Recursive Descent Interpreter

[shadow29014]

Thanks
now my only problems are the

'const class IdNode' has no member named 'end' /'begin' // for interpreter.h 
'class IdNode' has no member named 'push_front'/'end'/'begin' //for interpreter.cpp  

and the weird stl_algo.h header file

=)
=)
YOU'RE a GREAT HELP
=)

[shadow29014]

=) I made new progress
created member functions in the class IdNode to solve the error messages it kinda looks like this

class IdNode
{ 
IdNode *begin;
IdNode *end;
IdNode *push_front;
}

The error message were replaced by other error messages such as

  
In function `std::ostream& operator<<(std::ostream&, const Statement&)':
s->Statement::idList.IdNode::begin' cannot be used as a function
s->Statement::idList.IdNode::end' cannot be used as a function 
//for interpreter.h
In member function `double Statement::findValue(char*)': 
((Statement*)this)->Statement::idList.IdNode::begin' cannot be used as a function 
((Statement*)this)->Statement::idList.IdNode::end' cannot be used as a function 
 In member function `void Statement::processNode(char*, double)': 
((Statement*)this)->Statement::idList.IdNode::begin' cannot be used as a function 
((Statement*)this)->Statement::idList.IdNode::end' cannot be used as a function 
((Statement*)this)->Statement::idList.IdNode::push_front' cannot be used as a function 
//for intepreter.cpp 

Please help, I have no idea on what to do
=)

[sohguanh]

Can I have a look at the code within std::ostream& operator<<(std::ostream&, const Statement&) ?

class IdNode
{ 
IdNode *begin;
IdNode *end;
IdNode *push_front;
}

begin, end push_front are not functions so you cannot use them like a function I presume that is why the C++ compiler is complaining.

[shadow29014]

Here are my interpreter.cpp and interpreter.h files

//**************************  interpreter.cpp   ***********************

#include <cctype>
#include "interpreter.h"

Iterator list :: begin()
{
}

Iterator list :: end()
{
}

Iterator list :: push_front()
{
}

double Statement::findValue(char *id) {
    IdNode tmp(id);
    list::iterator i = find(idList.begin(),idList.end(),tmp);
    if (i != idList.end())
         return i->value;
    else issueError("Unknown variable");
    return 0;  // this statement will never be reached;
}

void Statement::processNode(char* id ,double e) {
    IdNode tmp(id,e);
    list::iterator i = find(idList.begin(),idList.end(),tmp);
    if (i != idList.end())
         i->value = e;
    else idList.push_front(tmp);
}

// readId() reads strings of letters and digits that start with
// a letter, and stores them in array passed to it as an actual
// parameter. 
// Examples of identifiers are: var1, x, pqr123xyz, aName, etc.

void Statement::readId(char *id) {
    int i = 0;
    if (isspace(ch))
         cin >> ch;       // skip blanks;
    if (isalpha(ch)) {
         while (isalnum(ch)) {
             id[i++] = ch;
             cin.get(ch); // don't skip blanks;
         }
         id[i] = '\0';
    }
    else issueError("Identifier expected");
}

double Statement::factor() {
    double var, minus = 1.0;
    static char id[200];
    cin >> ch;
    while (ch == '+' || ch == '-') {      // take all '+'s and '-'s.
        if (ch == '-')
            minus *= -1.0;
        cin >> ch;
    }
    if (isdigit(ch) || ch == '.') {      // Factor can be a number
         cin.putback(ch);
         cin >> var >> ch;
    }
    else if (ch == '(') {                  // or a parenthesized expression,
         var = expression();
         if (ch == ')')
              cin >> ch;
         else issueError("Right paren left out");
    }
    else {
         readId(id);                          // or an identifier.
         if (isspace(ch))
             cin >> ch;
         var = findValue(id);
    }
    return minus * var;
}

double Statement::term() {
    double f = factor();
    while (true) {
        switch (ch) {
            case '*' : f *= factor(); break;
            case '/' : f /= factor(); break;
            default  : return f;
        }
    }
}

double Statement::expression() {
    double t = term();
    while (true) {
        switch (ch) {
            case '+' : t += term(); break;
            case '-' : t -= term(); break;
            default  : return t;
        }
    }
}

void Statement::getStatement() {
    char id[20], command[20];
    double e;
    cout << "Enter a statement: ";
    cin  >> ch;
    readId(id);
    strcpy(command,id);
    for (int i = 0; i < strlen(command); i++)
	command[i] = toupper(command[i]);
    if (strcmp(command,"STATUS") == 0)
         cout << *this;
    else if (strcmp(command,"PRINT") == 0) {
         readId(id);
         cout << id << " = " << findValue(id) << endl;
    }
    else if (strcmp(command,"END") == 0)
         exit(0);
    else {
         if (isspace(ch))
             cin >> ch;
         if (ch == '=') {
              e = expression();
              if (ch != ';')
                   issueError("There are some extras in the statement");
              else processNode(id,e);
         }
         else issueError("'=' is missing");
    }
}

//**************************  interpreter.h   ***********************

#ifndef INTERPRETER
#define INTERPRETER

#include <iostream>

//#include <list>
//#include <algorithm> // find()

using namespace std;

class IdNode {
public:
    IdNode(char *s = "", double e = 0) {
        id = strdup(s);
        value = e;
    }
    bool operator== (const IdNode& node) const {
        return strcmp(id,node.id) == 0;
    }
     IdNode *end;
     IdNode *begin;
     IdNode *push_front;
     
private:
    char *id;
    double value;
    friend class Statement;
    friend ostream& operator<< (ostream& out, const IdNode& r) {
        out << r.id << " = " << r.value << endl;
        return out;
    }
};

class Iterator
{
      public:
      IdNode *node;
      Iterator &operator ++ (int);
      IdNode &operator * ();
      IdNode *operator -> ();
      bool operator != (bool);

};

class list
{
      IdNode *head, *tail;
      public:
             typedef Iterator iterator;
             typedef Iterator const_iterator;
             Iterator begin ();
             Iterator end ();
             Iterator push_front ();
             
};



class Statement {
public:
    Statement() { 
    }
    void getStatement();
private:
    IdNode idList;
    char  ch;
    double factor();
    double term();
    double expression();
    void readId(char*);
    void issueError(char *s) { 
        cerr << s << endl; exit(1); 
    }
    double findValue(char*);
    void  processNode(char*, double);
    friend ostream& operator<< (ostream& out, const Statement& s) {
        list::const_iterator i = s.idList.begin();
        for ( ; i != s.idList.end(); i++)
            out << *i;
        out << endl;
        return out;
    }
};

#endif 

My original problem was

'const class IdNode' has no member named 'end' /'begin' // for interpreter.h 
'class IdNode' has no member named 'push_front'/'end'/'begin' //for interpreter.cpp   

When created member functions end,begin, and push_front for the class IdNode that's when the new error codes appear.

Is there a way to link my class IdNode and my class list since my class list already has member functions end,begin, and push_front .

I tried inheritance but it does not seem to work since my class list uses my class Iterator which in turn uses class IdNode. Which is why i resulted into making member functions of the same name in class IdNode. The only problem is that I do not know which data type to use. That is why i declared it as IdNode *begin;/*end;/*push_front;

I tired using other data types such as int, void, struct, class, friend, etc but it still odes not work

In need of HUGE HELP PLEASE =)

Thanks =)