private CommonF Factor()
{
Pow pow = new Pow();
CommonF power = Power();
if (!power.IsZero())
{
pow.RaiseTo(power);
}
else
{
while (IsCaret(look))
{
Match('^');
Power();
}
return(new Constant(0));
}
while (IsCaret(look))
{
Match('^');
power = Power();
if (!power.IsZero())
{
pow.RaiseTo(power);
}
else
{
if (pow.baseAndPower.Count > 1)
{
pow.baseAndPower.RemoveAt(pow.baseAndPower.Count - 1);
while (IsCaret(look))
{
Match('^');
Power();
}
return(pow);
}
else
{
while (IsCaret(look))
{
Match('^');
Power();
}
return(new Constant(1));
}
}
}
if (pow.baseAndPower.Count == 1)
{
return(pow.baseAndPower[0]);
}
else
{
return(pow);
}
}
private CommonF Power()
{
CommonF result = null;
if (look == '(')
{
Match('(');
result = Expression();
Match(')');
return(result);
}
if (IsAlpha(look))
{
var name = GetName();
if (look == '(')
{
Match('(');
var arg = Expression();
result = new OneVar(builtInFunctions[name], arg, name + "(argument)");
Match(')');
}
else
{
if (variables.ContainsKey(name))
{
result = new Variable(variables[name], name);
}
else
{
if (name == "PI" || name == "pi" || name == "Pi")
{
return(new PI());
}
if (name == "e" || name == "E")
{
return(new E());
}
variables[name] = variables.Count != 0 ? variables.Last().Value + 1 : 0;
result = new Variable(variables[name], name);
}
((Variable)result).name = name;
}
}
else
{
double constant = GetNum();
result = new Constant(constant);
}
return(result);
}
private CommonF Term()
{
Mul mul = new Mul();
Constant constant = new Constant(1);
CommonF factor = Factor();
if (!factor.IsZero())
{
if (!(factor is Constant))
{
mul *= factor;
}
else
{
constant *= (Constant)factor;
}
}
else
{
while (IsMulOperator(look))
{
switch (look)
{
case '*':
Match('*'); break;
case '/':
Match('/'); break;
}
Factor();
}
return(new Constant(0));
}
while (IsMulOperator(look))
{
switch (look)
{
case '*':
Match('*');
factor = Factor();
if (!factor.IsZero())
{
if (!(factor is Constant))
{
mul *= factor;
}
else
{
constant *= (Constant)factor;
}
}
else
{
while (IsMulOperator(look))
{
switch (look)
{
case '*':
Match('*'); break;
case '/':
Match('/'); break;
}
Factor();
}
return(new Constant(0));
}
break;
case '/':
Match('/');
factor = Factor();
if (!factor.IsZero())
{
if (!(factor is Constant))
{
mul /= factor;
}
else
{
constant /= (Constant)factor;
}
}
else
{
throw new ArithmeticException("null division");
}
break;
default:
throw new Exception("unexpected parser error");
}
}
if (constant.IsZero())
{
return(new Constant(0));
}
if (mul.operands.Count == 0)
{
return(constant);
}
if (mul.operands.Count == 1)
{
if (constant.Value == 1)
{
return(mul.operands[0]);
}
else
{
return(mul.operands[0] * constant);
}
}
if (constant.Value == 1)
{
return(mul);
}
else
{
return(mul * constant);
}
}
//get expression as graph
private CommonF Expression()
{
Sum sum = new Sum();
Constant constant = new Constant(0);
CommonF term = null;
if (!IsAddOperator(look))
{
term = Term();
if (!term.IsZero())
{
if (!(term is Constant))
{
sum += term;
}
else
{
constant += (Constant)term;
}
}
}
while (IsAddOperator(look))
{
switch (look)
{
case '+':
Match('+');
term = Term();
if (!term.IsZero())
{
if (!(term is Constant))
{
sum += term;
}
else
{
constant += (Constant)term;
}
}
break;
case '-':
Match('-');
term = Term();
if (!term.IsZero())
{
if (!(term is Constant))
{
sum -= term;
}
else
{
constant -= (Constant)term;
}
}
break;
default:
throw new Exception();
}
}
if (sum.operands.Count == 0)
{
return(constant);
}
if (constant.Value != 0)
{
sum += constant;
}
return(sum);
}
