//P is
// if next is a unary operator
// const op := unary(next)
// consume
// q := prec( op )
// const t := Exp( q )
// return mkNode( op, t )
// else if next = "("
// consume
// const t := Exp( 0 )
// expect ")"
// return t
// else if next is a v
// const t := mkLeaf( next )
// consume
// return t
// else
// error
private Expression P()
{
Operator op = new Operator();
if (tokens.Tok == "+")
{
// Skip unary +.
tokens.Consume();
return(P());
}
else if (IsUnaryPreOperator(tokens.Tok, ref op))
{
// Unary operator.
tokens.Consume();
Expression t = Exp(Precedence(op));
return(Unary.New(op, t));
}
else if (tokens.Tok == "(")
{
// Group.
tokens.Consume();
Expression t = Exp(0);
tokens.Expect(")");
return(t);
}
else if (tokens.Tok == "{")
{
// Set.
tokens.Consume();
return(Set.New(L(",", "}")));
}
else if (tokens.Tok == "[")
{
// Matrix.
tokens.Consume();
List <List <Expression> > entries = new List <List <Expression> >();
while (tokens.Tok == "[")
{
tokens.Consume();
entries.Add(L(",", "]"));
}
tokens.Expect("]");
return(Matrix.New(entries));
}
else
{
string tok = tokens.Consume();
decimal dec = 0;
double dbl = 0.0;
if (decimal.TryParse(tok, NumberStyles.Float, culture, out dec))
{
return(Constant.New(dec));
}
if (double.TryParse(tok, NumberStyles.Float, culture, out dbl))
{
return(Constant.New(dbl));
}
else if (tok == "True")
{
return(Constant.New(true));
}
else if (tok == "False")
{
return(Constant.New(false));
}
else if (tok == "\u221E" || tok == "oo")
{
return(Constant.New(Real.Infinity));
}
else if (tokens.Tok == "[")
{
// Bracket function call.
tokens.Consume();
List <Expression> args = L(",", "]");
return(Call.New(Resolve(tok, args), args));
}
else if (tokens.Tok == "(")
{
// Paren function call.
tokens.Consume();
List <Expression> args = L(",", ")");
return(Call.New(Resolve(tok, args), args));
}
else
{
return(Resolve(tok));
}
}
}
protected override Expression VisitUnary(Unary U)
{
// Logic operators are mostly constant.
if (U.IsLogicOp)
return 0;
return base.VisitUnary(U);
}
protected override Expression VisitUnary(Unary U)
{
Expression O = Visit(U.Operand);
Real? C = AsReal(O);
switch (U.Operator)
{
case Operator.Not:
if (IsTrue(C))
return Constant.New(false);
else if (IsFalse(C))
return Constant.New(true);
break;
}
return Unary.New(U.Operator, O);
}
protected override int VisitUnary(Unary U)
{
return(Visit(U.Operand) + 1);
}
protected virtual T VisitUnary(Unary U)
{
return(VisitUnknown(U));
}
protected override bool VisitUnary(Unary U)
{
return(Visit(U.Operand));
}
public static LazyExpression operator -(Expression L, Expression R)
{
return(new LazyExpression(Sum.New(L, Unary.Negate(R))));
}
public static LazyExpression operator !(Expression O)
{
return(new LazyExpression(Unary.Not(O)));
}
protected override PrettyString VisitUnary(Unary U)
{
return(PrettyString.ConcatColumns(Unary.ToStringPrefix(U.Operator), Visit(U.Operand), Unary.ToStringPostfix(U.Operator)));
}
public Expression Solve(Expression x)
{
return(Unary.Negate(Sum.New(this.Where(i => !i.Key.Equals(x)).Select(i => Product.New(i.Key, i.Value)))) / this[x]);
}
protected override string VisitUnary(Unary U)
{
return(ToString(U.Operator) + Visit(U.Operand, Parser.Precedence(U.Operator)));
}
protected override string VisitUnary(Unary U)
{
return ToString(U.Operator) + Visit(U.Operand, Parser.Precedence(U.Operator));
}
public static LazyExpression operator -(LazyExpression L, LazyExpression R)
{
return(new LazyExpression(Sum.New(L.value, Unary.Negate(R.value))));
}