ChaiScript/include/chaiscript/dispatchkit/dynamic_object.hpp

#ifndef __DYNAMIC_OBJECT_HPP__
#define __DYNAMIC_OBJECT_HPP__

#include <boost/optional.hpp>

namespace chaiscript
{
  class Dynamic_Object
  {
    public:
      Dynamic_Object(const std::string &t_type_name)
        : m_type_name(t_type_name)
      {
      }

      std::string get_type_name() const
      {
        return m_type_name;
      }

      Boxed_Value get_attr(const std::string &t_attr_name)
      {
        return m_attrs[t_attr_name];
      }

      std::map<std::string, Boxed_Value> get_attrs()
      {
        return m_attrs;
      }

    private:
      std::string m_type_name;

      std::map<std::string, Boxed_Value> m_attrs;
  };

  Boxed_Value dynamic_object_attribute(const std::string &t_type_name, const std::string &t_attr_name,
      Dynamic_Object &t_do)
  {
    if (t_do.get_type_name() != t_type_name) 
    {
      throw bad_boxed_cast("Dynamic object type mismatch");
    }

    return t_do.get_attr(t_attr_name);
  }

  bool dynamic_object_typename_match(const std::vector<Boxed_Value> &bvs, const std::string &name,
      const boost::optional<Type_Info> &ti)
  {
    if (bvs.size() > 0)
    {
      try {
        const Dynamic_Object &d = boxed_cast<const Dynamic_Object &>(bvs[0]);
        return name == "Dynamic_Object" || d.get_type_name() == name;
      } catch (const std::bad_cast &) {
        if (ti)
        {
          return bvs[0].get_type_info().bare_equal(*ti);
        } else {
          return false;
        }
      }
    } else {
      return false;
    }
  }

  /**
   * A Proxy_Function implementation designed for calling a function
   * that is automatically guarded based on the first param based on the
   * param's type name
   */
  class Dynamic_Object_Function : public Proxy_Function_Base
  {
    public:
      Dynamic_Object_Function(
          const std::string &t_type_name,
          const Proxy_Function &t_func,
          const boost::optional<Type_Info> &t_ti = boost::optional<Type_Info>())
        : Proxy_Function_Base(t_func->get_param_types()),
          m_type_name(t_type_name), m_func(t_func), m_ti(t_ti)
      {
        assert( (t_func->get_arity() > 0 || t_func->get_arity() < 0)
            && "Programming error, Dynamic_Object_Function must have at least one parameter (this)");
      }

      virtual ~Dynamic_Object_Function() {}

      virtual bool operator==(const Proxy_Function_Base &f) const
      {
        try
        {
          const Dynamic_Object_Function &df = dynamic_cast<const Dynamic_Object_Function &>(f);
          return df.m_type_name == m_type_name && (*df.m_func) == (*m_func);
        } catch (const std::bad_cast &) {
          return false;
        }
      }

      virtual bool call_match(const std::vector<Boxed_Value> &vals) const
      {
        if (dynamic_object_typename_match(vals, m_type_name, m_ti))
        {
          return m_func->call_match(vals);
        } else {
          return false;
        }
      }    

      virtual Boxed_Value operator()(const std::vector<Boxed_Value> &params) const
      {
        if (dynamic_object_typename_match(params, m_type_name, m_ti))
        {
          return (*m_func)(params);
        } else {
          throw guard_error();
        } 
      }

      virtual int get_arity() const
      {
	return m_func->get_arity();
      }

      virtual std::string annotation() const
      {
        return m_func->annotation();
      }

    private:
      std::string m_type_name;
      Proxy_Function m_func;
      boost::optional<Type_Info> m_ti;

  };


  /**
   * A Proxy_Function implementation designed for creating a new
   * Dynamic_Object
   * that is automatically guarded based on the first param based on the
   * param's type name
   */
  class Dynamic_Object_Constructor : public Proxy_Function_Base
  {
    public:
      Dynamic_Object_Constructor(
          const std::string &t_type_name,
          const Proxy_Function &t_func)
        : Proxy_Function_Base(build_type_list(t_func->get_param_types())),
          m_type_name(t_type_name), m_func(t_func)
      {
        assert( (t_func->get_arity() > 0 || t_func->get_arity() < 0)
            && "Programming error, Dynamic_Object_Function must have at least one parameter (this)");
      }

      static std::vector<Type_Info> build_type_list(const std::vector<Type_Info> &tl)
      {
        std::vector<Type_Info>::const_iterator begin = tl.begin();
        std::vector<Type_Info>::const_iterator end = tl.end();

        if (begin != end)
        {
          ++begin;
        }

        return std::vector<Type_Info>(begin, end);
      }

      virtual ~Dynamic_Object_Constructor() {}

      virtual bool operator==(const Proxy_Function_Base &f) const
      {
        try
        {
          const Dynamic_Object_Constructor &dc = dynamic_cast<const Dynamic_Object_Constructor&>(f);
          return dc.m_type_name == m_type_name && (*dc.m_func) == (*m_func);
        } catch (const std::bad_cast &) {
          return false;
        }
      }

      virtual bool call_match(const std::vector<Boxed_Value> &vals) const
      {
        std::vector<Boxed_Value> new_vals;
        new_vals.push_back(Boxed_Value(Dynamic_Object(m_type_name)));
        new_vals.insert(new_vals.end(), vals.begin(), vals.end());

        return m_func->call_match(new_vals);
      }    

      virtual Boxed_Value operator()(const std::vector<Boxed_Value> &params) const
      {
        std::vector<Boxed_Value> new_params;
        chaiscript::Boxed_Value bv = var(Dynamic_Object(m_type_name));
        new_params.push_back(bv);
        new_params.insert(new_params.end(), params.begin(), params.end());

        (*m_func)(new_params);

        return bv;
      }

      virtual int get_arity() const
      {
        // "this" is not considered part of the arity
	return m_func->get_arity() - 1; 
      }

      virtual std::string annotation() const
      {
        return m_func->annotation();
      }

    private:
      std::string m_type_name;
      Proxy_Function m_func;

  };
}
#endif