/**
 * Author: dkanus
 * Home repo: https://www.insultplayers.ru/git/AcediaFramework/AcediaCore
 * License: GPL
 * Copyright 2022-2023 Anton Tarasenko
 *------------------------------------------------------------------------------
 * This file is part of Acedia.
 *
 * Acedia 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, version 3 of the License, or
 * (at your option) any later version.
 *
 * Acedia 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 Acedia.  If not, see <https://www.gnu.org/licenses/>.
 */
class Iter extends AcediaObject
    abstract;

//! Base class for iterator, an auxiliary object for iterating through
//! a set of objects obtained from some context-dependent source.

/// Status of the [`Iter`]'s filter regarding some specific property.
///
/// [`Iter`]s can filter objects they're iterating on by the presence or lack of a certain property,
/// recording this choice requires 3 values (for requiring having/not having a certain property and
/// for ignoring it).
/// This enumeration is for inner purposes and is there to unify iterator implementations.
enum IterFilter {
    /// We don't use relevant property for filtering
    IF_Nothing,
    /// Iterated objects must have that property
    IF_Have,
    /// Iterated objects must not have that property
    IF_NotHave
};

/// Advances iterator to the next item.
///
/// Makes iterator refer to the next item from the source and returns `true`, as long as the source
/// of items isn't yet exhausted.
/// In case there's no more items, method has to return `false` and do nothing else.
/// [`Iter::HasFinished()`] can also be used to check whether there are more items available.
public function bool Next();

/// Returns value currently pointed to by an iterator.
///
/// Does not advance iteration: use [`Iter::Next()`] to pick next value.
///
/// In case iterator has already reached the end (and [`Iter::Next()``] returned `false`), this
/// method will return `none`.
/// Note that depending on context `none` values can also be returned, use
/// [`Iter::LeaveOnlyNotNone()`] method to prevent that.
public function AcediaObject Get();

/// Checks if caller [`Iter`] has finished iterating.
public function bool HasFinished();

/// Makes caller iterator skip any `none` items during iteration.
public function LeaveOnlyNotNone();

defaultproperties {
}