snix/third_party/nix/src/libutil/args.cc

#include "libutil/args.hh"

#include "libutil/hash.hh"

namespace nix {

Args::FlagMaker Args::mkFlag() { return FlagMaker(*this); }

Args::FlagMaker::~FlagMaker() {
  assert(!flag->longName.empty());
  args.longFlags[flag->longName] = flag;
  if (flag->shortName != 0) {
    args.shortFlags[flag->shortName] = flag;
  }
}

void Args::parseCmdline(const Strings& _cmdline) {
  Strings pendingArgs;
  bool dashDash = false;

  Strings cmdline(_cmdline);

  for (auto pos = cmdline.begin(); pos != cmdline.end();) {
    auto arg = *pos;

    /* Expand compound dash options (i.e., `-qlf' -> `-q -l -f',
       `-j3` -> `-j 3`). */
    if (!dashDash && arg.length() > 2 && arg[0] == '-' && arg[1] != '-' &&
        (isalpha(arg[1]) != 0)) {
      *pos = std::string("-") + arg[1];
      auto next = pos;
      ++next;
      for (unsigned int j = 2; j < arg.length(); j++) {
        if (isalpha(arg[j]) != 0) {
          cmdline.insert(next, std::string("-") + arg[j]);
        } else {
          cmdline.insert(next, std::string(arg, j));
          break;
        }
      }
      arg = *pos;
    }

    if (!dashDash && arg == "--") {
      dashDash = true;
      ++pos;
    } else if (!dashDash && std::string(arg, 0, 1) == "-") {
      if (!processFlag(pos, cmdline.end())) {
        throw UsageError(format("unrecognised flag '%1%'") % arg);
      }
    } else {
      pendingArgs.push_back(*pos++);
      if (processArgs(pendingArgs, false)) {
        pendingArgs.clear();
      }
    }
  }

  processArgs(pendingArgs, true);
}

void Args::printHelp(const std::string& programName, std::ostream& out) {
  std::cout << "Usage: " << programName << " <FLAGS>...";
  for (auto& exp : expectedArgs) {
    std::cout << renderLabels({exp.label});
    // FIXME: handle arity > 1
    if (exp.arity == 0) {
      std::cout << "...";
    }
    if (exp.optional) {
      std::cout << "?";
    }
  }
  std::cout << "\n";

  auto s = description();
  if (!s.empty()) {
    std::cout << "\nSummary: " << s << ".\n";
  }

  if (!longFlags.empty() != 0u) {
    std::cout << "\n";
    std::cout << "Flags:\n";
    printFlags(out);
  }
}

void Args::printFlags(std::ostream& out) {
  Table2 table;
  for (auto& flag : longFlags) {
    if (hiddenCategories.count(flag.second->category) != 0u) {
      continue;
    }
    table.push_back(std::make_pair(
        (flag.second->shortName != 0
             ? std::string("-") + flag.second->shortName + ", "
             : "    ") +
            "--" + flag.first + renderLabels(flag.second->labels),
        flag.second->description));
  }
  printTable(out, table);
}

bool Args::processFlag(Strings::iterator& pos, Strings::iterator end) {
  assert(pos != end);

  auto process = [&](const std::string& name, const Flag& flag) -> bool {
    ++pos;
    std::vector<std::string> args;
    for (size_t n = 0; n < flag.arity; ++n) {
      if (pos == end) {
        if (flag.arity == ArityAny) {
          break;
        }
        throw UsageError(format("flag '%1%' requires %2% argument(s)") % name %
                         flag.arity);
      }
      args.push_back(*pos++);
    }
    flag.handler(std::move(args));
    return true;
  };

  if (std::string(*pos, 0, 2) == "--") {
    auto i = longFlags.find(std::string(*pos, 2));
    if (i == longFlags.end()) {
      return false;
    }
    return process("--" + i->first, *i->second);
  }

  if (std::string(*pos, 0, 1) == "-" && pos->size() == 2) {
    auto c = (*pos)[1];
    auto i = shortFlags.find(c);
    if (i == shortFlags.end()) {
      return false;
    }
    return process(std::string("-") + c, *i->second);
  }

  return false;
}

bool Args::processArgs(const Strings& args, bool finish) {
  if (expectedArgs.empty()) {
    if (!args.empty()) {
      throw UsageError(format("unexpected argument '%1%'") % args.front());
    }
    return true;
  }

  auto& exp = expectedArgs.front();

  bool res = false;

  if ((exp.arity == 0 && finish) ||
      (exp.arity > 0 && args.size() == exp.arity)) {
    std::vector<std::string> ss;
    for (auto& s : args) {
      ss.push_back(s);
    }
    exp.handler(std::move(ss));
    expectedArgs.pop_front();
    res = true;
  }

  if (finish && !expectedArgs.empty() && !expectedArgs.front().optional) {
    throw UsageError("more arguments are required");
  }

  return res;
}

Args::FlagMaker& Args::FlagMaker::mkHashTypeFlag(HashType* ht) {
  arity(1);
  label("type");
  description("hash algorithm ('md5', 'sha1', 'sha256', or 'sha512')");
  handler([ht](const std::string& s) {
    *ht = parseHashType(s);
    if (*ht == htUnknown) {
      throw UsageError("unknown hash type '%1%'", s);
    }
  });
  return *this;
}

Strings argvToStrings(int argc, char** argv) {
  Strings args;
  argc--;
  argv++;
  while ((argc--) != 0) {
    args.push_back(*argv++);
  }
  return args;
}

std::string renderLabels(const Strings& labels) {
  std::string res;
  for (auto label : labels) {
    for (auto& c : label) {
      c = std::toupper(c);
    }
    res += " <" + label + ">";
  }
  return res;
}

void printTable(std::ostream& out, const Table2& table) {
  size_t max = 0;
  for (auto& row : table) {
    max = std::max(max, row.first.size());
  }
  for (auto& row : table) {
    out << "  " << row.first << std::string(max - row.first.size() + 2, ' ')
        << row.second << "\n";
  }
}

}  // namespace nix