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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_UTF8_HPP
#define TAOCPP_PEGTL_INCLUDE_INTERNAL_PEEK_UTF8_HPP
#include "../config.hpp"
#include "input_pair.hpp"
namespace tao
{
namespace TAOCPP_PEGTL_NAMESPACE
{
namespace internal
{
struct peek_utf8
{
using data_t = char32_t;
using pair_t = input_pair< char32_t >;
template< typename Input >
static pair_t peek( Input& in )
{
char32_t c0 = in.peek_byte();
if( ( c0 & 0x80 ) == 0 ) {
return { c0, 1 };
}
if( ( c0 & 0xE0 ) == 0xC0 ) {
if( in.size( 2 ) >= 2 ) {
const char32_t c1 = in.peek_byte( 1 );
if( ( c1 & 0xC0 ) == 0x80 ) {
c0 &= 0x1F;
c0 <<= 6;
c0 |= ( c1 & 0x3F );
if( c0 >= 0x80 ) {
return { c0, 2 };
}
}
}
}
else if( ( c0 & 0xF0 ) == 0xE0 ) {
if( in.size( 3 ) >= 3 ) {
const char32_t c1 = in.peek_byte( 1 );
const char32_t c2 = in.peek_byte( 2 );
if( ( ( c1 & 0xC0 ) == 0x80 ) && ( ( c2 & 0xC0 ) == 0x80 ) ) {
c0 &= 0x0F;
c0 <<= 6;
c0 |= ( c1 & 0x3F );
c0 <<= 6;
c0 |= ( c2 & 0x3F );
if( c0 >= 0x800 ) {
return { c0, 3 };
}
}
}
}
else if( ( c0 & 0xF8 ) == 0xF0 ) {
if( in.size( 4 ) >= 4 ) {
const char32_t c1 = in.peek_byte( 1 );
const char32_t c2 = in.peek_byte( 2 );
const char32_t c3 = in.peek_byte( 3 );
if( ( ( c1 & 0xC0 ) == 0x80 ) && ( ( c2 & 0xC0 ) == 0x80 ) && ( ( c3 & 0xC0 ) == 0x80 ) ) {
c0 &= 0x07;
c0 <<= 6;
c0 |= ( c1 & 0x3F );
c0 <<= 6;
c0 |= ( c2 & 0x3F );
c0 <<= 6;
c0 |= ( c3 & 0x3F );
if( c0 >= 0x10000 && c0 <= 0x10FFFF ) {
return { c0, 4 };
}
}
}
}
return { 0, 0 };
}
};
} // namespace internal
} // namespace TAOCPP_PEGTL_NAMESPACE
} // namespace tao
#endif
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