// Statement.h     Dave Reed      3/1/05
//
// Expression class -- class for storing an expression in the SILLY language
//
//      public member functions:
//          void Read(Tokenizer & program);            // reads & stores the
//                                                     //   expression from program
//          void Execute(VarTable & variables) const;  // evaluates the expression
//                                                     //   given the variable table
//          void Display() const;                      // displays the expression
//
// Statement class -- base class for storing different types of SILLY statements
//   OutputStatement class -- derived class for storing output statements
//   AssignStatement class -- derived class for storing assignment statements
//   IfStatement class     -- derived class for storing if statements
//
//      Each class provides the following public member functions:
//          void Read(Tokenizer & program);            // reads & stores the
//                                                     //   statement from program
//          void Execute(VarTable & variables) const;  // executes the statement
//                                                     //   given the variable table
//          void Display() const;                      // displays the statement
//
//   Also, the following static member function is provided for reading a stmt
//          static Statement * GetNext(Tokenizer & program);
///////////////////////////////////////////////////////////////////////////////////

#ifndef _STATEMENT_H
#define _STATEMENT_H

#include <string>
#include <vector>
#include "Token.h"
#include "Tokenizer.h"
#include "VarTable.h"
using namespace std;

class Expression
{
  public:
    Expression() { }
    void Read(Tokenizer & program);
    int Evaluate(VarTable & variables) const;
    void Display() const;
  private:
      Token expr;
};

enum STATEMENT_TYPE {END, ASSIGN, OUTPUT, IF, ERROR};

class Statement
{
  public:
    Statement() { }
    virtual void Read(Tokenizer & program) = 0;
    virtual void Execute(VarTable & variables) const = 0;
    virtual STATEMENT_TYPE GetType() const = 0;
    virtual void Display() const = 0;
    static Statement * GetNext(Tokenizer & program);
};

class OutputStatement : public Statement
{
  public:
    OutputStatement() { }
    void Read(Tokenizer & program);
    void Execute(VarTable & variables) const;
    STATEMENT_TYPE GetType() const;
    void Display() const;
  private:
    Expression outValue;
};


class AssignStatement : public Statement
{
  public:
    AssignStatement() { }
    void Read(Tokenizer & program);
    void Execute(VarTable & variables) const;
    STATEMENT_TYPE GetType() const;
    void Display() const;
  private:
    string lhs;
    Expression rhs;
};

class IfStatement : public Statement
{
  public:
    IfStatement() { }
    void Read(Tokenizer & program);
    void Execute(VarTable & variables) const;
    STATEMENT_TYPE GetType() const;
    void Display() const;
  private:
    Expression test;
    vector< Statement* > stmts;
};


#endif