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/*
Copyright (c) 2007-2011 iMatix Corporation
Copyright (c) 2011-2012 Spotify AB
Copyright (c) 2007-2011 Other contributors as noted in the AUTHORS file
This file is part of 0MQ.
0MQ is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
0MQ 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <new>
#include <algorithm>
#include "platform.hpp"
#if defined ZMQ_HAVE_WINDOWS
#include "windows.hpp"
#endif
#include "err.hpp"
#include "trie.hpp"
zmq::trie_t::trie_t () :
refcnt (0),
min (0),
count (0),
live_nodes (0)
{
}
zmq::trie_t::~trie_t ()
{
if (count == 1) {
zmq_assert (next.node);
delete next.node;
next.node = 0;
}
else if (count > 1) {
for (unsigned short i = 0; i != count; ++i)
if (next.table [i])
delete next.table [i];
free (next.table);
}
}
void zmq::trie_t::add (unsigned char *prefix_, size_t size_)
{
// We are at the node corresponding to the prefix. We are done.
if (!size_) {
++refcnt;
return;
}
unsigned char c = *prefix_;
if (c < min || c >= min + count) {
// The character is out of range of currently handled
// charcters. We have to extend the table.
if (!count) {
min = c;
count = 1;
next.node = NULL;
}
else if (count == 1) {
unsigned char oldc = min;
trie_t *oldp = next.node;
count = (min < c ? c - min : min - c) + 1;
next.table = (trie_t**)
malloc (sizeof (trie_t*) * count);
alloc_assert (next.table);
for (unsigned short i = 0; i != count; ++i)
next.table [i] = 0;
min = std::min (min, c);
next.table [oldc - min] = oldp;
}
else if (min < c) {
// The new character is above the current character range.
unsigned short old_count = count;
count = c - min + 1;
next.table = (trie_t**) realloc ((void*) next.table,
sizeof (trie_t*) * count);
zmq_assert (next.table);
for (unsigned short i = old_count; i != count; i++)
next.table [i] = NULL;
}
else {
// The new character is below the current character range.
unsigned short old_count = count;
count = (min + old_count) - c;
next.table = (trie_t**) realloc ((void*) next.table,
sizeof (trie_t*) * count);
zmq_assert (next.table);
memmove (next.table + min - c, next.table,
old_count * sizeof (trie_t*));
for (unsigned short i = 0; i != min - c; i++)
next.table [i] = NULL;
min = c;
}
}
// If next node does not exist, create one.
if (count == 1) {
if (!next.node) {
next.node = new (std::nothrow) trie_t;
alloc_assert (next.node);
++live_nodes;
}
next.node->add (prefix_ + 1, size_ - 1);
}
else {
if (!next.table [c - min]) {
next.table [c - min] = new (std::nothrow) trie_t;
alloc_assert (next.table [c - min]);
++live_nodes;
}
next.table [c - min]->add (prefix_ + 1, size_ - 1);
}
}
bool zmq::trie_t::rm (unsigned char *prefix_, size_t size_)
{
if (!size_) {
if (!refcnt)
return false;
refcnt--;
return true;
}
unsigned char c = *prefix_;
if (!count || c < min || c >= min + count)
return false;
trie_t *next_node =
count == 1 ? next.node : next.table [c - min];
if (!next_node)
return false;
bool ret = next_node->rm (prefix_ + 1, size_ - 1);
if (next_node->is_redundant ()) {
delete next_node;
if (count == 1) {
next.node = 0;
count = 0;
}
else
next.table [c - min] = 0;
--live_nodes;
}
return ret;
}
bool zmq::trie_t::check (unsigned char *data_, size_t size_)
{
// This function is on critical path. It deliberately doesn't use
// recursion to get a bit better performance.
trie_t *current = this;
while (true) {
// We've found a corresponding subscription!
if (current->refcnt)
return true;
// We've checked all the data and haven't found matching subscription.
if (!size_)
return false;
// If there's no corresponding slot for the first character
// of the prefix, the message does not match.
unsigned char c = *data_;
if (c < current->min || c >= current->min + current->count)
return false;
// Move to the next character.
if (current->count == 1)
current = current->next.node;
else {
current = current->next.table [c - current->min];
if (!current)
return false;
}
data_++;
size_--;
}
}
bool zmq::trie_t::is_redundant() const
{
return refcnt == 0 && live_nodes == 0;
}
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