gecko/gfx/2d/UserData.h

/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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 * The Original Code is Mozilla Corporation code.
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 * Contributor(s):
 *   Jeff Muizelaar <jmuizelaar@mozilla.com>
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#include <stdlib.h>
#include "mozilla/mozalloc.h"

namespace mozilla {
namespace gfx {

struct UserDataKey {
  int unused;
};

/* this class is basically a clone of the user data concept from cairo */
class UserData
{
  typedef void (*destroyFunc)(void *data);
public:
  UserData() : count(0), entries(NULL) {}

  /* Attaches untyped userData associated with key. destroy is called on destruction */
  void Add(UserDataKey *key, void *userData, destroyFunc destroy)
  {
    // We could keep entries in a std::vector instead of managing it by hand
    // but that would propagate an stl dependency out which we'd rather not
    // do (see bug 666609). Plus, the entries array is expect to stay small
    // so doing a realloc everytime we add a new entry shouldn't be too costly
    entries = static_cast<Entry*>(moz_xrealloc(entries, sizeof(Entry)*(count+1)));

    entries[count].key      = key;
    entries[count].userData = userData;
    entries[count].destroy  = destroy;

    count++;
  }

  //XXX: we probably want to add a way to remove Keys

  /* Retrives the userData for the associated key */
  void *Get(UserDataKey *key)
  {
    for (int i=0; i<count; i++) {
      if (key == entries[i].key) {
        return entries[i].userData;
      }
    }
    return NULL;
  }

  ~UserData()
  {
    for (int i=0; i<count; i++) {
      entries[i].destroy(entries[i].userData);
    }
    free(entries);
  }

private:
  struct Entry {
    const UserDataKey *key;
    void *userData;
    destroyFunc destroy;
  };

  int count;
  Entry *entries;

};

}
}