[regexp] Experimental support for regexp named captures

src/runtime/runtime-regexp.cc

Index: src/runtime/runtime-regexp.cc
diff --git a/src/runtime/runtime-regexp.cc b/src/runtime/runtime-regexp.cc
index a8133d349538e4f0742f25042653b793d0f8b877..01c6f31c0b77d2c451623925efad07f6323f7adf 100644
--- a/src/runtime/runtime-regexp.cc
+++ b/src/runtime/runtime-regexp.cc
@@ -797,7 +797,6 @@ RUNTIME_FUNCTION(Runtime_RegExpSource) {
   return regexp->source();
 }
 
-
 RUNTIME_FUNCTION(Runtime_RegExpConstructResult) {
   HandleScope handle_scope(isolate);
   DCHECK(args.length() == 3);
@@ -1014,6 +1013,38 @@ RUNTIME_FUNCTION(Runtime_RegExpExecReThrow) {
   return isolate->ReThrow(exception);
 }
 
+RUNTIME_FUNCTION(Runtime_RegExpResultAttachNamedCaptures) {
+  HandleScope handle_scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_CHECKED(JSArray, result, 0);
+  CONVERT_ARG_CHECKED(JSRegExp, regexp, 1);
+
+  if (regexp->TypeTag() != JSRegExp::IRREGEXP ||
+      !regexp->DataAt(JSRegExp::kIrregexpCaptureNameMapIndex)->IsFixedArray())
+    return isolate->heap()->undefined_value();
+
+  FixedArray* captures =
+      FixedArray::cast(regexp->DataAt(JSRegExp::kIrregexpCaptureNameMapIndex));
+  DCHECK(captures->length() > 0);
+
+  Handle<JSArray> result_handle = handle(result, isolate);
+
+  for (int i = 0; i < captures->length(); i += 2) {
+    Handle<String> name = handle(String::cast(captures->get(i)), isolate);
+    const int ix = Smi::cast(captures->get(i + 1))->value();
+
+    MaybeHandle<Object> existing = Object::GetProperty(result_handle, name);
+    if (!existing.ToHandleChecked()->IsUndefined()) {
+      continue;  // Skip conflicts.
+    }
+
+    Handle<Object> value =
+        Object::GetElement(isolate, result_handle, ix).ToHandleChecked();
+    JSObject::AddProperty(result_handle, name, value, NONE);
+  }
+
+  return isolate->heap()->undefined_value();
+}
 
 RUNTIME_FUNCTION(Runtime_IsRegExp) {
   SealHandleScope shs(isolate);