Channels ▼
RSS

Associative Chains in C++


February, 2006: Associative Chains in C++

Listing 3

(a)
class Link
{
protected:
  virtual void *v_traverse(void *) = 0;
public:
  virtual Link *clone(void) const = 0;
  virtual size_t get_size(void) const { return 1; }
};
template<class Src, class Dst>
class Typed_Link : public Link
{
protected:
  void *v_traverse(void *src)
  { 
    return (void *)&traverse(*(Src *)src);
  }
public:
  Dst &traverse(Src &) = 0;
};


(b)
template<class Src, class Dst>
class Chain : private std::list<Link *>, public Typed_Link<Src, Dst>
{
public:
  // special constructors
  template<class Mid>
  Chain(const Typed_Link<Src,Mid> &a, const Typed_Link<Mid,Dst> &b);
  // etc.
  size_t get_size(void) const
  {
    size_t ret = 0;
    for (const_iterator i = begin(); i != end(); ++i) {
      ret += (*i)->get_size();
    }
    return ret;
  }
  Dst &traverse(Src &s)
  {
    void *tmp = &s;
    iterator i;
    try {
      for (i = begin(); i != end(); ++i) {
    tmp = (*i)->v_traverse(tmp);
      }
    } 
    // (exception handlers here)
    // ...
    return *(Dst *)tmp;
  }
};
// spc: this simplifies the object definitions
template<class Src, class Mid, class Dst>
class Chain<Src, Dst>
operator+(const Typed_Link<Src, Mid> &a, 
         const Typed_Link<Mid, Dst> &b)
{
  return Chain<Src, Dst>(a, b);
}


Related Reading


More Insights






Currently we allow the following HTML tags in comments:

Single tags

These tags can be used alone and don't need an ending tag.

<br> Defines a single line break

<hr> Defines a horizontal line

Matching tags

These require an ending tag - e.g. <i>italic text</i>

<a> Defines an anchor

<b> Defines bold text

<big> Defines big text

<blockquote> Defines a long quotation

<caption> Defines a table caption

<cite> Defines a citation

<code> Defines computer code text

<em> Defines emphasized text

<fieldset> Defines a border around elements in a form

<h1> This is heading 1

<h2> This is heading 2

<h3> This is heading 3

<h4> This is heading 4

<h5> This is heading 5

<h6> This is heading 6

<i> Defines italic text

<p> Defines a paragraph

<pre> Defines preformatted text

<q> Defines a short quotation

<samp> Defines sample computer code text

<small> Defines small text

<span> Defines a section in a document

<s> Defines strikethrough text

<strike> Defines strikethrough text

<strong> Defines strong text

<sub> Defines subscripted text

<sup> Defines superscripted text

<u> Defines underlined text

Dr. Dobb's encourages readers to engage in spirited, healthy debate, including taking us to task. However, Dr. Dobb's moderates all comments posted to our site, and reserves the right to modify or remove any content that it determines to be derogatory, offensive, inflammatory, vulgar, irrelevant/off-topic, racist or obvious marketing or spam. Dr. Dobb's further reserves the right to disable the profile of any commenter participating in said activities.

 
Disqus Tips To upload an avatar photo, first complete your Disqus profile. | View the list of supported HTML tags you can use to style comments. | Please read our commenting policy.
 

Video