udecode · 12joan · Mar 1, 2024 · Mar 1, 2024
diff --git a/.changeset/fluffy-donuts-roll.md b/.changeset/fluffy-donuts-roll.md
@@ -0,0 +1,21 @@
+---
+"@udecode/plate-diff": minor
+---
+
+- Add `shouldDiffDescendants` option to `computeDiff` to control whether a pair of descendant lists should be diffed. If false, the parent node will be deleted and re-inserted. Defaults to `() => true`.
+  - Example use case: To prevent `computeDiff` from diffing the text of unrelated paragraphs, use a text similarity checking algorithm to determine whether the paragraphs are sufficiently similar, and return false if not.
+- When multiple consecutive nodes have been deleted and inserted, `computeDiff` now groups all consecutive deletions together and does the same with all consecutive insertions.
+  - Example of a diff prior to this change:
+    ```diff
+    - Old paragraph 1
+    + New paragraph 1
+    - Old paragraph 2
+    + New paragraph 2
+    ```
+  - Example of a diff after this change:
+    ```diff
+    - Old paragraph 1
+    - Old paragraph 2
+    + New paragraph 1
+    + New paragraph 2
+    ```
diff --git a/packages/diff/src/computeDiff.spec.ts b/packages/diff/src/computeDiff.spec.ts
@@ -3,15 +3,15 @@
  * contributors. See /packages/diff/LICENSE for more information.
  */
 
-import { Value } from '@udecode/plate-common';
+import { isText, Value } from '@udecode/plate-common';
 
-import { computeDiff } from './computeDiff';
+import { computeDiff, ComputeDiffOptions } from './computeDiff';
 
 const ELEMENT_INLINE_VOID = 'inline-void';
 
-interface ComputeDiffFixture {
+interface ComputeDiffFixture
+  extends Pick<ComputeDiffOptions, 'lineBreakChar' | 'shouldDiffDescendants'> {
   it?: typeof it;
-  lineBreakChar?: string;
   input1: Value;
   input2: Value;
   expected: Value;
@@ -1448,16 +1448,113 @@ const fixtures: Record<string, ComputeDiffFixture> = {
       },
     ],
   },
+
+  shouldNotDiffDescendants: {
+    shouldDiffDescendants: ([firstNode]) =>
+      !firstNode ||
+      !isText(firstNode) ||
+      !firstNode.text.startsWith('NO_DIFF_INLINE'),
+    input1: [
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE FirstA' }],
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE SecondA' }],
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE ThirdA' }],
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'Same' }],
+      },
+    ],
+    input2: [
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE FirstB' }],
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE SecondB' }],
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE ThirdB' }],
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'Same' }],
+      },
+    ],
+    expected: [
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE FirstA' }],
+        diff: true,
+        diffOperation: {
+          type: 'delete',
+        },
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE SecondA' }],
+        diff: true,
+        diffOperation: {
+          type: 'delete',
+        },
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE ThirdA' }],
+        diff: true,
+        diffOperation: {
+          type: 'delete',
+        },
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE FirstB' }],
+        diff: true,
+        diffOperation: {
+          type: 'insert',
+        },
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE SecondB' }],
+        diff: true,
+        diffOperation: {
+          type: 'insert',
+        },
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'NO_DIFF_INLINE ThirdB' }],
+        diff: true,
+        diffOperation: {
+          type: 'insert',
+        },
+      },
+      {
+        type: 'paragraph',
+        children: [{ text: 'Same' }],
+      },
+    ],
+  },
 };
 
 describe('computeDiff', () => {
   Object.entries(fixtures).forEach(
-    ([name, { it: itFn = it, input1, input2, expected, lineBreakChar }]) => {
+    ([name, { it: itFn = it, input1, input2, expected, ...options }]) => {
       itFn(name, () => {
         const output = computeDiff(input1, input2, {
           isInline: (node) => node.type === ELEMENT_INLINE_VOID,
           ignoreProps: ['id'],
-          lineBreakChar,
+          ...options,
         });
 
         expect(output).toEqual(expected);

diff --git a/packages/diff/src/computeDiff.ts b/packages/diff/src/computeDiff.ts
@@ -14,6 +14,10 @@ export interface ComputeDiffOptions {
   isInline: PlateEditor['isInline'];
   ignoreProps?: string[];
   lineBreakChar?: string;
+  shouldDiffDescendants?: (
+    nodes: TDescendant[],
+    nextNodes: TDescendant[]
+  ) => boolean;
   getInsertProps: (node: TDescendant) => any;
   getDeleteProps: (node: TDescendant) => any;
   getUpdateProps: (

diff --git a/packages/diff/src/internal/transforms/transformDiffDescendants.ts b/packages/diff/src/internal/transforms/transformDiffDescendants.ts
@@ -32,21 +32,32 @@ export function transformDiffDescendants(
   let i = 0;
   const children: TDescendant[] = [];
 
-  const insertNodes = (...nodes: TDescendant[]) =>
-    children.push(
-      ...nodes.map((node) => ({
-        ...node,
-        ...getInsertProps(node),
-      }))
-    );
+  let insertBuffer: TDescendant[] = [];
+  let deleteBuffer: TDescendant[] = [];
+
+  const flushBuffers = () => {
+    // Return all deletions followed by all insertions
+    children.push(...deleteBuffer, ...insertBuffer);
+    insertBuffer = [];
+    deleteBuffer = [];
+  };
 
-  const removeNodes = (...nodes: TDescendant[]) =>
-    children.push(
-      ...nodes.map((node) => ({
-        ...node,
-        ...getDeleteProps(node),
-      }))
-    );
+  const insertNode = (node: TDescendant) =>
+    insertBuffer.push({
+      ...node,
+      ...getInsertProps(node),
+    });
+
+  const deleteNode = (node: TDescendant) =>
+    deleteBuffer.push({
+      ...node,
+      ...getDeleteProps(node),
+    });
+
+  const passThroughNodes = (...nodes: TDescendant[]) => {
+    flushBuffers();
+    children.push(...nodes);
+  };
 
   const areNodeListsEquivalent = (
     nodes0: TDescendant[],
@@ -72,7 +83,7 @@ export function transformDiffDescendants(
 
     // If operation code is 0, it means the chunk is unchanged
     if (op === 0) {
-      children.push(...nodes);
+      passThroughNodes(...nodes);
       // Move to the next diff chunk
       i += 1;
       continue;
@@ -92,15 +103,15 @@ export function transformDiffDescendants(
          * just return nextNodes.
          */
         if (areNodeListsEquivalent(nodes, nextNodes)) {
-          children.push(...nextNodes);
+          passThroughNodes(...nextNodes);
           // Consume two diff chunks (delete and insert)
           i += 2;
           continue;
         }
 
         // If both current and next chunks are text nodes, use transformTextNodes
         if (isInlineList(nodes) && isInlineList(nextNodes)) {
-          children.push(...transformDiffTexts(nodes, nextNodes, options));
+          passThroughNodes(...transformDiffTexts(nodes, nextNodes, options));
           // Consume two diff chunks (delete and insert)
           i += 2;
           continue;
@@ -110,23 +121,32 @@ export function transformDiffDescendants(
         const diffResult = diffNodes(nodes, nextNodes);
         diffResult.forEach((item: NodeRelatedItem) => {
           if (item.delete) {
-            removeNodes(item.originNode);
+            deleteNode(item.originNode);
           }
           if (item.insert) {
-            insertNodes(item.originNode);
+            insertNode(item.originNode);
           }
           if (item.relatedNode) {
-            children.push(
-              ...transformDiffNodes(item.originNode, item.relatedNode, options)
+            const diffNodesResult = transformDiffNodes(
+              item.originNode,
+              item.relatedNode,
+              options
             );
+
+            if (diffNodesResult) {
+              passThroughNodes(...diffNodesResult);
+            } else {
+              deleteNode(item.originNode);
+              insertNode(item.relatedNode);
+            }
           }
         });
         i += 2; // this consumed two entries from the diff array.
         continue;
       } else {
         // Plain delete of some nodes (with no insert immediately after)
         for (const node of nodes) {
-          removeNodes(node);
+          deleteNode(node);
         }
         i += 1; // consumes only one entry from diff array.
         continue;
@@ -135,7 +155,7 @@ export function transformDiffDescendants(
     if (op === 1) {
       // insert new nodes.
       for (const node of nodes) {
-        insertNodes(node);
+        insertNode(node);
       }
       i += 1;
       continue;
@@ -145,5 +165,7 @@ export function transformDiffDescendants(
     );
   }
 
+  flushBuffers();
+
   return children;
 }
diff --git a/packages/diff/src/internal/transforms/transformDiffNodes.ts b/packages/diff/src/internal/transforms/transformDiffNodes.ts
@@ -28,12 +28,18 @@ type Handler = (
  * algorithm on the children.
  */
 const childrenOnlyStrategy: Handler = (node, nextNode, options) => {
+  const { shouldDiffDescendants = () => true } = options;
+
   if (
     node['children'] != null &&
     nextNode['children'] != null &&
     isEqual(
       copyWithout(node, ['children']),
       copyWithout(nextNode, ['children'])
+    ) &&
+    shouldDiffDescendants(
+      node['children'] as TDescendant[],
+      nextNode['children'] as TDescendant[]
     )
   ) {
     const children = computeDiff(
@@ -83,36 +89,14 @@ const propsOnlyStrategy: Handler = (node, nextNode, { getUpdateProps }) => {
   ];
 };
 
-// No other strategy applies, so remove and insert the node.
-const fallbackStrategy: Handler = (
-  node,
-  nextNode,
-  { getInsertProps, getDeleteProps }
-) => {
-  return [
-    {
-      ...node,
-      ...getDeleteProps(node),
-    },
-    {
-      ...nextNode,
-      ...getInsertProps(nextNode),
-    },
-  ];
-};
-
-const strategies: Handler[] = [
-  childrenOnlyStrategy,
-  propsOnlyStrategy,
-  fallbackStrategy,
-];
+const strategies: Handler[] = [childrenOnlyStrategy, propsOnlyStrategy];
 
 // Replace node at path by nextNode using the first strategy that works.
 export function transformDiffNodes(
   node: TDescendant,
   nextNode: TDescendant,
   options: ComputeDiffOptions
-): TDescendant[] {
+): TDescendant[] | false {
   // Try each strategy in turn
   for (const strategy of strategies) {
     // Attempt to generate operations with the current strategy and return the operations if the strategy succeeds
@@ -121,6 +105,7 @@ export function transformDiffNodes(
       return ops;
     }
   }
-  // If no strategy succeeds, throw an error (should never happen because of the fallback strategy)
-  throw new Error('transformDiffNodes: No strategy succeeded');
+
+  // If no strategy succeeds, tell the caller that the nodes are not comparable
+  return false;
 }