I think this is correct way to use iterate over it as a hashmap. don't have much lua practice
/*
* Hedgewars, a free turn based strategy game
* Copyright (C) 2012 Simeon Maxein <smaxein@googlemail.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/**
* Functions for querying a map preview from the engine, which includes both a two-color image
* and the number of hogs this map is suitable for.
*
* The general usage is to first create a mapconn object by calling flib_mapconn_create.
* That will cause the frontlib to listen on a random port which can be queried using
* flib_mapconn_getport(). You should also register your callback functions right at the start
* to ensure you don't miss any callbacks.
*
* Next, start the engine (that part is up to you) with the appropriate command line arguments
* for a map preview request.
*
* In order to allow the mapconn to run, you should regularly call flib_mapconn_tick(), which
* performs network I/O and calls your callbacks if the map has been generated or an error
* has occurred. Once either the onSuccess or onFailure callback is called, you should destroy
* the mapconn and stop calling tick().
*/
#ifndef IPC_MAPCONN_H_
#define IPC_MAPCONN_H_
#include "../model/map.h"
#include <stdint.h>
#define MAPIMAGE_WIDTH 256
#define MAPIMAGE_HEIGHT 128
#define MAPIMAGE_BYTES (MAPIMAGE_WIDTH/8*MAPIMAGE_HEIGHT)
typedef struct _flib_mapconn flib_mapconn;
/**
* Start a new map rendering connection (mapconn). This means a listening socket
* will be started on a random unused port, waiting for a connection from the
* engine process. Once this connection is established, the required information
* will be sent to the engine, and the reply is read.
*
* The map must be a regular, maze or drawn map - for a preview of a named map,
* use the preview images in the map's directory, and for the hog count read the
* map information (e.g. using flib_mapcfg_read).
*
* No NULL parameters allowed, returns NULL on failure.
* Use flib_mapconn_destroy to free the returned object.
*/
flib_mapconn *flib_mapconn_create(const flib_map *mapdesc);
/**
* Destroy the mapconn object. Passing NULL is allowed and does nothing.
* flib_mapconn_destroy may be called from inside a callback function.
*/
void flib_mapconn_destroy(flib_mapconn *conn);
/**
* Returns the port on which the mapconn is listening. Only fails if you
* pass NULL (not allowed), in that case 0 is returned.
*/
int flib_mapconn_getport(flib_mapconn *conn);
/**
* Set a callback which will receive the rendered map if the rendering succeeds.
*
* Expected callback signature:
* void handleSuccess(void *context, const uint8_t *bitmap, int numHedgehogs)
*
* The context passed to the callback is the same pointer you provided when
* registering the callback. bitmap is a pointer to a buffer of size MAPIMAGE_BYTES
* containing a bit-packed image of size MAPIMAGE_WIDTH * MAPIMAGE_HEIGHT.
* numHedgehogs is the number of hogs that fit on this map.
*
* The bitmap pointer passed to the callback belongs to the caller,
* so it should not be stored elsewhere. Note that it remains valid
* inside the callback method even if flib_mapconn_destroy is called.
*/
void flib_mapconn_onSuccess(flib_mapconn *conn, void (*callback)(void* context, const uint8_t *bitmap, int numHedgehogs), void *context);
/**
* Set a callback which will receive an error message if rendering fails.
*
* Expected callback signature:
* void handleFailure(void *context, const char *errormessage)
*
* The context passed to the callback is the same pointer you provided when
* registering the callback.
*
* The error message passed to the callback belongs to the caller,
* so it should not be stored elsewhere. Note that it remains valid
* inside the callback method even if flib_mapconn_destroy is called.
*/
void flib_mapconn_onFailure(flib_mapconn *conn, void (*callback)(void* context, const char *errormessage), void *context);
/**
* Perform I/O operations and call callbacks if something interesting happens.
* Should be called regularly.
*/
void flib_mapconn_tick(flib_mapconn *conn);
#endif