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Kotlin library for creating finite state machines.

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package com.toxicbakery.kfinstatemachine.graph

/**
 * Map all unique acyclic paths from a given starting point.
 *
 * @param start the node to begin the search for unique paths through the graph
 */
fun  IDirectedGraph.mapAcyclicPaths(
    start: N
): Set> = mapAcyclicPaths(mutableListOf(start))
    .minus>(listOf(start))

/**
 * Recursively walk unique acyclic paths from a given path and map of known paths.
 *
 * @param currentPath path to be walked
 * @param pathSet paths previously walked
 */
private fun  IDirectedGraph.mapAcyclicPaths(
    currentPath: List,
    pathSet: MutableSet> = mutableSetOf()
): Set> = edges(currentPath.last()) { mapOf() }
    .let { edges ->
        if (edges.isNotEmpty()) {
            edges.forEach { edge ->
                when {
                    // Avoid loops and end the path
                    currentPath.contains(edge.value) -> pathSet.add(currentPath)
                    // Copy the path and start a recursive search
                    else -> mapAcyclicPaths(
                        currentPath = currentPath.plus(edge.value),
                        pathSet = pathSet
                    )
                }
            }
        } else pathSet.add(currentPath)
        return pathSet
    }