kc3-lang/libxkbcommon/src/state.c

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• Hash : 11df0632
  Author :
  Date : 2012-09-27T21:11:11
  

  state: add missing const in get_one_sym Signed-off-by: Ran Benita <ran234@gmail.com>

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• src/state.c

• /************************************************************
   * Copyright (c) 1993 by Silicon Graphics Computer Systems, Inc.
   *
   * Permission to use, copy, modify, and distribute this
   * software and its documentation for any purpose and without
   * fee is hereby granted, provided that the above copyright
   * notice appear in all copies and that both that copyright
   * notice and this permission notice appear in supporting
   * documentation, and that the name of Silicon Graphics not be
   * used in advertising or publicity pertaining to distribution
   * of the software without specific prior written permission.
   * Silicon Graphics makes no representation about the suitability
   * of this software for any purpose. It is provided "as is"
   * without any express or implied warranty.
   *
   * SILICON GRAPHICS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
   * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
   * AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
   * GRAPHICS BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
   * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
   * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
   * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION  WITH
   * THE USE OR PERFORMANCE OF THIS SOFTWARE.
   *
   ********************************************************/
  
  /*
   * Copyright © 2012 Intel Corporation
   * Copyright © 2012 Ran Benita <ran234@gmail.com>
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   * DEALINGS IN THE SOFTWARE.
   *
   * Author: Daniel Stone <daniel@fooishbar.org>
   */
  
  /*
   * This is a bastardised version of xkbActions.c from the X server which
   * does not support, for the moment:
   *   - AccessX sticky/debounce/etc (will come later)
   *   - pointer keys (may come later)
   *   - key redirects (unlikely)
   *   - messages (very unlikely)
   */
  
  #include "keymap.h"
  
  struct xkb_filter {
      union xkb_action action;
      const struct xkb_key *key;
      uint32_t priv;
      int (*func)(struct xkb_state *state,
                  struct xkb_filter *filter,
                  const struct xkb_key *key,
                  enum xkb_key_direction direction);
      int refcnt;
  };
  
  struct xkb_state {
      /* These may be negative, because of -1 group actions. */
      int32_t base_group; /**< depressed */
      int32_t latched_group;
      int32_t locked_group;
      xkb_layout_index_t group; /**< effective */
  
      xkb_mod_mask_t base_mods; /**< depressed */
      xkb_mod_mask_t latched_mods;
      xkb_mod_mask_t locked_mods;
      xkb_mod_mask_t mods; /**< effective */
  
      /*
       * At each event, we accumulate all the needed modifications to the base
       * modifiers, and apply them at the end. These keep track of this state.
       */
      xkb_mod_mask_t set_mods;
      xkb_mod_mask_t clear_mods;
      /*
       * We mustn't clear a base modifier if there's another depressed key
       * which affects it, e.g. given this sequence
       * < Left Shift down, Right Shift down, Left Shift Up >
       * the modifier should still be set. This keeps the count.
       */
      int16_t mod_key_count[sizeof(xkb_mod_mask_t) * 8];
  
      uint32_t leds;
  
      int refcnt;
      darray(struct xkb_filter) filters;
      struct xkb_keymap *keymap;
  };
  
  static const struct xkb_kt_map_entry *
  get_entry_for_key_state(struct xkb_state *state, const struct xkb_key *key,
                          xkb_layout_index_t group)
  {
      const struct xkb_key_type *type;
      xkb_mod_mask_t active_mods;
      unsigned int i;
  
      type = key->groups[group].type;
      active_mods = xkb_state_serialize_mods(state, XKB_STATE_EFFECTIVE);
      active_mods &= type->mods.mask;
  
      for (i = 0; i < type->num_entries; i++)
          if (type->map[i].mods.mask == active_mods)
              return &type->map[i];
  
      return NULL;
  }
  
  /**
   * Returns the level to use for the given key and state, or
   * XKB_LEVEL_INVALID.
   */
  XKB_EXPORT xkb_level_index_t
  xkb_state_key_get_level(struct xkb_state *state, xkb_keycode_t kc,
                          xkb_layout_index_t layout)
  {
      const struct xkb_key *key = XkbKey(state->keymap, kc);
      const struct xkb_kt_map_entry *entry;
  
      if (!key || layout >= key->num_groups)
          return XKB_LEVEL_INVALID;
  
      /* If we don't find an explicit match the default is 0. */
      entry = get_entry_for_key_state(state, key, layout);
      if (!entry)
          return 0;
  
      return entry->level;
  }
  
  static xkb_layout_index_t
  wrap_group_into_range(int32_t group,
                        xkb_layout_index_t num_groups,
                        enum xkb_range_exceed_type out_of_range_group_action,
                        xkb_layout_index_t out_of_range_group_number)
  {
      if (num_groups == 0)
          return XKB_LAYOUT_INVALID;
  
      if (group < num_groups)
          return group;
  
      switch (out_of_range_group_action) {
      case RANGE_REDIRECT:
          if (out_of_range_group_number >= num_groups)
              return 0;
          return out_of_range_group_number;
  
      case RANGE_SATURATE:
          if (group < 0)
              return 0;
          else
              return num_groups - 1;
  
      case RANGE_WRAP:
      default:
          /*
           * C99 says a negative dividend in a modulo operation always
           * gives a negative result.
           */
          if (group < 0)
              return ((int) num_groups + (group % (int) num_groups));
          else
              return group % num_groups;
      }
  }
  
  /**
   * Returns the layout to use for the given key and state, taking
   * wrapping/clamping/etc into account, or XKB_LAYOUT_INVALID.
   */
  XKB_EXPORT xkb_layout_index_t
  xkb_state_key_get_layout(struct xkb_state *state, xkb_keycode_t kc)
  {
      xkb_layout_index_t group =
          xkb_state_serialize_layout(state, XKB_STATE_EFFECTIVE);
      const struct xkb_key *key = XkbKey(state->keymap, kc);
  
      if (!key)
          return XKB_LAYOUT_INVALID;
  
      return wrap_group_into_range(group, key->num_groups,
                                   key->out_of_range_group_action,
                                   key->out_of_range_group_number);
  }
  
  static const union xkb_action fake = { .type = ACTION_TYPE_NONE };
  
  static const union xkb_action *
  xkb_key_get_action(struct xkb_state *state, const struct xkb_key *key)
  {
      xkb_layout_index_t layout;
      xkb_level_index_t level;
  
      layout = xkb_state_key_get_layout(state, key->keycode);
      if (layout == XKB_LAYOUT_INVALID)
          return &fake;
  
      level = xkb_state_key_get_level(state, key->keycode, layout);
      if (level == XKB_LEVEL_INVALID)
          return &fake;
  
      return &key->groups[layout].levels[level].action;
  }
  
  static struct xkb_filter *
  xkb_filter_new(struct xkb_state *state)
  {
      struct xkb_filter *filter = NULL, *iter;
  
      darray_foreach(iter, state->filters) {
          if (iter->func)
              continue;
          filter = iter;
          break;
      }
  
      if (!filter) {
          darray_resize0(state->filters, darray_size(state->filters) + 1);
          filter = &darray_item(state->filters, darray_size(state->filters) -1);
      }
  
      filter->refcnt = 1;
      return filter;
  }
  
  /***====================================================================***/
  
  static int
  xkb_filter_group_set_func(struct xkb_state *state,
                            struct xkb_filter *filter,
                            const struct xkb_key *key,
                            enum xkb_key_direction direction)
  {
      if (key != filter->key) {
          filter->action.group.flags &= ~ACTION_LOCK_CLEAR;
          return 1;
      }
  
      if (direction == XKB_KEY_DOWN) {
          filter->refcnt++;
          return 0;
      }
      else if (--filter->refcnt > 0) {
          return 0;
      }
  
      state->base_group = filter->priv;
  
      if (filter->action.group.flags & ACTION_LOCK_CLEAR)
          state->locked_group = 0;
  
      filter->func = NULL;
      return 1;
  }
  
  static void
  xkb_filter_group_set_new(struct xkb_state *state, struct xkb_filter *filter)
  {
      filter->priv = state->base_group;
      if (filter->action.group.flags & ACTION_ABSOLUTE_SWITCH)
          state->base_group = filter->action.group.group;
      else
          state->base_group += filter->action.group.group;
  }
  
  static int
  xkb_filter_group_lock_func(struct xkb_state *state,
                             struct xkb_filter *filter,
                             const struct xkb_key *key,
                             enum xkb_key_direction direction)
  {
      if (key != filter->key)
          return 1;
  
      if (direction == XKB_KEY_DOWN) {
          filter->refcnt++;
          return 0;
      }
      if (--filter->refcnt > 0)
          return 0;
  
      filter->func = NULL;
      return 1;
  }
  
  static void
  xkb_filter_group_lock_new(struct xkb_state *state, struct xkb_filter *filter)
  {
      if (filter->action.group.flags & ACTION_ABSOLUTE_SWITCH)
          state->locked_group = filter->action.group.group;
      else
          state->locked_group += filter->action.group.group;
  }
  
  static int
  xkb_filter_mod_set_func(struct xkb_state *state,
                          struct xkb_filter *filter,
                          const struct xkb_key *key,
                          enum xkb_key_direction direction)
  {
      if (key != filter->key) {
          filter->action.mods.flags &= ~ACTION_LOCK_CLEAR;
          return 1;
      }
  
      if (direction == XKB_KEY_DOWN) {
          filter->refcnt++;
          return 0;
      }
      else if (--filter->refcnt > 0) {
          return 0;
      }
  
      state->clear_mods = filter->action.mods.mods.mask;
      if (filter->action.mods.flags & ACTION_LOCK_CLEAR)
          state->locked_mods &= ~filter->action.mods.mods.mask;
  
      filter->func = NULL;
      return 1;
  }
  
  static void
  xkb_filter_mod_set_new(struct xkb_state *state, struct xkb_filter *filter)
  {
      state->set_mods = filter->action.mods.mods.mask;
  }
  
  static int
  xkb_filter_mod_lock_func(struct xkb_state *state,
                           struct xkb_filter *filter,
                           const struct xkb_key *key,
                           enum xkb_key_direction direction)
  {
      if (key != filter->key)
          return 1;
  
      if (direction == XKB_KEY_DOWN) {
          filter->refcnt++;
          return 0;
      }
      if (--filter->refcnt > 0)
          return 0;
  
      state->clear_mods |= filter->action.mods.mods.mask;
      if (!(filter->action.mods.flags & ACTION_LOCK_NO_UNLOCK))
          state->locked_mods &= ~filter->priv;
  
      filter->func = NULL;
      return 1;
  }
  
  static void
  xkb_filter_mod_lock_new(struct xkb_state *state, struct xkb_filter *filter)
  {
      filter->priv = state->locked_mods & filter->action.mods.mods.mask;
      state->set_mods |= filter->action.mods.mods.mask;
      if (!(filter->action.mods.flags & ACTION_LOCK_NO_LOCK))
          state->locked_mods |= filter->action.mods.mods.mask;
  }
  
  enum xkb_key_latch_state {
      NO_LATCH,
      LATCH_KEY_DOWN,
      LATCH_PENDING,
  };
  
  static bool
  xkb_action_breaks_latch(const union xkb_action *action)
  {
      switch (action->type) {
      case ACTION_TYPE_NONE:
      case ACTION_TYPE_PTR_BUTTON:
      case ACTION_TYPE_PTR_LOCK:
      case ACTION_TYPE_CTRL_SET:
      case ACTION_TYPE_CTRL_LOCK:
      case ACTION_TYPE_KEY_REDIRECT:
      case ACTION_TYPE_SWITCH_VT:
      case ACTION_TYPE_TERMINATE:
          return true;
      default:
          return false;
      }
  }
  
  static int
  xkb_filter_mod_latch_func(struct xkb_state *state,
                            struct xkb_filter *filter,
                            const struct xkb_key *key,
                            enum xkb_key_direction direction)
  {
      enum xkb_key_latch_state latch = filter->priv;
  
      if (direction == XKB_KEY_DOWN && latch == LATCH_PENDING) {
          /* If this is a new keypress and we're awaiting our single latched
           * keypress, then either break the latch if any random key is pressed,
           * or promote it to a lock or plain base set if it's the same
           * modifier. */
          const union xkb_action *action = xkb_key_get_action(state, key);
          if (action->type == ACTION_TYPE_MOD_LATCH &&
              action->mods.flags == filter->action.mods.flags &&
              action->mods.mods.mask == filter->action.mods.mods.mask) {
              filter->action = *action;
              if (filter->action.mods.flags & ACTION_LATCH_TO_LOCK) {
                  filter->action.type = ACTION_TYPE_MOD_LOCK;
                  filter->func = xkb_filter_mod_lock_func;
                  state->locked_mods |= filter->action.mods.mods.mask;
              }
              else {
                  filter->action.type = ACTION_TYPE_MOD_SET;
                  filter->func = xkb_filter_mod_set_func;
                  state->set_mods = filter->action.mods.mods.mask;
              }
              filter->key = key;
              state->latched_mods &= ~filter->action.mods.mods.mask;
              /* XXX beep beep! */
              return 0;
          }
          else if (xkb_action_breaks_latch(action)) {
              /* XXX: This may be totally broken, we might need to break the
               *      latch in the next run after this press? */
              state->latched_mods &= ~filter->action.mods.mods.mask;
              filter->func = NULL;
              return 1;
          }
      }
      else if (direction == XKB_KEY_UP && key == filter->key) {
          /* Our key got released.  If we've set it to clear locks, and we
           * currently have the same modifiers locked, then release them and
           * don't actually latch.  Else we've actually hit the latching
           * stage, so set PENDING and move our modifier from base to
           * latched. */
          if (latch == NO_LATCH ||
              ((filter->action.mods.flags & ACTION_LOCK_CLEAR) &&
               (state->locked_mods & filter->action.mods.mods.mask) ==
               filter->action.mods.mods.mask)) {
              /* XXX: We might be a bit overenthusiastic about clearing
               *      mods other filters have set here? */
              if (latch == LATCH_PENDING)
                  state->latched_mods &= ~filter->action.mods.mods.mask;
              else
                  state->clear_mods = filter->action.mods.mods.mask;
              state->locked_mods &= ~filter->action.mods.mods.mask;
              filter->func = NULL;
          }
          else {
              latch = LATCH_PENDING;
              state->clear_mods = filter->action.mods.mods.mask;
              state->latched_mods |= filter->action.mods.mods.mask;
              /* XXX beep beep! */
          }
      }
      else if (direction == XKB_KEY_DOWN && latch == LATCH_KEY_DOWN) {
          /* Someone's pressed another key while we've still got the latching
           * key held down, so keep the base modifier state active (from
           * xkb_filter_mod_latch_new), but don't trip the latch, just clear
           * it as soon as the modifier gets released. */
          latch = NO_LATCH;
      }
  
      filter->priv = latch;
  
      return 1;
  }
  
  static void
  xkb_filter_mod_latch_new(struct xkb_state *state, struct xkb_filter *filter)
  {
      filter->priv = LATCH_KEY_DOWN;
      state->set_mods = filter->action.mods.mods.mask;
  }
  
  static const struct {
      void (*new)(struct xkb_state *state, struct xkb_filter *filter);
      int (*func)(struct xkb_state *state, struct xkb_filter *filter,
                  const struct xkb_key *key, enum xkb_key_direction direction);
  } filter_action_funcs[_ACTION_TYPE_NUM_ENTRIES] = {
      [ACTION_TYPE_MOD_SET]    = { xkb_filter_mod_set_new,
                                   xkb_filter_mod_set_func },
      [ACTION_TYPE_MOD_LATCH]  = { xkb_filter_mod_latch_new,
                                   xkb_filter_mod_latch_func },
      [ACTION_TYPE_MOD_LOCK]   = { xkb_filter_mod_lock_new,
                                   xkb_filter_mod_lock_func },
      [ACTION_TYPE_GROUP_SET]  = { xkb_filter_group_set_new,
                                   xkb_filter_group_set_func },
      [ACTION_TYPE_GROUP_LOCK] = { xkb_filter_group_lock_new,
                                   xkb_filter_group_lock_func },
  };
  
  /**
   * Applies any relevant filters to the key, first from the list of filters
   * that are currently active, then if no filter has claimed the key, possibly
   * apply a new filter from the key action.
   */
  static void
  xkb_filter_apply_all(struct xkb_state *state,
                       const struct xkb_key *key,
                       enum xkb_key_direction direction)
  {
      struct xkb_filter *filter;
      const union xkb_action *action;
      int send = 1;
  
      /* First run through all the currently active filters and see if any of
       * them have claimed this event. */
      darray_foreach(filter, state->filters) {
          if (!filter->func)
              continue;
          send &= filter->func(state, filter, key, direction);
      }
  
      if (!send || direction == XKB_KEY_UP)
          return;
  
      action = xkb_key_get_action(state, key);
      if (!filter_action_funcs[action->type].new)
          return;
  
      filter = xkb_filter_new(state);
      if (!filter)
          return; /* WSGO */
  
      filter->key = key;
      filter->func = filter_action_funcs[action->type].func;
      filter->action = *action;
      filter_action_funcs[action->type].new(state, filter);
  }
  
  XKB_EXPORT struct xkb_state *
  xkb_state_new(struct xkb_keymap *keymap)
  {
      struct xkb_state *ret;
  
      ret = calloc(sizeof(*ret), 1);
      if (!ret)
          return NULL;
  
      ret->refcnt = 1;
      ret->keymap = xkb_keymap_ref(keymap);
  
      return ret;
  }
  
  XKB_EXPORT struct xkb_state *
  xkb_state_ref(struct xkb_state *state)
  {
      state->refcnt++;
      return state;
  }
  
  XKB_EXPORT void
  xkb_state_unref(struct xkb_state *state)
  {
      if (--state->refcnt > 0)
          return;
  
      xkb_keymap_unref(state->keymap);
      darray_free(state->filters);
      free(state);
  }
  
  XKB_EXPORT struct xkb_keymap *
  xkb_state_get_keymap(struct xkb_state *state)
  {
      return state->keymap;
  }
  
  /**
   * Update the LED state to match the rest of the xkb_state.
   */
  static void
  xkb_state_led_update_all(struct xkb_state *state)
  {
      xkb_led_index_t led;
  
      state->leds = 0;
  
      for (led = 0; led < XKB_NUM_INDICATORS; led++) {
          struct xkb_indicator_map *map = &state->keymap->indicators[led];
          xkb_mod_mask_t mod_mask = 0;
          uint32_t group_mask = 0;
  
          if (map->which_mods & XKB_STATE_DEPRESSED)
              mod_mask |= state->base_mods;
          if (map->which_mods & XKB_STATE_LATCHED)
              mod_mask |= state->latched_mods;
          if (map->which_mods & XKB_STATE_LOCKED)
              mod_mask |= state->locked_mods;
          if ((map->mods.mask & mod_mask))
              state->leds |= (1 << led);
  
          if (map->which_groups & XKB_STATE_DEPRESSED)
              group_mask |= (1 << state->base_group);
          if (map->which_groups & XKB_STATE_LATCHED)
              group_mask |= (1 << state->latched_group);
          if (map->which_groups & XKB_STATE_LOCKED)
              group_mask |= (1 << state->locked_group);
          if ((map->groups & group_mask))
              state->leds |= (1 << led);
  
          if (map->ctrls) {
              if ((map->ctrls & state->keymap->enabled_ctrls))
                  state->leds |= (1 << led);
          }
      }
  }
  
  /**
   * Calculates the derived state (effective mods/group and LEDs) from an
   * up-to-date xkb_state.
   */
  static void
  xkb_state_update_derived(struct xkb_state *state)
  {
      xkb_layout_index_t num_groups = xkb_keymap_num_layouts(state->keymap);
  
      state->mods = (state->base_mods |
                     state->latched_mods |
                     state->locked_mods);
  
      /* TODO: Use groups_wrap control instead of always RANGE_WRAP. */
  
      state->locked_group = wrap_group_into_range(state->locked_group,
                                                  num_groups,
                                                  RANGE_WRAP, 0);
  
      state->group = wrap_group_into_range(state->base_group +
                                           state->latched_group +
                                           state->locked_group,
                                           num_groups,
                                           RANGE_WRAP, 0);
  
      xkb_state_led_update_all(state);
  }
  
  /**
   * Given a particular key event, updates the state structure to reflect the
   * new modifiers.
   */
  XKB_EXPORT void
  xkb_state_update_key(struct xkb_state *state, xkb_keycode_t kc,
                       enum xkb_key_direction direction)
  {
      xkb_mod_index_t i;
      xkb_mod_mask_t bit;
      const struct xkb_key *key = XkbKey(state->keymap, kc);
  
      if (!key)
          return;
  
      state->set_mods = 0;
      state->clear_mods = 0;
  
      xkb_filter_apply_all(state, key, direction);
  
      for (i = 0, bit = 1; state->set_mods; i++, bit <<= 1) {
          if (state->set_mods & bit) {
              state->mod_key_count[i]++;
              state->base_mods |= bit;
              state->set_mods &= ~bit;
          }
      }
  
      for (i = 0, bit = 1; state->clear_mods; i++, bit <<= 1) {
          if (state->clear_mods & bit) {
              state->mod_key_count[i]--;
              if (state->mod_key_count[i] <= 0) {
                  state->base_mods &= ~bit;
                  state->mod_key_count[i] = 0;
              }
              state->clear_mods &= ~bit;
          }
      }
  
      xkb_state_update_derived(state);
  }
  
  /**
   * Updates the state from a set of explicit masks as gained from
   * xkb_state_serialize_mods and xkb_state_serialize_groups.  As noted in the
   * documentation for these functions in xkbcommon.h, this round-trip is
   * lossy, and should only be used to update a slave state mirroring the
   * master, e.g. in a client/server window system.
   */
  XKB_EXPORT void
  xkb_state_update_mask(struct xkb_state *state,
                        xkb_mod_mask_t base_mods,
                        xkb_mod_mask_t latched_mods,
                        xkb_mod_mask_t locked_mods,
                        xkb_layout_index_t base_group,
                        xkb_layout_index_t latched_group,
                        xkb_layout_index_t locked_group)
  {
      xkb_mod_index_t num_mods;
      xkb_mod_index_t idx;
  
      state->base_mods = 0;
      state->latched_mods = 0;
      state->locked_mods = 0;
      num_mods = xkb_keymap_num_mods(state->keymap);
  
      for (idx = 0; idx < num_mods; idx++) {
          xkb_mod_mask_t mod = (1 << idx);
          if (base_mods & mod)
              state->base_mods |= mod;
          if (latched_mods & mod)
              state->latched_mods |= mod;
          if (locked_mods & mod)
              state->locked_mods |= mod;
      }
  
      state->base_group = base_group;
      state->latched_group = latched_group;
      state->locked_group = locked_group;
  
      xkb_state_update_derived(state);
  }
  
  /**
   * Provides the symbols to use for the given key and state.  Returns the
   * number of symbols pointed to in syms_out.
   */
  XKB_EXPORT int
  xkb_state_key_get_syms(struct xkb_state *state, xkb_keycode_t kc,
                         const xkb_keysym_t **syms_out)
  {
      xkb_layout_index_t layout;
      xkb_level_index_t level;
      const struct xkb_key *key = XkbKey(state->keymap, kc);
  
      if (!key)
          return -1;
  
      layout = xkb_state_key_get_layout(state, kc);
      if (layout == XKB_LAYOUT_INVALID)
          goto err;
  
      level = xkb_state_key_get_level(state, kc, layout);
      if (level == XKB_LEVEL_INVALID)
          goto err;
  
      return xkb_keymap_key_get_syms_by_level(state->keymap, kc, layout, level,
                                              syms_out);
  
  err:
      *syms_out = NULL;
      return 0;
  }
  
  /**
   * Provides either exactly one symbol, or XKB_KEY_NoSymbol.
   */
  XKB_EXPORT xkb_keysym_t
  xkb_state_key_get_one_sym(struct xkb_state *state, xkb_keycode_t kc)
  {
      const xkb_keysym_t *syms;
      int num_syms;
  
      num_syms = xkb_state_key_get_syms(state, kc, &syms);
      if (num_syms != 1)
          return XKB_KEY_NoSymbol;
  
      return syms[0];
  }
  
  /**
   * Serialises the requested modifier state into an xkb_mod_mask_t, with all
   * the same disclaimers as in xkb_state_update_mask.
   */
  XKB_EXPORT xkb_mod_mask_t
  xkb_state_serialize_mods(struct xkb_state *state,
                           enum xkb_state_component type)
  {
      xkb_mod_mask_t ret = 0;
  
      if (type == XKB_STATE_EFFECTIVE)
          return state->mods;
  
      if (type & XKB_STATE_DEPRESSED)
          ret |= state->base_mods;
      if (type & XKB_STATE_LATCHED)
          ret |= state->latched_mods;
      if (type & XKB_STATE_LOCKED)
          ret |= state->locked_mods;
  
      return ret;
  }
  
  /**
   * Serialises the requested group state, with all the same disclaimers as
   * in xkb_state_update_mask.
   */
  XKB_EXPORT xkb_layout_index_t
  xkb_state_serialize_layout(struct xkb_state *state,
                             enum xkb_state_component type)
  {
      xkb_layout_index_t ret = 0;
  
      if (type == XKB_STATE_EFFECTIVE)
          return state->group;
  
      if (type & XKB_STATE_DEPRESSED)
          ret += state->base_group;
      if (type & XKB_STATE_LATCHED)
          ret += state->latched_group;
      if (type & XKB_STATE_LOCKED)
          ret += state->locked_group;
  
      return ret;
  }
  
  /**
   * Returns 1 if the given modifier is active with the specified type(s), 0 if
   * not, or -1 if the modifier is invalid.
   */
  XKB_EXPORT int
  xkb_state_mod_index_is_active(struct xkb_state *state,
                                xkb_mod_index_t idx,
                                enum xkb_state_component type)
  {
      int ret = 0;
  
      if (idx >= xkb_keymap_num_mods(state->keymap))
          return -1;
  
      if (type & XKB_STATE_EFFECTIVE)
          return !!(state->mods & (1 << idx));
  
      if (type & XKB_STATE_DEPRESSED)
          ret |= (state->base_mods & (1 << idx));
      if (type & XKB_STATE_LATCHED)
          ret |= (state->latched_mods & (1 << idx));
      if (type & XKB_STATE_LOCKED)
          ret |= (state->locked_mods & (1 << idx));
  
      return !!ret;
  }
  
  /**
   * Helper function for xkb_state_mod_indices_are_active and
   * xkb_state_mod_names_are_active.
   */
  static int
  match_mod_masks(struct xkb_state *state, enum xkb_state_match match,
                  uint32_t wanted)
  {
      uint32_t active = xkb_state_serialize_mods(state, XKB_STATE_EFFECTIVE);
  
      if (!(match & XKB_STATE_MATCH_NON_EXCLUSIVE) && (active & ~wanted))
          return 0;
  
      if (match & XKB_STATE_MATCH_ANY)
          return !!(active & wanted);
      else
          return (active & wanted) == wanted;
  
      return 0;
  }
  
  /**
   * Returns 1 if the modifiers are active with the specified type(s), 0 if
   * not, or -1 if any of the modifiers are invalid.
   */
  XKB_EXPORT int
  xkb_state_mod_indices_are_active(struct xkb_state *state,
                                   enum xkb_state_component type,
                                   enum xkb_state_match match,
                                   ...)
  {
      va_list ap;
      xkb_mod_index_t idx = 0;
      uint32_t wanted = 0;
      int ret = 0;
      xkb_mod_index_t num_mods = xkb_keymap_num_mods(state->keymap);
  
      va_start(ap, match);
      while (1) {
          idx = va_arg(ap, xkb_mod_index_t);
          if (idx == XKB_MOD_INVALID)
              break;
          if (idx >= num_mods) {
              ret = -1;
              break;
          }
          wanted |= (1 << idx);
      }
      va_end(ap);
  
      if (ret == -1)
          return ret;
  
      return match_mod_masks(state, match, wanted);
  }
  
  /**
   * Returns 1 if the given modifier is active with the specified type(s), 0 if
   * not, or -1 if the modifier is invalid.
   */
  XKB_EXPORT int
  xkb_state_mod_name_is_active(struct xkb_state *state, const char *name,
                               enum xkb_state_component type)
  {
      xkb_mod_index_t idx = xkb_keymap_mod_get_index(state->keymap, name);
  
      if (idx == XKB_MOD_INVALID)
          return -1;
  
      return xkb_state_mod_index_is_active(state, idx, type);
  }
  
  /**
   * Returns 1 if the modifiers are active with the specified type(s), 0 if
   * not, or -1 if any of the modifiers are invalid.
   */
  XKB_EXPORT ATTR_NULL_SENTINEL int
  xkb_state_mod_names_are_active(struct xkb_state *state,
                                 enum xkb_state_component type,
                                 enum xkb_state_match match,
                                 ...)
  {
      va_list ap;
      xkb_mod_index_t idx = 0;
      const char *str;
      uint32_t wanted = 0;
      int ret = 0;
  
      va_start(ap, match);
      while (1) {
          str = va_arg(ap, const char *);
          if (str == NULL)
              break;
          idx = xkb_keymap_mod_get_index(state->keymap, str);
          if (idx == XKB_MOD_INVALID) {
              ret = -1;
              break;
          }
          wanted |= (1 << idx);
      }
      va_end(ap);
  
      if (ret == -1)
          return ret;
  
      return match_mod_masks(state, match, wanted);
  }
  
  /**
   * Returns 1 if the given group is active with the specified type(s), 0 if
   * not, or -1 if the group is invalid.
   */
  XKB_EXPORT int
  xkb_state_layout_index_is_active(struct xkb_state *state,
                                  xkb_layout_index_t idx,
                                  enum xkb_state_component type)
  {
      int ret = 0;
  
      if (idx >= xkb_keymap_num_layouts(state->keymap))
          return -1;
  
      /* Can only have one effective group. */
      if (type & XKB_STATE_EFFECTIVE)
          return state->group == idx;
  
      if (type & XKB_STATE_DEPRESSED)
          ret |= (state->base_group == idx);
      if (type & XKB_STATE_LATCHED)
          ret |= (state->latched_group == idx);
      if (type & XKB_STATE_LOCKED)
          ret |= (state->locked_group == idx);
  
      return ret;
  }
  
  /**
   * Returns 1 if the given modifier is active with the specified type(s), 0 if
   * not, or -1 if the modifier is invalid.
   */
  XKB_EXPORT int
  xkb_state_layout_name_is_active(struct xkb_state *state, const char *name,
                                  enum xkb_state_component type)
  {
      xkb_layout_index_t idx = xkb_keymap_layout_get_index(state->keymap, name);
  
      if (idx == XKB_LAYOUT_INVALID)
          return -1;
  
      return xkb_state_layout_index_is_active(state, idx, type);
  }
  
  /**
   * Returns 1 if the given LED is active, 0 if not, or -1 if the LED is invalid.
   */
  XKB_EXPORT int
  xkb_state_led_index_is_active(struct xkb_state *state, xkb_led_index_t idx)
  {
      if (idx >= xkb_keymap_num_leds(state->keymap))
          return -1;
  
      return !!(state->leds & (1 << idx));
  }
  
  /**
   * Returns 1 if the given LED is active, 0 if not, or -1 if the LED is invalid.
   */
  XKB_EXPORT int
  xkb_state_led_name_is_active(struct xkb_state *state, const char *name)
  {
      xkb_led_index_t idx = xkb_keymap_led_get_index(state->keymap, name);
  
      if (idx == XKB_LED_INVALID)
          return -1;
  
      return xkb_state_led_index_is_active(state, idx);
  }
  
  static xkb_mod_mask_t
  key_get_consumed(struct xkb_state *state, const struct xkb_key *key)
  {
      const struct xkb_kt_map_entry *entry;
      xkb_layout_index_t group;
  
      group = xkb_state_key_get_layout(state, key->keycode);
      if (group == XKB_LAYOUT_INVALID)
          return 0;
  
      entry = get_entry_for_key_state(state, key, group);
      if (!entry)
          return 0;
  
      return entry->mods.mask & ~entry->preserve.mask;
  }
  
  /**
   * Tests to see if a modifier is used up by our translation of a
   * keycode to keysyms, taking note of the current modifier state and
   * the appropriate key type's preserve information, if any. This allows
   * the user to mask out the modifier in later processing of the
   * modifiers, e.g. when implementing hot keys or accelerators.
   *
   * See also, for example:
   * - XkbTranslateKeyCode(3), mod_rtrn retrun value, from libX11.
   * - gdk_keymap_translate_keyboard_state, consumed_modifiers return value,
   *   from gtk+.
   */
  XKB_EXPORT int
  xkb_state_mod_index_is_consumed(struct xkb_state *state, xkb_keycode_t kc,
                                  xkb_mod_index_t idx)
  {
      const struct xkb_key *key = XkbKey(state->keymap, kc);
  
      if (!key)
          return 0;
  
      return !!((1 << idx) & key_get_consumed(state, key));
  }
  
  /**
   * Calculates which modifiers should be consumed during key processing,
   * and returns the mask with all these modifiers removed.  e.g. if
   * given a state of Alt and Shift active for a two-level alphabetic
   * key containing plus and equal on the first and second level
   * respectively, will return a mask of only Alt, as Shift has been
   * consumed by the type handling.
   */
  XKB_EXPORT xkb_mod_mask_t
  xkb_state_mod_mask_remove_consumed(struct xkb_state *state, xkb_keycode_t kc,
                                     xkb_mod_mask_t mask)
  {
      const struct xkb_key *key = XkbKey(state->keymap, kc);
  
      if (!key)
          return 0;
  
      return mask & ~key_get_consumed(state, key);
  }
  

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