path_set.hpp

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#ifndef GENESIS_TREE_ITERATOR_PATH_SET_H_
#define GENESIS_TREE_ITERATOR_PATH_SET_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/function/functions.hpp"
#include "genesis/utils/containers/range.hpp"
 
#include <cassert>
#include <iterator>
#include <stdexcept>
#include <type_traits>
#include <vector>
 
namespace genesis {
namespace tree {
 
// =================================================================================================
//     Forward Declarations
// =================================================================================================
 
class Tree;
class TreeNode;
class TreeEdge;
class TreeLink;
 
// =================================================================================================
//     Path Set Iterator
// =================================================================================================
 
template< bool is_const = true >
class IteratorPathSet
{
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         = IteratorPathSet< 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
    // -----------------------------------------------------
 
    IteratorPathSet()
        : start_(  nullptr )
        , finish_( nullptr )
        , lca_(    nullptr )
        , link_(   nullptr )
    {}
 
    IteratorPathSet( NodeType& start, NodeType& finish, NodeType& lca )
        : IteratorPathSet( start.link(), finish.link(), lca.link() )
    {}
 
    IteratorPathSet( LinkType& start, LinkType& finish, LinkType& lca )
        : start_(  &start.node().primary_link()  )
        , finish_( &finish.node().primary_link() )
        , lca_(    &lca.node().primary_link()  )
        , link_(   start_  )
    {
        // Edge case: No real path.
        if( start_ == finish_ ) {
            // In this case, the LCA has also to be the same, otherwise it is a wrong LCA.
            if( lca_ != start_ ) {
                throw std::runtime_error(
                    "Invalid LCA provided for iterating a path with identical start/finish node."
                );
            }
 
            // We will just traverse one node, so start at the finish_ node,
            // and after one incrementation, we will be done.
            doing_first_part_ = false;
            return;
 
        // Special case: The start is also the LCA. In this case, we go immediately to the
        // second path (finish_ to lca_), and the LCA (= start) will be visited at the end.
        } else if( start_ == lca_ ) {
            doing_first_part_ = false;
            link_ = finish_;
        }
    }
 
    ~IteratorPathSet() = default;
 
    IteratorPathSet( IteratorPathSet const& ) = default;
    IteratorPathSet( IteratorPathSet&& )      = default;
 
    IteratorPathSet& operator= ( IteratorPathSet const& ) = default;
    IteratorPathSet& operator= ( IteratorPathSet&& )      = default;
 
    // -----------------------------------------------------
    //     Operators
    // -----------------------------------------------------
 
    self_type operator * ()
    {
        return *this;
    }
 
    self_type operator ++ ()
    {
        // If we are on the second path (from finish_ to lca_) ...
        if( ! doing_first_part_ ) {
 
            // ... and we reach the LCA, this means, we are completely done iterating, so stop here.
            if( link_ == lca_ ) {
                link_ = nullptr;
                return *this;
            }
 
            // ... and we reach the root, we have an error! The LCA cannot be more upwards than the
            // root, but even if the root was the LCA, we would have checked this in the above
            // condition. Thus, the LCA is wrong.
            if( is_root( link_->node() )) {
                throw std::runtime_error( "Found invalid LCA while iterating path." );
            }
        }
 
        // Go to the next node towards the LCA.
        link_ = &link_->outer().node().primary_link();
 
        // If we are on the first path (from start_ to lca_) ...
        if( doing_first_part_ ) {
 
            // ... and we reach the LCA, we are done with the first path.
            // Start again at finish_ for the second path.
            if( link_ == lca_ ) {
                doing_first_part_ = false;
                link_ = finish_;
                return *this;
            }
 
            // ... and we reach the root in the firth path, the LCA is wrong,
            // by the same reasoning as above.
            if( is_root( link_->node() )) {
                throw std::runtime_error( "Found invalid LCA while iterating path." );
            }
        }
 
        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_last_common_ancestor() const
    {
        return link_ == lca_;
    }
 
    bool is_lca() const
    {
        return is_last_common_ancestor();
    }
 
    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();
    }
 
    LinkType& finish_link() const
    {
        return *finish_;
    }
 
    NodeType& finish_node() const
    {
        return finish_->node();
    }
 
    LinkType& lca_link() const
    {
        return *lca_;
    }
 
    NodeType& lca_node() const
    {
        return lca_->node();
    }
 
    // -----------------------------------------------------
    //     Data Members
    // -----------------------------------------------------
 
private:
 
    LinkType* const        start_;
    LinkType* const        finish_;
    LinkType* const        lca_;
 
    LinkType*              link_;
    bool                   doing_first_part_ = true;
};
 
// =================================================================================================
//     Path Wrapper Functions
// =================================================================================================
 
template<typename ElementType>
utils::Range< IteratorPathSet< true >>
path_set( ElementType const& start, ElementType const& finish, ElementType const& lca )
{
    return {
        IteratorPathSet< true >( start, finish, lca ),
        IteratorPathSet< true >()
    };
}
 
template<typename ElementType>
utils::Range< IteratorPathSet< false >>
path_set( ElementType& start, ElementType& finish, ElementType& lca )
{
    return {
        IteratorPathSet< false >( start, finish, lca ),
        IteratorPathSet< false >()
    };
}
 
} // namespace tree
} // namespace genesis
 
#endif // include guard