@ -21,423 +21,556 @@
# define ANTKEEPER_GEOM_HYPEROCTREE_HPP
# define ANTKEEPER_GEOM_HYPEROCTREE_HPP
# include "math/compile.hpp"
# include "math/compile.hpp"
# include <algorithm>
# include <array>
# include <bit>
# include <bit>
# include <cstdint>
# include <limits>
# include <concepts>
# include <cstddef>
# include <set>
# include <type_traits>
# include <type_traits>
# include <unordered_set>
# include <unordered_set>
# include <stack>
namespace geom { namespace geom {
/// Orders in which hyperoctree nodes can be stored and iterated.
enum class hyperoctree_order
{
/// Hyperoctree nodes are unordered, potentially resulting in faster insertions through the internal use of `std::unordered_set` rather than `std::set`.
unordered ,
/// Hyperoctree nodes are stored and iterated in depth-first preorder.
dfs_pre ,
/// Hyperoctree nodes are stored and iterated in breadth-first order.
bfs
} ;
/// @private
template < std : : unsigned_integral T >
using hyperoctree_dfs_pre_compare = std : : less < T > ;
/// @private
template < std : : unsigned_integral T , std : : size_t DepthBits >
struct hyperoctree_bfs_compare
{
constexpr bool operator ( ) ( const T & lhs , const T & rhs ) const noexcept
{
return std : : rotr ( lhs , DepthBits ) < std : : rotr ( rhs , DepthBits ) ;
}
} ;
/// @private
template < hyperoctree_order Order , std : : unsigned_integral T , std : : size_t DepthBits >
struct hyperoctree_container { } ;
/// @private
template < std : : unsigned_integral T , std : : size_t DepthBits >
struct hyperoctree_container < hyperoctree_order : : unordered , T , DepthBits >
{
typedef std : : unordered_set < T > type ;
} ;
/// @private
template < std : : unsigned_integral T , std : : size_t DepthBits >
struct hyperoctree_container < hyperoctree_order : : dfs_pre , T , DepthBits >
{
typedef std : : set < T , hyperoctree_dfs_pre_compare < T > > type ;
} ;
/// @private
template < std : : unsigned_integral T , std : : size_t DepthBits >
struct hyperoctree_container < hyperoctree_order : : bfs , T , DepthBits >
{
typedef std : : set < T , hyperoctree_bfs_compare < T , DepthBits > > type ;
} ;
/**
/**
* Hashed linear hyperoctree . * Hashed linear hyperoctree .
* *
* @ tparam T Integer node type .
* @ tparam T Unsigned integral node identifier type .
* @ tparam N Number of dimensions . * @ tparam N Number of dimensions .
* @ tparam D Max depth .
*
* Max depth can likely be determined by a generalized formula . 2 D and 3 D cases are given below :
*
* 2 D :
* 8 bit ( 1 byte ) = max depth 1 ( 4 loc bits , 1 depth bits , 1 divider bit ) = 6 bits
* 16 bit ( 2 byte ) = max depth 5 ( 12 loc bits , 3 depth bits , 1 divider bit ) = 16 bits
* 32 bit ( 4 byte ) = max depth 12 ( 26 loc bits , 4 depth bits , 1 divider bit ) = 31 bits
* 64 bit ( 8 byte ) = max depth 28 ( 58 loc bits , 5 depth bits , 1 divider bit ) = 64 bits
* 128 bit ( 16 byte ) = max depth 59 ( 120 loc bits , 6 depth bits , 1 divider bit ) = 127 bits
* 256 bit ( 32 byte ) = max depth 123 ( 248 loc bits , 7 depth bits , 1 divider bit ) = 256 bits
* @ see https : //oeis.org/A173009
*
* 3 D :
* 8 bit ( 1 byte ) = max depth 1 ( 6 loc bits , 1 depth bits , 1 divider bit ) = 8 bits
* 16 bit ( 2 byte ) = max depth 3 ( 12 loc bits , 2 depth bits , 1 divider bit ) = 15 bits
* 32 bit ( 4 byte ) = max depth 8 ( 27 loc bits , 4 depth bits , 1 divider bit ) = 32 bits
* 64 bit ( 8 byte ) = max depth 18 ( 57 loc bits , 5 depth bits , 1 divider bit ) = 63 bits
* 128 bit ( 16 byte ) = max depth 39 ( 120 loc bits , 6 depth bits , 1 divider bit ) = 127 bits
* 256 bit ( 32 byte ) = max depth 81 ( 243 loc bits , 7 depth bits , 1 divider bit ) = 251 bits
* @ see https : //oeis.org/A178420
* @ tparam Order Order in which nodes are stored and iterated .
* *
* @ see http : //codervil.blogspot.com/2015/10/octree-node-identifiers.html
* @ see http : //codervil.blogspot.com/2015/10/octree-node-identifiers.html
* @ see https : //geidav.wordpress.com/2014/08/18/advanced-octrees-2-node-representations/
* @ see https : //geidav.wordpress.com/2014/08/18/advanced-octrees-2-node-representations/
*/ */
template < class T , std : : size_t N , std : : size_t D >
template < std : : unsigned_integral T , std : : size_t N , hyperoctree_order Order = hyperoctree_order : : dfs_pre >
class hyperoctree class hyperoctree
{ {
private :
/**
* Finds the maximum hyperoctree depth level from the size of the node type ` T ` and number of dimensions ` N ` .
*
* @ return Maximum hyperoctree depth level .
*
* @ note There is likely a more elegant formula for this . Information about the 2 D and 3 D cases is given below :
*
* 2 D :
* 8 bit ( 1 byte ) = max depth 1 ( 4 loc bits , 1 depth bits , 1 divider bit ) = 6 bits
* 16 bit ( 2 byte ) = max depth 5 ( 12 loc bits , 3 depth bits , 1 divider bit ) = 16 bits
* 32 bit ( 4 byte ) = max depth 12 ( 26 loc bits , 4 depth bits , 1 divider bit ) = 31 bits
* 64 bit ( 8 byte ) = max depth 28 ( 58 loc bits , 5 depth bits , 1 divider bit ) = 64 bits
* 128 bit ( 16 byte ) = max depth 59 ( 120 loc bits , 6 depth bits , 1 divider bit ) = 127 bits
* 256 bit ( 32 byte ) = max depth 123 ( 248 loc bits , 7 depth bits , 1 divider bit ) = 256 bits
*
* @ see https : //oeis.org/A173009
*
* 3 D :
* 8 bit ( 1 byte ) = max depth 1 ( 6 loc bits , 1 depth bits , 1 divider bit ) = 8 bits
* 16 bit ( 2 byte ) = max depth 3 ( 12 loc bits , 2 depth bits , 1 divider bit ) = 15 bits
* 32 bit ( 4 byte ) = max depth 8 ( 27 loc bits , 4 depth bits , 1 divider bit ) = 32 bits
* 64 bit ( 8 byte ) = max depth 18 ( 57 loc bits , 5 depth bits , 1 divider bit ) = 63 bits
* 128 bit ( 16 byte ) = max depth 39 ( 120 loc bits , 6 depth bits , 1 divider bit ) = 127 bits
* 256 bit ( 32 byte ) = max depth 81 ( 243 loc bits , 7 depth bits , 1 divider bit ) = 251 bits
*
* @ see https : //oeis.org/A178420
*/
static consteval std : : size_t find_max_depth ( ) noexcept
{
std : : size_t max_depth = 0 ;
for ( std : : size_t i = 1 ; i < = sizeof ( T ) * 8 ; + + i )
{
const std : : size_t location_bits = sizeof ( T ) * 8 - i ;
max_depth = location_bits / N - 1 ;
const std : : size_t depth_bits = static_cast < std : : size_t > ( std : : bit_width ( max_depth ) ) ;
if ( depth_bits + location_bits < sizeof ( T ) * 8 )
break ;
}
return static_cast < T > ( max_depth ) ;
}
public : public :
/// Integral node type.
/// Node identifier type.
typedef T node_type ; typedef T node_type ;
/// Ensure the node type is integral
static_assert ( std : : is_integral < T > : : value , " Node type must be integral. " ) ;
/// Number of dimensions.
static constexpr std : : size_t dimensions = N ;
/// Maximum node depth.
static constexpr std : : size_t max_depth = D ;
/// Node storage and traversal order .
static constexpr hyperoctree_order order = Order ;
/// Number of bits required to encode the depth of a node.
static constexpr T depth_bits = math : : compile : : ceil_log2 ( max_depth + 1 ) ;
/// Number of bits required to encode the location of a node.
static constexpr T location_bits = ( max_depth + 1 ) * N ;
/// Maximum node depth level.
static constexpr node_type max_depth = find_max_depth ( ) ;
/// Number of bits in the node type.
/// Number of bits in the node type.
static constexpr T node_bits = sizeof ( node_type ) * 8 ;
static constexpr node_type node_bits = sizeof ( node_type ) * 8 ;
/// Number of bits required to encode the depth of a node.
static constexpr node_type depth_bits = std : : bit_width ( max_depth ) ;
/// Number of bits required to encode the Morton location code of a node.
static constexpr node_type location_bits = ( max_depth + 1 ) * N ;
// Ensure the node type has enough bits
static_assert ( depth_bits + location_bits + 1 < = node_bits , " Size of hyperoctree node type is insufficient to encode the maximum depth " ) ;
/// Number of bits separating the depth and Morton location code in a node identifier.
static constexpr node_type divider_bits = node_bits - ( depth_bits + location_bits ) ;
/// Number of children per node.
/// Number of children per node.
static constexpr T children_per_node = ( N ) ? ( 2 < < ( N - 1 ) ) : 1 ;
static constexpr node_type children_per_node = math : : compile : : exp2 < node_type > ( N ) ;
/// Number of siblings per node.
/// Number of siblings per node.
static constexpr T siblings_per_node = children_per_node - 1 ;
static constexpr node_type siblings_per_node = children_per_node - 1 ;
/// Root node which is always guaranteed to exist.
/// Resolution in each dimension.
static constexpr node_type resolution = math : : compile : : exp2 < node_type > ( max_depth + 1 ) ;
/// Number of nodes in a full hyperoctree.
static constexpr std : : size_t max_node_count = ( math : : compile : : pow < std : : size_t > ( resolution , N ) - 1 ) / siblings_per_node ;
/// Node identifier of the persistent root node.
static constexpr node_type root = 0 ; static constexpr node_type root = 0 ;
/// Node container type.
typedef typename hyperoctree_container < order , node_type , depth_bits > : : type container_type ;
/// Iterator type.
typedef typename container_type : : iterator iterator ;
/// Constant iterator type.
typedef typename container_type : : const_iterator const_iterator ;
/// Reverse iterator type.
typedef std : : conditional < order ! = hyperoctree_order : : unordered , std : : reverse_iterator < iterator > , iterator > : : type reverse_iterator ;
/// Constant reverse iterator type.
typedef std : : conditional < order ! = hyperoctree_order : : unordered , std : : reverse_iterator < const_iterator > , const_iterator > : : type const_reverse_iterator ;
/// @name Nodes
/// @{
/**
/**
* Accesses nodes in their internal hashmap order .
* Extracts the depth of a node from its identifier .
*
* @ param node Node identifier .
*
* @ return Depth of the node .
*/ */
struct unordered_iterator
{
inline unordered_iterator ( const unordered_iterator & other ) : set_iterator ( other . set_iterator ) { } ;
inline unordered_iterator & operator = ( const unordered_iterator & other ) { this - > set_iterator = other . set_iterator ; return * this ; } ;
inline unordered_iterator & operator + + ( ) { + + ( this - > set_iterator ) ; return * this ; } ;
inline unordered_iterator & operator - - ( ) { - - ( this - > set_iterator ) ; return * this ; } ;
inline bool operator = = ( const unordered_iterator & other ) const { return this - > set_iterator = = other . set_iterator ; } ;
inline bool operator ! = ( const unordered_iterator & other ) const { return this - > set_iterator ! = other . set_iterator ; } ;
inline node_type operator * ( ) const { return * this - > set_iterator ; } ;
private :
friend class hyperoctree ;
inline explicit unordered_iterator ( const typename std : : unordered_set < node_type > : : const_iterator & it ) : set_iterator ( it ) { } ;
typename std : : unordered_set < node_type > : : const_iterator set_iterator ;
} ;
static constexpr inline node_type depth ( node_type node ) noexcept
{
constexpr node_type mask = math : : compile : : exp2 < node_type > ( depth_bits ) - 1 ;
return node & mask ;
}
/**
/**
* Accesses nodes in z - ord er.
* Extracts the Morton location code of a node from its identifier .
* *
* @ TODO Can this be implemented without a stack ?
* @ param node Node identifier .
*
* @ return Morton location code of the node .
*/ */
struct iterator
{
inline iterator ( const iterator & other ) : hyperoctree ( other . hyperoctree ) , stack ( other . stack ) { } ;
inline iterator & operator = ( const iterator & other ) { this - > hyperoctree = other . hyperoctree ; this - > stack = other . stack ; return * this ; } ;
iterator & operator + + ( ) ;
inline bool operator = = ( const iterator & other ) const { return * * this = = * other ; } ;
inline bool operator ! = ( const iterator & other ) const { return * * this ! = * other ; } ;
inline node_type operator * ( ) const { return stack . top ( ) ; } ;
private :
friend class hyperoctree ;
inline explicit iterator ( const hyperoctree * hyperoctree , node_type node ) : hyperoctree ( hyperoctree ) , stack ( { node } ) { } ;
const hyperoctree * hyperoctree ;
std : : stack < node_type > stack ;
} ;
static constexpr inline node_type location ( node_type node ) noexcept
{
return node > > ( ( node_bits - 1 ) - depth ( node ) * N ) ;
}
/**
/**
* Return sthe depth of a node .
* Extracts the depth and Morton location code of a node from its identifier .
* *
* @ param node Node .
* @ return Depth of the node .
* @ param node Node identifier .
*
* @ return Array containing the depth of the node , followed by the Morton location code of the node .
*/ */
static T depth ( node_type node ) ;
static constexpr std : : array < node_type , 2 > split ( node_type node ) noexcept
{
const node_type depth = hyperoctree : : depth ( node ) ;
const node_type location = node > > ( ( node_bits - 1 ) - depth * N ) ;
return { depth , location } ;
}
/**
/**
* Returns the Morton code location of a node .
* Constructs an identifier for a node at the given depth and location .
*
* @ param depth Depth level .
* @ param location Morton location code .
*
* @ return Identifier of a node at the given depth and location .
* *
* @ param node Node .
* @ return Morton code location of the node .
* @ warning If @ p depth exceeds ` max_depth ` , the returned node identifier is not valid .
*/ */
static T location ( node_type node ) ;
static constexpr inline node_type node ( node_type depth , node_type location ) noexcept
{
return ( location < < ( ( node_bits - 1 ) - depth * N ) ) | depth ;
}
/**
/**
* Returns the node at the given depth and location .
* Constructs an identifier for the ancestor of a node at a given depth .
*
* @ param node Node identifier .
* @ param depth Absolute depth of an ancestor node .
*
* @ return Identifier of the ancestor of the node at the given depth .
* *
* @ param depth Node depth .
* @ param location Node Morton code location .
* @ warning If @ p depth exceeds the depth of @ p node , the returned node identifier is not valid .
*/ */
static node_type node ( T depth , T location ) ;
static constexpr inline node_type ancestor ( node_type node , node_type depth ) noexcept
{
const node_type mask = ( ~ node_type ( 0 ) ) < < ( ( node_bits - 1 ) - depth * N ) ;
return ( node & mask ) | depth ;
}
/**
/**
* Returns the ancestor of a node at the specified depth .
* Constructs an identifier for the parent of a node .
* *
* @ param node Node whose ancestor will be located .
* @ param depth Absolute depth of the ancestors .
* @ return Ancestral node .
* @ param node Node identifier .
*
* @ return Identifier of the parent node .
*/ */
static node_type ancestor ( node_type node , T depth ) ;
static constexpr inline node_type parent ( node_type node ) noexcept
{
return ancestor ( node , depth ( node ) - 1 ) ;
}
/**
/**
* Returns the parent of a node .
* Constructs an identifier for the nth sibling of a node .
* *
* @ param node Node .
* @ return Parent node .
* @ param node Node identifier .
* @ param n Offset to a sibling , automatically wrapped to ` [ 0 , siblings_per_node ] ` .
*
* @ return Identifier of the nth sibling node .
*/ */
static node_type parent ( node_type node ) ;
static constexpr node_type sibling ( node_type node , node_type n ) noexcept
{
constexpr node_type mask = ( 1 < < N ) - 1 ;
const auto [ depth , location ] = split ( node ) ;
const node_type sibling_location = ( location & ( ~ mask ) ) | ( ( location + n ) & mask ) ;
return hyperoctree : : node ( depth , sibling_location ) ;
}
/**
/**
* Returns the nth sibling of a node .
* Constructs an identifier for the nth child of a node .
* *
* @ param node Node .
* @ param n Offset to next sibling . ( Automatically wraps to ` [ 0 , siblings_per_node ] ` )
* @ return Next sibling node .
* @ param node Node identifier .
* @ param n Offset to a sibling of the first child node , automatically wrapped to ` [ 0 , siblings_per_node ] ` .
*
* @ return Identifier of the nth child node .
*/ */
static node_type sibling ( node_type node , T n ) ;
static constexpr inline node_type child ( node_type node , T n ) noexcept
{
return sibling ( node + 1 , n ) ;
}
/**
/**
* Returns the nth child of a node .
* Constructs an identifier for first common ancestor of two nodes
*
* @ param a Identifier of the first node .
* @ param b Identifier of the second node .
* *
* @ param node Parent node .
* @ param n Offset to the nth sibling of the first child node . ( Automatically wraps to 0. . children_per_node - 1 )
* @ return nth child node .
* @ return Identifier of the first common ancestor of the two nodes .
*/ */
static node_type child ( node_type node , T n ) ;
static constexpr node_type common_ancestor ( node_type a , node_type b ) noexcept
{
const node_type bits = std : : min < node_type > ( depth ( a ) , depth ( b ) ) * N ;
const node_type marker = ( node_type ( 1 ) < < ( node_bits - 1 ) ) > > bits ;
const node_type depth = node_type ( std : : countl_zero ( ( a ^ b ) | marker ) / N ) ;
return ancestor ( a , depth ) ;
}
/// @}
/// Constructs a hyperoctree with a single root node.
hyperoctree ( ) :
nodes ( { root } )
{ }
/// @name Iterators
/// @{
/**
/**
* Calculates the first common ancestor of two nodes .
* Returns an iterator to the first node , in the traversal order specified by hyperoctree : : order .
* *
* @ param a First node .
* @ param b Second node .
* @ return First common ancestor of the two nodes .
* @ note Node identifiers cannot be modified through iterators .
*/ */
static node_type common_ancestor ( node_type a , node_type b ) ;
/// Creates an hyperoctree with a single root node.
hyperoctree ( ) ;
/// Returns a z-order iterator to the root node.
iterator begin ( ) const ;
/// Returns a z-order iterator indicating the end of a traversal.
iterator end ( ) const ;
/// Returns an iterator to the specified node.
iterator find ( node_type node ) const ;
/// Returns an unordered iterator indicating the beginning of a traversal.
unordered_iterator unordered_begin ( ) const ;
/// Returns an unordered iterator indicating the end of a traversal.
unordered_iterator unordered_end ( ) const ;
/// @{
inline iterator begin ( ) noexcept
{
return nodes . begin ( ) ;
}
inline const_iterator begin ( ) const noexcept
{
return nodes . begin ( ) ;
}
inline const_iterator cbegin ( ) const noexcept
{
return nodes . cbegin ( ) ;
}
/// @}
/**
/**
* Inserts a node and its siblings into the hyperoctree , creating its ancestors as necessary . Note : The root node is persistent and cannot be inserted .
* Returns an iterator to the node following the last node , in the traversal order specified by hyperoctree : : order .
* *
* @ param node Node to insert .
* @ note Node identifiers cannot be modified through iterators .
*/ */
void insert ( node_type node ) ;
/// @{
inline iterator end ( ) noexcept
{
return nodes . end ( ) ;
}
inline const_iterator end ( ) const noexcept
{
return nodes . end ( ) ;
}
inline const_iterator cend ( ) const noexcept
{
return nodes . cend ( ) ;
}
/// @}
/**
/**
* Erases a node along with its siblings and descendants . Note : The root node is persistent and cannot be erased .
* Returns a reverse iterator to the first node of the revered hyperoctree , in the traversal order specified by hyperoctree : : order .
* *
* @ param node Node to erase .
* @ note Node identifiers cannot be modified through iterators .
* @ note If the hyperoctree is unordered , reverse iteration and forward iteration will be identical .
*/ */
void erase ( node_type node ) ;
/// @{
inline reverse_iterator rbegin ( ) noexcept
{
if constexpr ( order ! = hyperoctree_order : : unordered )
return nodes . rbegin ( ) ;
else
return nodes . begin ( ) ;
}
inline const_reverse_iterator rbegin ( ) const noexcept
{
if constexpr ( order ! = hyperoctree_order : : unordered )
return nodes . rbegin ( ) ;
else
return nodes . begin ( ) ;
}
inline const_reverse_iterator crbegin ( ) const noexcept
{
if constexpr ( order ! = hyperoctree_order : : unordered )
return nodes . crbegin ( ) ;
else
return nodes . cbegin ( ) ;
}
/// @}
/**
/**
* Erases all nodes except the root .
* Returns a reverse iterator to the node following the last node of the reverse hyperoctree , in the traversal order specified by hyperoctree : : order .
*
* @ note Node identifiers cannot be modified through iterators .
* @ note If the hyperoctree is unordered , reverse iteration and forward iteration will be identical .
*/ */
void clear ( ) ;
/// Returns `true` if the node is contained within the hyperoctree, and `false` otherwise.
bool contains ( node_type node ) const ;
/// Returns `true` if the node has no children, and `false` otherwise.
bool is_leaf ( node_type node ) const ;
/// Returns the number of nodes in the hyperoctree.
std : : size_t size ( ) const ;
/// Returns the total number of nodes the hyperoctree is capable of containing.
static consteval std : : size_t max_size ( ) noexcept
/// @{
inline reverse_iterator rend ( ) noexcept
{ {
return ( math : : compile : : pow < std : : size_t > ( children_per_node , max_depth + 1 ) - 1 ) / ( children_per_node - 1 ) ;
if constexpr ( order ! = hyperoctree_order : : unordered )
return nodes . rend ( ) ;
else
return nodes . end ( ) ;
} }
private :
std : : unordered_set < node_type > nodes ;
} ;
template < class T , std : : size_t N , std : : size_t D >
typename hyperoctree < T , N , D > : : iterator & hyperoctree < T , N , D > : : iterator : : operator + + ( )
{
// Get next node from top of stack
node_type node = stack . top ( ) ;
stack . pop ( ) ;
inline const_reverse_iterator rend ( ) const noexcept
{
if constexpr ( order ! = hyperoctree_order : : unordered )
return nodes . rend ( ) ;
else
return nodes . end ( ) ;
}
inline const_reverse_iterator crend ( ) const noexcept
{
if constexpr ( order ! = hyperoctree_order : : unordered )
return nodes . crend ( ) ;
else
return nodes . cend ( ) ;
}
/// @}
/// @}
// If the node has children
if ( ! hyperoctree - > is_leaf ( node ) )
/// @name Capacity
/// @{
/**
* Checks if the hyperoctree has no nodes .
*
* @ return ` true ` if the hyperoctree is empty , ` false ` otherwise .
*
* @ note This function should always return ` false ` , as the root node is persistent .
*/
inline bool empty ( ) const noexcept
{ {
// Push first child onto the stack
for ( T i = 0 ; i < children_per_node ; + + i )
stack . push ( child ( node , siblings_per_node - i ) ) ;
return nodes . empty ( ) ;
} }
if ( stack . empty ( ) )
stack . push ( std : : numeric_limits < T > : : max ( ) ) ;
/**
* Checks if the hyperoctree is full .
*
* @ return ` true ` if the hyperoctree is full , ` false ` otherwise .
*/
inline bool full ( ) const noexcept
{
return size ( ) = = max_size ( ) ;
}
return * this ;
}
template < class T , std : : size_t N , std : : size_t D >
inline T hyperoctree < T , N , D > : : depth ( node_type node )
{
// Extract depth using a bit mask
constexpr T mask = math : : compile : : pow < node_type > ( 2 , depth_bits ) - 1 ;
return node & mask ;
}
template < class T , std : : size_t N , std : : size_t D >
inline T hyperoctree < T , N , D > : : location ( node_type node )
{
return node > > ( ( node_bits - 1 ) - depth ( node ) * N ) ;
}
template < class T , std : : size_t N , std : : size_t D >
inline typename hyperoctree < T , N , D > : : node_type hyperoctree < T , N , D > : : node ( T depth , T location )
{
return ( location < < ( ( node_bits - 1 ) - depth * N ) ) | depth ;
}
template < class T , std : : size_t N , std : : size_t D >
inline typename hyperoctree < T , N , D > : : node_type hyperoctree < T , N , D > : : ancestor ( node_type node , T depth )
{
const T mask = std : : numeric_limits < T > : : max ( ) < < ( ( node_bits - 1 ) - depth * N ) ;
return ( node & mask ) | depth ;
}
template < class T , std : : size_t N , std : : size_t D >
inline typename hyperoctree < T , N , D > : : node_type hyperoctree < T , N , D > : : parent ( node_type node )
{
return ancestor ( node , depth ( node ) - 1 ) ;
}
template < class T , std : : size_t N , std : : size_t D >
inline typename hyperoctree < T , N , D > : : node_type hyperoctree < T , N , D > : : sibling ( node_type node , T n )
{
constexpr T mask = ( 1 < < N ) - 1 ;
/**
* Returns the number of nodes in the hyperoctree .
*
* @ return Number of nodes in the hyperoctree .
*
* @ note Hyperoctree size will always be greater than or equal to one , as the root node is persistent .
*/
inline std : : size_t size ( ) const noexcept
{
return nodes . size ( ) ;
}
T depth = hyperoctree : : depth ( node ) ;
T location = node > > ( ( node_bits - 1 ) - depth * N ) ;
/// Returns the total number of nodes the hyperoctree is capable of containing.
static consteval std : : size_t max_size ( ) noexcept
{
return max_node_count ;
}
/// @}
return hyperoctree : : node ( depth , ( location & ( ~ mask ) ) | ( ( location + n ) & mask ) ) ;
}
template < class T , std : : size_t N , std : : size_t D >
inline typename hyperoctree < T , N , D > : : node_type hyperoctree < T , N , D > : : child ( node_type node , T n )
{
return sibling ( node + 1 , n ) ;
}
template < class T , std : : size_t N , std : : size_t D >
inline typename hyperoctree < T , N , D > : : node_type hyperoctree < T , N , D > : : common_ancestor ( node_type a , node_type b )
{
T bits = std : : min < T > ( depth ( a ) , depth ( b ) ) * N ;
T marker = ( T ( 1 ) < < ( node_bits - 1 ) ) > > bits ;
T depth = T ( std : : countl_zero ( ( a ^ b ) | marker ) / N ) ;
return ancestor ( a , depth ) ;
}
template < class T , std : : size_t N , std : : size_t D >
inline hyperoctree < T , N , D > : : hyperoctree ( ) :
nodes ( { 0 } )
{ }
template < class T , std : : size_t N , std : : size_t D >
void hyperoctree < T , N , D > : : insert ( node_type node )
{
if ( contains ( node ) )
return ;
/// @name Modifiers
/// @{
/**
* Erases all nodes except the root node , which is persistent .
*/
inline void clear ( )
{
nodes = { root } ;
}
// Insert node
nodes . emplace ( node ) ;
// Insert siblings
for ( T i = 1 ; i < children_per_node ; + + i )
nodes . emplace ( sibling ( node , i ) ) ;
// Insert parent as necessary
node_type parent = hyperoctree : : parent ( node ) ;
if ( ! contains ( parent ) )
insert ( parent ) ;
}
template < class T , std : : size_t N , std : : size_t D >
void hyperoctree < T , N , D > : : erase ( node_type node )
{
// Don't erase the root!
if ( node = = root )
return ;
/**
* Inserts a node and its siblings into the hyperoctree , creating ancestors as necessary .
*
* @ param node Node to insert .
*
* @ note The root node is persistent and does not need to be inserted .
*/
void insert ( node_type node )
{
if ( contains ( node ) )
return ;
// Insert node
nodes . emplace ( node ) ;
// Insert node siblings
for ( node_type i = 1 ; i < children_per_node ; + + i )
nodes . emplace ( sibling ( node , i ) ) ;
// Insert node ancestors
insert ( parent ( node ) ) ;
}
for ( T i = 0 ; i < children_per_node ; + + i )
/**
* Erases a node , along with its descendants , siblings , and descendants of siblings .
*
* @ param node Identifier of the node to erase .
*
* @ note The root node is persistent and cannot be erased .
*/
void erase ( node_type node )
{ {
// Erase node
if ( node = = root | | ! contains ( node ) )
return ;
// Erase node and its descendants
nodes . erase ( node ) ; nodes . erase ( node ) ;
// Erase descendants
if ( ! is_leaf ( node ) )
erase ( child ( node , 0 ) ) ;
// Erase node siblings
for ( node_type i = 0 ; i < siblings_per_node ; + + i )
{ {
for ( T j = 0 ; j < children_per_node ; + + j )
erase ( child ( node , j ) ) ;
node = sibling ( node , 1 ) ;
// Erase sibling and its descendants
nodes . erase ( node ) ;
erase ( child ( node , 0 ) ) ;
} }
// Go to next sibling
if ( i < siblings_per_node )
node = sibling ( node , i ) ;
} }
}
template < class T , std : : size_t N , std : : size_t D >
void hyperoctree < T , N , D > : : clear ( )
{
nodes = { 0 } ;
}
template < class T , std : : size_t N , std : : size_t D >
inline bool hyperoctree < T , N , D > : : contains ( node_type node ) const
{
return nodes . count ( node ) ;
}
template < class T , std : : size_t N , std : : size_t D >
inline bool hyperoctree < T , N , D > : : is_leaf ( node_type node ) const
{
return ! contains ( child ( node , 0 ) ) ;
}
template < class T , std : : size_t N , std : : size_t D >
inline std : : size_t hyperoctree < T , N , D > : : size ( ) const
{
return nodes . size ( ) ;
}
template < class T , std : : size_t N , std : : size_t D >
typename hyperoctree < T , N , D > : : iterator hyperoctree < T , N , D > : : begin ( ) const
{
return iterator ( this , hyperoctree : : root ) ;
}
template < class T , std : : size_t N , std : : size_t D >
typename hyperoctree < T , N , D > : : iterator hyperoctree < T , N , D > : : end ( ) const
{
return iterator ( this , std : : numeric_limits < T > : : max ( ) ) ;
}
template < class T , std : : size_t N , std : : size_t D >
typename hyperoctree < T , N , D > : : iterator hyperoctree < T , N , D > : : find ( node_type node ) const
{
return contains ( node ) ? iterator ( node ) : end ( ) ;
}
template < class T , std : : size_t N , std : : size_t D >
typename hyperoctree < T , N , D > : : unordered_iterator hyperoctree < T , N , D > : : unordered_begin ( ) const
{
return unordered_iterator ( nodes . begin ( ) ) ;
}
/// @}
/// @name Lookup
/// @{
/**
* Checks if a node is contained within the hyperoctree .
*
* @ param node Identifier of the node to check for .
*
* @ return ` true ` if the hyperoctree contains the node , ` false ` otherwise .
*/
inline bool contains ( node_type node ) const
{
return nodes . contains ( node ) ;
}
/**
* Checks if a node has no children .
*
* @ param node Node identififer .
*
* @ return ` true ` if the node has no children , and ` false ` otherwise .
*/
inline bool is_leaf ( node_type node ) const
{
return ! contains ( child ( node , 0 ) ) ;
}
/// @}
private :
container_type nodes ;
} ;
template < class T , std : : size_t N , std : : size_t D >
typename hyperoctree < T , N , D > : : unordered_iterator hyperoctree < T , N , D > : : unordered_end ( ) const
{
return unordered_iterator ( nodes . end ( ) ) ;
}
/// Hyperoctree with unordered node storage and traversal.
template < std : : unsigned_integral T , std : : size_t N >
using unordered_hyperoctree = hyperoctree < T , N , hyperoctree_order : : unordered > ;
} // namespace geom
} // namespace geom
