expr.hpp

#ifndef __EXPR_HPP___
#define __EXPR_HPP___
#include <cstdio>
#include <cstdlib>
#include <sstream>
#include <string>

class Expression {
 public:
  Expression() {}
  virtual std::string toString() const = 0;
  virtual ~Expression() {}
};
class NumExpression : public Expression {
  long number;

 public:
  NumExpression(long n) : number(n) {}
  virtual std::string toString() const {
    std::stringstream answer;
    answer << number;
    return answer.str();
  }
  virtual ~NumExpression() {}
};
class PlusExpression : public Expression {
  Expression * l;
  Expression * r;

 public:
  PlusExpression(Expression * lhs, Expression * rhs) : l(lhs), r(rhs) {}
  virtual std::string toString() const {
    std::stringstream answer;
    answer << "(" << l->toString() << "+" << r->toString() << ")";
    return answer.str();
  }
  virtual ~PlusExpression() {
    delete l;
    delete r;
  }
};
class MinusExpression : public Expression {
  Expression * l;
  Expression * r;

 public:
  MinusExpression(Expression * lhs, Expression * rhs) : l(lhs), r(rhs) {}
  virtual std::string toString() const {
    std::stringstream answer;
    answer << "(" << l->toString() << "-" << r->toString() << ")";
    return answer.str();
  }
  virtual ~MinusExpression() {
    delete l;
    delete r;
  }
};
class TimesExpression : public Expression {
  Expression * l;
  Expression * r;

 public:
  TimesExpression(Expression * lhs, Expression rhs) : l(lhs), r(rhs) {}
  virtual std::string toString() const {
    std::stringstream answer;
    answer << "(" << l->toString() << "*" << r->toString() << ")";
    return answer.str();
  }
  virtual ~TimesExpression() {
    delete l;
    delete r;
  }
};
class DivExpression : public Expression {
  Expression * l;
  Expression * r;

 public:
  DivExpression(Expression * lhs, Expression * rhs) : l(lhs), r(rhs) {}
  virtual std::string toString() const {
    std::stringstream answer;
    answer << "(" << l->toString() << " / " << r->toString() << ")";
    return answer.str();
  }
  virtual ~DivExpression() {
    delete l;
    delete r;
  }
};

#endif