feat(graph-support): bump Guava and add new APIs to Graphs.

gradle/libs.versions.toml

@@ -8,7 +8,7 @@ dagp = "2.4.2"
 error-prone = "2.26.1"
 gradle-publish-plugin = "1.1.0"
 grammar = "0.3"
-guava = "33.1.0-jre"
+guava = "33.3.1-jre"
 java = "11"
 junit = "5.10.2"
 kotlin = "1.9.25"

graph-support/src/main/kotlin/com/autonomousapps/graph/Graphs.kt

@@ -29,12 +29,24 @@ public object Graphs {
     inDegree(it) == 0
   }
 
+  /**
+   * Returns the list of nodes that have an in-degree of 0.
+   */
+  public fun <N : Any> Graph<N>.roots(): List<N> = nodes().filter {
+    inDegree(it) == 0
+  }
+
   /** Returns the nodes in this graph that are immediate [predecessors][Graph.predecessors] to [node]. */
   public fun <N : Any> Graph<N>.parents(node: N): Set<N> = predecessors(node)
 
   /** Returns the nodes in this graph that are immediate [successors][Graph.successors] to [node]. */
   public fun <N : Any> Graph<N>.children(node: N): Set<N> = successors(node)
 
+  /** Returns a [ShortestPath] from [source] to any other node in [this][Graph] graph. */
+  public fun <N : Any> Graph<N>.shortestPaths(source: N): ShortestPath<N> {
+    return ShortestPath(this, source)
+  }
+
   /**
    * Returns an ordered list of nodes if there is a path from [source] to [target]. If there is no path, returns an
    * empty list.

graph-support/src/main/kotlin/com/autonomousapps/graph/ShortestPath.kt

@@ -31,6 +31,11 @@ public class ShortestPath<N>(
     }
   }
 
+  /** Returns the distance from [source] to [other] if there is a path, otherwise null. */
+  public fun distanceTo(other: N): Int? {
+    return distTo[other]?.toInt()
+  }
+
   public fun hasPathTo(other: N): Boolean {
     val dist = distTo[other] ?: return false
     return dist < Float.MAX_VALUE

graph-support/src/main/kotlin/com/autonomousapps/graph/Topological.kt

@@ -6,11 +6,11 @@ import com.google.common.graph.Graph
 import com.google.common.graph.Traverser
 import java.util.*
 
-/** With thanks to Algorithms, 4th Ed. See p582 for the explanation for why we want the reverse postorder. */
+/** With thanks to Algorithms, 4th Ed. See p582 for the explanation of why we want the reverse postorder. */
 @Suppress("UnstableApiUsage") // Guava graphs
 public class Topological<N>(
   graph: Graph<N>,
-  source: N
+  source: N,
 ) where N : Any {
 
   public val order: Iterable<N>