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//
 
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// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
 
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// Copyright (c) 2022 Alan de Freitas (alandefreitas@gmail.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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#include <boost/url/detail/config.hpp>
 
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#include "path.hpp"
 
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#include <boost/url/detail/decode.hpp>
 
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#include <boost/url/detail/segments_iter_impl.hpp>
 
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#include "boost/url/rfc/detail/path_rules.hpp"
 
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#include <boost/assert.hpp>
 
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namespace boost {
 
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namespace urls {
 
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namespace detail {
 
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// begin
 
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segments_iter_impl::
 
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segments_iter_impl(
 
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    detail::path_ref const& ref_) noexcept
 
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    : ref(ref_)
 
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{
 
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    pos = path_prefix(ref.buffer());
 
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    // begin() starts after any malleable prefix but remembers decoded chars skipped
 
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    decoded_prefix = pos;
 
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    update();
 
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}
 
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// end
 
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segments_iter_impl::
 
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segments_iter_impl(
 
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    detail::path_ref const& ref_,
 
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    int) noexcept
 
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    : ref(ref_)
 
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    , pos(ref.size())
 
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    , next(ref.size())
 
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    , index(ref.nseg())
 
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{
 
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    // end() carries the total decoded length for O(1) range math
 
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    decoded_prefix = ref.decoded_size();
 
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}
 
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segments_iter_impl::
 
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segments_iter_impl(
 
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    url_impl const& u_,
 
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    std::size_t pos_,
 
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    std::size_t index_) noexcept
 
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    : ref(u_)
 
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    , pos(pos_)
 
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    , index(index_)
 
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{
 
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    auto const total = ref.nseg();
 
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    if(index >= total)
 
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    {
 
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        pos = ref.size();
 
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        next = ref.size();
 
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        decoded_prefix = ref.decoded_size();
 
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        // iterator equal to end: nothing to decode
 
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        dn = 0;
 
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        return;
 
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    }
 
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    if(index == 0)
 
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    {
 
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        pos = path_prefix(ref.buffer());
 
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        // first segment inherits the prefix size (including leading '/')
 
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        decoded_prefix = pos;
 
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        update();
 
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        return;
 
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    }
 
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    BOOST_ASSERT(pos <= ref.size());
 
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    // compute decoded prefix by scanning once up to the encoded offset
 
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    decoded_prefix = detail::decode_bytes_unsafe(
 
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        core::string_view(ref.data(), pos));
 
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    if(pos != ref.size())
 
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    {
 
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        BOOST_ASSERT(
 
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            ref.data()[pos] == '/');
 
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        ++pos; // skip '/'
 
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        update();
 
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        --pos;
 
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        return;
 
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    }
 
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    update();
 
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}
 
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void
 
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segments_iter_impl::
 
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update() noexcept
 
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{
 
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    auto const end = ref.end();
 
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    char const* const p0 =
 
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        ref.data() + pos;
 
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    dn = 0;
 
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    auto p = p0;
 
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    while(p != end)
 
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    {
 
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        if(*p == '/')
 
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            break;
 
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        if(*p != '%')
 
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        {
 
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            ++p;
 
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            continue;
 
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        }
 
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        p += 3;
 
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        dn += 2;
 
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    }
 
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    next = p - ref.data();
 
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    dn = p - p0 - dn;
 
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    s_ = make_pct_string_view_unsafe(
 
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        p0, p - p0, dn);
 
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}
 
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void
 
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segments_iter_impl::
 
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increment() noexcept
 
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{
 
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    BOOST_ASSERT(
 
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        index != ref.nseg());
 
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    auto const old_index = index;
 
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    auto const old_dn = dn;
 
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    // add decoded length of previous segment
 
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    decoded_prefix += old_dn;
 
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    if(old_index > 0)
 
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        // account for the '/' separator we just crossed
 
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        ++decoded_prefix;
 
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    ++index;
 
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    pos = next;
 
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    if(index == ref.nseg())
 
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        return;
 
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    // "/" segment
 
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    auto const end = ref.end();
 
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    auto p = ref.data() + pos;
 
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    BOOST_ASSERT(p != end);
 
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    BOOST_ASSERT(*p == '/');
 
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    dn = 0;
 
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    ++p; // skip '/'
 
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    auto const p0 = p;
 
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    while(p != end)
 
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    {
 
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        if(*p == '/')
 
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            break;
 
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        if(*p != '%')
 
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        {
 
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            ++p;
 
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            continue;
 
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        }
 
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        p += 3;
 
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        dn += 2;
 
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    }
 
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    next = p - ref.data();
 
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    dn = p - p0 - dn;
 
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    s_ = make_pct_string_view_unsafe(
 
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        p0, p - p0, dn);
 
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}
 
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void
 
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segments_iter_impl::
 
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decrement() noexcept
 
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{
 
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    BOOST_ASSERT(index != 0);
 
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    auto const current_dn = dn;
 
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    auto const current_index = index;
 
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    // remove the decoded length of the segment we're leaving
 
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    decoded_prefix -= current_dn;
 
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    if(current_index > 0 && decoded_prefix > 0)
 
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        // drop the '/' separator when stepping left of it
 
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        --decoded_prefix;
 
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    --index;
 
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    if(index == 0)
 
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    {
 
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        next = pos;
 
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        pos = path_prefix(ref.buffer());
 
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        decoded_prefix = pos;
 
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        s_ = core::string_view(
 
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            ref.data() + pos,
 
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            next - pos);
 
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        BOOST_ASSERT(! s_.ends_with('/'));
 
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        return;
 
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    }
 
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    auto const begin = ref.data() +
 
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        path_prefix(ref.buffer());
 
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    next = pos;
 
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    auto p = ref.data() + next;
 
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    auto const p1 = p;
 
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    BOOST_ASSERT(p != begin);
 
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    dn = 0;
 
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    while(p != begin)
 
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    {
 
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        --p;
 
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        if(*p == '/')
 
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        {
 
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            ++dn;
 
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            break;
 
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        }
 
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        if(*p == '%')
 
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            dn += 2;
 
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    }
 
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    dn = p1 - p - dn;
 
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    pos = p - ref.data();
 
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    // keep decoded_prefix consistent with new pos
 
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    // (already adjusted above)
 
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    s_ = make_pct_string_view_unsafe(
 
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        p + 1, p1 - p - 1, dn);
 
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}
 
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} // detail
 
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} // url
 
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} // boost