text: #include <stdbool.h>
  #include <stdint.h>
  #include <stdlib.h>
  
  #include "nvim/api/tabpage.h"
  #include "nvim/api/vim.h"
  #include "nvim/api/private/defs.h"
  #include "nvim/api/private/helpers.h"
  #include "nvim/memory.h"
  #include "nvim/window.h"
  
  /// Gets the windows in a tabpage
  ///
  /// @param tabpage  Tabpage
  /// @param[out] err Error details, if any
  /// @return List of windows in `tabpage`
  ArrayOf(Window) nvim_tabpage_list_wins(Tabpage tabpage, Error *err)
      FUNC_API_SINCE(1)
  {
    Array rv = ARRAY_DICT_INIT;
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab || !valid_tabpage(tab)) {
      return rv;
    }
  
    FOR_ALL_WINDOWS_IN_TAB(wp, tab) {
      rv.size++;
    }
  
    rv.items = xmalloc(sizeof(Object) * rv.size);
    size_t i = 0;
  
    FOR_ALL_WINDOWS_IN_TAB(wp, tab) {
      rv.items[i++] = WINDOW_OBJ(wp->handle);
    }
  
    return rv;
  }
  
  /// Gets a tab-scoped (t:) variable
  ///
  /// @param tabpage  Tabpage handle
  /// @param name     Variable name
  /// @param[out] err Error details, if any
  /// @return Variable value
  Object nvim_tabpage_get_var(Tabpage tabpage, String name, Error *err)
      FUNC_API_SINCE(1)
  {
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab) {
      return (Object) OBJECT_INIT;
    }
  
    return dict_get_value(tab->tp_vars, name, err);
  }
  
  /// Sets a tab-scoped (t:) variable
  ///
  /// @param tabpage  Tabpage handle
  /// @param name     Variable name
  /// @param value    Variable value
  /// @param[out] err Error details, if any
  void nvim_tabpage_set_var(Tabpage tabpage,
                            String name,
                            Object value,
                            Error *err)
      FUNC_API_SINCE(1)
  {
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab) {
      return;
    }
  
    dict_set_var(tab->tp_vars, name, value, false, false, err);
  }
  
  /// Removes a tab-scoped (t:) variable
  ///
  /// @param tabpage  Tabpage handle
  /// @param name     Variable name
  /// @param[out] err Error details, if any
  void nvim_tabpage_del_var(Tabpage tabpage, String name, Error *err)
      FUNC_API_SINCE(1)
  {
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab) {
      return;
    }
  
    dict_set_var(tab->tp_vars, name, NIL, true, false, err);
  }
  
  /// Sets a tab-scoped (t:) variable
  ///
  /// @deprecated
  ///
  /// @param tabpage  Tabpage handle
  /// @param name     Variable name
  /// @param value    Variable value
  /// @param[out] err Error details, if any
  /// @return Old value or nil if there was no previous value.
  ///
  ///         @warning It may return nil if there was no previous value
  ///                  or if previous value was `v:null`.
  Object tabpage_set_var(Tabpage tabpage, String name, Object value, Error *err)
  {
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab) {
      return (Object) OBJECT_INIT;
    }
  
    return dict_set_var(tab->tp_vars, name, value, false, true, err);
  }
  
  /// Removes a tab-scoped (t:) variable
  ///
  /// @deprecated
  ///
  /// @param tabpage  Tabpage handle
  /// @param name     Variable name
  /// @param[out] err Error details, if any
  /// @return Old value
  Object tabpage_del_var(Tabpage tabpage, String name, Error *err)
  {
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab) {
      return (Object) OBJECT_INIT;
    }
  
    return dict_set_var(tab->tp_vars, name, NIL, true, true, err);
  }
  
  /// Gets the current window in a tabpage
  ///
  /// @param tabpage  Tabpage handle
  /// @param[out] err Error details, if any
  /// @return Window handle
  Window nvim_tabpage_get_win(Tabpage tabpage, Error *err)
      FUNC_API_SINCE(1)
  {
    Window rv = 0;
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab || !valid_tabpage(tab)) {
      return rv;
    }
  
    if (tab == curtab) {
      return nvim_get_current_win();
    } else {
      FOR_ALL_WINDOWS_IN_TAB(wp, tab) {
        if (wp == tab->tp_curwin) {
          return wp->handle;
        }
      }
      // There should always be a current window for a tabpage
      abort();
    }
  }
  
  /// Gets the tabpage number
  ///
  /// @param tabpage  Tabpage handle
  /// @param[out] err Error details, if any
  /// @return Tabpage number
  Integer nvim_tabpage_get_number(Tabpage tabpage, Error *err)
      FUNC_API_SINCE(1)
  {
    Integer rv = 0;
    tabpage_T *tab = find_tab_by_handle(tabpage, err);
  
    if (!tab) {
      return rv;
    }
  
    return tabpage_index(tab);
  }
  
  /// Checks if a tabpage is valid
  ///
  /// @param tabpage Tabpage handle
  /// @return true if the tabpage is valid, false otherwise
  Boolean nvim_tabpage_is_valid(Tabpage tabpage)
      FUNC_API_SINCE(1)
  {
    Error stub = ERROR_INIT;
    return find_tab_by_handle(tabpage, &stub) != NULL;
  }
  
  