/**
* Parse the given expression
* @param new_expr A string containing an expression, for example "2+3"
* @return ans A string containing the answer, or an error when
* an error occurred
*/
public String ParseAndEval(String new_expr, ICheckModelName checkModelName, JongErrWarn errW)
{
try
{
_checkModelName = checkModelName;
// initialize all variables
expr = new_expr;
ans = 0.0;
// Pare the expression into a function tree format
JongFunction function = parse_start();
String dbgString = FuncToString(function, " ", "----", errW);
dbgString += "\n";
//System.out.print(dbgString);
// evaluate the expression
ans = function.eval();
if (function is JongFunctionAssign)
{
// function assignment
JongFunctionAssign fa = (JongFunctionAssign)function;
String desc = "";
desc += fa.getName();
desc += "(";
for (int i = 0; i < fa.getVariables().Count(); i++)
{
if (i > 0)
{
desc += ", ";
}
desc += fa.getVariables().ElementAt(i).getName();
}
desc += ")";
ans_str = "Function " + desc + " defined";
}
else if (function is JongVariableAssign)
{
// variable assignment
JongVariableAssign JongVariableAssign = (JongVariableAssign)function;
ans_str = string.Format("%s = %g",
JongVariableAssign.getName(),
ans);
// add the answer to memory as variable "Ans"
variablelist["ANS"] = ans;
}
else
{
//DecimalFormat formatter = new DecimalFormat("#.##########");
ans_str = string.Format("{0:#.##########}", ans);
// add the answer to memory as variable "Ans"
variablelist["ANS"] = ans;
}
}
catch (JongError err)
{
errW.Init(ErrWStat.UNKNOWN_ERROR, err.get(), false);
ans_str = err.get();
expr = "";
}
return(ans_str);
}
/*
* assignment of variable, for example "a = 3.4/2"
*/
private JongFunction parse_function_ass() //throws JongError
{
if (token_type == TOKENTYPE.FUNCTION)
{
// check for a function assignment like "f(a,b)=a*b"
// copy current token (we may have to revert to it)
char t_now = t;
int t_pos_now = t_pos;
TOKENTYPE token_type_now = token_type;
String token_now = token;
String name = token; //.ToUpper();
getToken();
if (token.Equals("("))
{
// possible assignment of a function.
// Verify this by checking if it has the form "f(a,b,c,...)="
bool hasCorrectParams = true;
localvariablelist = new List <JongLocalVariable>();
while (true)
{
getToken();
if (token_type != TOKENTYPE.VARIABLE)
{
// wrong, we would have expected a variable name.
// So this is no function assignment.
hasCorrectParams = false;
break;
}
// add this variable to the local variable list
String var_name = token; //.ToUpper();
localvariablelist.Add(new JongLocalVariable(var_name));
getToken();
if (token.Equals(")"))
{
// closing parenthesis found
hasCorrectParams = true;
break;
}
if (!token.Equals(","))
{
// wrong, we would have expected a comma.
// So this is no function assignment.
hasCorrectParams = false;
break;
}
}
if (hasCorrectParams)
{
getToken();
if (token.Equals("="))
{
// we have a function assignment like "f(a,b)=a*b"
// assign a new function
// note: the localvariablelinks will be copied and owned by
// the assigned function. We do not need to delete the links
getToken();
JongFunctionAssign function =
new JongFunctionAssign(functionlist,
name,
localvariablelist,
parse_conditions());
return(function);
}
}
// Function not assigned. Clear the created local variables
localvariablelist.Clear();
// revert to previous token
t = t_now;
t_pos = t_pos_now;
token_type = token_type_now;
token = token_now;
}
}
return(parse_conditions());
}
