perf(javascript): cache canonical export comparison sort keys (#1028)

src/domain/javascript/javascriptExportShapeComparison.ts

@@ -1,5 +1,8 @@
-import { uniqueSorted } from "../canonicalOrdering.js";
-import { digestExportShapeValue } from "./javascriptExportShapeComparisonIdentity.js";
+import { compareCodePoints, uniqueSorted } from "../canonicalOrdering.js";
+import {
+  canonicalExportShapeValue,
+  digestExportShapeValue,
+} from "./javascriptExportShapeComparisonIdentity.js";
 import {
   javaScriptExportShapeComparisonResultSchema,
   type JavaScriptExportShapeComparisonChange,
@@ -14,7 +17,6 @@ import {
 } from "./javascriptExportShapeSelection.js";
 import {
   buildJavaScriptExportShapeChanges,
-  compareJavaScriptExportShapeChanges,
   hasPartialJavaScriptExportPropertyCoverage,
   pairJavaScriptExportShapeVariants,
   type JavaScriptExportShapePairing,
@@ -42,14 +44,16 @@ export const compareJavaScriptExportShapes = (
     input.left.evidenceId,
     input.right.evidenceId,
   );
-  const allChanges = buildJavaScriptExportShapeChanges({
-    leftSelection: left,
-    rightSelection: right,
-    pairing,
-    leftShapes: leftRetained.shapes,
-    rightShapes: rightRetained.shapes,
-    evidenceLinks,
-  }).sort(compareJavaScriptExportShapeChanges);
+  const allChanges = sortChanges(
+    buildJavaScriptExportShapeChanges({
+      leftSelection: left,
+      rightSelection: right,
+      pairing,
+      leftShapes: leftRetained.shapes,
+      rightShapes: rightRetained.shapes,
+      evidenceLinks,
+    }),
+  );
   const changes = allChanges;
   const omittedChanges = 0;
   const coverage = comparisonCoverage({
@@ -78,6 +82,29 @@ export const compareJavaScriptExportShapes = (
   });
 };
 
+const sortChanges = (
+  changes: readonly JavaScriptExportShapeComparisonChange[],
+): JavaScriptExportShapeComparisonChange[] =>
+  changes
+    .map((change, index) => ({
+      change,
+      index,
+      sortKey: canonicalExportShapeValue({
+        discriminant: change.discriminant,
+        path: change.path,
+        status: change.status,
+        left_source_range: change.left_source_range,
+        right_source_range: change.right_source_range,
+        change_id: change.change_id,
+      }),
+    }))
+    .sort(
+      (left, right) =>
+        compareCodePoints(left.sortKey, right.sortKey) ||
+        left.index - right.index,
+    )
+    .map(({ change }) => change);
+
 interface CoverageInput {
   readonly input: JavaScriptExportShapeComparisonProjectionInput;
   readonly left: SelectedJavaScriptExport;