Apoc仓库中PathFinder的findAllPaths重写位置及Dijkstra最大深度扩展问题

Hey there! Let's tackle your two questions step by step:

Where is PathFinder.findAllPaths() overridden in the APOC repository? #

The PathFinder interface is defined in src/main/java/apoc/path/PathFinder.java, and its concrete implementations that override findAllPaths() are all located in the same apoc.path package. For your Dijkstra use case, the key implementation you'll care about is DijkstraPathFinder.java—this is where the weighted path-finding logic (including Dijkstra's algorithm) lives.

Other related implementations that override findAllPaths() include:

• AllPathsFinder.java: Handles unweighted all-path searches
• ShortestPathFinder.java: Focuses on finding the single shortest path
• YenPathFinder.java: Implements Yen's algorithm for k-shortest paths

How to add a maxDepth parameter to terminate paths exceeding a length limit #

Here's a rough outline of the changes you'll need to make:

1. Update the PathFinder interface:
   Modify the findAllPaths() method signature to accept a maxDepth parameter:

   Iterable<Path> findAllPaths(Node startNode, Node endNode, int maxDepth);
   

   For implementations that don't need this parameter (like some shortest-path finders), you can set a default value like Integer.MAX_VALUE to maintain backward compatibility.

2. Modify DijkstraPathFinder's findAllPaths() implementation:
   In the path expansion loop, add a check to skip extending paths that already exceed maxDepth. For example, when considering adding a new node to the current path:

   if (currentPath.length() >= maxDepth) {
       continue; // Skip further expansion for this path
   }
   

   You'll need to integrate this check into the algorithm's priority queue processing logic to ensure paths don't grow beyond your depth limit.

3. Pass maxDepth through to the stream method:
   Update WeightedPathResult.streamWeightedPathResult() to accept the maxDepth parameter, then pass it to the pathFinder.findAllPaths(startNode, endNode, maxDepth) call.

4. Expose the parameter in the procedure:
   Finally, update the relevant APOC procedure (like apoc.path.dijkstra) to accept a maxDepth input parameter, and pass it down through the call chain to streamWeightedPathResult().

Just a heads-up: Make sure to test edge cases (like maxDepth = 0 or paths that hit the depth limit before reaching the end node) to ensure your changes don't break existing functionality!

内容的提问来源于stack exchange，提问作者KhribiHamza