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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include "raw_attribute.h"
#include <cassert>
namespace search::attribute {
RawAttribute::RawAttribute(const vespalib::string& name, const Config& config)
: NotImplementedAttribute(name, config)
{
}
RawAttribute::~RawAttribute() = default;
namespace {
template <bool desc>
unsigned char remap(unsigned char val)
{
return (desc ? (0xff - val) : val);
}
/*
* Serialize raw data to a sort blob that can be passed to memcmp.
*
* End of raw data is encoded as 0, while a bias of 1 is added to raw data byte values to
* differentiate from end of raw data. To avoid wraparound, 0xfe and 0xff are encoded
* as two bytes (0xfe => [0xff, 0xfe] and 0xff => [0xff, 0xff]).
*
* If sort order is descending, all encoded values are inverted, this
* is done by remap function above.
*/
template <bool desc>
long serialize_for_sort(vespalib::ConstArrayRef<char> raw, void* serTo, long available)
{
auto src = reinterpret_cast<const unsigned char *>(raw.data());
auto src_end = src + raw.size();
size_t extra = 1;
for (auto p = src; p != src_end; ++p) {
if (*p >= 0xfe) {
++extra;
}
}
if (available >= (long)(raw.size() + extra)) {
auto dst = static_cast<unsigned char *>(serTo);
auto dst_orig = dst;
for (auto p = src; p != src_end; ++p) {
if (*p >= 0xfe) {
*dst++ = remap<desc>(0xff);
*dst++ = remap<desc>(*p);
} else {
*dst++ = remap<desc>(*p + 1);
}
}
*dst++ = remap<desc>(0);
assert(raw.size() + extra + dst_orig == dst);
} else {
return -1;
}
return raw.size() + extra;
}
}
long
RawAttribute::onSerializeForAscendingSort(DocId doc, void* serTo, long available, const common::BlobConverter*) const
{
auto raw = get_raw(doc);
return serialize_for_sort<false>(raw, serTo, available);
}
long
RawAttribute::onSerializeForDescendingSort(DocId doc, void* serTo, long available, const common::BlobConverter*) const
{
auto raw = get_raw(doc);
return serialize_for_sort<true>(raw, serTo, available);
}
}
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