tile.c

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/***********************************************************************
 Freeciv - Copyright (C) 2005 - The Freeciv Project
   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, 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.
***********************************************************************/
 
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
/* utility */
#include "bitvector.h"
#include "log.h"
#include "support.h"
 
/* common */
#include "fc_interface.h"
#include "game.h"
#include "map.h"
#include "movement.h"
#include "road.h"
#include "unit.h"
#include "unitlist.h"
 
#include "tile.h"
 
static bv_extras empty_extras;
 
#ifndef tile_index
/************************************************************************/
int tile_index(const struct tile *ptile)
{
  return ptile->index;
}
#endif
 
#ifndef tile_owner
/************************************************************************/
struct player *tile_owner(const struct tile *ptile)
{
  return ptile->owner;
}
#endif
 
#ifndef tile_claimer
/************************************************************************/
struct tile *tile_claimer(const struct tile *ptile)
{
  return ptile->claimer;
}
#endif
 
/************************************************************************/
void tile_set_owner(struct tile *ptile, struct player *pplayer,
                    struct tile *claimer)
{
  if (BORDERS_DISABLED != game.info.borders
      /* City tiles are always owned by the city owner. */
      || (tile_city(ptile) != NULL || ptile->owner != NULL)) {
    ptile->owner = pplayer;
    ptile->claimer = claimer;
  }
}
 
/************************************************************************/
struct city *tile_city(const struct tile *ptile)
{
  struct city *pcity = ptile->worked;
 
  if (NULL != pcity && is_city_center(pcity, ptile)) {
    return pcity;
  }
  return NULL;
}
 
#ifndef tile_worked
/************************************************************************/
struct city *tile_worked(const struct tile *ptile)
{
  return ptile->worked;
}
#endif
 
/************************************************************************/
void tile_set_worked(struct tile *ptile, struct city *pcity)
{
  ptile->worked = pcity;
}
 
#ifndef tile_terrain
/************************************************************************/
struct terrain *tile_terrain(const struct tile *ptile)
{
  return ptile->terrain;
}
#endif
 
/************************************************************************/
void tile_set_terrain(struct tile *ptile, struct terrain *pterrain)
{
  /* The terrain change is valid if one of the following is TRUE:
   * - pterrain is NULL (= unknown terrain)
   * - ptile is a virtual tile, or otherwise not on the map being checked
   * - pterrain does not has the flag TER_NO_CITIES
   * - there is no city on ptile
   * - client may have had tile fogged and is receiving terrain change before
   *   city removal
   * This should be read as: The terrain change is INVALID if a terrain with
   * the flag TER_NO_CITIES is given for a real tile with a city (i.e. all
   * check evaluate to TRUE). */
 
  /* Assert disabled for now, so we don't need to make this function
   * care about what map is being changed. */
#if 0
  fc_assert_msg(NULL == pterrain
                || !is_server()
                || !tile_map_check(nmap, ptile)
                || !terrain_has_flag(pterrain, TER_NO_CITIES)
                || NULL == tile_city(ptile),
                "At (%d, %d), the terrain \"%s\" (nb %d) doesn't "
                "support cities, whereas \"%s\" (nb %d) is built there.",
                TILE_XY(ptile), terrain_rule_name(pterrain),
                terrain_number(pterrain), city_name_get(tile_city(ptile)),
                tile_city(ptile)->id);
#endif /* 0 */
 
  ptile->terrain = pterrain;
  if (ptile->resource != NULL) {
    if (NULL != pterrain
        && terrain_has_resource(pterrain, ptile->resource)) {
      BV_SET(ptile->extras, extra_index(ptile->resource));
    } else {
      BV_CLR(ptile->extras, extra_index(ptile->resource));
    }
  }
}
 
/************************************************************************/
const bv_extras *tile_extras_null(void)
{
  static bool empty_cleared = FALSE;
 
  if (!empty_cleared) {
    BV_CLR_ALL(empty_extras);
    empty_cleared = TRUE;
  }
 
  return &(empty_extras);  
}
 
/************************************************************************/
const bv_extras *tile_extras_safe(const struct tile *ptile)
{
  if (!ptile) {
    return tile_extras_null();
  }
 
  return &(ptile->extras);
}
 
/************************************************************************/
bool tile_has_not_aggressive_extra_for_unit(const struct tile *ptile,
                                            const struct unit_type *punittype)
{
  extra_type_by_cause_iterate(EC_NOT_AGGRESSIVE, pextra) {
    if (tile_has_extra(ptile, pextra)
        && is_native_extra_to_utype(pextra, punittype)) {
      return TRUE;
    }
  } extra_type_by_cause_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
bool tile_has_claimable_base(const struct tile *ptile,
                             const struct unit_type *punittype)
{
  extra_type_list_iterate(utype_class(punittype)->cache.native_bases, pextra) {
    struct base_type *pbase = extra_base_get(pextra);
 
    if (tile_has_extra(ptile, pextra)
        && territory_claiming_base(pbase)) {
      return TRUE;
    }
  } extra_type_list_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
int tile_extras_defense_bonus(const struct tile *ptile,
                              const struct unit_type *punittype)
{
  return tile_extras_class_defense_bonus(ptile, utype_class(punittype));
}
 
/************************************************************************/
int tile_extras_class_defense_bonus(const struct tile *ptile,
                                    const struct unit_class *pclass)
{
  int natural_bonus = 0;
  int fortification_bonus = 0;
  int total_bonus;
 
  extra_type_by_cause_iterate(EC_NATURAL_DEFENSIVE, pextra) {
    if (tile_has_extra(ptile, pextra)
        && is_native_extra_to_uclass(pextra, pclass)) {
      natural_bonus += pextra->defense_bonus;
    }
  } extra_type_by_cause_iterate_end;
 
  extra_type_by_cause_iterate(EC_DEFENSIVE, pextra) {
    if (tile_has_extra(ptile, pextra)
        && is_native_extra_to_uclass(pextra, pclass)) {
      fortification_bonus += pextra->defense_bonus;
    }
  } extra_type_by_cause_iterate_end;
 
  total_bonus = (100 + natural_bonus) * (100 + fortification_bonus) / 100 - 100;
 
  return total_bonus;
}
 
/************************************************************************/
int tile_roads_output_incr(const struct tile *ptile, enum output_type_id o)
{
  int const_incr = 0;
  int incr = 0;
 
  extra_type_by_cause_iterate(EC_ROAD, pextra) {
    if (tile_has_extra(ptile, pextra)) {
      struct road_type *proad = extra_road_get(pextra);
 
      const_incr += proad->tile_incr_const[o];
      incr += proad->tile_incr[o];
    }
  } extra_type_by_cause_iterate_end;
 
  return const_incr + incr * tile_terrain(ptile)->road_output_incr_pct[o] / 100;
}
 
/************************************************************************/
int tile_roads_output_bonus(const struct tile *ptile, enum output_type_id o)
{
  int bonus = 0;
 
  extra_type_by_cause_iterate(EC_ROAD, pextra) {
    if (tile_has_extra(ptile, pextra)) {
      struct road_type *proad = extra_road_get(pextra);
 
      bonus += proad->tile_bonus[o];
    }
  } extra_type_by_cause_iterate_end;
 
  return bonus;
}
 
/************************************************************************/
bool tile_has_refuel_extra(const struct tile *ptile,
                           const struct unit_class *uclass)
{
  extra_type_list_iterate(uclass->cache.refuel_extras, pextra) {
    if (tile_has_extra(ptile, pextra)) {
      return TRUE;
    }
  } extra_type_list_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
bool tile_has_native_base(const struct tile *ptile,
                          const struct unit_type *punittype)
{
  extra_type_list_iterate(utype_class(punittype)->cache.native_bases, pextra) {
    if (tile_has_extra(ptile, pextra)) {
      return TRUE;
    }
  } extra_type_list_iterate_end;
 
  return FALSE;
}
 
#ifndef tile_resource
/************************************************************************/
const struct resource_type *tile_resource(const struct tile *ptile)
{
  return ptile->resource;
}
#endif
 
/************************************************************************/
void tile_set_resource(struct tile *ptile, struct extra_type *presource)
{
  if (presource == ptile->resource) {
    return; /* No change */
  }
 
  if (ptile->resource != NULL) {
    tile_remove_extra(ptile, ptile->resource);
  }
  if (presource != NULL) {
    if (ptile->terrain && terrain_has_resource(ptile->terrain, presource)) {
      tile_add_extra(ptile, presource);
    }
  }
 
  ptile->resource = presource;
}
 
#ifndef tile_continent
/************************************************************************/
Continent_id tile_continent(const struct tile *ptile)
{
  return ptile->continent;
}
#endif
 
/************************************************************************/
void tile_set_continent(struct tile *ptile, Continent_id val)
{
  ptile->continent = val;
}
 
/************************************************************************/
enum known_type tile_get_known(const struct tile *ptile,
                               const struct player *pplayer)
{
  if (!dbv_isset(&pplayer->tile_known, tile_index(ptile))) {
    return TILE_UNKNOWN;
  } else if (!fc_funcs->player_tile_vision_get(ptile, pplayer, V_MAIN)) {
    return TILE_KNOWN_UNSEEN;
  } else {
    return TILE_KNOWN_SEEN;
  }
}
 
/************************************************************************/
bool tile_is_seen(const struct tile *target_tile,
                  const struct player *pow_player)
{
  return tile_get_known(target_tile, pow_player) == TILE_KNOWN_SEEN;
}
 
/************************************************************************/
int tile_activity_time(enum unit_activity activity, const struct tile *ptile,
                       const struct extra_type *tgt)
{
  struct terrain *pterrain = tile_terrain(ptile);
 
  /* Make sure nobody uses old activities */
  fc_assert_ret_val(activity != ACTIVITY_FORTRESS
                    && activity != ACTIVITY_AIRBASE, FC_INFINITY);
 
  switch (activity) {
  case ACTIVITY_POLLUTION:
  case ACTIVITY_FALLOUT:
  case ACTIVITY_PILLAGE:
    return terrain_extra_removal_time(pterrain, activity, tgt) * ACTIVITY_FACTOR;
  case ACTIVITY_TRANSFORM:
    return pterrain->transform_time * ACTIVITY_FACTOR;
  case ACTIVITY_CULTIVATE:
    return pterrain->cultivate_time * ACTIVITY_FACTOR;
  case ACTIVITY_PLANT:
    return pterrain->plant_time * ACTIVITY_FACTOR;
  case ACTIVITY_IRRIGATE:
  case ACTIVITY_MINE:
  case ACTIVITY_BASE:
  case ACTIVITY_GEN_ROAD:
    return terrain_extra_build_time(pterrain, activity, tgt) * ACTIVITY_FACTOR;
  default:
    return 0;
  }
}
 
/************************************************************************/
static void tile_create_extra(struct tile *ptile, struct extra_type *pextra)
{
  if (fc_funcs->create_extra != NULL) {
    /* Assume callback calls tile_add_extra() itself. */
    fc_funcs->create_extra(ptile, pextra, NULL);
  } else {
    tile_add_extra(ptile, pextra);
  }
}
 
/************************************************************************/
static void tile_destroy_extra(struct tile *ptile, struct extra_type *pextra)
{
  if (fc_funcs->destroy_extra != NULL) {
    /* Assume callback calls tile_remove_extra() itself. */
    fc_funcs->destroy_extra(ptile, pextra);
  } else {
    tile_remove_extra(ptile, pextra);
  }
}
 
/************************************************************************/
void tile_change_terrain(struct tile *ptile, struct terrain *pterrain)
{
  tile_set_terrain(ptile, pterrain);
 
  /* Remove unsupported extras */
  extra_type_iterate(pextra) {
    if (tile_has_extra(ptile, pextra)
        && (!is_native_tile_to_extra(pextra, ptile)
            || extra_has_flag(pextra, EF_TERR_CHANGE_REMOVES))) {
      tile_destroy_extra(ptile, pextra);
    }
  } extra_type_iterate_end;
}
 
/************************************************************************/
static bool add_recursive_extras(struct tile *ptile, struct extra_type *pextra,
                                 int rec)
{
  if (rec > MAX_EXTRA_TYPES) {
    /* Infinite recursion */
    return FALSE;
  }
 
  /* First place dependency extras */
  extra_deps_iterate(&(pextra->reqs), pdep) {
    if (!tile_has_extra(ptile, pdep)) {
      add_recursive_extras(ptile, pdep, rec + 1);
    }
  } extra_deps_iterate_end;
 
  /* Is tile native for extra after that? */
  if (!is_native_tile_to_extra(pextra, ptile)) {
    return FALSE;
  }
 
  tile_create_extra(ptile, pextra);
 
  return TRUE;
}
 
/************************************************************************/
static bool rm_recursive_extras(struct tile *ptile, struct extra_type *pextra,
                                int rec)
{
  if (rec > MAX_EXTRA_TYPES) {
    /* Infinite recursion */
    return FALSE;
  }
 
  extra_type_iterate(pdepending) {
    if (tile_has_extra(ptile, pdepending)) {
      extra_deps_iterate(&(pdepending->reqs), pdep) {
        if (pdep == pextra) {
          /* Depends on what we are going to remove */
          if (!rm_recursive_extras(ptile, pdepending, rec + 1)) {
            return FALSE;
          }
        }
      } extra_deps_iterate_end;
    }
  } extra_type_iterate_end;
 
  tile_destroy_extra(ptile, pextra);
 
  return TRUE;
}
 
/************************************************************************/
bool tile_extra_apply(struct tile *ptile, struct extra_type *tgt)
{
  /* Add extra with its dependencies */
  if (!add_recursive_extras(ptile, tgt, 0)) {
    return FALSE;
  }
 
  /* Remove conflicting extras */
  extra_type_iterate(pextra) {
    if (tile_has_extra(ptile, pextra)
        && !can_extras_coexist(pextra, tgt)) {
      tile_destroy_extra(ptile, pextra);
    }
  } extra_type_iterate_end;
 
  return TRUE;
}
 
/************************************************************************/
bool tile_extra_rm_apply(struct tile *ptile, struct extra_type *tgt)
{
  /* Remove extra with everything depending on it. */
  if (!rm_recursive_extras(ptile, tgt, 0)) {
    return FALSE;
  }
 
  return TRUE;
}
 
/************************************************************************/
static void tile_irrigate(struct tile *ptile, struct extra_type *tgt)
{
  fc_assert(tgt != NULL);
 
  if (tgt != NULL) {
    tile_extra_apply(ptile, tgt);
  }
}
 
/************************************************************************/
static void tile_mine(struct tile *ptile, struct extra_type *tgt)
{
  fc_assert(tgt != NULL);
 
  if (tgt != NULL) {
    tile_extra_apply(ptile, tgt);
  }
}
 
/************************************************************************/
static void tile_transform(struct tile *ptile)
{
  struct terrain *pterrain = tile_terrain(ptile);
 
  if (pterrain->transform_result != T_NONE) {
    tile_change_terrain(ptile, pterrain->transform_result);
  }
}
 
/************************************************************************/
static void tile_plant(struct tile *ptile)
{
  struct terrain *pterrain = tile_terrain(ptile);
 
  if (pterrain->plant_result != T_NONE) {
    tile_change_terrain(ptile, pterrain->plant_result);
  }
}
 
/************************************************************************/
static void tile_cultivate(struct tile *ptile)
{
  struct terrain *pterrain = tile_terrain(ptile);
 
  if (pterrain->cultivate_result != T_NONE) {
    tile_change_terrain(ptile, pterrain->cultivate_result);
  }
}
 
/************************************************************************/
bool tile_apply_activity(struct tile *ptile, Activity_type_id act,
                         struct extra_type *tgt)
{
  /* FIXME: for irrigate, mine, and transform we always return TRUE
   * even if the activity fails. */
  switch (act) {
  case ACTIVITY_MINE:
    tile_mine(ptile, tgt);
    return TRUE;
 
  case ACTIVITY_IRRIGATE: 
    tile_irrigate(ptile, tgt);
    return TRUE;
 
  case ACTIVITY_TRANSFORM:
    tile_transform(ptile);
    return TRUE;
 
  case ACTIVITY_CULTIVATE:
    tile_cultivate(ptile);
    return TRUE;
 
  case ACTIVITY_PLANT:
    tile_plant(ptile);
    return TRUE;
 
  case ACTIVITY_OLD_ROAD:
  case ACTIVITY_OLD_RAILROAD:
  case ACTIVITY_FORTRESS:
  case ACTIVITY_AIRBASE:
    fc_assert(FALSE);
    return FALSE;
 
  case ACTIVITY_PILLAGE:
  case ACTIVITY_BASE:
  case ACTIVITY_GEN_ROAD:
  case ACTIVITY_POLLUTION:
  case ACTIVITY_FALLOUT:
    /* do nothing  - not implemented */
    return FALSE;
 
  case ACTIVITY_IDLE:
  case ACTIVITY_FORTIFIED:
  case ACTIVITY_SENTRY:
  case ACTIVITY_GOTO:
  case ACTIVITY_EXPLORE:
  case ACTIVITY_CONVERT:
  case ACTIVITY_UNKNOWN:
  case ACTIVITY_FORTIFYING:
  case ACTIVITY_PATROL_UNUSED:
  case ACTIVITY_LAST:
    /* do nothing - these activities have no effect
       on terrain type or tile extras */
    return FALSE;
  }
  fc_assert(FALSE);
  return FALSE;
}
 
/************************************************************************/
static bool tile_info_pollution(char *buf, int bufsz,
                                const struct tile *ptile,
                                struct extra_type *pextra,
                                bool prevp, bool linebreak)
{
  if (tile_has_visible_extra(ptile, pextra)) {
    if (!prevp) {
      if (linebreak) {
        fc_strlcat(buf, "\n[", bufsz);
      } else {
        fc_strlcat(buf, " [", bufsz);
      }
    } else {
      fc_strlcat(buf, "/", bufsz);
    }
 
    fc_strlcat(buf, extra_name_translation(pextra), bufsz);
 
    return TRUE;
  }
 
  return prevp;
}
 
/************************************************************************/
const char *tile_get_info_text(const struct tile *ptile,
                               bool include_nuisances, int linebreaks)
{
  static char s[256];
  bool pollution;
  bool lb = FALSE;
  int bufsz = sizeof(s);
 
  sz_strlcpy(s, terrain_name_translation(tile_terrain(ptile)));
  if (linebreaks & TILE_LB_TERRAIN_RIVER) {
    /* Linebreak needed before next text */
    lb = TRUE;
  }
 
  extra_type_iterate(pextra) {
    if (pextra->category == ECAT_NATURAL
        && tile_has_visible_extra(ptile, pextra)) {
      if (lb) {
        sz_strlcat(s, "\n");
        lb = FALSE;
      } else {
        sz_strlcat(s, "/");
      }
      sz_strlcat(s, extra_name_translation(pextra));
    }
  } extra_type_iterate_end;
  if (linebreaks & TILE_LB_RIVER_RESOURCE) {
    /* New linebreak requested */
    lb = TRUE;
  }
 
  if (tile_resource_is_valid(ptile)) {
    if (lb) {
      sz_strlcat(s, "\n");
      lb = FALSE;
    } else {
      sz_strlcat(s, " ");
    }
    cat_snprintf(s, sizeof(s), "(%s)",
                 extra_name_translation(ptile->resource));
  }
  if (linebreaks & TILE_LB_RESOURCE_POLL) {
    /* New linebreak requested */
    lb = TRUE;
  }
 
  if (include_nuisances) {
    pollution = FALSE;
    extra_type_iterate(pextra) {
      if (pextra->category == ECAT_NUISANCE) {
        pollution = tile_info_pollution(s, bufsz, ptile, pextra, pollution,
                                        lb);
      }
    } extra_type_iterate_end;
    if (pollution) {
      sz_strlcat(s, "]");
    }
  }
 
  return s;
}
 
/************************************************************************/
bool tile_has_base(const struct tile *ptile, const struct base_type *pbase)
{
  return tile_has_extra(ptile, base_extra_get(pbase));
}
 
/************************************************************************/
bool tile_has_road(const struct tile *ptile, const struct road_type *proad)
{
  return tile_has_extra(ptile, road_extra_get(proad));
}
 
/************************************************************************/
bool tile_has_river(const struct tile *ptile)
{
  /* TODO: Have a list of rivers and iterate only that */
  extra_type_by_cause_iterate(EC_ROAD, priver) {
    if (tile_has_extra(ptile, priver)
        && road_has_flag(extra_road_get(priver), RF_RIVER)) {
      return TRUE;
    }
  } extra_type_by_cause_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
bool tile_has_road_flag(const struct tile *ptile, enum road_flag_id flag)
{
  extra_type_by_cause_iterate(EC_ROAD, pextra) {
    if (tile_has_extra(ptile, pextra)) {
      struct road_type *proad = extra_road_get(pextra);
 
      if (road_has_flag(proad, flag)) {
        return TRUE;
      }
    }
  } extra_type_by_cause_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
bool tile_has_extra_flag(const struct tile *ptile, enum extra_flag_id flag)
{
  extra_type_iterate(pextra) {
    if (tile_has_extra(ptile, pextra)
        && extra_has_flag(pextra, flag)) {
      return TRUE;
    }
  } extra_type_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
bool tile_has_conflicting_extra(const struct tile *ptile,
                                const struct extra_type *pextra)
{
  extra_type_iterate(pconfl) {
    if (BV_ISSET(pextra->conflicts, extra_index(pconfl))
        && tile_has_extra(ptile, pconfl)) {
      return TRUE;
    }
  } extra_type_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
bool tile_has_visible_extra(const struct tile *ptile, const struct extra_type *pextra)
{
  bool hidden = FALSE;
 
  if (!BV_ISSET(ptile->extras, extra_index(pextra))) {
    return FALSE;
  }
 
  extra_type_iterate(top) {
    int topi = extra_index(top);
 
    if (BV_ISSET(pextra->hidden_by, topi)
        && BV_ISSET(ptile->extras, topi)) {
      hidden = TRUE;
      break;
    }
  } extra_type_iterate_end;
 
  return !hidden;
}
 
/************************************************************************/
bool tile_has_cause_extra(const struct tile *ptile, enum extra_cause cause)
{
  extra_type_by_cause_iterate(cause, pextra) {
    if (tile_has_extra(ptile, pextra)) {
      return TRUE;
    }
  } extra_type_by_cause_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
void tile_add_extra(struct tile *ptile, const struct extra_type *pextra)
{
  if (pextra != NULL) {
    BV_SET(ptile->extras, extra_index(pextra));
  }
}
 
/************************************************************************/
void tile_remove_extra(struct tile *ptile, const struct extra_type *pextra)
{
  if (pextra != NULL) {
    BV_CLR(ptile->extras, extra_index(pextra));
    if (ptile->resource == pextra) {
      ptile->resource = NULL;
    }
  }
}
 
/************************************************************************/
struct tile *tile_virtual_new(const struct tile *ptile)
{
  struct tile *vtile;
 
  vtile = fc_calloc(1, sizeof(*vtile));
 
  /* initialise some values */
  vtile->index = TILE_INDEX_NONE;
  vtile->continent = -1;
 
  BV_CLR_ALL(vtile->extras);
  vtile->resource = NULL;
  vtile->terrain = NULL;
  vtile->units = unit_list_new();
  vtile->worked = NULL;
  vtile->owner = NULL;
  vtile->placing = NULL;
  vtile->extras_owner = NULL;
  vtile->claimer = NULL;
  vtile->spec_sprite = NULL;
 
  if (ptile) {
    /* Used by is_city_center to give virtual tiles the output bonuses
     * they deserve. */
    vtile->index = tile_index(ptile);
 
    /* Copy all but the unit list. */
    extra_type_iterate(pextra) {
      if (BV_ISSET(ptile->extras, extra_number(pextra))) {
        BV_SET(vtile->extras, extra_number(pextra));
      }
    } extra_type_iterate_end;
 
    vtile->resource = ptile->resource;
    vtile->terrain = ptile->terrain;
    vtile->worked = ptile->worked;
    vtile->owner = ptile->owner;
    vtile->extras_owner = ptile->extras_owner;
    vtile->claimer = ptile->claimer;
    vtile->spec_sprite = NULL;
  }
 
  return vtile;
}
 
/************************************************************************/
void tile_virtual_destroy(struct tile *vtile)
{
  struct city *vcity;
 
  if (!vtile) {
    return;
  }
 
  if (vtile->units) {
    unit_list_iterate(vtile->units, vunit) {
      if (unit_is_virtual(vunit)) {
        unit_virtual_destroy(vunit);
      }
    } unit_list_iterate_end;
    unit_list_destroy(vtile->units);
    vtile->units = NULL;
  }
 
  vcity = tile_city(vtile);
  if (vcity) {
    if (city_is_virtual(vcity)) {
      destroy_city_virtual(vcity);
    }
    tile_set_worked(vtile, NULL);
  }
 
  free(vtile);
}
 
/************************************************************************/
bool tile_map_check(struct civ_map *nmap, struct tile *vtile)
{
  int tindex;
 
  if (!vtile || map_is_empty()) {
    return FALSE;
  }
 
  tindex = tile_index(vtile);
  fc_assert_ret_val(0 <= tindex && tindex < map_num_tiles(), FALSE);
 
  return (vtile == nmap->tiles + tindex);
}
 
/************************************************************************/
void *tile_hash_key(const struct tile *ptile)
{
  void *key = 0; /* Initialize whole sizeof(void *) */
 
  key = FC_INT_TO_PTR(ptile->index);
 
  return key;
}
 
/************************************************************************/
bool tile_set_label(struct tile *ptile, const char *label)
{
  bool changed = FALSE;
 
  /* Handle empty label as NULL label */
  if (label != NULL && label[0] == '\0') {
    label = NULL;
  }
 
  if (ptile->label != NULL) {
    if (label == NULL) {
      changed = TRUE;
    } else if (strcmp(ptile->label, label)) {
      changed = TRUE;
    }
    FC_FREE(ptile->label);
    ptile->label = NULL;
  } else if (label != NULL) {
    changed = TRUE;
  }
 
  if (label != NULL) {
    if (strlen(label) >= MAX_LEN_MAP_LABEL) {
      log_error("Overlong map label '%s'", label);
    }
    ptile->label = fc_strdup(label);
  }
 
  return changed;
}
 
/************************************************************************/
bool tile_is_placing(const struct tile *ptile)
{
  return ptile->placing != NULL;
}