AStar< T > Class Template Reference

Flexible A* pathfinding algorithm for any map implementing IMap<T> and using Coordinate<T> nodes. More...

#include <AStar.h>

Classes
struct	NodeRecord

Public Types
using	CostCallback = std::function< float(const Coordinate< T > &, const Coordinate< T > &, void *ref)>
using	ValidCallback = std::function< bool(const Coordinate< T > &, void *ref)>

Public Member Functions
void	setCostCallback (CostCallback cb)
void	setValidCallback (ValidCallback cb)
	provide a callback to determine if a node is valid (e.g., not an obstacle)
void	setReference (void *reference)
Path< Coordinate< T > >	findPath (const IMapNeighbors< T > &map, const Coordinate< T > &start, const Coordinate< T > &goal)
Coordinate< T >	nextStep (const IMapNeighbors< T > &map, const Coordinate< T > &start, const Coordinate< T > &goal)

Protected Member Functions
bool	aStarSearch (const IMapNeighbors< T > &map, const Coordinate< T > &start, const Coordinate< T > &goal, std::unordered_map< Coordinate< T >, Coordinate< T >, std::hash< Coordinate< T > >, std::equal_to< Coordinate< T > >, AllocatorPSRAM< std::pair< const Coordinate< T >, Coordinate< T > > > > *cameFrom, std::unordered_map< Coordinate< T >, float, std::hash< Coordinate< T > >, std::equal_to< Coordinate< T > >, AllocatorPSRAM< std::pair< const Coordinate< T >, float > > > *outCostSoFar)
Path< Coordinate< T > >	reconstructPath (const std::unordered_map< Coordinate< T >, Coordinate< T >, std::hash< Coordinate< T > >, std::equal_to< Coordinate< T > >, AllocatorPSRAM< std::pair< const Coordinate< T >, Coordinate< T > > > > &cameFrom, const Coordinate< T > &start, const Coordinate< T > &goal)

Static Protected Member Functions
static float	defaultCost (const Coordinate< T > &from, const Coordinate< T > &to, void *ref)
static bool	defaultValid (const Coordinate< T > &node, void *ref)

Protected Attributes
CostCallback	cost_cb = defaultCost
ValidCallback	valid_cb = defaultValid
void *	ref = this

Detailed Description

template<typename T = DistanceM>
class tinyrobotics::AStar< T >

Flexible A* pathfinding algorithm for any map implementing IMap<T> and using Coordinate<T> nodes.

The AStar class implements the A* search algorithm for any map or graph that implements the IMap<T> interface. It uses Coordinate<T> as the node type and supports user-defined cost and validity callbacks for custom metrics, obstacle handling, and heuristics.

Features:

• Finds the optimal path from a start node to a goal node using A* search
• Works with any map implementing IMap<T> (e.g., grids, navigation graphs, road networks)
• Supports user-provided cost and validity callbacks for maximum flexibility
• Allows passing a user reference/context pointer to callbacks (for map data, etc.)
• Provides both full path reconstruction and efficient next-step queries

Usage:

1. Create an AStar instance (optionally providing cost and validity callbacks).
2. Call findPath(map, start, goal) to get the optimal path as a Path<Coordinate<T>> object.
3. Optionally, use nextStep(map, start, goal) to get only the next move.
4. Customize cost and heuristic logic via the cost callback (e.g., Euclidean, Manhattan, or domain-specific).

Example:

AStar astar;
astar.setCostCallback([](const Coordinate<DistanceM>& from, const Coordinate<DistanceM>& to, void*) {
  // Custom cost (e.g., Euclidean distance)
  return from.distance(to);
});
auto path = astar.findPath(map, start, goal);
if (!path.empty()) {
  // Use the path
}

This class is suitable for embedded and desktop robotics, navigation, and any application requiring flexible, efficient pathfinding.

Member Function Documentation

findPath()

Path< Coordinate< T > > findPath ( const IMapNeighbors< T > &  map, const Coordinate< T > &  start, const Coordinate< T > &  goal  )

inline

Finds the optimal path from start to goal. Returns an empty path if no path

nextStep()

Coordinate< T > nextStep ( const IMapNeighbors< T > &  map, const Coordinate< T > &  start, const Coordinate< T > &  goal  )

inline

Returns the next node on the optimal path from start to goal. If no path is found, returns start.

setCostCallback()

void setCostCallback ( CostCallback  cb )

inline

provide a callback to determine the cost of moving from one node to another

setReference()

void setReference ( void *  reference )

inline

provide reference for callbacks (e.g., to access map data or other context)

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The documentation for this class was generated from the following file:

• src/TinyRobotics/planning/AStar.h