clipp.h

/*****************************************************************************
 *
 * CLIPP - command line interfaces for modern C++
 *
 * released under MIT license
 *
 * (c) 2017 André Müller; foss@andremueller-online.de
 *
 *****************************************************************************/

#ifndef AM_CLIPP_H__
#define AM_CLIPP_H__

#include <cstring>
#include <string>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <cmath>
#include <memory>
#include <vector>
#include <limits>
#include <stack>
#include <algorithm>
#include <sstream>
#include <utility>
#include <iterator>
#include <functional>


/*************************************************************************//**
 *
 * @brief primary namespace
 *
 *****************************************************************************/
namespace clipp {



/*****************************************************************************
 *
 * basic constants and datatype definitions
 *
 *****************************************************************************/
using arg_index = int;

using arg_string = std::string;
using doc_string = std::string;

using arg_list  = std::vector<arg_string>;



/*************************************************************************//**
 *
 * @brief tristate
 *
 *****************************************************************************/
enum class tri : char { no, yes, either };

inline constexpr bool operator == (tri t, bool b) noexcept {
    return b ? t != tri::no : t != tri::yes;
}
inline constexpr bool operator == (bool b, tri t) noexcept { return  (t == b); }
inline constexpr bool operator != (tri t, bool b) noexcept { return !(t == b); }
inline constexpr bool operator != (bool b, tri t) noexcept { return !(t == b); }



/*************************************************************************//**
 *
 * @brief (start,size) index range
 *
 *****************************************************************************/
class subrange {
public:
    using size_type = arg_string::size_type;

    /** @brief default: no match */
    explicit constexpr
    subrange() noexcept :
        at_{arg_string::npos}, length_{0}
    {}

    /** @brief match length & position within subject string */
    explicit constexpr
    subrange(size_type pos, size_type len) noexcept :
        at_{pos}, length_{len}
    {}

    /** @brief position of the match within the subject string */
    constexpr size_type at()     const noexcept { return at_; }
    /** @brief length of the matching subsequence */
    constexpr size_type length() const noexcept { return length_; }

    /** @brief returns true, if query string is a prefix of the subject string */
    constexpr bool prefix() const noexcept {
        return at_ == 0 && length_ > 0;
    }

    /** @brief returns true, if query is a substring of the query string */
    constexpr explicit operator bool () const noexcept {
        return at_ != arg_string::npos && length_ > 0;
    }

private:
    size_type at_;
    size_type length_;
};



/*************************************************************************//**
 *
 * @brief match predicates
 *
 *****************************************************************************/
using match_predicate = std::function<bool(const arg_string&)>;
using match_function  = std::function<subrange(const arg_string&)>;






/*************************************************************************//**
 *
 * @brief type traits (NOT FOR DIRECT USE IN CLIENT CODE!)
 *        no interface guarantees; might be changed or removed in the future
 *
 *****************************************************************************/
namespace traits {

/*************************************************************************//**
 *
 * @brief function (class) signature type trait
 *
 *****************************************************************************/
template<class Fn, class Ret, class... Args>
constexpr auto
check_is_callable(int) -> decltype(
    std::declval<Fn>()(std::declval<Args>()...),
    std::integral_constant<bool,
        std::is_same<Ret,typename std::result_of<Fn(Args...)>::type>::value>{} );

template<class,class,class...>
constexpr auto
check_is_callable(long) -> std::false_type;

template<class Fn, class Ret>
constexpr auto
check_is_callable_without_arg(int) -> decltype(
    std::declval<Fn>()(),
    std::integral_constant<bool,
        std::is_same<Ret,typename std::result_of<Fn()>::type>::value>{} );

template<class,class>
constexpr auto
check_is_callable_without_arg(long) -> std::false_type;



template<class Fn, class... Args>
constexpr auto
check_is_void_callable(int) -> decltype(
    std::declval<Fn>()(std::declval<Args>()...), std::true_type{});

template<class,class,class...>
constexpr auto
check_is_void_callable(long) -> std::false_type;

template<class Fn>
constexpr auto
check_is_void_callable_without_arg(int) -> decltype(
    std::declval<Fn>()(), std::true_type{});

template<class>
constexpr auto
check_is_void_callable_without_arg(long) -> std::false_type;



template<class Fn, class Ret>
struct is_callable;


template<class Fn, class Ret, class... Args>
struct is_callable<Fn, Ret(Args...)> :
    decltype(check_is_callable<Fn,Ret,Args...>(0))
{};

template<class Fn, class Ret>
struct is_callable<Fn,Ret()> :
    decltype(check_is_callable_without_arg<Fn,Ret>(0))
{};


template<class Fn, class... Args>
struct is_callable<Fn, void(Args...)> :
    decltype(check_is_void_callable<Fn,Args...>(0))
{};

template<class Fn>
struct is_callable<Fn,void()> :
    decltype(check_is_void_callable_without_arg<Fn>(0))
{};



/*************************************************************************//**
 *
 * @brief input range type trait
 *
 *****************************************************************************/
template<class T>
constexpr auto
check_is_input_range(int) -> decltype(
    begin(std::declval<T>()), end(std::declval<T>()),
    std::true_type{});

template<class T>
constexpr auto
check_is_input_range(char) -> decltype(
    std::begin(std::declval<T>()), std::end(std::declval<T>()),
    std::true_type{});

template<class>
constexpr auto
check_is_input_range(long) -> std::false_type;

template<class T>
struct is_input_range :
    decltype(check_is_input_range<T>(0))
{};



/*************************************************************************//**
 *
 * @brief size() member type trait
 *
 *****************************************************************************/
template<class T>
constexpr auto
check_has_size_getter(int) ->
    decltype(std::declval<T>().size(), std::true_type{});

template<class>
constexpr auto
check_has_size_getter(long) -> std::false_type;

template<class T>
struct has_size_getter :
    decltype(check_has_size_getter<T>(0))
{};

} // namespace traits






/*************************************************************************//**
 *
 * @brief helpers (NOT FOR DIRECT USE IN CLIENT CODE!)
 *        no interface guarantees; might be changed or removed in the future
 *
 *****************************************************************************/
namespace detail {


/*************************************************************************//**
 * @brief forwards string to first non-whitespace char;
 *        std string -> unsigned conv yields max value, but we want 0;
 *        also checks for nullptr
 *****************************************************************************/
inline bool
fwd_to_unsigned_int(const char*& s)
{
    if(!s) return false;
    for(; std::isspace(*s); ++s);
    if(!s[0] || s[0] == '-') return false;
    if(s[0] == '-') return false;
    return true;
}


/*************************************************************************//**
 *
 * @brief value limits clamping
 *
 *****************************************************************************/
template<class T, class V, bool = (sizeof(V) > sizeof(T))>
struct limits_clamped {
    static T from(const V& v) {
        if(v > V(std::numeric_limits<T>::max())) {
            return std::numeric_limits<T>::max();
        }
        if(v < V(std::numeric_limits<T>::lowest())) {
            return std::numeric_limits<T>::lowest();
        }
        return T(v);
    }
};

template<class T, class V>
struct limits_clamped<T,V,false> {
    static T from(const V& v) { return T(v); }
};


/*************************************************************************//**
 *
 * @brief returns value of v as a T, clamped at T's maximum
 *
 *****************************************************************************/
template<class T, class V>
inline T clamped_on_limits(const V& v) {
    return limits_clamped<T,V>::from(v);
}




/*************************************************************************//**
 *
 * @brief type conversion helpers
 *
 *****************************************************************************/
template<class T>
struct make;

template<>
struct make<bool> {
    static inline bool from(const char* s) {
        if(!s) return false;
        return static_cast<bool>(s);
    }
};

template<>
struct make<unsigned char> {
    static inline unsigned char from(const char* s) {
        if(!fwd_to_unsigned_int(s)) return (0);
        return clamped_on_limits<unsigned char>(std::strtoull(s,nullptr,10));
    }
};

template<>
struct make<unsigned short int> {
    static inline unsigned short int from(const char* s) {
        if(!fwd_to_unsigned_int(s)) return (0);
        return clamped_on_limits<unsigned short int>(std::strtoull(s,nullptr,10));
    }
};

template<>
struct make<unsigned int> {
    static inline unsigned int from(const char* s) {
        if(!fwd_to_unsigned_int(s)) return (0);
        return clamped_on_limits<unsigned int>(std::strtoull(s,nullptr,10));
    }
};

template<>
struct make<unsigned long int> {
    static inline unsigned long int from(const char* s) {
        if(!fwd_to_unsigned_int(s)) return (0);
        return clamped_on_limits<unsigned long int>(std::strtoull(s,nullptr,10));
    }
};

template<>
struct make<unsigned long long int> {
    static inline unsigned long long int from(const char* s) {
        if(!fwd_to_unsigned_int(s)) return (0);
        return clamped_on_limits<unsigned long long int>(std::strtoull(s,nullptr,10));
    }
};

template<>
struct make<char> {
    static inline char from(const char* s) {
        //parse as single character?
        const auto n = std::strlen(s);
        if(n == 1) return s[0];
        //parse as integer
        return clamped_on_limits<char>(std::strtoll(s,nullptr,10));
    }
};

template<>
struct make<short int> {
    static inline short int from(const char* s) {
        return clamped_on_limits<short int>(std::strtoll(s,nullptr,10));
    }
};

template<>
struct make<int> {
    static inline int from(const char* s) {
        return clamped_on_limits<int>(std::strtoll(s,nullptr,10));
    }
};

template<>
struct make<long int> {
    static inline long int from(const char* s) {
        return clamped_on_limits<long int>(std::strtoll(s,nullptr,10));
    }
};

template<>
struct make<long long int> {
    static inline long long int from(const char* s) {
        return (std::strtoll(s,nullptr,10));
    }
};

template<>
struct make<float> {
    static inline float from(const char* s) {
        return (std::strtof(s,nullptr));
    }
};

template<>
struct make<double> {
    static inline double from(const char* s) {
        return (std::strtod(s,nullptr));
    }
};

template<>
struct make<long double> {
    static inline long double from(const char* s) {
        return (std::strtold(s,nullptr));
    }
};

template<>
struct make<std::string> {
    static inline std::string from(const char* s) {
        return std::string(s);
    }
};



/*************************************************************************//**
 *
 * @brief assigns boolean constant to one or multiple target objects
 *
 *****************************************************************************/
template<class T, class V = T>
class assign_value
{
public:
    template<class X>
    explicit constexpr
    assign_value(T& target, X&& value) noexcept :
        t_{std::addressof(target)}, v_{std::forward<X>(value)}
    {}

    void operator () () const {
        if(t_) *t_ = v_;
    }

private:
    T* t_;
    V v_;
};



/*************************************************************************//**
 *
 * @brief flips bools
 *
 *****************************************************************************/
class flip_bool
{
public:
    explicit constexpr
    flip_bool(bool& target) noexcept :
        b_{&target}
    {}

    void operator () () const {
        if(b_) *b_ = !*b_;
    }

private:
    bool* b_;
};



/*************************************************************************//**
 *
 * @brief increments using operator ++
 *
 *****************************************************************************/
template<class T>
class increment
{
public:
    explicit constexpr
    increment(T& target) noexcept : t_{std::addressof(target)} {}

    void operator () () const {
        if(t_) ++(*t_);
    }

private:
    T* t_;
};



/*************************************************************************//**
 *
 * @brief decrements using operator --
 *
 *****************************************************************************/
template<class T>
class decrement
{
public:
    explicit constexpr
    decrement(T& target) noexcept : t_{std::addressof(target)} {}

    void operator () () const {
        if(t_) --(*t_);
    }

private:
    T* t_;
};



/*************************************************************************//**
 *
 * @brief increments by a fixed amount using operator +=
 *
 *****************************************************************************/
template<class T>
class increment_by
{
public:
    explicit constexpr
    increment_by(T& target, T by) noexcept :
        t_{std::addressof(target)}, by_{std::move(by)}
    {}

    void operator () () const {
        if(t_) (*t_) += by_;
    }

private:
    T* t_;
    T by_;
};




/*************************************************************************//**
 *
 * @brief makes a value from a string and assigns it to an object
 *
 *****************************************************************************/
template<class T>
class map_arg_to
{
public:
    explicit constexpr
    map_arg_to(T& target) noexcept : t_{std::addressof(target)} {}

    void operator () (const char* s) const {
        if(t_ && s && (std::strlen(s) > 0))
            *t_ = detail::make<T>::from(s);
    }

private:
    T* t_;
};


//-------------------------------------------------------------------
/**
 * @brief specialization for vectors: append element
 */
template<class T>
class map_arg_to<std::vector<T>>
{
public:
    map_arg_to(std::vector<T>& target): t_{std::addressof(target)} {}

    void operator () (const char* s) const {
        if(t_ && s) t_->push_back(detail::make<T>::from(s));
    }

private:
    std::vector<T>* t_;
};


//-------------------------------------------------------------------
/**
 * @brief specialization for bools:
 *        set to true regardless of string content
 */
template<>
class map_arg_to<bool>
{
public:
    map_arg_to(bool& target): t_{&target} {}

    void operator () (const char* s) const {
        if(t_ && s) *t_ = true;
    }

private:
    bool* t_;
};


} // namespace detail






/*************************************************************************//**
 *
 * @brief string matching and processing tools
 *
 *****************************************************************************/

namespace str {


/*************************************************************************//**
 *
 * @brief converts string to value of target type 'T'
 *
 *****************************************************************************/
template<class T>
T make(const arg_string& s)
{
    return detail::make<T>::from(s);
}



/*************************************************************************//**
 *
 * @brief removes trailing whitespace from string
 *
 *****************************************************************************/
template<class C, class T, class A>
inline void
trimr(std::basic_string<C,T,A>& s)
{
    if(s.empty()) return;

    s.erase(
        std::find_if_not(s.rbegin(), s.rend(),
                         [](char c) { return std::isspace(c);} ).base(),
        s.end() );
}


/*************************************************************************//**
 *
 * @brief removes leading whitespace from string
 *
 *****************************************************************************/
template<class C, class T, class A>
inline void
triml(std::basic_string<C,T,A>& s)
{
    if(s.empty()) return;

    s.erase(
        s.begin(),
        std::find_if_not(s.begin(), s.end(),
                         [](char c) { return std::isspace(c);})
    );
}


/*************************************************************************//**
 *
 * @brief removes leading and trailing whitespace from string
 *
 *****************************************************************************/
template<class C, class T, class A>
inline void
trim(std::basic_string<C,T,A>& s)
{
    triml(s);
    trimr(s);
}


/*************************************************************************//**
 *
 * @brief removes all whitespaces from string
 *
 *****************************************************************************/
template<class C, class T, class A>
inline void
remove_ws(std::basic_string<C,T,A>& s)
{
    if(s.empty()) return;

    s.erase(std::remove_if(s.begin(), s.end(),
                           [](char c) { return std::isspace(c); }),
            s.end() );
}


/*************************************************************************//**
 *
 * @brief returns true, if the 'prefix' argument
 *        is a prefix of the 'subject' argument
 *
 *****************************************************************************/
template<class C, class T, class A>
inline bool
has_prefix(const std::basic_string<C,T,A>& subject,
           const std::basic_string<C,T,A>& prefix)
{
    if(prefix.size() > subject.size()) return false;
    return subject.find(prefix) == 0;
}


/*************************************************************************//**
 *
 * @brief returns true, if the 'postfix' argument
 *        is a postfix of the 'subject' argument
 *
 *****************************************************************************/
template<class C, class T, class A>
inline bool
has_postfix(const std::basic_string<C,T,A>& subject,
            const std::basic_string<C,T,A>& postfix)
{
    if(postfix.size() > subject.size()) return false;
    return (subject.size() - postfix.size()) == subject.find(postfix);
}



/*************************************************************************//**
*
* @brief   returns longest common prefix of several
*          sequential random access containers
*
* @details InputRange require begin and end (member functions or overloads)
*          the elements of InputRange require a size() member
*
*****************************************************************************/
template<class InputRange>
auto
longest_common_prefix(const InputRange& strs)
    -> typename std::decay<decltype(*begin(strs))>::type
{
    static_assert(traits::is_input_range<InputRange>(),
        "parameter must satisfy the InputRange concept");

    static_assert(traits::has_size_getter<
        typename std::decay<decltype(*begin(strs))>::type>(),
        "elements of input range must have a ::size() member function");

    using std::begin;
    using std::end;

    using item_t = typename std::decay<decltype(*begin(strs))>::type;
    using str_size_t = typename std::decay<decltype(begin(strs)->size())>::type;

    const auto n = size_t(distance(begin(strs), end(strs)));
    if(n < 1) return item_t("");
    if(n == 1) return *begin(strs);

    //length of shortest string
    auto m = std::min_element(begin(strs), end(strs),
                [](const item_t& a, const item_t& b) {
                    return a.size() < b.size(); })->size();

    //check each character until we find a mismatch
    for(str_size_t i = 0; i < m; ++i) {
        for(str_size_t j = 1; j < n; ++j) {
            if(strs[j][i] != strs[j-1][i])
                return strs[0].substr(0, i);
        }
    }
    return strs[0].substr(0, m);
}



/*************************************************************************//**
 *
 * @brief  returns longest substring range that could be found in 'arg'
 *
 * @param  arg         string to be searched in
 * @param  substrings  range of candidate substrings
 *
 *****************************************************************************/
template<class C, class T, class A, class InputRange>
subrange
longest_substring_match(const std::basic_string<C,T,A>& arg,
                        const InputRange& substrings)
{
    using string_t = std::basic_string<C,T,A>;

    static_assert(traits::is_input_range<InputRange>(),
        "parameter must satisfy the InputRange concept");

    static_assert(std::is_same<string_t,
        typename std::decay<decltype(*begin(substrings))>::type>(),
        "substrings must have same type as 'arg'");

    auto i = string_t::npos;
    auto n = string_t::size_type(0);
    for(const auto& s : substrings) {
        auto j = arg.find(s);
        if(j != string_t::npos && s.size() > n) {
            i = j;
            n = s.size();
        }
    }
    return subrange{i,n};
}



/*************************************************************************//**
 *
 * @brief  returns longest prefix range that could be found in 'arg'
 *
 * @param  arg       string to be searched in
 * @param  prefixes  range of candidate prefix strings
 *
 *****************************************************************************/
template<class C, class T, class A, class InputRange>
subrange
longest_prefix_match(const std::basic_string<C,T,A>& arg,
                     const InputRange& prefixes)
{
    using string_t = std::basic_string<C,T,A>;
    using s_size_t = typename string_t::size_type;

    static_assert(traits::is_input_range<InputRange>(),
        "parameter must satisfy the InputRange concept");

    static_assert(std::is_same<string_t,
        typename std::decay<decltype(*begin(prefixes))>::type>(),
        "prefixes must have same type as 'arg'");

    auto i = string_t::npos;
    auto n = s_size_t(0);
    for(const auto& s : prefixes) {
        auto j = arg.find(s);
        if(j == 0 && s.size() > n) {
            i = 0;
            n = s.size();
        }
    }
    return subrange{i,n};
}



/*************************************************************************//**
 *
 * @brief returns the first occurrence of 'query' within 'subject'
 *
 *****************************************************************************/
template<class C, class T, class A>
inline subrange
substring_match(const std::basic_string<C,T,A>& subject,
                const std::basic_string<C,T,A>& query)
{
    if(subject.empty() || query.empty()) return subrange{};
    auto i = subject.find(query);
    if(i == std::basic_string<C,T,A>::npos) return subrange{};
    return subrange{i,query.size()};
}



/*************************************************************************//**
 *
 * @brief returns first substring match (pos,len) within the input string
 *        that represents a number
 *        (with at maximum one decimal point and digit separators)
 *
 *****************************************************************************/
template<class C, class T, class A>
subrange
first_number_match(std::basic_string<C,T,A> s,
                   C digitSeparator = C(','),
                   C decimalPoint = C('.'),
                   C exponential = C('e'))
{
    using string_t = std::basic_string<C,T,A>;

    str::trim(s);
    if(s.empty()) return subrange{};

    auto i = s.find_first_of("0123456789+-");
    if(i == string_t::npos) {
        i = s.find(decimalPoint);
        if(i == string_t::npos) return subrange{};
    }

    bool point = false;
    bool sep = false;
    auto exp = string_t::npos;
    auto j = i + 1;
    for(; j < s.size(); ++j) {
        if(s[j] == digitSeparator) {
            if(!sep) sep = true; else break;
        }
        else {
            sep = false;
            if(s[j] == decimalPoint) {
                //only one decimal point before exponent allowed
                if(!point && exp == string_t::npos) point = true; else break;
            }
            else if(std::tolower(s[j]) == std::tolower(exponential)) {
                //only one exponent separator allowed
                if(exp == string_t::npos) exp = j; else break;
            }
            else if(exp != string_t::npos && (exp+1) == j) {
                //only sign or digit after exponent separator
                if(s[j] != '+' && s[j] != '-' && !std::isdigit(s[j])) break;
            }
            else if(!std::isdigit(s[j])) {
                break;
            }
        }
    }

    //if length == 1 then must be a digit
    if(j-i == 1 && !std::isdigit(s[i])) return subrange{};

    return subrange{i,j-i};
}



/*************************************************************************//**
 *
 * @brief returns first substring match (pos,len)
 *        that represents an integer (with optional digit separators)
 *
 *****************************************************************************/
template<class C, class T, class A>
subrange
first_integer_match(std::basic_string<C,T,A> s,
                    C digitSeparator = C(','))
{
    using string_t = std::basic_string<C,T,A>;

    str::trim(s);
    if(s.empty()) return subrange{};

    auto i = s.find_first_of("0123456789+-");
    if(i == string_t::npos) return subrange{};

    bool sep = false;
    auto j = i + 1;
    for(; j < s.size(); ++j) {
        if(s[j] == digitSeparator) {
            if(!sep) sep = true; else break;
        }
        else {
            sep = false;
            if(!std::isdigit(s[j])) break;
        }
    }

    //if length == 1 then must be a digit
    if(j-i == 1 && !std::isdigit(s[i])) return subrange{};

    return subrange{i,j-i};
}



/*************************************************************************//**