scope_guard.h

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#ifndef SCOPE_GUARD_H
#define SCOPE_GUARD_H
 
template <typename TLambda>
class Scope_guard {
 public:
  Scope_guard(const TLambda &rollback_lambda)
      : m_committed(false), m_rollback_lambda(rollback_lambda) {}
  Scope_guard(const Scope_guard<TLambda> &) = delete;
  Scope_guard(Scope_guard<TLambda> &&moved)
      : m_committed(moved.m_committed),
        m_rollback_lambda(moved.m_rollback_lambda) {
    /* Set moved guard to "invalid" state, the one in which the rollback lambda
      will not be executed. */
    moved.m_committed = true;
  }
  ~Scope_guard() {
    if (!m_committed) {
      m_rollback_lambda();
    }
  }
 
  inline void commit() { m_committed = true; }
 
  inline void rollback() {
    if (!m_committed) {
      m_rollback_lambda();
      m_committed = true;
    }
  }
 
 private:
  bool m_committed;
  const TLambda m_rollback_lambda;
};
 
template <typename TLambda>
Scope_guard<TLambda> create_scope_guard(const TLambda rollback_lambda) {
  return Scope_guard<TLambda>(rollback_lambda);
}
 
/**
  Template class to scope guard variables.
*/
template <typename T>
class Variable_scope_guard {
 public:
  Variable_scope_guard() = delete;
  Variable_scope_guard(T &var) : m_var_ref(var), m_var_val(var) {}
 
  Variable_scope_guard(const Variable_scope_guard &) = delete;
  Variable_scope_guard(Variable_scope_guard &&) = delete;
 
  Variable_scope_guard &operator=(const Variable_scope_guard &) = delete;
  Variable_scope_guard &operator=(Variable_scope_guard &&) = delete;
 
  ~Variable_scope_guard() { m_var_ref = m_var_val; }
 
 private:
  T &m_var_ref;
  T m_var_val;
};
#endif /* SCOPE_GUARD_H */