/// <summary>
/// This method immediatly calles the "Expression function"
/// </summary>
/// <param name="st"></param>
/// <param name="store"></param>
/// <returns></returns>
private static Sexpr assignment(Tokenizer st, Hashtable store)
{
Sexpr ans = expr(st, store); //Calling the expr function
st.NextToken(); //Next token
if (st.getString().Equals("=")) //If the next token equals "=" the function will call the next token and store the number assigned to the letter earlier recognized in the hashtable store.
{
st.NextToken();
if (!st.isNumber())
{
try
{
ans = new Assignment(ans, new Variable(st.getString()));
st.NextToken();
}
catch
{
}
}
else
{
throw new ArithmeticException("Obs!! endast bokstäver kan tilldelas värden");
}
}
else
{
st.PushBack();
return ans;
}
st.PushBack();
return ans;
}
private static Sexpr factor(Tokenizer st, Hashtable store)
{
Sexpr ans = prim(st, store);
st.NextToken();
while(st.getString() == "")
{
st.NextToken();
if (!st.isNumber())
ans = new Diff(ans, prim(st, store));
else
throw new ArgumentException("Nothing to apply the differentiate operator on");
}
st.PushBack();
return ans;
}
private static Sexpr prim(Tokenizer st, Hashtable store)
{
st.NextToken();
Sexpr ans;
if (st.getString().Equals("("))
{
ans = assignment(st, store);
st.NextToken();
if (!st.getString().Equals(")"))
{
throw new ArgumentException("missing )");
}
}
else if (st.ToString() == "-")
{
ans = new Negation(prim(st, store));
return ans;
}
else if (st.ToString() == "&")
{
ans = new Eval(prim(st,store));
return ans;
}
else if (st.isNumber())
{
double v = st.GetNumber();
ans = new Constant(v);
return ans;
}
else if (!st.isNumber())
{
string id = st.getString();
st.NextToken();
if(st.getString()=="(")
{
st.PushBack();
if (id.Equals("sin"))
{
ans = new Sin(prim(st, store));
st.NextToken();
}
else if (id.Equals("cos"))
{
ans = new Cos(prim(st, store));
st.NextToken();
}
else if (id.Equals("exp"))
{
ans = new Exp(prim(st, store));
st.NextToken();
}
else if (id.Equals("log"))
{
ans = new Log(prim(st, store));
st.NextToken();
}
else
throw new ArgumentException("Incorrect function call");
}
else
ans = new Variable(id);
st.PushBack();
}
else
{
st.PushBack();
throw new ArgumentException("Incorrect function call or incorrect variable assignment");
}
return ans;
}
