githubmirror/node

src/json_utils.cc
69 строк2 KB
Daniel Lemire
src: replace static const string_view by static constexpr
15 апр 2023, 23:28
15 апр 2023, 23:28a777bbd
#include "json_utils.h"

namespace node {

std::string EscapeJsonChars(std::string_view str) {
  // 'static constexpr' is slightly better than static const
  // since the initialization occurs at compile time.
  // See https://lemire.me/blog/I3Cah
  static constexpr std::string_view control_symbols[0x20] = {
      "\\u0000", "\\u0001", "\\u0002", "\\u0003", "\\u0004", "\\u0005",
      "\\u0006", "\\u0007", "\\b",     "\\t",     "\\n",     "\\u000b",
      "\\f",     "\\r",     "\\u000e", "\\u000f", "\\u0010", "\\u0011",
      "\\u0012", "\\u0013", "\\u0014", "\\u0015", "\\u0016", "\\u0017",
      "\\u0018", "\\u0019", "\\u001a", "\\u001b", "\\u001c", "\\u001d",
      "\\u001e", "\\u001f"};

  std::string ret;
  size_t last_pos = 0;
  size_t pos = 0;
  for (; pos < str.size(); ++pos) {
    std::string replace;
    char ch = str[pos];
    if (ch == '\\') {
      replace = "\\\\";
    } else if (ch == '\"') {
      replace = "\\\"";
    } else {
      size_t num = static_cast<size_t>(ch);
      if (num < 0x20) replace = control_symbols[num];
    }
    if (!replace.empty()) {
      if (pos > last_pos) {
        ret += str.substr(last_pos, pos - last_pos);
      }
      last_pos = pos + 1;
      ret += replace;
    }
  }
  // Append any remaining symbols.
  if (last_pos < str.size()) {
    ret += str.substr(last_pos, pos - last_pos);
  }
  return ret;
}

std::string Reindent(const std::string& str, int indent_depth) {
  if (indent_depth <= 0) return str;
  const std::string indent(indent_depth, ' ');
  std::string out;
  std::string::size_type pos = 0;
  for (;;) {
    std::string::size_type prev_pos = pos;
    pos = str.find('\n', pos);

    out.append(indent);

    if (pos == std::string::npos) {
      out.append(str, prev_pos, std::string::npos);
      break;
    } else {
      pos++;
      out.append(str, prev_pos, pos - prev_pos);
    }
  }

  return out;
}

}  // namespace node