daw_json_string_util.h

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// Copyright (c) Darrell Wright
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/beached/daw_json_link
//
 
#pragma once
 
#include "daw/json/impl/version.h"
 
#include "daw/json/impl/daw_json_exec_modes.h"
#include "daw/json/impl/daw_json_parse_policy_policy_details.h"
#include "daw/json/impl/daw_not_const_ex_functions.h"
 
#include <daw/daw_is_constant_evaluated.h>
#include <daw/daw_likely.h>
#include <daw/daw_traits.h>
 
#include <cstring>
 
namespace daw::json {
  inline namespace DAW_JSON_VER {
    namespace json_details {
      template<char c, typename ExecTag>
      DAW_ATTRIB_FLATINLINE static constexpr daw::not_null<char const *>
      memchr_unchecked_long( daw::not_null<char const *> first,
                             daw::not_null<char const *> last ) {
#if not defined( NDEBUG )
        daw_json_ensure( first <= last, ErrorReason::Unknown );
#endif
#if DAW_HAS_BUILTIN( __builtin_char_memchr )
        return __builtin_char_memchr(
          first, '"', static_cast<std::size_t>( last - first ) );
#else
        if( not json_details::use_constexpr_exec_mode<ExecTag>( ) ) {
          return static_cast<char const *>(
            std::memchr( static_cast<void const *>( first ),
                         '"',
                         static_cast<std::size_t>( last - first ) ) );
        }
        (void)last;
        while( *first != c ) {
          ++first;
        }
        return first;
#endif
      }
 
      template<char c>
      DAW_ATTRIB_FLATINLINE static constexpr daw::not_null<char const *>
      memchr_unchecked_short( daw::not_null<char const *> first ) {
        while( *first != c ) {
          ++first;
        }
        return first;
      }
 
      template<char c, typename ExecTag, bool expect_long>
      DAW_ATTRIB_FLATINLINE static constexpr daw::not_null<char const *>
      memchr_unchecked( daw::not_null<char const *> first,
                        daw::not_null<char const *> last ) {
#if not defined( NDEBUG )
        daw_json_ensure( first <= last, ErrorReason::Unknown );
#endif
        if constexpr( expect_long ) {
          return memchr_unchecked_long<c, ExecTag>( first, last );
        } else {
          return memchr_unchecked_short<c>( first );
        }
      }
 
      template<char c, typename ExecTag>
      DAW_ATTRIB_FLATINLINE static constexpr daw::not_null<char const *>
      memchr_checked_long( daw::not_null<char const *> first,
                           daw::not_null<char const *> last ) {
#if not defined( NDEBUG )
        daw_json_ensure( first <= last, ErrorReason::Unknown );
#endif
#if DAW_HAS_BUILTIN( __builtin_char_memchr )
        return __builtin_char_memchr(
          first, '"', static_cast<std::size_t>( last - first ) );
#elif DAW_HAS_BUILTIN( __builtin_memchr )
        return static_cast<char const *>( __builtin_memchr(
          first, '"', static_cast<std::size_t>( last - first ) ) );
#else
        if( not json_details::use_constexpr_exec_mode<ExecTag>( ) ) {
          return static_cast<char const *>(
            std::memchr( static_cast<void const *>( first ),
                         '"',
                         static_cast<std::size_t>( last - first ) ) );
        }
        while( DAW_LIKELY( first < last ) and *first != c ) {
          ++first;
        }
        return first;
#endif
      }
 
      template<char c>
      DAW_ATTRIB_INLINE static constexpr daw::not_null<char const *>
      memchr_checked_short( daw::not_null<char const *> first,
                            daw::not_null<char const *> const last ) {
#if not defined( NDEBUG )
        daw_json_ensure( first <= last, ErrorReason::Unknown );
#endif
        while( DAW_LIKELY( first < last ) and *first != c ) {
          ++first;
        }
        return first;
      }
 
      template<char c, typename ExecTag, bool expect_long>
      DAW_ATTRIB_FLATINLINE static constexpr daw::not_null<char const *>
      memchr_checked( daw::not_null<char const *> first,
                      daw::not_null<char const *> last ) {
        if constexpr( expect_long ) {
          return memchr_checked_long<c, ExecTag>( first, last );
        } else {
          return memchr_checked_short<c>( first, last );
        }
      }
 
      template<typename ExecTag, char... chars>
      DAW_ATTRIB_FLATINLINE constexpr daw::not_null<char const *>
      mempbrk_unchecked_long( daw::not_null<char const *> first ) {
#if DAW_HAS_BUILTIN( __builtin_strpbrk )
        constexpr char const needles[]{ chars..., '\0' };
        daw::not_null<char const *> res = __builtin_strpbrk( first, needles );
        return res;
#else
        if( not json_details::use_constexpr_exec_mode<ExecTag>( ) ) {
          constexpr char const needles[]{ chars..., '\0' };
          char const *res = std::strpbrk( first, needles );
#if not defined( NDEBUG )
          daw_json_ensure( res != nullptr, ErrorReason::UnexpectedEndOfData );
#endif
          return res;
        }
        while( not parse_policy_details::in<chars...>( *first ) ) {
          ++first;
        }
        return first;
#endif
      }
 
      template<char... chars>
      DAW_ATTRIB_INLINE constexpr daw::not_null<char const *>
      mempbrk_unchecked_short( daw::not_null<char const *> first ) {
        while( not parse_policy_details::in<chars...>( *first ) ) {
          ++first;
        }
        return first;
      }
 
      template<typename ExecTag, bool expect_long, char... chars>
      DAW_ATTRIB_FLATINLINE constexpr daw::not_null<char const *>
      mempbrk_unchecked( daw::not_null<char const *> first ) {
        if constexpr( expect_long ) {
          return mempbrk_unchecked_long<ExecTag, chars...>( first );
        } else {
          return mempbrk_unchecked_short<chars...>( first );
        }
      }
 
      template<typename ExecTag, char... chars>
      DAW_ATTRIB_FLATINLINE constexpr daw::not_null<char const *>
      mempbrk_checked_long( daw::not_null<char const *> first,
                            daw::not_null<char const *> last ) {
#if not defined( NDEBUG )
        daw_json_ensure( first <= last, ErrorReason::Unknown );
#endif
        if( not json_details::use_constexpr_exec_mode<ExecTag>( ) ) {
          return mem_move_to_next_of<false, ExecTag, chars...>( first, last );
        }
        while( DAW_LIKELY( first < last ) and
               not parse_policy_details::in<chars...>( *first ) ) {
          ++first;
        }
        return first;
      }
 
      template<char... chars>
      DAW_ATTRIB_FLATINLINE constexpr daw::not_null<char const *>
      mempbrk_checked_short( daw::not_null<char const *> first,
                             daw::not_null<char const *> last ) {
#if not defined( NDEBUG )
        daw_json_ensure( first <= last, ErrorReason::Unknown );
#endif
        while( DAW_LIKELY( first < last ) and
               not parse_policy_details::in<chars...>( *first ) ) {
          ++first;
        }
        return first;
      }
 
      template<typename ExecTag, bool expect_long, char... chars>
      DAW_ATTRIB_FLATINLINE constexpr daw::not_null<char const *>
      mempbrk_checked( daw::not_null<char const *> first,
                       daw::not_null<char const *> last ) {
        if constexpr( expect_long ) {
          return mempbrk_checked_long<ExecTag, chars...>( first, last );
        } else {
          return mempbrk_checked_short<chars...>( first, last );
        }
      }
 
      template<bool is_unchecked_input, typename ExecTag, bool expect_long,
               char... chars>
      DAW_ATTRIB_FLATINLINE constexpr daw::not_null<char const *>
      mempbrk( daw::not_null<char const *> first,
               daw::not_null<char const *> last ) {
 
        if constexpr( is_unchecked_input ) {
          return mempbrk_unchecked<ExecTag, expect_long, chars...>( first );
        } else {
          return mempbrk_checked<ExecTag, expect_long, chars...>( first, last );
        }
      }
    } // namespace json_details
  } // namespace DAW_JSON_VER
} // namespace daw::json