Waybar/include/util/clara.hpp

// Copyright 2017 Two Blue Cubes Ltd. All rights reserved.
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See https://github.com/philsquared/Clara for more details

// Clara v1.1.5

#ifndef CLARA_HPP_INCLUDED
#define CLARA_HPP_INCLUDED

#ifndef CLARA_CONFIG_CONSOLE_WIDTH
#define CLARA_CONFIG_CONSOLE_WIDTH 80
#endif

#ifndef CLARA_TEXTFLOW_CONFIG_CONSOLE_WIDTH
#define CLARA_TEXTFLOW_CONFIG_CONSOLE_WIDTH CLARA_CONFIG_CONSOLE_WIDTH
#endif

#ifndef CLARA_CONFIG_OPTIONAL_TYPE
#ifdef __has_include
#if __has_include(<optional>) && __cplusplus >= 201703L
#include <optional>
#define CLARA_CONFIG_OPTIONAL_TYPE std::optional
#endif
#endif
#endif

// ----------- #included from clara_textflow.hpp -----------

// TextFlowCpp
//
// A single-header library for wrapping and laying out basic text, by Phil Nash
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// This project is hosted at https://github.com/philsquared/textflowcpp

#ifndef CLARA_TEXTFLOW_HPP_INCLUDED
#define CLARA_TEXTFLOW_HPP_INCLUDED

#include <cassert>
#include <ostream>
#include <sstream>
#include <vector>

#ifndef CLARA_TEXTFLOW_CONFIG_CONSOLE_WIDTH
#define CLARA_TEXTFLOW_CONFIG_CONSOLE_WIDTH 80
#endif

namespace clara {
namespace TextFlow {

inline auto isWhitespace(char c) -> bool {
  static std::string chars = " \t\n\r";
  return chars.find(c) != std::string::npos;
}
inline auto isBreakableBefore(char c) -> bool {
  static std::string chars = "[({<|";
  return chars.find(c) != std::string::npos;
}
inline auto isBreakableAfter(char c) -> bool {
  static std::string chars = "])}>.,:;*+-=&/\\";
  return chars.find(c) != std::string::npos;
}

class Columns;

class Column {
  std::vector<std::string> m_strings;
  size_t m_width = CLARA_TEXTFLOW_CONFIG_CONSOLE_WIDTH;
  size_t m_indent = 0;
  size_t m_initialIndent = std::string::npos;

 public:
  class iterator {
    friend Column;

    Column const &m_column;
    size_t m_stringIndex = 0;
    size_t m_pos = 0;

    size_t m_len = 0;
    size_t m_end = 0;
    bool m_suffix = false;

    iterator(Column const &column, size_t stringIndex)
        : m_column(column), m_stringIndex(stringIndex) {}

    auto line() const -> std::string const & { return m_column.m_strings[m_stringIndex]; }

    auto isBoundary(size_t at) const -> bool {
      assert(at > 0);
      assert(at <= line().size());

      return at == line().size() || (isWhitespace(line()[at]) && !isWhitespace(line()[at - 1])) ||
             isBreakableBefore(line()[at]) || isBreakableAfter(line()[at - 1]);
    }

    void calcLength() {
      assert(m_stringIndex < m_column.m_strings.size());

      m_suffix = false;
      auto width = m_column.m_width - indent();
      m_end = m_pos;
      while (m_end < line().size() && line()[m_end] != '\n') ++m_end;

      if (m_end < m_pos + width) {
        m_len = m_end - m_pos;
      } else {
        size_t len = width;
        while (len > 0 && !isBoundary(m_pos + len)) --len;
        while (len > 0 && isWhitespace(line()[m_pos + len - 1])) --len;

        if (len > 0) {
          m_len = len;
        } else {
          m_suffix = true;
          m_len = width - 1;
        }
      }
    }

    auto indent() const -> size_t {
      auto initial =
          m_pos == 0 && m_stringIndex == 0 ? m_column.m_initialIndent : std::string::npos;
      return initial == std::string::npos ? m_column.m_indent : initial;
    }

    auto addIndentAndSuffix(std::string const &plain) const -> std::string {
      return std::string(indent(), ' ') + (m_suffix ? plain + "-" : plain);
    }

   public:
    using difference_type = std::ptrdiff_t;
    using value_type = std::string;
    using pointer = value_type *;
    using reference = value_type &;
    using iterator_category = std::forward_iterator_tag;

    explicit iterator(Column const &column) : m_column(column) {
      assert(m_column.m_width > m_column.m_indent);
      assert(m_column.m_initialIndent == std::string::npos ||
             m_column.m_width > m_column.m_initialIndent);
      calcLength();
      if (m_len == 0) m_stringIndex++;  // Empty string
    }

    auto operator*() const -> std::string {
      assert(m_stringIndex < m_column.m_strings.size());
      assert(m_pos <= m_end);
      return addIndentAndSuffix(line().substr(m_pos, m_len));
    }

    auto operator++() -> iterator & {
      m_pos += m_len;
      if (m_pos < line().size() && line()[m_pos] == '\n')
        m_pos += 1;
      else
        while (m_pos < line().size() && isWhitespace(line()[m_pos])) ++m_pos;

      if (m_pos == line().size()) {
        m_pos = 0;
        ++m_stringIndex;
      }
      if (m_stringIndex < m_column.m_strings.size()) calcLength();
      return *this;
    }
    auto operator++(int) -> iterator {
      iterator prev(*this);
      operator++();
      return prev;
    }

    auto operator==(iterator const &other) const -> bool {
      return m_pos == other.m_pos && m_stringIndex == other.m_stringIndex &&
             &m_column == &other.m_column;
    }
    auto operator!=(iterator const &other) const -> bool { return !operator==(other); }
  };
  using const_iterator = iterator;

  explicit Column(std::string const &text) { m_strings.push_back(text); }

  auto width(size_t newWidth) -> Column & {
    assert(newWidth > 0);
    m_width = newWidth;
    return *this;
  }
  auto indent(size_t newIndent) -> Column & {
    m_indent = newIndent;
    return *this;
  }
  auto initialIndent(size_t newIndent) -> Column & {
    m_initialIndent = newIndent;
    return *this;
  }

  auto width() const -> size_t { return m_width; }
  auto begin() const -> iterator { return iterator(*this); }
  auto end() const -> iterator { return {*this, m_strings.size()}; }

  inline friend std::ostream &operator<<(std::ostream &os, Column const &col) {
    bool first = true;
    for (auto line : col) {
      if (first)
        first = false;
      else
        os << "\n";
      os << line;
    }
    return os;
  }

  auto operator+(Column const &other) -> Columns;

  auto toString() const -> std::string {
    std::ostringstream oss;
    oss << *this;
    return oss.str();
  }
};

class Spacer : public Column {
 public:
  explicit Spacer(size_t spaceWidth) : Column("") { width(spaceWidth); }
};

class Columns {
  std::vector<Column> m_columns;

 public:
  class iterator {
    friend Columns;
    struct EndTag {};

    std::vector<Column> const &m_columns;
    std::vector<Column::iterator> m_iterators;
    size_t m_activeIterators;

    iterator(Columns const &columns, EndTag) : m_columns(columns.m_columns), m_activeIterators(0) {
      m_iterators.reserve(m_columns.size());

      for (auto const &col : m_columns) m_iterators.push_back(col.end());
    }

   public:
    using difference_type = std::ptrdiff_t;
    using value_type = std::string;
    using pointer = value_type *;
    using reference = value_type &;
    using iterator_category = std::forward_iterator_tag;

    explicit iterator(Columns const &columns)
        : m_columns(columns.m_columns), m_activeIterators(m_columns.size()) {
      m_iterators.reserve(m_columns.size());

      for (auto const &col : m_columns) m_iterators.push_back(col.begin());
    }

    auto operator==(iterator const &other) const -> bool {
      return m_iterators == other.m_iterators;
    }
    auto operator!=(iterator const &other) const -> bool {
      return m_iterators != other.m_iterators;
    }
    auto operator*() const -> std::string {
      std::string row, padding;

      for (size_t i = 0; i < m_columns.size(); ++i) {
        auto width = m_columns[i].width();
        if (m_iterators[i] != m_columns[i].end()) {
          std::string col = *m_iterators[i];
          row += padding + col;
          if (col.size() < width)
            padding = std::string(width - col.size(), ' ');
          else
            padding = "";
        } else {
          padding += std::string(width, ' ');
        }
      }
      return row;
    }
    auto operator++() -> iterator & {
      for (size_t i = 0; i < m_columns.size(); ++i) {
        if (m_iterators[i] != m_columns[i].end()) ++m_iterators[i];
      }
      return *this;
    }
    auto operator++(int) -> iterator {
      iterator prev(*this);
      operator++();
      return prev;
    }
  };
  using const_iterator = iterator;

  auto begin() const -> iterator { return iterator(*this); }
  auto end() const -> iterator { return {*this, iterator::EndTag()}; }

  auto operator+=(Column const &col) -> Columns & {
    m_columns.push_back(col);
    return *this;
  }
  auto operator+(Column const &col) -> Columns {
    Columns combined = *this;
    combined += col;
    return combined;
  }

  inline friend std::ostream &operator<<(std::ostream &os, Columns const &cols) {
    bool first = true;
    for (auto line : cols) {
      if (first)
        first = false;
      else
        os << "\n";
      os << line;
    }
    return os;
  }

  auto toString() const -> std::string {
    std::ostringstream oss;
    oss << *this;
    return oss.str();
  }
};

inline auto Column::operator+(Column const &other) -> Columns {
  Columns cols;
  cols += *this;
  cols += other;
  return cols;
}
}  // namespace TextFlow
}  // namespace clara

#endif  // CLARA_TEXTFLOW_HPP_INCLUDED

// ----------- end of #include from clara_textflow.hpp -----------
// ........... back in clara.hpp

#include <algorithm>
#include <memory>
#include <set>

#if !defined(CLARA_PLATFORM_WINDOWS) && \
    (defined(WIN32) || defined(__WIN32__) || defined(_WIN32) || defined(_MSC_VER))
#define CLARA_PLATFORM_WINDOWS
#endif

namespace clara {
namespace detail {

// Traits for extracting arg and return type of lambdas (for single argument lambdas)
template <typename L>
struct UnaryLambdaTraits : UnaryLambdaTraits<decltype(&L::operator())> {};

template <typename ClassT, typename ReturnT, typename... Args>
struct UnaryLambdaTraits<ReturnT (ClassT::*)(Args...) const> {
  static const bool isValid = false;
};

template <typename ClassT, typename ReturnT, typename ArgT>
struct UnaryLambdaTraits<ReturnT (ClassT::*)(ArgT) const> {
  static const bool isValid = true;
  using ArgType = typename std::remove_const<typename std::remove_reference<ArgT>::type>::type;
  using ReturnType = ReturnT;
};

class TokenStream;

// Transport for raw args (copied from main args, or supplied via init list for testing)
class Args {
  friend TokenStream;
  std::string m_exeName;
  std::vector<std::string> m_args;

 public:
  Args(int argc, char const *const *argv) : m_exeName(argv[0]), m_args(argv + 1, argv + argc) {}

  Args(std::initializer_list<std::string> args)
      : m_exeName(*args.begin()), m_args(args.begin() + 1, args.end()) {}

  auto exeName() const -> std::string { return m_exeName; }
};

// Wraps a token coming from a token stream. These may not directly correspond to strings as a
// single string may encode an option + its argument if the : or = form is used
enum class TokenType { Option, Argument };
struct Token {
  TokenType type;
  std::string token;
};

inline auto isOptPrefix(char c) -> bool {
  return c == '-'
#ifdef CLARA_PLATFORM_WINDOWS
         || c == '/'
#endif
      ;
}

// Abstracts iterators into args as a stream of tokens, with option arguments uniformly handled
class TokenStream {
  using Iterator = std::vector<std::string>::const_iterator;
  Iterator it;
  Iterator itEnd;
  std::vector<Token> m_tokenBuffer;

  void loadBuffer() {
    m_tokenBuffer.resize(0);

    // Skip any empty strings
    while (it != itEnd && it->empty()) ++it;

    if (it != itEnd) {
      auto const &next = *it;
      if (isOptPrefix(next[0])) {
        auto delimiterPos = next.find_first_of(" :=");
        if (delimiterPos != std::string::npos) {
          m_tokenBuffer.push_back({TokenType::Option, next.substr(0, delimiterPos)});
          m_tokenBuffer.push_back({TokenType::Argument, next.substr(delimiterPos + 1)});
        } else {
          if (next[1] != '-' && next.size() > 2) {
            std::string opt = "- ";
            for (size_t i = 1; i < next.size(); ++i) {
              opt[1] = next[i];
              m_tokenBuffer.push_back({TokenType::Option, opt});
            }
          } else {
            m_tokenBuffer.push_back({TokenType::Option, next});
          }
        }
      } else {
        m_tokenBuffer.push_back({TokenType::Argument, next});
      }
    }
  }

 public:
  explicit TokenStream(Args const &args) : TokenStream(args.m_args.begin(), args.m_args.end()) {}

  TokenStream(Iterator it, Iterator itEnd) : it(it), itEnd(itEnd) { loadBuffer(); }

  explicit operator bool() const { return !m_tokenBuffer.empty() || it != itEnd; }

  auto count() const -> size_t { return m_tokenBuffer.size() + (itEnd - it); }

  auto operator*() const -> Token {
    assert(!m_tokenBuffer.empty());
    return m_tokenBuffer.front();
  }

  auto operator->() const -> Token const * {
    assert(!m_tokenBuffer.empty());
    return &m_tokenBuffer.front();
  }

  auto operator++() -> TokenStream & {
    if (m_tokenBuffer.size() >= 2) {
      m_tokenBuffer.erase(m_tokenBuffer.begin());
    } else {
      if (it != itEnd) ++it;
      loadBuffer();
    }
    return *this;
  }
};

class ResultBase {
 public:
  enum Type { Ok, LogicError, RuntimeError };

 protected:
  ResultBase(Type type) : m_type(type) {}
  virtual ~ResultBase() = default;

  virtual void enforceOk() const = 0;

  Type m_type;
};

template <typename T>
class ResultValueBase : public ResultBase {
 public:
  auto value() const -> T const & {
    enforceOk();
    return m_value;
  }

 protected:
  ResultValueBase(Type type) : ResultBase(type) {}

  ResultValueBase(ResultValueBase const &other) : ResultBase(other) {
    if (m_type == ResultBase::Ok) new (&m_value) T(other.m_value);
  }

  ResultValueBase(Type, T const &value) : ResultBase(Ok) { new (&m_value) T(value); }

  auto operator=(ResultValueBase const &other) -> ResultValueBase & {
    if (m_type == ResultBase::Ok) m_value.~T();
    ResultBase::operator=(other);
    if (m_type == ResultBase::Ok) new (&m_value) T(other.m_value);
    return *this;
  }

  ~ResultValueBase() override {
    if (m_type == Ok) m_value.~T();
  }

  union {
    T m_value;
  };
};

template <>
class ResultValueBase<void> : public ResultBase {
 protected:
  using ResultBase::ResultBase;
};

template <typename T = void>
class BasicResult : public ResultValueBase<T> {
 public:
  template <typename U>
  explicit BasicResult(BasicResult<U> const &other)
      : ResultValueBase<T>(other.type()), m_errorMessage(other.errorMessage()) {
    assert(type() != ResultBase::Ok);
  }

  template <typename U>
  static auto ok(U const &value) -> BasicResult {
    return {ResultBase::Ok, value};
  }
  static auto ok() -> BasicResult { return {ResultBase::Ok}; }
  static auto logicError(std::string const &message) -> BasicResult {
    return {ResultBase::LogicError, message};
  }
  static auto runtimeError(std::string const &message) -> BasicResult {
    return {ResultBase::RuntimeError, message};
  }

  explicit operator bool() const { return m_type == ResultBase::Ok; }
  auto type() const -> ResultBase::Type { return m_type; }
  auto errorMessage() const -> std::string { return m_errorMessage; }

 protected:
  void enforceOk() const override {
    // Errors shouldn't reach this point, but if they do
    // the actual error message will be in m_errorMessage
    assert(m_type != ResultBase::LogicError);
    assert(m_type != ResultBase::RuntimeError);
    if (m_type != ResultBase::Ok) std::abort();
  }

  std::string m_errorMessage;  // Only populated if resultType is an error

  BasicResult(ResultBase::Type type, std::string const &message)
      : ResultValueBase<T>(type), m_errorMessage(message) {
    assert(m_type != ResultBase::Ok);
  }

  using ResultValueBase<T>::ResultValueBase;
  using ResultBase::m_type;
};

enum class ParseResultType { Matched, NoMatch, ShortCircuitAll, ShortCircuitSame };

class ParseState {
 public:
  ParseState(ParseResultType type, TokenStream const &remainingTokens)
      : m_type(type), m_remainingTokens(remainingTokens) {}

  auto type() const -> ParseResultType { return m_type; }
  auto remainingTokens() const -> TokenStream { return m_remainingTokens; }

 private:
  ParseResultType m_type;
  TokenStream m_remainingTokens;
};

using Result = BasicResult<void>;
using ParserResult = BasicResult<ParseResultType>;
using InternalParseResult = BasicResult<ParseState>;

struct HelpColumns {
  std::string left;
  std::string right;
};

template <typename T>
inline auto convertInto(std::string const &source, T &target) -> ParserResult {
  std::stringstream ss;
  ss << source;
  ss >> target;
  if (ss.fail())
    return ParserResult::runtimeError("Unable to convert '" + source + "' to destination type");
  else
    return ParserResult::ok(ParseResultType::Matched);
}
inline auto convertInto(std::string const &source, std::string &target) -> ParserResult {
  target = source;
  return ParserResult::ok(ParseResultType::Matched);
}
inline auto convertInto(std::string const &source, bool &target) -> ParserResult {
  std::string srcLC = source;
  std::transform(srcLC.begin(), srcLC.end(), srcLC.begin(),
                 [](char c) { return static_cast<char>(::tolower(c)); });
  if (srcLC == "y" || srcLC == "1" || srcLC == "true" || srcLC == "yes" || srcLC == "on")
    target = true;
  else if (srcLC == "n" || srcLC == "0" || srcLC == "false" || srcLC == "no" || srcLC == "off")
    target = false;
  else
    return ParserResult::runtimeError("Expected a boolean value but did not recognise: '" + source +
                                      "'");
  return ParserResult::ok(ParseResultType::Matched);
}
#ifdef CLARA_CONFIG_OPTIONAL_TYPE
template <typename T>
inline auto convertInto(std::string const &source, CLARA_CONFIG_OPTIONAL_TYPE<T> &target)
    -> ParserResult {
  T temp;
  auto result = convertInto(source, temp);
  if (result) target = std::move(temp);
  return result;
}
#endif  // CLARA_CONFIG_OPTIONAL_TYPE

struct NonCopyable {
  NonCopyable() = default;
  NonCopyable(NonCopyable const &) = delete;
  NonCopyable(NonCopyable &&) = delete;
  NonCopyable &operator=(NonCopyable const &) = delete;
  NonCopyable &operator=(NonCopyable &&) = delete;
};

struct BoundRef : NonCopyable {
  virtual ~BoundRef() = default;
  virtual auto isContainer() const -> bool { return false; }
  virtual auto isFlag() const -> bool { return false; }
};
struct BoundValueRefBase : BoundRef {
  virtual auto setValue(std::string const &arg) -> ParserResult = 0;
};
struct BoundFlagRefBase : BoundRef {
  virtual auto setFlag(bool flag) -> ParserResult = 0;
  virtual auto isFlag() const -> bool { return true; }
};

template <typename T>
struct BoundValueRef : BoundValueRefBase {
  T &m_ref;

  explicit BoundValueRef(T &ref) : m_ref(ref) {}

  auto setValue(std::string const &arg) -> ParserResult override { return convertInto(arg, m_ref); }
};

template <typename T>
struct BoundValueRef<std::vector<T>> : BoundValueRefBase {
  std::vector<T> &m_ref;

  explicit BoundValueRef(std::vector<T> &ref) : m_ref(ref) {}

  auto isContainer() const -> bool override { return true; }

  auto setValue(std::string const &arg) -> ParserResult override {
    T temp;
    auto result = convertInto(arg, temp);
    if (result) m_ref.push_back(temp);
    return result;
  }
};

struct BoundFlagRef : BoundFlagRefBase {
  bool &m_ref;

  explicit BoundFlagRef(bool &ref) : m_ref(ref) {}

  auto setFlag(bool flag) -> ParserResult override {
    m_ref = flag;
    return ParserResult::ok(ParseResultType::Matched);
  }
};

template <typename ReturnType>
struct LambdaInvoker {
  static_assert(std::is_same<ReturnType, ParserResult>::value,
                "Lambda must return void or clara::ParserResult");

  template <typename L, typename ArgType>
  static auto invoke(L const &lambda, ArgType const &arg) -> ParserResult {
    return lambda(arg);
  }
};

template <>
struct LambdaInvoker<void> {
  template <typename L, typename ArgType>
  static auto invoke(L const &lambda, ArgType const &arg) -> ParserResult {
    lambda(arg);
    return ParserResult::ok(ParseResultType::Matched);
  }
};

template <typename ArgType, typename L>
inline auto invokeLambda(L const &lambda, std::string const &arg) -> ParserResult {
  ArgType temp{};
  auto result = convertInto(arg, temp);
  return !result ? result
                 : LambdaInvoker<typename UnaryLambdaTraits<L>::ReturnType>::invoke(lambda, temp);
}

template <typename L>
struct BoundLambda : BoundValueRefBase {
  L m_lambda;

  static_assert(UnaryLambdaTraits<L>::isValid, "Supplied lambda must take exactly one argument");
  explicit BoundLambda(L const &lambda) : m_lambda(lambda) {}

  auto setValue(std::string const &arg) -> ParserResult override {
    return invokeLambda<typename UnaryLambdaTraits<L>::ArgType>(m_lambda, arg);
  }
};

template <typename L>
struct BoundFlagLambda : BoundFlagRefBase {
  L m_lambda;

  static_assert(UnaryLambdaTraits<L>::isValid, "Supplied lambda must take exactly one argument");
  static_assert(std::is_same<typename UnaryLambdaTraits<L>::ArgType, bool>::value,
                "flags must be boolean");

  explicit BoundFlagLambda(L const &lambda) : m_lambda(lambda) {}

  auto setFlag(bool flag) -> ParserResult override {
    return LambdaInvoker<typename UnaryLambdaTraits<L>::ReturnType>::invoke(m_lambda, flag);
  }
};

enum class Optionality { Optional, Required };

struct Parser;

class ParserBase {
 public:
  virtual ~ParserBase() = default;
  virtual auto validate() const -> Result { return Result::ok(); }
  virtual auto parse(std::string const &exeName, TokenStream const &tokens) const
      -> InternalParseResult = 0;
  virtual auto cardinality() const -> size_t { return 1; }

  auto parse(Args const &args) const -> InternalParseResult {
    return parse(args.exeName(), TokenStream(args));
  }
};

template <typename DerivedT>
class ComposableParserImpl : public ParserBase {
 public:
  template <typename T>
  auto operator|(T const &other) const -> Parser;

  template <typename T>
  auto operator+(T const &other) const -> Parser;
};

// Common code and state for Args and Opts
template <typename DerivedT>
class ParserRefImpl : public ComposableParserImpl<DerivedT> {
 protected:
  Optionality m_optionality = Optionality::Optional;
  std::shared_ptr<BoundRef> m_ref;
  std::string m_hint;
  std::string m_description;

  explicit ParserRefImpl(std::shared_ptr<BoundRef> const &ref) : m_ref(ref) {}

 public:
  template <typename T>
  ParserRefImpl(T &ref, std::string const &hint)
      : m_ref(std::make_shared<BoundValueRef<T>>(ref)), m_hint(hint) {}

  template <typename LambdaT>
  ParserRefImpl(LambdaT const &ref, std::string const &hint)
      : m_ref(std::make_shared<BoundLambda<LambdaT>>(ref)), m_hint(hint) {}

  auto operator()(std::string const &description) -> DerivedT & {
    m_description = description;
    return static_cast<DerivedT &>(*this);
  }

  auto optional() -> DerivedT & {
    m_optionality = Optionality::Optional;
    return static_cast<DerivedT &>(*this);
  };

  auto required() -> DerivedT & {
    m_optionality = Optionality::Required;
    return static_cast<DerivedT &>(*this);
  };

  auto isOptional() const -> bool { return m_optionality == Optionality::Optional; }

  auto cardinality() const -> size_t override {
    if (m_ref->isContainer())
      return 0;
    else
      return 1;
  }

  auto hint() const -> std::string { return m_hint; }
};

class ExeName : public ComposableParserImpl<ExeName> {
  std::shared_ptr<std::string> m_name;
  std::shared_ptr<BoundValueRefBase> m_ref;

  template <typename LambdaT>
  static auto makeRef(LambdaT const &lambda) -> std::shared_ptr<BoundValueRefBase> {
    return std::make_shared<BoundLambda<LambdaT>>(lambda);
  }

 public:
  ExeName() : m_name(std::make_shared<std::string>("<executable>")) {}

  explicit ExeName(std::string &ref) : ExeName() {
    m_ref = std::make_shared<BoundValueRef<std::string>>(ref);
  }

  template <typename LambdaT>
  explicit ExeName(LambdaT const &lambda) : ExeName() {
    m_ref = std::make_shared<BoundLambda<LambdaT>>(lambda);
  }

  // The exe name is not parsed out of the normal tokens, but is handled specially
  auto parse(std::string const &, TokenStream const &tokens) const -> InternalParseResult override {
    return InternalParseResult::ok(ParseState(ParseResultType::NoMatch, tokens));
  }

  auto name() const -> std::string { return *m_name; }
  auto set(std::string const &newName) -> ParserResult {
    auto lastSlash = newName.find_last_of("\\/");
    auto filename = (lastSlash == std::string::npos) ? newName : newName.substr(lastSlash + 1);

    *m_name = filename;
    if (m_ref)
      return m_ref->setValue(filename);
    else
      return ParserResult::ok(ParseResultType::Matched);
  }
};

class Arg : public ParserRefImpl<Arg> {
 public:
  using ParserRefImpl::ParserRefImpl;

  auto parse(std::string const &, TokenStream const &tokens) const -> InternalParseResult override {
    auto validationResult = validate();
    if (!validationResult) return InternalParseResult(validationResult);

    auto remainingTokens = tokens;
    auto const &token = *remainingTokens;
    if (token.type != TokenType::Argument)
      return InternalParseResult::ok(ParseState(ParseResultType::NoMatch, remainingTokens));

    assert(!m_ref->isFlag());
    auto valueRef = static_cast<detail::BoundValueRefBase *>(m_ref.get());

    auto result = valueRef->setValue(remainingTokens->token);
    if (!result)
      return InternalParseResult(result);
    else
      return InternalParseResult::ok(ParseState(ParseResultType::Matched, ++remainingTokens));
  }
};

inline auto normaliseOpt(std::string const &optName) -> std::string {
#ifdef CLARA_PLATFORM_WINDOWS
  if (optName[0] == '/')
    return "-" + optName.substr(1);
  else
#endif
    return optName;
}

class Opt : public ParserRefImpl<Opt> {
 protected:
  std::vector<std::string> m_optNames;

 public:
  template <typename LambdaT>
  explicit Opt(LambdaT const &ref)
      : ParserRefImpl(std::make_shared<BoundFlagLambda<LambdaT>>(ref)) {}

  explicit Opt(bool &ref) : ParserRefImpl(std::make_shared<BoundFlagRef>(ref)) {}

  template <typename LambdaT>
  Opt(LambdaT const &ref, std::string const &hint) : ParserRefImpl(ref, hint) {}

  template <typename T>
  Opt(T &ref, std::string const &hint) : ParserRefImpl(ref, hint) {}

  auto operator[](std::string const &optName) -> Opt & {
    m_optNames.push_back(optName);
    return *this;
  }

  auto getHelpColumns() const -> std::vector<HelpColumns> {
    std::ostringstream oss;
    bool first = true;
    for (auto const &opt : m_optNames) {
      if (first)
        first = false;
      else
        oss << ", ";
      oss << opt;
    }
    if (!m_hint.empty()) oss << " <" << m_hint << ">";
    return {{oss.str(), m_description}};
  }

  auto isMatch(std::string const &optToken) const -> bool {
    auto normalisedToken = normaliseOpt(optToken);
    for (auto const &name : m_optNames) {
      if (normaliseOpt(name) == normalisedToken) return true;
    }
    return false;
  }

  using ParserBase::parse;

  auto parse(std::string const &, TokenStream const &tokens) const -> InternalParseResult override {
    auto validationResult = validate();
    if (!validationResult) return InternalParseResult(validationResult);

    auto remainingTokens = tokens;
    if (remainingTokens && remainingTokens->type == TokenType::Option) {
      auto const &token = *remainingTokens;
      if (isMatch(token.token)) {
        if (m_ref->isFlag()) {
          auto flagRef = static_cast<detail::BoundFlagRefBase *>(m_ref.get());
          auto result = flagRef->setFlag(true);
          if (!result) return InternalParseResult(result);
          if (result.value() == ParseResultType::ShortCircuitAll)
            return InternalParseResult::ok(ParseState(result.value(), remainingTokens));
        } else {
          auto valueRef = static_cast<detail::BoundValueRefBase *>(m_ref.get());
          ++remainingTokens;
          if (!remainingTokens)
            return InternalParseResult::runtimeError("Expected argument following " + token.token);
          auto const &argToken = *remainingTokens;
          if (argToken.type != TokenType::Argument)
            return InternalParseResult::runtimeError("Expected argument following " + token.token);
          auto result = valueRef->setValue(argToken.token);
          if (!result) return InternalParseResult(result);
          if (result.value() == ParseResultType::ShortCircuitAll)
            return InternalParseResult::ok(ParseState(result.value(), remainingTokens));
        }
        return InternalParseResult::ok(ParseState(ParseResultType::Matched, ++remainingTokens));
      }
    }
    return InternalParseResult::ok(ParseState(ParseResultType::NoMatch, remainingTokens));
  }

  auto validate() const -> Result override {
    if (m_optNames.empty()) return Result::logicError("No options supplied to Opt");
    for (auto const &name : m_optNames) {
      if (name.empty()) return Result::logicError("Option name cannot be empty");
#ifdef CLARA_PLATFORM_WINDOWS
      if (name[0] != '-' && name[0] != '/')
        return Result::logicError("Option name must begin with '-' or '/'");
#else
      if (name[0] != '-') return Result::logicError("Option name must begin with '-'");
#endif
    }
    return ParserRefImpl::validate();
  }
};

struct Help : Opt {
  Help(bool &showHelpFlag)
      : Opt([&](bool flag) {
          showHelpFlag = flag;
          return ParserResult::ok(ParseResultType::ShortCircuitAll);
        }) {
    static_cast<Opt &> (*this)("display usage information")["-?"]["-h"]["--help"].optional();
  }
};

struct Parser : ParserBase {
  mutable ExeName m_exeName;
  std::vector<Opt> m_options;
  std::vector<Arg> m_args;

  auto operator|=(ExeName const &exeName) -> Parser & {
    m_exeName = exeName;
    return *this;
  }

  auto operator|=(Arg const &arg) -> Parser & {
    m_args.push_back(arg);
    return *this;
  }

  auto operator|=(Opt const &opt) -> Parser & {
    m_options.push_back(opt);
    return *this;
  }

  auto operator|=(Parser const &other) -> Parser & {
    m_options.insert(m_options.end(), other.m_options.begin(), other.m_options.end());
    m_args.insert(m_args.end(), other.m_args.begin(), other.m_args.end());
    return *this;
  }

  template <typename T>
  auto operator|(T const &other) const -> Parser {
    return Parser(*this) |= other;
  }

  // Forward deprecated interface with '+' instead of '|'
  template <typename T>
  auto operator+=(T const &other) -> Parser & {
    return operator|=(other);
  }
  template <typename T>
  auto operator+(T const &other) const -> Parser {
    return operator|(other);
  }

  auto getHelpColumns() const -> std::vector<HelpColumns> {
    std::vector<HelpColumns> cols;
    for (auto const &o : m_options) {
      auto childCols = o.getHelpColumns();
      cols.insert(cols.end(), childCols.begin(), childCols.end());
    }
    return cols;
  }

  void writeToStream(std::ostream &os) const {
    if (!m_exeName.name().empty()) {
      os << "usage:\n"
         << "  " << m_exeName.name() << " ";
      bool required = true, first = true;
      for (auto const &arg : m_args) {
        if (first)
          first = false;
        else
          os << " ";
        if (arg.isOptional() && required) {
          os << "[";
          required = false;
        }
        os << "<" << arg.hint() << ">";
        if (arg.cardinality() == 0) os << " ... ";
      }
      if (!required) os << "]";
      if (!m_options.empty()) os << " options";
      os << "\n\nwhere options are:" << std::endl;
    }

    auto rows = getHelpColumns();
    size_t consoleWidth = CLARA_CONFIG_CONSOLE_WIDTH;
    size_t optWidth = 0;
    for (auto const &cols : rows) optWidth = (std::max)(optWidth, cols.left.size() + 2);

    optWidth = (std::min)(optWidth, consoleWidth / 2);

    for (auto const &cols : rows) {
      auto row = TextFlow::Column(cols.left).width(optWidth).indent(2) + TextFlow::Spacer(4) +
                 TextFlow::Column(cols.right).width(consoleWidth - 7 - optWidth);
      os << row << std::endl;
    }
  }

  friend auto operator<<(std::ostream &os, Parser const &parser) -> std::ostream & {
    parser.writeToStream(os);
    return os;
  }

  auto validate() const -> Result override {
    for (auto const &opt : m_options) {
      auto result = opt.validate();
      if (!result) return result;
    }
    for (auto const &arg : m_args) {
      auto result = arg.validate();
      if (!result) return result;
    }
    return Result::ok();
  }

  using ParserBase::parse;

  auto parse(std::string const &exeName, TokenStream const &tokens) const
      -> InternalParseResult override {
    struct ParserInfo {
      ParserBase const *parser = nullptr;
      size_t count = 0;
    };
    const size_t totalParsers = m_options.size() + m_args.size();
    assert(totalParsers < 512);
    // ParserInfo parseInfos[totalParsers]; // <-- this is what we really want to do
    ParserInfo parseInfos[512];

    {
      size_t i = 0;
      for (auto const &opt : m_options) parseInfos[i++].parser = &opt;
      for (auto const &arg : m_args) parseInfos[i++].parser = &arg;
    }

    m_exeName.set(exeName);

    auto result = InternalParseResult::ok(ParseState(ParseResultType::NoMatch, tokens));
    while (result.value().remainingTokens()) {
      bool tokenParsed = false;

      for (size_t i = 0; i < totalParsers; ++i) {
        auto &parseInfo = parseInfos[i];
        if (parseInfo.parser->cardinality() == 0 ||
            parseInfo.count < parseInfo.parser->cardinality()) {
          result = parseInfo.parser->parse(exeName, result.value().remainingTokens());
          if (!result) return result;
          if (result.value().type() != ParseResultType::NoMatch) {
            tokenParsed = true;
            ++parseInfo.count;
            break;
          }
        }
      }

      if (result.value().type() == ParseResultType::ShortCircuitAll) return result;
      if (!tokenParsed)
        return InternalParseResult::runtimeError("Unrecognised token: " +
                                                 result.value().remainingTokens()->token);
    }
    // !TBD Check missing required options
    return result;
  }
};

template <typename DerivedT>
template <typename T>
auto ComposableParserImpl<DerivedT>::operator|(T const &other) const -> Parser {
  return Parser() | static_cast<DerivedT const &>(*this) | other;
}
}  // namespace detail

// A Combined parser
using detail::Parser;

// A parser for options
using detail::Opt;

// A parser for arguments
using detail::Arg;

// Wrapper for argc, argv from main()
using detail::Args;

// Specifies the name of the executable
using detail::ExeName;

// Convenience wrapper for option parser that specifies the help option
using detail::Help;

// enum of result types from a parse
using detail::ParseResultType;

// Result type for parser operation
using detail::ParserResult;

}  // namespace clara

#endif  // CLARA_HPP_INCLUDED