muform_Identifier:
// <muForm> ::= Identifier
result = new Proposition((string)r[0].Data);
break;
case ProductionIndex.Muform_Variable:
// <muForm> ::= Variable
result = new Variable((string)r[0].Data);
break;
case ProductionIndex.Muform_Lparen_Pipepipe_Rparen:
// <muForm> ::= '(' <muForm> '||' <muForm> ')'
result = new Disjunction((MuFormula)r[1].Data, (MuFormula)r[3].Data);
break;
case ProductionIndex.Muform_Lparen_Ampamp_Rparen:
// <muForm> ::= '(' <muForm> '&&' <muForm> ')'
result = new Conjunction((MuFormula)r[1].Data, (MuFormula)r[3].Data);
break;
case ProductionIndex.Muform_Lt_Gt:
// <muForm> ::= '<' <regForm> '>' <muForm>
result = new Diamond((RegularFormula)r[1].Data, (MuFormula)r[3].Data);
break;
case ProductionIndex.Muform_Lbracket_Rbracket:
// <muForm> ::= '[' <regForm> ']' <muForm>
result = new Box((RegularFormula)r[1].Data, (MuFormula)r[3].Data);
break;
case ProductionIndex.Muform_Mu_Variable_Dot:
// <muForm> ::= mu Variable '.' <muForm>
result = new Mu(new Variable((string)r[1].Data), (MuFormula)r[3].Data);
break;
case ProductionIndex.Muform_Nu_Variable_Dot:
// <muForm> ::= nu Variable '.' <muForm>
result = new Nu(new Variable((string)r[1].Data), (MuFormula)r[3].Data);
break;
case ProductionIndex.Muform_Not:
// <muForm> ::= not <muForm>
result = new Negation((MuFormula)r[1].Data);
break;
case ProductionIndex.Muform_Lparen_Rparen:
result = r[1].Data as MuFormula;
break;
case ProductionIndex.Line_Commentl:
// <Line> ::= CommentL <nl>
break;
case ProductionIndex.Line:
// <Line> ::= <muForm> <nl>
var form = (MuFormula)r[0].Data;
FormulaRewriter.ResetFreeVars();
form = FormulaRewriter.Rewrite(form);
form.SetParents(null /* root has no parent */);
formulas.Add(form);
break;
case ProductionIndex.Line2:
// <Line> ::= <nl>
break;
case ProductionIndex.Lines:
// <Lines> ::= <Line> <Lines>
break;
case ProductionIndex.Lines2:
// <Lines> ::=
break;
} //switch
return result;
}
public Mu(Variable var, MuFormula pred)
{
Variable = var;
Formula = pred;
}