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// Copyright (c) 2014-2017 Dr. Colin Hirsch and Daniel Frey
// Please see LICENSE for license or visit https://github.com/taocpp/PEGTL/
#ifndef TAOCPP_PEGTL_INCLUDE_INTERNAL_PEEK_UTF16_HPP
#define TAOCPP_PEGTL_INCLUDE_INTERNAL_PEEK_UTF16_HPP
#include <type_traits>
#include "../config.hpp"
#include "input_pair.hpp"
namespace tao
{
namespace TAOCPP_PEGTL_NAMESPACE
{
namespace internal
{
struct peek_utf16
{
using data_t = char32_t;
using pair_t = input_pair< char32_t >;
using short_t = std::make_unsigned< char16_t >::type;
static_assert( sizeof( short_t ) == 2, "expected size 2 for 16bit value" );
static_assert( sizeof( char16_t ) == 2, "expected size 2 for 16bit value" );
template< typename Input >
static pair_t peek( Input& in )
{
const std::size_t s = in.size( 4 );
if( s >= 2 ) {
const char32_t t = *reinterpret_cast< const short_t* >( in.current() );
if( ( t < 0xd800 ) || ( t > 0xdbff ) || ( s < 4 ) ) {
return { t, 2 };
}
const char32_t u = *reinterpret_cast< const short_t* >( in.current() + 2 );
if( ( u < 0xdc00 ) || ( u > 0xdfff ) ) {
return { t, 2 };
}
return { ( ( ( t & 0x03ff ) << 10 ) | ( u & 0x03ff ) ) + 0x10000, 4 };
}
return { 0, 0 };
}
};
} // namespace internal
} // namespace TAOCPP_PEGTL_NAMESPACE
} // namespace tao
#endif
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