tree/iterator/levelorder.hpp

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#ifndef GENESIS_TREE_ITERATOR_LEVELORDER_H_
#define GENESIS_TREE_ITERATOR_LEVELORDER_H_
 
/*
    Genesis - A toolkit for working with phylogenetic data.
    Copyright (C) 2014-2020 Lucas Czech and HITS gGmbH
 
    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 3 of the License, 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.
 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
    Contact:
    Lucas Czech <lucas.czech@h-its.org>
    Exelixis Lab, Heidelberg Institute for Theoretical Studies
    Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany
*/
 
#include "genesis/tree/tree.hpp"
#include "genesis/tree/tree/subtree.hpp"
#include "genesis/utils/containers/range.hpp"
 
#include <cassert>
#include <deque>
#include <iterator>
#include <type_traits>
 
namespace genesis {
namespace tree {
 
// =================================================================================================
//     Forward Declarations
// =================================================================================================
 
class Tree;
class TreeNode;
class TreeEdge;
class TreeLink;
class Subtree;
 
// =================================================================================================
//     Levelorder Iterator
// =================================================================================================
 
template< bool is_const = true >
class IteratorLevelorder
{
 
public:
 
    // -----------------------------------------------------
    //     Typedefs
    // -----------------------------------------------------
 
    // Make the memer types const or not, depending on iterator type.
    using TreeType = typename std::conditional< is_const, Tree const, Tree >::type;
    using LinkType = typename std::conditional< is_const, TreeLink const, TreeLink >::type;
    using NodeType = typename std::conditional< is_const, TreeNode const, TreeNode >::type;
    using EdgeType = typename std::conditional< is_const, TreeEdge const, TreeEdge >::type;
 
    using self_type         = IteratorLevelorder< is_const >;
    using iterator_category = std::forward_iterator_tag;
    // using value_type        = NodeType;
    // using pointer           = NodeType*;
    // using reference         = NodeType&;
    // using difference_type   = std::ptrdiff_t;
 
    // -----------------------------------------------------
    //     Constructors and Rule of Five
    // -----------------------------------------------------
 
    IteratorLevelorder()
        : start_( nullptr )
        , link_(  nullptr )
        , depth_( 0       )
    {}
 
    explicit IteratorLevelorder( TreeType& tree )
        : IteratorLevelorder( tree.root_link() )
    {}
 
    explicit IteratorLevelorder( NodeType& node )
        : IteratorLevelorder( node.primary_link() )
    {}
 
    explicit IteratorLevelorder( LinkType& link )
        : start_( &link )
        , link_(  &link )
        , depth_( 0     )
    {
        // Add all neighouring nodes in all directions of the given starting link.
        // Because the push back function leaves out the outer() node, we need to do this extra.
        push_back_children_( &link, 0 );
        stack_.push_front({ &link.outer(), 1 });
    }
 
    explicit IteratorLevelorder( Subtree const& subtree )
        : start_( &(subtree.link()) )
        , link_(  &(subtree.link()) )
        , depth_( 0     )
    {
        // Only add the neighouring nodes in the direction away from the link.
        // Leave out the outer() one, as we do not want this part when iterating a subtree.
        push_back_children_( &(subtree.link()), 0 );
    }
 
    ~IteratorLevelorder() = default;
 
    IteratorLevelorder( IteratorLevelorder const& ) = default;
    IteratorLevelorder( IteratorLevelorder&& )      = default;
 
    IteratorLevelorder& operator= ( IteratorLevelorder const& ) = default;
    IteratorLevelorder& operator= ( IteratorLevelorder&& )      = default;
 
    // -----------------------------------------------------
    //     Operators
    // -----------------------------------------------------
 
    self_type operator * ()
    {
        return *this;
    }
 
    self_type operator ++ ()
    {
        if (stack_.empty()) {
            link_  = nullptr;
            depth_ = -1;
        } else {
            auto const& se = stack_.front();
            link_  = se.link;
            depth_ = se.depth;
            stack_.pop_front();
            push_back_children_(link_, depth_);
        }
 
        return *this;
    }
 
    self_type operator ++ (int)
    {
        self_type tmp = *this;
        ++(*this);
        return tmp;
    }
 
    bool operator == (const self_type &other) const
    {
        return other.link_ == link_;
    }
 
    bool operator != (const self_type &other) const
    {
        return !(other == *this);
    }
 
    // -----------------------------------------------------
    //     Members
    // -----------------------------------------------------
 
    bool is_first_iteration() const
    {
        return link_ == start_;
    }
 
    int depth() const
    {
        return depth_;
    }
 
    LinkType& link() const
    {
        return *link_;
    }
 
    NodeType& node() const
    {
        return link_->node();
    }
 
    EdgeType& edge() const
    {
        return link_->edge();
    }
 
    LinkType& start_link() const
    {
        return *start_;
    }
 
    NodeType& start_node() const
    {
        return start_->node();
    }
 
private:
 
    // -----------------------------------------------------
    //     Internal Helper Functions
    // -----------------------------------------------------
 
    void push_back_children_( LinkType* link, int link_depth )
    {
        LinkType* c = &link->next();
        while( c != link ) {
            stack_.push_back({ &c->outer(), link_depth + 1 });
            c = &c->next();
        }
    }
 
    // -----------------------------------------------------
    //     Internal Helper Typedefs
    // -----------------------------------------------------
 
    // TODO add depth information to other iterators, as well.
    typedef struct {
        LinkType*     link;
        int           depth;
    } StackElement;
 
    // -----------------------------------------------------
    //     Data Members
    // -----------------------------------------------------
 
    LinkType* const   start_;
    LinkType*         link_;
    int               depth_;
 
    std::deque<StackElement> stack_;
};
 
// =================================================================================================
//     Levelorder Wrapper Functions
// =================================================================================================
 
template<typename ElementType>
utils::Range< IteratorLevelorder< true >>
levelorder( ElementType const& element )
{
    return {
        IteratorLevelorder< true >( element ),
        IteratorLevelorder< true >()
    };
}
 
template<typename ElementType>
utils::Range< IteratorLevelorder< false >>
levelorder( ElementType& element )
{
    return {
        IteratorLevelorder< false >( element ),
        IteratorLevelorder< false >()
    };
}
 
} // namespace tree
} // namespace genesis
 
#endif // include guard