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/** @file
* @brief Build key strings for MSet ordering or collapsing.
*/
/* Copyright (C) 2007,2009,2011,2015,2019 Olly Betts
* Copyright (C) 2010 Richard Boulton
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see
* <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include "xapian/keymaker.h"
#include "xapian/document.h"
#include "xapian/error.h"
#include "pack.h"
#include <memory>
#include <string>
using namespace std;
namespace Xapian {
KeyMaker::~KeyMaker() { }
[[noreturn]]
static void
throw_unimplemented(const char* message)
{
throw Xapian::UnimplementedError(message);
}
string
KeyMaker::name() const
{
throw_unimplemented("KeyMaker subclass not suitable for use with remote "
"searches - name() method not implemented");
}
string
KeyMaker::serialise() const
{
throw_unimplemented("KeyMaker subclass not suitable for use with remote"
"searches - serialise() method not implemented");
}
KeyMaker*
KeyMaker::unserialise(const string&, const Registry&) const
{
throw_unimplemented("KeyMaker subclass not suitable for use with remote"
"searches - unserialise() method not implemented");
}
string
MultiValueKeyMaker::operator()(const Xapian::Document & doc) const
{
string result;
auto i = slots.begin();
// Don't crash if slots is empty.
if (rare(i == slots.end())) return result;
size_t last_not_empty_forwards = 0;
while (true) {
// All values (except for the last if it's sorted forwards) need to
// be adjusted.
//
// FIXME: allow Xapian::BAD_VALUENO to mean "relevance?"
string v = doc.get_value(i->slot);
bool reverse_sort = i->reverse;
if (v.empty()) {
v = i->defvalue;
}
if (reverse_sort || !v.empty())
last_not_empty_forwards = result.size();
if (++i == slots.end() && !reverse_sort) {
if (v.empty()) {
// Trim off all the trailing empty forwards values.
result.resize(last_not_empty_forwards);
} else {
// No need to adjust the last value if it's sorted forwards.
result += v;
}
break;
}
if (reverse_sort) {
// For a reverse ordered value, we subtract each byte from '\xff',
// except for '\0' which we convert to "\xff\0". We insert
// "\xff\xff" after the encoded value.
for (string::const_iterator j = v.begin(); j != v.end(); ++j) {
unsigned char ch = static_cast<unsigned char>(*j);
result += char(255 - ch);
if (ch == 0) result += '\0';
}
result.append("\xff\xff", 2);
if (i == slots.end()) break;
last_not_empty_forwards = result.size();
} else {
// For a forward ordered value (unless it's the last value), we
// convert any '\0' to "\0\xff". We insert "\0\0" after the
// encoded value.
string::size_type j = 0, nul;
while ((nul = v.find('\0', j)) != string::npos) {
++nul;
result.append(v, j, nul - j);
result += '\xff';
j = nul;
}
result.append(v, j, string::npos);
if (!v.empty())
last_not_empty_forwards = result.size();
result.append("\0", 2);
}
}
return result;
}
string
MultiValueKeyMaker::name() const
{
return "Xapian::MultiValueKeyMaker";
}
static constexpr unsigned char KEYSPEC_REVERSE = 1;
static constexpr unsigned char KEYSPEC_DEFVALUE = 2;
string
MultiValueKeyMaker::serialise() const
{
string result;
for (auto& keyspec : slots) {
pack_uint(result, keyspec.slot);
if (keyspec.defvalue.empty()) {
result += char((keyspec.reverse ? KEYSPEC_REVERSE : 0));
} else {
result += char((keyspec.reverse ? KEYSPEC_REVERSE : 0) |
KEYSPEC_DEFVALUE);
pack_string(result, keyspec.defvalue);
}
}
return result;
}
KeyMaker*
MultiValueKeyMaker::unserialise(const string& serialised,
const Registry&) const
{
const char* p = serialised.data();
const char* end = p + serialised.size();
unique_ptr<MultiValueKeyMaker> result(new MultiValueKeyMaker());
while (p != end) {
Xapian::valueno slot;
bool reverse;
if (!unpack_uint(&p, end, &slot) || p == end) {
unpack_throw_serialisation_error(p);
}
unsigned char bits = *p++;
reverse = (bits & KEYSPEC_REVERSE);
if (bits & KEYSPEC_DEFVALUE) {
string defvalue;
if (!unpack_string(&p, end, defvalue)) {
unpack_throw_serialisation_error(p);
}
result->add_value(slot, reverse, defvalue);
} else {
result->add_value(slot, reverse);
}
}
return result.release();
}
}
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