string_util.cc

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/******************************************************************************
 * Copyright 2017 The Apollo Authors. All Rights Reserved.
 *
 * 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
 *
 * http://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.
 *****************************************************************************/
 
#include "modules/common/util/string_util.h"
 
#include <cmath>
#include <vector>
 
#include "absl/strings/str_cat.h"
 
namespace apollo {
namespace common {
namespace util {
namespace {
 
static const char kBase64Array[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
std::string Base64Piece(const char in0, const char in1, const char in2) {
  const int triplet = in0 << 16 | in1 << 8 | in2;
  std::string out(4, '=');
  out[0] = kBase64Array[(triplet >> 18) & 0x3f];
  out[1] = kBase64Array[(triplet >> 12) & 0x3f];
  if (in1) {
    out[2] = kBase64Array[(triplet >> 6) & 0x3f];
  }
  if (in2) {
    out[3] = kBase64Array[triplet & 0x3f];
  }
  return out;
}
 
}  // namespace
 
std::string EncodeBase64(std::string_view in) {
  std::string out;
  if (in.empty()) {
    return out;
  }
 
  const size_t in_size = in.length();
  out.reserve(((in_size - 1) / 3 + 1) * 4);
  for (size_t i = 0; i + 2 < in_size; i += 3) {
    absl::StrAppend(&out, Base64Piece(in[i], in[i + 1], in[i + 2]));
  }
  if (in_size % 3 == 1) {
    absl::StrAppend(&out, Base64Piece(in[in_size - 1], 0, 0));
  }
  if (in_size % 3 == 2) {
    absl::StrAppend(&out, Base64Piece(in[in_size - 2], in[in_size - 1], 0));
  }
  return out;
}
 
}  // namespace util
}  // namespace common
}  // namespace apollo