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/* chert_alltermslist.cc: A termlist containing all terms in a chert database.
*
* Copyright (C) 2005,2007,2008,2009,2010 Olly Betts
*
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
* USA
*/
#include <config.h>
#include "chert_alltermslist.h"
#include "chert_postlist.h"
#include "debuglog.h"
#include "pack.h"
#include "stringutils.h"
void
ChertAllTermsList::read_termfreq_and_collfreq() const
{
LOGCALL_VOID(DB, "ChertAllTermsList::read_termfreq_and_collfreq", NO_ARGS);
Assert(!current_term.empty());
Assert(!at_end());
// Unpack the termfreq and collfreq from the tag. Only do this if
// one or other is actually read.
cursor->read_tag();
const char *p = cursor->current_tag.data();
const char *pend = p + cursor->current_tag.size();
ChertPostList::read_number_of_entries(&p, pend, &termfreq, &collfreq);
}
ChertAllTermsList::~ChertAllTermsList()
{
LOGCALL_DTOR(DB, "ChertAllTermsList");
delete cursor;
}
string
ChertAllTermsList::get_termname() const
{
LOGCALL(DB, string, "ChertAllTermsList::get_termname", NO_ARGS);
Assert(!current_term.empty());
Assert(!at_end());
RETURN(current_term);
}
Xapian::doccount
ChertAllTermsList::get_termfreq() const
{
LOGCALL(DB, Xapian::doccount, "ChertAllTermsList::get_termfreq", NO_ARGS);
Assert(!current_term.empty());
Assert(!at_end());
if (termfreq == 0) read_termfreq_and_collfreq();
RETURN(termfreq);
}
Xapian::termcount
ChertAllTermsList::get_collection_freq() const
{
LOGCALL(DB, Xapian::termcount, "ChertAllTermsList::get_collection_freq", NO_ARGS);
Assert(!current_term.empty());
Assert(!at_end());
if (termfreq == 0) read_termfreq_and_collfreq();
RETURN(collfreq);
}
TermList *
ChertAllTermsList::next()
{
LOGCALL(DB, TermList *, "ChertAllTermsList::next", NO_ARGS);
Assert(!at_end());
// Set termfreq to 0 to indicate no termfreq/collfreq have been read for
// the current term.
termfreq = 0;
if (rare(!cursor)) {
cursor = database->postlist_table.cursor_get();
Assert(cursor); // The postlist table isn't optional.
if (prefix.empty()) {
(void)cursor->find_entry_ge(string("\x00\xff", 2));
} else {
const string & key = pack_chert_postlist_key(prefix);
if (cursor->find_entry_ge(key)) {
// The exact term we asked for is there, so just copy it rather
// than wasting effort unpacking it from the key.
current_term = prefix;
RETURN(NULL);
}
}
goto first_time;
}
while (true) {
cursor->next();
first_time:
if (cursor->after_end()) {
current_term.resize(0);
RETURN(NULL);
}
const char *p = cursor->current_key.data();
const char *pend = p + cursor->current_key.size();
if (!unpack_string_preserving_sort(&p, pend, current_term)) {
throw Xapian::DatabaseCorruptError("PostList table key has unexpected format");
}
// If this key is for the first chunk of a postlist, we're done.
// Otherwise we need to skip past continuation chunks until we find the
// first chunk of the next postlist.
if (p == pend) break;
}
if (!startswith(current_term, prefix)) {
// We've reached the end of the prefixed terms.
cursor->to_end();
current_term.resize(0);
}
RETURN(NULL);
}
TermList *
ChertAllTermsList::skip_to(const string &term)
{
LOGCALL(DB, TermList *, "ChertAllTermsList::skip_to", term);
Assert(!at_end());
// Set termfreq to 0 to indicate no termfreq/collfreq have been read for
// the current term.
termfreq = 0;
if (rare(!cursor)) {
cursor = database->postlist_table.cursor_get();
Assert(cursor); // The postlist table isn't optional.
}
string key = pack_chert_postlist_key(term);
if (cursor->find_entry_ge(key)) {
// The exact term we asked for is there, so just copy it rather than
// wasting effort unpacking it from the key.
current_term = term;
} else {
if (cursor->after_end()) {
current_term.resize(0);
RETURN(NULL);
}
const char *p = cursor->current_key.data();
const char *pend = p + cursor->current_key.size();
if (!unpack_string_preserving_sort(&p, pend, current_term)) {
throw Xapian::DatabaseCorruptError("PostList table key has unexpected format");
}
}
if (!startswith(current_term, prefix)) {
// We've reached the end of the prefixed terms.
cursor->to_end();
current_term.resize(0);
}
RETURN(NULL);
}
bool
ChertAllTermsList::at_end() const
{
LOGCALL(DB, bool, "ChertAllTermsList::at_end", NO_ARGS);
RETURN(cursor && cursor->after_end());
}
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