cord_data_edge.h - mozsearch

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// 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_