node.h

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#ifndef META_PARSE_TREE_NODE_H_
#define META_PARSE_TREE_NODE_H_

#include <memory>
#include "meta.h"
#include "parser/trees/visitors/visitor.h"

namespace meta
{
namespace parser
{

class node
{
  public:
    node(class_label cat);

    const class_label& category() const;

    virtual bool is_leaf() const = 0;

    bool is_temporary() const;

    virtual bool equal(const node& other) const = 0;

    virtual std::unique_ptr<node> clone() const = 0;

    template <class Visitor>
    typename std::remove_reference<Visitor>::type::result_type
        accept(Visitor&& vtor)
    {
        // this is ugly, but since we cannot have virtual template member
        // functions, it's a necessary evil
        if (is_leaf())
            return vtor(as<leaf_node>());
        return vtor(as<internal_node>());
    }

    template <class Visitor>
    typename std::remove_reference<Visitor>::type::result_type
        accept(Visitor&& vtor) const
    {
        if (is_leaf())
            return vtor(as<leaf_node>());
        return vtor(as<internal_node>());
    }

    template <class Node>
    Node& as()
    {
        return static_cast<Node&>(*this);
    }

    template <class Node>
    typename std::add_const<Node>::type& as() const
    {
        return static_cast<typename std::add_const<Node>::type&>(*this);
    }

    virtual ~node() = default;

  private:
    const class_label category_;
};
}
}
#endif