1 files changed, 63 insertions, 0 deletions
diff --git a/third_party/abseil-cpp/absl/strings/internal/cord_data_edge.h b/third_party/abseil-cpp/absl/strings/internal/cord_data_edge.h
new file mode 100644
index 0000000000..e18b33e1b0
--- /dev/null
+++ b/third_party/abseil-cpp/absl/strings/internal/cord_data_edge.h
@@ -0,0 +1,63 @@
+// Copyright 2022 The Abseil Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_STRINGS_INTERNAL_CORD_DATA_EDGE_H_
+#define ABSL_STRINGS_INTERNAL_CORD_DATA_EDGE_H_
+
+#include <cassert>
+#include <cstddef>
+
+#include "absl/base/config.h"
+#include "absl/strings/internal/cord_internal.h"
+#include "absl/strings/internal/cord_rep_flat.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace cord_internal {
+
+// Returns true if the provided rep is a FLAT, EXTERNAL or a SUBSTRING node
+// holding a FLAT or EXTERNAL child rep. Requires `rep != nullptr`.
+inline bool IsDataEdge(const CordRep* edge) {
+  assert(edge != nullptr);
+
+  // The fast path is that `edge` is an EXTERNAL or FLAT node, making the below
+  // if a single, well predicted branch. We then repeat the FLAT or EXTERNAL
+  // check in the slow path of the SUBSTRING check to optimize for the hot path.
+  if (edge->tag == EXTERNAL || edge->tag >= FLAT) return true;
+  if (edge->tag == SUBSTRING) edge = edge->substring()->child;
+  return edge->tag == EXTERNAL || edge->tag >= FLAT;
+}
+
+// Returns the `absl::string_view` data reference for the provided data edge.
+// Requires 'IsDataEdge(edge) == true`.
+inline absl::string_view EdgeData(const CordRep* edge) {
+  assert(IsDataEdge(edge));
+
+  size_t offset = 0;
+  const size_t length = edge->length;
+  if (edge->IsSubstring()) {
+    offset = edge->substring()->start;
+    edge = edge->substring()->child;
+  }
+  return edge->tag >= FLAT
+             ? absl::string_view{edge->flat()->Data() + offset, length}
+             : absl::string_view{edge->external()->base + offset, length};
+}
+
+}  // namespace cord_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_CORD_DATA_EDGE_H_