Get rid of call to detachNodeFromParent().

lib/svgo/tools.js

@@ -65,6 +65,19 @@ export const decodeSVGDatauri = (str) => {
   return str;
 };
 
+/**
+ * @param {Map<import('../types.js').XastParent,Set<import('../types.js').XastChild>>} childrenToDeleteByParent
+ * @param {import('../types.js').XastChild} child
+ */
+export function addChildToDelete(childrenToDeleteByParent, child) {
+  let childrenToDelete = childrenToDeleteByParent.get(child.parentNode);
+  if (!childrenToDelete) {
+    childrenToDelete = new Set();
+    childrenToDeleteByParent.set(child.parentNode, childrenToDelete);
+  }
+  childrenToDelete.add(child);
+}
+
 /**
  * @typedef {{
  *   noSpaceAfterFlags?: boolean,
@@ -124,6 +137,16 @@ export const cleanupOutData = (data, params, command) => {
   return str;
 };
 
+/**
+ * @param {Map<import('../types.js').XastParent,Set<import('../types.js').XastChild>>} childrenToDeleteByParent
+ */
+export function deleteChildren(childrenToDeleteByParent) {
+  // For each parent, delete no longer needed children.
+  for (const [parent, childrenToDelete] of childrenToDeleteByParent) {
+    parent.children = parent.children.filter((c) => !childrenToDelete.has(c));
+  }
+}
+
 /**
  * @param {number} n
  * @param {number} m

plugins/removeEmptyContainers.js

@@ -1,4 +1,8 @@
-import { getHrefId } from '../lib/svgo/tools.js';
+import {
+  addChildToDelete,
+  deleteChildren,
+  getHrefId,
+} from '../lib/svgo/tools.js';
 import { detachNodeFromParent } from '../lib/xast.js';
 
 export const name = 'removeEmptyContainers';
@@ -28,9 +32,7 @@ const removableEls = new Set([
  */
 export const fn = () => {
   const removedIds = new Set();
-  /**
-   * @type {Map<string, import('../lib/types.js').XastElement[]>}
-   */
+  /** @type {Map<string, import('../lib/types.js').XastElement[]>} */
   const usesById = new Map();
 
   return {
@@ -49,48 +51,57 @@ export const fn = () => {
           }
         }
       },
-      exit: (node, parentNode) => {
+      exit: (element, parentNode) => {
         // remove only empty non-svg containers
-        if (!removableEls.has(node.name) || node.children.length !== 0) {
+        if (!removableEls.has(element.name) || element.children.length !== 0) {
           return;
         }
         // empty patterns may contain reusable configuration
         if (
-          node.name === 'pattern' &&
-          Object.keys(node.attributes).length !== 0
+          element.name === 'pattern' &&
+          Object.keys(element.attributes).length !== 0
         ) {
           return;
         }
         // The <g> may not have content, but the filter may cause a rectangle
         // to be created and filled with pattern.
-        if (node.name === 'g' && node.attributes.filter != null) {
+        if (element.name === 'g' && element.attributes.filter != null) {
           return;
         }
         // empty <mask> hides masked element
-        if (node.name === 'mask' && node.attributes.id != null) {
+        if (element.name === 'mask' && element.attributes.id != null) {
           return;
         }
         if (parentNode.type === 'element' && parentNode.name === 'switch') {
           return;
         }
 
-        detachNodeFromParent(node, parentNode);
-        if (node.attributes.id) {
-          removedIds.add(node.attributes.id);
+        // TODO: Change the way this works so that parent removes empty children. We can't queue them for deletion in
+        // root exit; this is running in element exit so that nested empty elements are removed from bottom up, the nesting
+        // would be hard to detect in root exit.
+        detachNodeFromParent(element, parentNode);
+        if (element.attributes.id) {
+          removedIds.add(element.attributes.id);
         }
       },
     },
     root: {
       exit: () => {
         // Remove any <use> elements that referenced an empty container.
+
+        /** @type {Map<import('../lib/types.js').XastParent,Set<import('../lib/types.js').XastChild>>} */
+        const childrenToDelete = new Map();
+
         for (const id of removedIds) {
           const usingEls = usesById.get(id);
           if (usingEls) {
             for (const element of usingEls) {
-              detachNodeFromParent(element);
+              addChildToDelete(childrenToDelete, element);
             }
           }
         }
+
+        deleteChildren(childrenToDelete);
       },
     },
   };

plugins/removeHiddenElems.js

@@ -1,5 +1,9 @@
 import { parsePathCommands, PathParseError } from '../lib/pathutils.js';
-import { getEllipseProperties } from '../lib/svgo/tools.js';
+import {
+  addChildToDelete,
+  deleteChildren,
+  getEllipseProperties,
+} from '../lib/svgo/tools.js';
 import { elemsGroups } from './_collections.js';
 
 export const name = 'removeHiddenElems';
@@ -44,12 +48,7 @@ export const fn = (root, params, info) => {
    * @param {import('../lib/types.js').XastElement} element
    */
   function removeElement(element) {
-    let childrenToDelete = childrenToDeleteByParent.get(element.parentNode);
-    if (!childrenToDelete) {
-      childrenToDelete = new Set();
-      childrenToDeleteByParent.set(element.parentNode, childrenToDelete);
-    }
-    childrenToDelete.add(element);
+    addChildToDelete(childrenToDeleteByParent, element);
   }
 
   /**
@@ -200,12 +199,7 @@ export const fn = (root, params, info) => {
     },
     root: {
       exit: () => {
-        // For each parent, delete no longer needed children.
-        for (const [parent, childrenToDelete] of childrenToDeleteByParent) {
-          parent.children = parent.children.filter(
-            (c) => !childrenToDelete.has(c),
-          );
-        }
+        deleteChildren(childrenToDeleteByParent);
       },
     },
   };