BkTree: Add graphviz .dot file generation

experiments/bktree/BkTree.php

@@ -292,6 +292,40 @@ class BkTree
 		return $result;
 	}
 	
+	public function walk() {
+		$stack = [ (object)[
+			"id" => 0,
+			"node" => $this->box->get("node|0"),
+			"parent_id" => -1,
+			"parent" => null,
+			"depth" => 0
+		] ];
+		$stack_top = 0;
+		
+		// https://softwareengineering.stackexchange.com/a/226162/58491
+		while(!empty($stack)) {
+			// Take the topmost node off the stack
+			$current = $stack[$stack_top];
+			unset($stack[$stack_top]);
+			$stack_top--;
+			
+			// echo("Visiting "); var_dump($current);
+			yield $current;
+			
+			// Iterate over the child nodes
+			foreach($current->node->children as $child_distance => $child_id) {
+				$stack_top++;
+				$stack[$stack_top] = (object) [
+					"id" => $child_id,
+					"node" => $this->box->get("node|{$current->node->children->$child_distance}"),
+					"parent_id" => $current->id,
+					"parent" => $current->node,
+					"depth" => $current->depth + 1
+				];
+			}
+		}
+	}
+	
 	/**
 	 * Saves changes to the tree back to disk.
 	 * @return	void

experiments/bktree/bktreetest.php

@@ -46,6 +46,25 @@ function test_search_linear() {
 	exit();
 }
 
+function writegraph() {
+	global $tree;
+	
+	echo("Writing graph to bktree.dot\n");
+	$handle = fopen("bktree.dot", "w");
+	fwrite($handle, "// Generated by bktreetest.php by Starbeamrainbowlabs\n");
+	fwrite($handle, "// Date: ".date("r")."\n");
+	fwrite($handle, "digraph BkTree {\n");
+	fwrite($handle, "\tgraph [bgcolor=\"transparent\", nodesep=\"5\", root=\"N0\"];\n");
+	fwrite($handle, "\tnode [shape=\"point\", color=\"#cb3d38\"];\n");
+	fwrite($handle, "\tedge [arrowhead=\"open\", gradientangle=\"90\", style=\"filled\", color=\"#fcba2280\"];\n"); // #8cc03280
+	foreach($tree->walk() as $next) {
+		if($next->id == 0) continue; // Skip the first node
+		fwrite($handle, "\tN$next->parent_id -> N$next->id;\n");
+	}
+	fwrite($handle, "}\n");
+	fclose($handle);
+}
+
 if(file_exists("bktree.sqlite"))
 	$tree = time_callable("tree_load");
 else
@@ -54,8 +73,7 @@ else
 echo("Tree created in ".($tree["time"]*1000)."ms\n");
 $tree = $tree["value"];
 
-echo("Tree stats: ");
+writegraph(); exit();
-var_dump($tree->stats());
 
 function test_auto() {
 	global $tree;
@@ -67,7 +85,7 @@ function test_auto() {
 	exit();
 }
 
-test_auto();
+// test_auto();
 
 echo("BkTree Test CLI\n");
 echo("Exit with .exit\n");
@@ -89,6 +107,23 @@ while(true) {
 				echo("Serialised tree in ".round($result["time"] * 1000, 2)."ms\n");
 				exit("exit\n");
 				break;
+			
+			case ".help":
+				echo("dot commands:
+.exit          Exit, saving edits to the tree to disk
+.writegraph    Write a graphviz dot file to disk representing the tree in the current directory
+.stats         Compute statistics about the tree
+");
+				break;
+			
+			case ".writegraph":
+				writegraph();
+				break;
+			
+			case ".stats":
+				echo("Tree stats: ");
+				var_dump($tree->stats());
+				break;
 		}
 		continue;
 	}