util/string_util.cc

// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "util/string_util.h"

namespace openscreen::string_util {
namespace internal {
// clang-format off
// Array of bitfields holding character information. Note that bitfields for all
// characters above ASCII 127 are zero-initialized.
// Position      Meaning
// --------      -------
//    1          alphabetic
//    2          alphanumeric
//    3          whitespace
//    4          punctuation
//    5          tab or space
//    6          control character
//    7          hex digit
const unsigned char kPropertyBits[256] = {
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  // 0x00
  0x40, 0x68, 0x48, 0x48, 0x48, 0x48, 0x40, 0x40,
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,  // 0x10
  0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
  0x28, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,  // 0x20
  0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
  0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84,  // 0x30
  0x84, 0x84, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
  0x10, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x05,  // 0x40
  0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
  0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,  // 0x50
  0x05, 0x05, 0x05, 0x10, 0x10, 0x10, 0x10, 0x10,
  0x10, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x05,  // 0x60
  0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
  0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,  // 0x70
  0x05, 0x05, 0x05, 0x10, 0x10, 0x10, 0x10, 0x40,
};

// Array of characters for the ascii_tolower() function.
const char kToLower[256] = {
  '\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07',
  '\x08', '\x09', '\x0a', '\x0b', '\x0c', '\x0d', '\x0e', '\x0f',
  '\x10', '\x11', '\x12', '\x13', '\x14', '\x15', '\x16', '\x17',
  '\x18', '\x19', '\x1a', '\x1b', '\x1c', '\x1d', '\x1e', '\x1f',
  '\x20', '\x21', '\x22', '\x23', '\x24', '\x25', '\x26', '\x27',
  '\x28', '\x29', '\x2a', '\x2b', '\x2c', '\x2d', '\x2e', '\x2f',
  '\x30', '\x31', '\x32', '\x33', '\x34', '\x35', '\x36', '\x37',
  '\x38', '\x39', '\x3a', '\x3b', '\x3c', '\x3d', '\x3e', '\x3f',
  '\x40',    'a',    'b',    'c',    'd',    'e',    'f',    'g',
     'h',    'i',    'j',    'k',    'l',    'm',    'n',    'o',
     'p',    'q',    'r',    's',    't',    'u',    'v',    'w',
     'x',    'y',    'z', '\x5b', '\x5c', '\x5d', '\x5e', '\x5f',
  '\x60', '\x61', '\x62', '\x63', '\x64', '\x65', '\x66', '\x67',
  '\x68', '\x69', '\x6a', '\x6b', '\x6c', '\x6d', '\x6e', '\x6f',
  '\x70', '\x71', '\x72', '\x73', '\x74', '\x75', '\x76', '\x77',
  '\x78', '\x79', '\x7a', '\x7b', '\x7c', '\x7d', '\x7e', '\x7f',
  '\x80', '\x81', '\x82', '\x83', '\x84', '\x85', '\x86', '\x87',
  '\x88', '\x89', '\x8a', '\x8b', '\x8c', '\x8d', '\x8e', '\x8f',
  '\x90', '\x91', '\x92', '\x93', '\x94', '\x95', '\x96', '\x97',
  '\x98', '\x99', '\x9a', '\x9b', '\x9c', '\x9d', '\x9e', '\x9f',
  '\xa0', '\xa1', '\xa2', '\xa3', '\xa4', '\xa5', '\xa6', '\xa7',
  '\xa8', '\xa9', '\xaa', '\xab', '\xac', '\xad', '\xae', '\xaf',
  '\xb0', '\xb1', '\xb2', '\xb3', '\xb4', '\xb5', '\xb6', '\xb7',
  '\xb8', '\xb9', '\xba', '\xbb', '\xbc', '\xbd', '\xbe', '\xbf',
  '\xc0', '\xc1', '\xc2', '\xc3', '\xc4', '\xc5', '\xc6', '\xc7',
  '\xc8', '\xc9', '\xca', '\xcb', '\xcc', '\xcd', '\xce', '\xcf',
  '\xd0', '\xd1', '\xd2', '\xd3', '\xd4', '\xd5', '\xd6', '\xd7',
  '\xd8', '\xd9', '\xda', '\xdb', '\xdc', '\xdd', '\xde', '\xdf',
  '\xe0', '\xe1', '\xe2', '\xe3', '\xe4', '\xe5', '\xe6', '\xe7',
  '\xe8', '\xe9', '\xea', '\xeb', '\xec', '\xed', '\xee', '\xef',
  '\xf0', '\xf1', '\xf2', '\xf3', '\xf4', '\xf5', '\xf6', '\xf7',
  '\xf8', '\xf9', '\xfa', '\xfb', '\xfc', '\xfd', '\xfe', '\xff',
};

// Array of characters for the ascii_toupper() function.
const char kToUpper[256] = {
  '\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07',
  '\x08', '\x09', '\x0a', '\x0b', '\x0c', '\x0d', '\x0e', '\x0f',
  '\x10', '\x11', '\x12', '\x13', '\x14', '\x15', '\x16', '\x17',
  '\x18', '\x19', '\x1a', '\x1b', '\x1c', '\x1d', '\x1e', '\x1f',
  '\x20', '\x21', '\x22', '\x23', '\x24', '\x25', '\x26', '\x27',
  '\x28', '\x29', '\x2a', '\x2b', '\x2c', '\x2d', '\x2e', '\x2f',
  '\x30', '\x31', '\x32', '\x33', '\x34', '\x35', '\x36', '\x37',
  '\x38', '\x39', '\x3a', '\x3b', '\x3c', '\x3d', '\x3e', '\x3f',
  '\x40', '\x41', '\x42', '\x43', '\x44', '\x45', '\x46', '\x47',
  '\x48', '\x49', '\x4a', '\x4b', '\x4c', '\x4d', '\x4e', '\x4f',
  '\x50', '\x51', '\x52', '\x53', '\x54', '\x55', '\x56', '\x57',
  '\x58', '\x59', '\x5a', '\x5b', '\x5c', '\x5d', '\x5e', '\x5f',
  '\x60',    'A',    'B',    'C',    'D',    'E',    'F',    'G',
     'H',    'I',    'J',    'K',    'L',    'M',    'N',    'O',
     'P',    'Q',    'R',    'S',    'T',    'U',    'V',    'W',
     'X',    'Y',    'Z', '\x7b', '\x7c', '\x7d', '\x7e', '\x7f',
  '\x80', '\x81', '\x82', '\x83', '\x84', '\x85', '\x86', '\x87',
  '\x88', '\x89', '\x8a', '\x8b', '\x8c', '\x8d', '\x8e', '\x8f',
  '\x90', '\x91', '\x92', '\x93', '\x94', '\x95', '\x96', '\x97',
  '\x98', '\x99', '\x9a', '\x9b', '\x9c', '\x9d', '\x9e', '\x9f',
  '\xa0', '\xa1', '\xa2', '\xa3', '\xa4', '\xa5', '\xa6', '\xa7',
  '\xa8', '\xa9', '\xaa', '\xab', '\xac', '\xad', '\xae', '\xaf',
  '\xb0', '\xb1', '\xb2', '\xb3', '\xb4', '\xb5', '\xb6', '\xb7',
  '\xb8', '\xb9', '\xba', '\xbb', '\xbc', '\xbd', '\xbe', '\xbf',
  '\xc0', '\xc1', '\xc2', '\xc3', '\xc4', '\xc5', '\xc6', '\xc7',
  '\xc8', '\xc9', '\xca', '\xcb', '\xcc', '\xcd', '\xce', '\xcf',
  '\xd0', '\xd1', '\xd2', '\xd3', '\xd4', '\xd5', '\xd6', '\xd7',
  '\xd8', '\xd9', '\xda', '\xdb', '\xdc', '\xdd', '\xde', '\xdf',
  '\xe0', '\xe1', '\xe2', '\xe3', '\xe4', '\xe5', '\xe6', '\xe7',
  '\xe8', '\xe9', '\xea', '\xeb', '\xec', '\xed', '\xee', '\xef',
  '\xf0', '\xf1', '\xf2', '\xf3', '\xf4', '\xf5', '\xf6', '\xf7',
  '\xf8', '\xf9', '\xfa', '\xfb', '\xfc', '\xfd', '\xfe', '\xff',
};
// clang-format on
}  // namespace internal

void AsciiStrToLower(std::string& s) {
  for (auto& c : s)
    c = ascii_tolower(c);
}

std::string AsciiStrToLower(std::string_view s) {
  std::string result(s);
  AsciiStrToLower(result);
  return result;
}

void AsciiStrToUpper(std::string& s) {
  for (auto& c : s)
    c = ascii_toupper(c);
}

std::string AsciiStrToUpper(std::string_view s) {
  std::string result(s);
  AsciiStrToUpper(result);
  return result;
}

bool EqualsIgnoreCase(std::string_view piece1, std::string_view piece2) {
  if (piece1.size() != piece2.size())
    return false;
  if (piece1.empty() && piece2.empty())
    return true;
  auto it1 = piece1.cbegin();
  auto it2 = piece2.cbegin();
  while (it1 != piece1.cend()) {
    if (ascii_tolower(*it1) != ascii_tolower(*it2))
      return false;
    it1++;
    it2++;
  }
  return true;
}

[[nodiscard]] std::string StrCat(
    std::initializer_list<std::string_view> pieces) {
  std::string result;
  size_t length = 0;
  for (const auto& piece : pieces)
    length += piece.size();
  result.reserve(length);
  for (const auto& piece : pieces)
    result.append(piece);
  return result;
}

[[nodiscard]] std::vector<std::string_view> Split(std::string_view value,
                                                  char delim) {
  // Count the number of tokens in the string to size the result.
  size_t num_tokens = 0;
  auto it = value.cbegin();
  const auto end = value.cend();
  while (it != end) {
    while (it != end && *it == delim)
      it++;
    if (it != end)
      num_tokens++;
    while (it != end && *it != delim)
      it++;
  }
  std::vector<std::string_view> result;
  if (num_tokens == 0)
    return result;
  result.reserve(num_tokens);

  // Now find tokens and add them to `result`.
  auto string_begin = value.cbegin();
  auto token_begin = value.cbegin();
  auto token_end = token_begin;
  while (token_begin != end) {
    while (token_begin != end && *token_begin == delim)
      token_begin++;
    token_end = token_begin;
    while (token_end != end && *token_end != delim)
      token_end++;
    if (token_end != token_begin) {
      // TODO(https://issuetracker.google.com/364687926): Replace with
      // iterator-accepting constructor once C++20 is allowed.
      result.emplace_back(value.data() + (token_begin - string_begin),
                          token_end - token_begin);
    }
    token_begin = token_end;
  }
  return result;
}

}  // namespace openscreen::string_util