Fix some bugs in how we use unist

package-lock.json

@@ -1,14 +1,15 @@
 {
   "name": "@thefarce/loom",
-  "version": "0.0.2",
+  "version": "0.1.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@thefarce/loom",
-      "version": "0.0.2",
+      "version": "0.1.0",
       "dependencies": {
         "unist-util-is": "^6.0.0",
+        "unist-util-visit": "^5.0.0",
         "unist-util-visit-parents": "^6.0.1"
       },
       "devDependencies": {
@@ -4527,6 +4528,20 @@
         "url": "https://opencollective.com/unified"
       }
     },
+    "node_modules/unist-util-visit": {
+      "version": "5.0.0",
+      "resolved": "https://registry.npmjs.org/unist-util-visit/-/unist-util-visit-5.0.0.tgz",
+      "integrity": "sha512-MR04uvD+07cwl/yhVuVWAtw+3GOR/knlL55Nd/wAdblk27GCVt3lqpTivy/tkJcZoNPzTwS1Y+KMojlLDhoTzg==",
+      "dependencies": {
+        "@types/unist": "^3.0.0",
+        "unist-util-is": "^6.0.0",
+        "unist-util-visit-parents": "^6.0.0"
+      },
+      "funding": {
+        "type": "opencollective",
+        "url": "https://opencollective.com/unified"
+      }
+    },
     "node_modules/unist-util-visit-parents": {
       "version": "6.0.1",
       "resolved": "https://registry.npmjs.org/unist-util-visit-parents/-/unist-util-visit-parents-6.0.1.tgz",

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@thefarce/loom",
-  "version": "0.1.0",
+  "version": "0.1.1",
   "description": "A module for weaving form data with content data",
   "type": "module",
   "main": "index.mjs",
@@ -16,6 +16,7 @@
   },
   "dependencies": {
     "unist-util-is": "^6.0.0",
+    "unist-util-visit": "^5.0.0",
     "unist-util-visit-parents": "^6.0.1"
   }
 }

src/transform.mjs

@@ -4,7 +4,7 @@
  * (ASTs).
  */
 
-import { visitParents } from 'unist-util-visit-parents';
+import { visit, SKIP } from 'unist-util-visit';
 import { isAstNode } from './util.mjs';
 import { is } from 'unist-util-is';
 
@@ -25,7 +25,10 @@ export function transform (ast, ...transformers) {
 	// AST and stop processing it.  If the function returns an AST node,
 	// replace the node with that AST node and continue processing with the
 	// new node.
-	visitParents(tree, (node, ancestors) => {
+	visit(tree, (node, index, parent) => {
+		let replaced = false;
+		let removed  = false;
+
 		let transformed = transformers.reduce((workingNode, transformer) => {
 			// If the current node is null, just skip any further processing.
 			if (workingNode === null) {
@@ -35,10 +38,11 @@ export function transform (ast, ...transformers) {
 			// Process the working node through the current function.  Make sure
 			// the transformer function knows not only the node but also its
 			// ancestors.
-			let result = transformer(workingNode, ancestors);
+			let result = transformer(workingNode);
 
 			// If the function returned null, just skip any further processing.
 			if (result === null) {
+				removed = true;
 				return null;
 			}
 			// If the function returned 'undefined', this means that there's no
@@ -51,6 +55,7 @@ export function transform (ast, ...transformers) {
 			// If the function returned an AST node, we replace the working node
 			// with that AST node and continue processing with the new node.
 			else if (isAstNode(result)) {
+				replaced = true;
 				return result;
 			}
 
@@ -58,37 +63,19 @@ export function transform (ast, ...transformers) {
 			throw new Error(`Invalid transformer result: ${JSON.stringify(result)}`);
 		}, node);
 
-		let parent = ancestors[ancestors.length - 1];
-
-		if (!parent) {
-			return;
+		// If we need to replace the node, do it here.
+		if (replaced && transformed && parent) {
+			parent.children.splice(index, 1, transformed);
 		}
 
-		// Loop through the first most recent ancestor and replace the current
-		// node with the transformed node.  If transformed is null, just delete
-		// the current node.
-		if (transformed === null) {
-			let index = -1;
-			parent.children.forEach((child, i) => {
-				if (is(child, node)) {
-					index = i;
-				}
-			})
-
+		if (removed && parent) {
 			parent.children.splice(index, 1);
+			// This is special magick required by unist.  It hints to the visit
+			// function that we removed this node from the tree, so skip it when
+			// walking further..
+			return [SKIP, index];
 		}
-		// If the transformed node is the same as the current node, do nothing.
-		else if (is(node, transformed)) {
-			// do nothing
-		}
-		// Finally, replace the current node with the transformed node.
-		else {
-			parent.children.forEach((child, index) => {
-				if (is(child, node)) {
-					parent.children[index] = transformed;
-				}
-			});
-		}
+
 	});
 
 	return tree;