int split2monodb::parse_upstreams()

in src/split2monodb.h [64:179]

• 109 lines of code
• 53 McCabe index (conditional complexity)

int split2monodb::parse_upstreams() {
  assert(!has_read_upstreams);
  assert(upstreamsfd != -1);
  mmapped_file file(upstreamsfd);
  upstreamsfd = -1;
  if (!file.num_bytes) {
    // No upstreams.
    has_read_upstreams = true;
    return 0;
  }
  struct context {
    const char *beg;
    const char *cur;
    const char *end;
    context() = delete;
    explicit context(const mmapped_file &file)
        : beg(file.bytes), cur(file.bytes), end(file.bytes + file.num_bytes) {}
  };

  // Create some simple parsers.
  context c(file);
  auto parse_name = [&c](std::string &name) {
    auto *last = c.cur;
    for (; last != c.end; ++last) {
      // Allow "[0-9a-zA-Z-+_.]".
      if (*last >= '0' && *last <= '9' && last != c.cur)
        continue;
      if (*last >= 'a' && *last <= 'z')
        continue;
      if (*last >= 'A' && *last <= 'Z')
        continue;
      if (*last == '.' || *last == '-' || *last == '+' || *last == '_')
        continue;
      break;
    }
    if (c.cur == last)
      return error("invalid name");
    name.assign(c.cur, last);
    c.cur = last;
    return 0;
  };
  auto parse_number = [&c](long &num) {
    auto *last = c.cur;
    for (; last != c.end; ++last) {
      if (*last >= '0' && *last <= '9')
        continue;
      break;
    }
    if (c.cur == last)
      return error("invalid non-negative integer");
    std::string digits(c.cur, last);
    c.cur = last;
    num = strtol(digits.c_str(), nullptr, 10);
    assert(num >= 0);
    return 0;
  };
  auto parse_space = [&c](bool needs_any, bool newlines) {
    // Pull out a separate flag for needing newlines, for simplicity.
    bool needs_newline = newlines && needs_any;
    while (*c.cur == ' ' || *c.cur == '\t' || *c.cur == '\n') {
      if (*c.cur == '\n') {
        if (!newlines)
          return error("unexpected newline");
        needs_newline = false;
      }
      ++c.cur;
      needs_any = false;
    }
    if (needs_newline)
      return error("missing newline");
    if (needs_any)
      return error("expected space");
    return 0;
  };
  auto parse_string = [&c](const char *label) {
    auto impl = [&c](const char *label) {
      for (; c.cur != c.end && *label; ++c.cur, ++label) {
        if (*c.cur == *label)
          continue;
        return 1;
      }
      return *label ? 1 : 0;
    };
    if (impl(label))
      return error("could not parse label '" + std::string(label) + "'");
    return 0;
  };

  // Parse.
  if (parse_space(/*needs_any=*/false, /*newlines=*/true) ||
      parse_string("name:") ||
      parse_space(/*needs_any=*/true, /*newlines=*/false) || parse_name(name) ||
      parse_space(/*needs_any=*/true, /*newlines=*/true))
    return error("could not parse name");
  while (c.cur != c.end) {
    upstream_entry ue;
    if (parse_string("upstream:") ||
        parse_space(/*needs_any=*/true, /*newlines=*/false) ||
        parse_name(ue.name) ||
        parse_space(/*needs_any=*/true, /*newlines=*/false) ||
        parse_string("num-upstreams=") || parse_number(ue.num_upstreams) ||
        parse_space(/*needs_any=*/true, /*newlines=*/false) ||
        parse_string("commits-size=") || parse_number(ue.commits_size) ||
        parse_space(/*needs_any=*/true, /*newlines=*/false) ||
        parse_string("svnbase-size=") || parse_number(ue.svnbase_size) ||
        parse_space(/*needs_any=*/true, /*newlines=*/true))
      return 1;
    if (ue.name == name)
      return error("upstream has same name as main repo");
    std::string copy_name = ue.name;
    if (!upstreams.emplace(std::move(copy_name), std::move(ue)).second)
      return error("duplicate upstream");
  }
  has_read_upstreams = true;
  return 0;
}