xml_children.h

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/*  Copyright (c) SILVERCODERS Ltd, http://silvercoders.com                                                                                  */
/*  Project homepage: https://github.com/docwire/docwire                                                                                     */
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/*  SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-DocWire-Commercial                                                                  */
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#ifndef DOCWIRE_XML_CHILDREN_VIEW_H
#define DOCWIRE_XML_CHILDREN_VIEW_H
 
#include "xml_descendants.h"
#include "log_scope.h"
#include <ranges>
#include "xml_node_ref.h"
 
namespace docwire::xml
{
 
template <safety_policy safety_level = default_safety_level>
class children_view : public std::ranges::view_base
{
public:
    class iterator;
    iterator begin() const
    {
        return iterator{m_state, m_depth};
    }
    sentinel end() const
    {
        return {};
    }
 
    explicit children_view(not_null<std::shared_ptr<iterator_state<safety_level>>, safety_level> state, int depth)
        : m_state(std::move(state)), m_depth(depth) {}
 
private:
    not_null<std::shared_ptr<iterator_state<safety_level>>, safety_level> m_state;
    int m_depth;
};
 
template <safety_policy safety_level>
class children_view<safety_level>::iterator final
{
    friend class children_view<safety_level>;
 
public:
    using iterator_concept  = std::input_iterator_tag;
    using difference_type   = std::ptrdiff_t;
    using value_type        = node_ref<safety_level>;
    using pointer           = const value_type*;
    using reference         = const value_type&;
 
    bool operator==(const sentinel& s) const { return m_desc_iter == s; }
 
    reference operator*() const { return *m_desc_iter; }
    pointer operator->() const { return m_desc_iter.operator->(); }
 
    iterator& operator++()
    {
        log::scope _{ "depth"_v = m_depth };
        ++m_desc_iter;
        find_next_child();
        return *this;
    }
 
    void operator++(int)
    {
        ++(*this);
    }
 
private:
    explicit iterator(not_null<std::shared_ptr<iterator_state<safety_level>>, safety_level> state, int depth)
        : m_depth{depth}, m_desc_iter(descendants_view<safety_level>{state, m_depth - 1}.begin())
    {
        find_next_child();
    }
 
    void find_next_child()
    {
        while (m_desc_iter != sentinel{} && ((*m_desc_iter).depth() != m_depth || (*m_desc_iter).type() == node_type::end_element))
        {
            ++m_desc_iter;
        }
    }
 
    int m_depth;
    typename descendants_view<safety_level>::iterator m_desc_iter;
};
 
template<safety_policy safety_level>
children_view<safety_level> children(const node_ref<safety_level>& node)
{
    return children_view<safety_level>{node.state(), node.depth() + 1};
}
 
template<safety_policy safety_level>
children_view<safety_level> children(reader<safety_level>& reader)
{
    return children_view<safety_level>{std::make_shared<iterator_state<safety_level>>(reader), 0};
}
 
}
 
#endif