ascii.hpp

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// Copyright (C) 2020-2024 Jonathan Müller and lexy contributors
// SPDX-License-Identifier: BSL-1.0
 
#ifndef LEXY_DSL_ASCII_HPP_INCLUDED
#define LEXY_DSL_ASCII_HPP_INCLUDED
 
#include <lexy/_detail/nttp_string.hpp>
#include <lexy/dsl/base.hpp>
#include <lexy/dsl/char_class.hpp>
 
// SWAR tricks inspired by https://garbagecollected.org/2017/01/31/four-column-ascii/.
 
namespace lexyd::ascii
{
//=== control ===//
struct _control : char_class_base<_control>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.control";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(0x00, 0x1F);
        result.insert(0x7F);
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        using char_type         = typename Encoding::char_type;
        constexpr auto mask     = lexy::_detail::swar_fill_compl(char_type(0b11111));
        constexpr auto expected = lexy::_detail::swar_fill(char_type(0b00'00000));
 
        // We're only checking for 0x00-0x1F, and allow a false negative for 0x7F.
        return (c & mask) == expected;
    }
};
inline constexpr auto control = _control{};
 
//=== whitespace ===//
struct _blank : char_class_base<_blank>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.blank";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(' ');
        result.insert('\t');
        return result;
    }
};
inline constexpr auto blank = _blank{};
 
struct _newline : char_class_base<_newline>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.newline";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('\n');
        result.insert('\r');
        return result;
    }
};
inline constexpr auto newline = _newline{};
 
struct _other_space : char_class_base<_other_space>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.other-space";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('\f');
        result.insert('\v');
        return result;
    }
};
inline constexpr auto other_space = _other_space{};
 
struct _space : char_class_base<_space>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.space";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(_blank::char_class_ascii());
        result.insert(_newline::char_class_ascii());
        result.insert(_other_space::char_class_ascii());
        return result;
    }
};
inline constexpr auto space = _space{};
 
//=== alpha ===//
struct _lower : char_class_base<_lower>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.lower";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('a', 'z');
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        using char_type = typename Encoding::char_type;
 
        // All interesting characters are in column 4.
        constexpr auto mask     = lexy::_detail::swar_fill_compl(char_type(0b11111));
        constexpr auto expected = lexy::_detail::swar_fill(char_type(0b11'00000));
 
        // But we need to eliminate ~ at the beginning and {|}~\x7F at the end.
        constexpr auto offset_low  = lexy::_detail::swar_fill(char_type(1));
        constexpr auto offset_high = lexy::_detail::swar_fill(char_type(5));
 
        return ((c - offset_low) & mask) == expected && ((c + offset_high) & mask) == expected;
    }
};
inline constexpr auto lower = _lower{};
 
struct _upper : char_class_base<_upper>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.upper";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('A', 'Z');
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        using char_type = typename Encoding::char_type;
 
        // All interesting characters are in column 3.
        constexpr auto mask     = lexy::_detail::swar_fill_compl(char_type(0b11111));
        constexpr auto expected = lexy::_detail::swar_fill(char_type(0b10'00000));
 
        // But we need to eliminate @ at the beginning and [\]^_ at the end.
        constexpr auto offset_low  = lexy::_detail::swar_fill(char_type(1));
        constexpr auto offset_high = lexy::_detail::swar_fill(char_type(5));
 
        return ((c - offset_low) & mask) == expected && ((c + offset_high) & mask) == expected;
    }
};
inline constexpr auto upper = _upper{};
 
struct _alpha : char_class_base<_alpha>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.alpha";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('a', 'z');
        result.insert('A', 'Z');
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        // We're assuming lower characters are more common, so do the efficient check only for them.
        return _lower::template char_class_match_swar<Encoding>(c);
    }
};
inline constexpr auto alpha = _alpha{};
 
struct _alphau : char_class_base<_alphau>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.alpha-underscore";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('a', 'z');
        result.insert('A', 'Z');
        result.insert('_');
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        // We're assuming alpha characters are more common, so do the efficient check only for them.
        return _alpha::template char_class_match_swar<Encoding>(c);
    }
};
inline constexpr auto alpha_underscore = _alphau{};
 
//=== digit ===//
struct _digit : char_class_base<_digit>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.digit";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('0', '9');
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        using char_type = typename Encoding::char_type;
 
        // All interesting characters are in the second half of column 1.
        constexpr auto mask     = lexy::_detail::swar_fill_compl(char_type(0b01111));
        constexpr auto expected = lexy::_detail::swar_fill(char_type(0b01'10000));
 
        // But we need to eliminate :;<=>? at the end.
        constexpr auto offset_high = lexy::_detail::swar_fill(char_type(6));
 
        return (c & mask) == expected && ((c + offset_high) & mask) == expected;
    }
};
inline constexpr auto digit = _digit{};
 
struct _alnum : char_class_base<_alnum>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.alpha-digit";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(_alpha::char_class_ascii());
        result.insert(_digit::char_class_ascii());
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        // We're assuming alpha characters are more common, so do the efficient check only for them.
        return _alpha::template char_class_match_swar<Encoding>(c);
    }
};
inline constexpr auto alnum       = _alnum{};
inline constexpr auto alpha_digit = _alnum{};
 
struct _word : char_class_base<_word>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.word";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(_alphau::char_class_ascii());
        result.insert(_digit::char_class_ascii());
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        // We're assuming alphau characters are more common, so do the efficient check only for
        // them.
        return _alphau::template char_class_match_swar<Encoding>(c);
    }
};
inline constexpr auto word                   = _word{};
inline constexpr auto alpha_digit_underscore = _word{};
 
//=== punct ===//
struct _punct : char_class_base<_punct>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.punct";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert('!');
        result.insert('"');
        result.insert('#');
        result.insert('$');
        result.insert('%');
        result.insert('&');
        result.insert('\'');
        result.insert('(');
        result.insert(')');
        result.insert('*');
        result.insert('+');
        result.insert(',');
        result.insert('-');
        result.insert('.');
        result.insert('/');
        result.insert(':');
        result.insert(';');
        result.insert('<');
        result.insert('=');
        result.insert('>');
        result.insert('?');
        result.insert('@');
        result.insert('[');
        result.insert('\\');
        result.insert(']');
        result.insert('^');
        result.insert('_');
        result.insert('`');
        result.insert('{');
        result.insert('|');
        result.insert('}');
        result.insert('~');
        return result;
    }
};
inline constexpr auto punct = _punct{};
 
//=== categories ===//
struct _graph : char_class_base<_graph>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.graph";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(0x21, 0x7E);
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        using char_type = typename Encoding::char_type;
 
        // First check that we have only ASCII, but shifted by one, so we also exclude 0x7F.
        constexpr auto ascii_mask     = lexy::_detail::swar_fill_compl(char_type(0b11'11111));
        constexpr auto ascii_offset   = lexy::_detail::swar_fill(char_type(1));
        constexpr auto ascii_expected = lexy::_detail::swar_fill(char_type(0));
        if (((c + ascii_offset) & ascii_mask) != ascii_expected)
            return false;
 
        // The above check also included 0xFF for single byte encodings where it overflowed,
        // so do a separate check in those cases.
        if constexpr (sizeof(char_type) == 1)
        {
            if ((c & ascii_mask) != ascii_expected)
                return false;
        }
 
        // Then we must not have a character in column 0, or space.
        // If we subtract one we turn 0x21-0x01 into column 0 and 0x00 to a value definitely not in
        // column 0, so need to check both.
        constexpr auto mask       = lexy::_detail::swar_fill_compl(char_type(0b11111));
        constexpr auto offset_low = lexy::_detail::swar_fill(char_type(1));
        return !lexy::_detail::swar_has_zero<char_type>(c & mask)
               && !lexy::_detail::swar_has_zero<char_type>((c - offset_low) & mask);
    }
};
inline constexpr auto graph = _graph{};
 
struct _print : char_class_base<_print>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII.print";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(0x20, 0x7E);
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        using char_type = typename Encoding::char_type;
 
        // First check that we have only ASCII, but shifted by one, so we also exclude 0x7F.
        constexpr auto ascii_mask     = lexy::_detail::swar_fill_compl(char_type(0b11'11111));
        constexpr auto ascii_offset   = lexy::_detail::swar_fill(char_type(1));
        constexpr auto ascii_expected = lexy::_detail::swar_fill(char_type(0));
        if (((c + ascii_offset) & ascii_mask) != ascii_expected)
            return false;
 
        // The above check also included 0xFF for single byte encodings where it overflowed,
        // so do a separate check in those cases.
        if constexpr (sizeof(char_type) == 1)
        {
            if ((c & ascii_mask) != ascii_expected)
                return false;
        }
 
        // Then we must not have a character in column 0.
        constexpr auto mask = lexy::_detail::swar_fill_compl(char_type(0b11111));
        return !lexy::_detail::swar_has_zero<char_type>(c & mask);
    }
};
inline constexpr auto print = _print{};
 
struct _char : char_class_base<_char>
{
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return "ASCII";
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        result.insert(0x00, 0x7F);
        return result;
    }
 
    template <typename Encoding>
    static constexpr auto char_class_match_swar(lexy::_detail::swar_int c)
    {
        using char_type = typename Encoding::char_type;
 
        constexpr auto mask     = lexy::_detail::swar_fill_compl(char_type(0b11'11111));
        constexpr auto expected = lexy::_detail::swar_fill(char_type(0));
 
        return (c & mask) == expected;
    }
};
inline constexpr auto character = _char{};
} // namespace lexyd::ascii
 
namespace lexyd::ascii
{
template <char... C>
struct _alt : char_class_base<_alt<C...>>
{
    static_assert(sizeof...(C) > 0);
 
    static LEXY_CONSTEVAL auto char_class_name()
    {
        return lexy::_detail::type_string<char, C...>::template c_str<char>;
    }
 
    static LEXY_CONSTEVAL auto char_class_ascii()
    {
        lexy::_detail::ascii_set result;
        (result.insert(C), ...);
        return result;
    }
};
 
template <typename CharT, CharT... C>
struct _one_of
{
    static_assert((std::is_same_v<CharT, char> && ... && lexy::_detail::is_ascii(C)),
                  "only ASCII characters are supported");
 
    using rule = _alt<C...>;
};
 
#if LEXY_HAS_NTTP
template <lexy::_detail::string_literal Str>
constexpr auto one_of = typename lexy::_detail::to_type_string<_one_of, Str>::rule{};
#endif
 
#define LEXY_ASCII_ONE_OF(Str)                                                                     \
    LEXY_NTTP_STRING(::lexyd::ascii::_one_of, Str)::rule {}
} // namespace lexyd::ascii
 
#endif // LEXY_DSL_ASCII_HPP_INCLUDED