Start setup for notebook merge diffs

Author: navn-r

jupyterlab_git/git.py

@@ -14,7 +14,7 @@
 import pexpect
 import tornado
 import tornado.locks
-from nbdime import diff_notebooks
+from nbdime import diff_notebooks, merge_notebooks
 from jupyter_server.utils import ensure_async
 
 from .log import get_logger
@@ -320,14 +320,20 @@ async def fetch(self, path):
 
         return result
 
-    async def get_nbdiff(self, prev_content: str, curr_content: str) -> dict:
+    async def get_nbdiff(
+        self, prev_content: str, curr_content: str, base_content=None
+    ) -> dict:
         """Compute the diff between two notebooks.
 
         Args:
             prev_content: Notebook previous content
             curr_content: Notebook current content
+            base_content: Notebook base content - only passed during a merge conflict
         Returns:
-            {"base": Dict, "diff": Dict}
+            if not base_content:
+                {"base": Dict, "diff": Dict}
+            else:
+                {"base": Dict, "merge_decisions": Dict}
         """
 
         def read_notebook(content):
@@ -348,11 +354,21 @@ def read_notebook(content):
         current_loop = tornado.ioloop.IOLoop.current()
         prev_nb = await current_loop.run_in_executor(None, read_notebook, prev_content)
         curr_nb = await current_loop.run_in_executor(None, read_notebook, curr_content)
-        thediff = await current_loop.run_in_executor(
-            None, diff_notebooks, prev_nb, curr_nb
-        )
+        if base_content:
+            base_nb = await current_loop.run_in_executor(
+                None, read_notebook, base_content
+            )
+            _, merge_decisions = await current_loop.run_in_executor(
+                None, merge_notebooks, base_nb, prev_nb, curr_nb
+            )
+
+            return {"base": base_nb, "merge_decisions": merge_decisions}
+        else:
+            thediff = await current_loop.run_in_executor(
+                None, diff_notebooks, prev_nb, curr_nb
+            )
 
-        return {"base": prev_nb, "diff": thediff}
+            return {"base": prev_nb, "diff": thediff}
 
     async def status(self, path):
         """

jupyterlab_git/handlers.py

@@ -705,7 +705,10 @@ async def post(self):
                 status_code=400, reason=f"Missing POST key: {e}"
             )
         try:
-            content = await self.git.get_nbdiff(prev_content, curr_content)
+            base_content = data.get("baseContent")
+            content = await self.git.get_nbdiff(
+                prev_content, curr_content, base_content
+            )
         except Exception as e:
             get_logger().error(f"Error computing notebook diff.", exc_info=e)
             raise tornado.web.HTTPError(

src/components/diff/NotebookDiff.ts

@@ -12,6 +12,9 @@ import { PromiseDelegate } from '@lumino/coreutils';
 import { Message } from '@lumino/messaging';
 import { Panel, Widget } from '@lumino/widgets';
 import { IDiffEntry } from 'nbdime/lib/diff/diffentries';
+import { IMergeDecision } from 'nbdime/lib/merge/decisions';
+import { NotebookMergeModel } from 'nbdime/lib/merge/model';
+import { NotebookMergeWidget } from 'nbdime/lib/merge/widget';
 import { NotebookDiffModel } from 'nbdime/lib/diff/model';
 import { CELLDIFF_CLASS, NotebookDiffWidget } from 'nbdime/lib/diff/widget';
 import {
@@ -50,6 +53,18 @@ interface INbdimeDiff {
   diff: IDiffEntry[];
 }
 
+interface INbdimeMergeDiff {
+  /**
+   * Base notebook content
+   */
+  base: INotebookContent;
+  /**
+   * Set of decisions made by comparing
+   * reference, challenger, and base notebooks
+   */
+  merge_decisions: IMergeDecision[];
+}
+
 /**
  * Diff callback to be registered for notebook files.
  *
@@ -142,8 +157,13 @@ export class NotebookDiff
     return this._isReady;
   }
 
+  /**
+   * Gets the file contents of a resolved merge conflict,
+   * and rejects if unable to retrieve.
+   */
   async getResolvedFile(): Promise<string> {
-    return Promise.resolve('');
+    // TODO: Implement
+    return Promise.reject('TODO');
   }
 
   /**
@@ -159,6 +179,7 @@ export class NotebookDiff
 
       const header = Private.diffHeader(
         this._model.reference.label,
+        this._model.base?.label,
         this._model.challenger.label
       );
       this.addWidget(header);
@@ -173,10 +194,16 @@ export class NotebookDiff
       // ENH request content only if it changed
       const referenceContent = await this._model.reference.content();
       const challengerContent = await this._model.challenger.content();
+      const baseContent = await this._model.base?.content();
 
-      const nbdWidget = await this.createDiffView(
+      const createView = baseContent
+        ? this.createMergeView.bind(this)
+        : this.createDiffView.bind(this);
+
+      const nbdWidget = await createView(
         challengerContent,
-        referenceContent
+        referenceContent,
+        baseContent
       );
 
       while (this._scroller.widgets.length > 0) {
@@ -215,6 +242,24 @@ export class NotebookDiff
     return new NotebookDiffWidget(model, this._renderMime);
   }
 
+  protected async createMergeView(
+    challengerContent: string,
+    referenceContent: string,
+    baseContent: string
+  ): Promise<NotebookMergeWidget> {
+    const data = await requestAPI<INbdimeMergeDiff>('diffnotebook', 'POST', {
+      currentContent: challengerContent,
+      previousContent: referenceContent,
+      baseContent
+    });
+
+    const model = new NotebookMergeModel(data.base, data.merge_decisions);
+
+    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+    // @ts-ignore
+    return new NotebookMergeWidget(model, this._renderMime);
+  }
+
   /**
    * Handle `'activate-request'` messages.
    */
@@ -258,14 +303,16 @@ namespace Private {
   /**
    * Create a header widget for the diff view.
    */
-  export function diffHeader(baseLabel: string, remoteLabel: string): Widget {
+  export function diffHeader(...labels: string[]): Widget {
     const node = document.createElement('div');
     node.className = 'jp-git-diff-header';
-    node.innerHTML = `<div class="jp-git-diff-banner">
-        <span>${baseLabel}</span>
-        <span class="jp-spacer"></span>
-        <span>${remoteLabel}</span>
-      </div>`;
+    node.innerHTML = `
+    <div class="jp-git-diff-banner">
+      ${labels
+        .filter(label => !!label)
+        .map(label => `<span>${label}</span>`)
+        .join('<span class="jp-spacer"></span>')}
+    </div>`;
 
     return new Widget({ node });
   }

tsconfig.json

@@ -18,6 +18,7 @@
     "rootDir": "src",
     "sourceMap": true,
     "sourceRoot": "./@jupyterlab/git/src",
+    "skipLibCheck": true,
     "strict": true,
     "strictNullChecks": false,
     "target": "es2017",