159 lines
4.0 KiB
C++
159 lines
4.0 KiB
C++
//
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// Copyright (c) 2021 Vinnie Falco (vinnie dot falco at gmail dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Official repository: https://github.com/boostorg/url
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//
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#ifndef BOOST_URL_GRAMMAR_HEXDIG_CHARS_HPP
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#define BOOST_URL_GRAMMAR_HEXDIG_CHARS_HPP
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#include <boost/url/detail/config.hpp>
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#include <boost/url/grammar/detail/charset.hpp>
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namespace boost {
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namespace urls {
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namespace grammar {
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/** The set of hexadecimal digits
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@par Example
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Character sets are used with rules and the
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functions @ref find_if and @ref find_if_not.
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@code
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result< string_view > rv = parse( "8086FC19", token_rule( hexdig_chars ) );
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@endcode
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@par BNF
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@code
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HEXDIG = DIGIT
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/ "A" / "B" / "C" / "D" / "E" / "F"
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/ "a" / "b" / "c" / "d" / "e" / "f"
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@endcode
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@note The RFCs are inconsistent on the case
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sensitivity of hexadecimal digits. Existing
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uses suggest case-insensitivity is a de-facto
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standard.
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@par Specification
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@li <a href="https://datatracker.ietf.org/doc/html/rfc5234#appendix-B.1"
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>B.1. Core Rules (rfc5234)</a>
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@li <a href="https://datatracker.ietf.org/doc/html/rfc7230#section-1.2"
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>1.2. Syntax Notation (rfc7230)</a>
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@li <a href="https://datatracker.ietf.org/doc/html/rfc5952#section-2.3"
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>2.3. Uppercase or Lowercase (rfc5952)</a>
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@li <a href="https://datatracker.ietf.org/doc/html/rfc5952#section-4.3"
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>4.3. Lowercase (rfc5952)</a>
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@see
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@ref find_if,
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@ref find_if_not,
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@ref hexdig_value,
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@ref parse,
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@ref token_rule.
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*/
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#ifdef BOOST_URL_DOCS
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constexpr __implementation_defined__ hexdig_chars;
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#else
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struct hexdig_chars_t
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{
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/** Return true if c is in the character set.
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*/
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constexpr
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bool
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operator()(char c) const noexcept
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{
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return
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(c >= '0' && c <= '9') ||
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(c >= 'A' && c <= 'F') ||
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(c >= 'a' && c <= 'f');
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}
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#ifdef BOOST_URL_USE_SSE2
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char const*
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find_if(
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char const* first,
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char const* last) const noexcept
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{
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return detail::find_if_pred(
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*this, first, last);
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}
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char const*
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find_if_not(
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char const* first,
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char const* last) const noexcept
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{
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return detail::find_if_not_pred(
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*this, first, last);
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}
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#endif
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};
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constexpr hexdig_chars_t hexdig_chars{};
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#endif
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// VFALCO We can declare
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// these later if needed
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//
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//struct hexdig_upper_chars;
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//struct hexdig_lower_chars;
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/** Return the decimal value of a hex character
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This function returns the decimal
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value of a hexadecimal character,
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or -1 if the argument is not a
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valid hexadecimal digit.
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@par BNF
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@code
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HEXDIG = DIGIT
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/ "A" / "B" / "C" / "D" / "E" / "F"
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/ "a" / "b" / "c" / "d" / "e" / "f"
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@endcode
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@param ch The character to check
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@return The decimal value or -1
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*/
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inline
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signed char
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hexdig_value(char ch) noexcept
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{
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// Idea for switch statement to
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// minimize emitted assembly from
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// Glen Fernandes
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signed char res;
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switch(ch)
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{
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default: res = -1; break;
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case '0': res = 0; break;
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case '1': res = 1; break;
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case '2': res = 2; break;
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case '3': res = 3; break;
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case '4': res = 4; break;
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case '5': res = 5; break;
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case '6': res = 6; break;
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case '7': res = 7; break;
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case '8': res = 8; break;
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case '9': res = 9; break;
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case 'a': case 'A': res = 10; break;
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case 'b': case 'B': res = 11; break;
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case 'c': case 'C': res = 12; break;
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case 'd': case 'D': res = 13; break;
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case 'e': case 'E': res = 14; break;
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case 'f': case 'F': res = 15; break;
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}
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return res;
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}
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} // grammar
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} // urls
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} // boost
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#endif
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