libcruft-util/ascii.hpp

222 lines
6.1 KiB
C++

/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* Copyright 2016-2019 Danny Robson <danny@nerdcruft.net>
*/
#pragma once
#include "annotation.hpp"
#include "debug/assert.hpp"
#include <array>
#include <cstdint>
#include <stdexcept>
namespace cruft::ascii {
///////////////////////////////////////////////////////////////////////////
/// Returns true if the supplied character is an ASCII digit.
constexpr inline
bool
is_digit (char c) noexcept
{
return c >= '0' && c <= '9';
}
///------------------------------------------------------------------------
/// Converts an ASCII character into a corresponding integer.
///
/// Specifically does not convert multiple characters.
constexpr inline
uint8_t
to_integer (char c)
{
return likely (is_digit (c)) ?
c - '0'
: throw std::invalid_argument ("character is not a digit");
}
///------------------------------------------------------------------------
/// Returns true if the supplied character is an upper case letter in the
/// "C" locale.
constexpr inline
bool
is_upper (char c) noexcept
{
return c >= 'A' && c <= 'Z';
}
///------------------------------------------------------------------------
/// Returns true if the supplied character is a lower case letter in the
/// "C" locale.
constexpr inline
bool
is_lower (char c) noexcept
{
return c >= 'a' && c <= 'z';
}
///------------------------------------------------------------------------
/// Returns true if the supplied character is an alphabetical character in
/// the "C" locale.
constexpr inline
bool
is_alpha (char c) noexcept
{
return is_lower (c) || is_upper (c);
}
///------------------------------------------------------------------------
/// Returns true if the supplied ASCII character is a hexadecimal digit.
constexpr inline
bool
is_hex (const char c) noexcept
{
switch (c) {
case '0'...'9': return true;
case 'a'...'f': return true;
case 'A'...'F': return true;
}
return false;
}
///------------------------------------------------------------------------
/// Converts a supplied ASCII character from a hexadecimal digit into a
/// corresponding integer.
///
/// Explicitly does not cover any multi-character case.
constexpr inline
uint8_t
from_hex (char c)
{
return c >= '0' && c <= '9' ? (c - '0' ) :
c >= 'a' && c <= 'f' ? (c - 'a' + 10) :
c >= 'A' && c <= 'F' ? (c - 'A' + 10) :
throw std::invalid_argument ("character is not hexademical");
}
///////////////////////////////////////////////////////////////////////////
/// Converts a lower case ASCII character into an upper case character.
///
/// The results are undefined if the character isn't a lowercase
/// alphabetical character in the "C" locale.
constexpr inline
char
to_upper (char c) noexcept
{
CHECK (is_lower (c));
return c - 'a' + 'A';
}
///------------------------------------------------------------------------
/// Convert an ASCII character into a upper case character if it is lower
/// case, else return it unchanged.
///
/// If you know the character is always lower case then prefer to_upper.
constexpr inline
char
try_upper (char c) noexcept
{
return is_lower (c) ? to_upper (c) : c;
}
///------------------------------------------------------------------------
/// Converts an upper case ASCII character into a lower case character.
///
/// The results are undefined if the character isn't an uppercase
/// alphabetical character in the "C" locale.
constexpr inline
char
to_lower (char c) noexcept
{
CHECK (is_upper (c));
return c - 'A' + 'a';
}
///------------------------------------------------------------------------
/// Convert an ASCII character into a lower case character if it is upper
/// case, else return it unchanged.
///
/// If you know the character is always upper case then prefer to_lower.
constexpr inline
char
try_lower (char c) noexcept
{
return is_upper (c) ? to_lower (c) : c;
}
///////////////////////////////////////////////////////////////////////////
/// Returns true if the supplied ASCII character is whitespace.
constexpr inline
bool
is_space (char c)
{
switch (c) {
case ' ':
case '\f':
case '\n':
case '\r':
case '\t':
case '\v':
return true;
default:
return false;
}
}
}
///////////////////////////////////////////////////////////////////////////////
#include <vector>
/// Converts a string of ASCII hex digits into a vector of u08 values.
///
/// The supplied string must have a length that is a multiple of 2.
std::vector<std::uint8_t>
inline
operator"" _hex2u08 (const char *str, size_t len)
{
CHECK_MOD (len, 2);
std::vector<uint8_t> res (len/2);
for (size_t i = 0; i < len; i += 2)
res[i/2] = cruft::ascii::from_hex (str[i]) << 4 | cruft::ascii::from_hex (str[i+1]);
return res;
};
///////////////////////////////////////////////////////////////////////////////
/// Converts a string of ASCII hex digits into an array of u08 values.
///
/// The supplied string must have a length that is a multiple of 2.
template <typename CharT, CharT ...StrV>
constexpr auto
operator"" _hex2array (void)
{
static_assert (sizeof ...(StrV) % 2 == 0);
std::array<std::uint8_t,sizeof...(StrV)/2> res {};
constexpr CharT literal[] = { StrV... };
for (size_t i = 0; i < res.size (); ++i)
res[i] = cruft::ascii::from_hex (literal[i*2+0]) << 4 |
cruft::ascii::from_hex (literal[i*2+1]);
return res;
}