diff options
Diffstat (limited to 'src/prefix_tree.cpp')
| -rw-r--r-- | src/prefix_tree.cpp | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/src/prefix_tree.cpp b/src/prefix_tree.cpp new file mode 100644 index 0000000..51225d6 --- /dev/null +++ b/src/prefix_tree.cpp @@ -0,0 +1,180 @@ +/* + Copyright (c) 2007-2010 iMatix Corporation + + This file is part of 0MQ. + + 0MQ is free software; you can redistribute it and/or modify it under + the terms of the Lesser GNU 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 + Lesser GNU General Public License for more details. + + You should have received a copy of the Lesser GNU 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 "prefix_tree.hpp" + +zmq::prefix_tree_t::prefix_tree_t () : + refcnt (0), + min (0), + count (0) +{ +} + +zmq::prefix_tree_t::~prefix_tree_t () +{ + if (count == 1) + delete next.node; + else if (count > 1) { + for (unsigned char i = 0; i != count; ++i) + if (next.table [i]) + delete next.table [i]; + free (next.table); + } +} + +void zmq::prefix_tree_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; + prefix_tree_t *oldp = next.node; + count = (min < c ? c - min : min - c) + 1; + next.table = (prefix_tree_t**) + malloc (sizeof (prefix_tree_t*) * count); + zmq_assert (next.table); + for (unsigned char 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 char old_count = count; + count = c - min + 1; + next.table = (prefix_tree_t**) realloc ((void*) next.table, + sizeof (prefix_tree_t*) * count); + zmq_assert (next.table); + for (unsigned char i = old_count; i != count; i++) + next.table [i] = NULL; + } + else { + + // The new character is below the current character range. + unsigned char old_count = count; + count = (min + old_count) - c; + next.table = (prefix_tree_t**) realloc ((void*) next.table, + sizeof (prefix_tree_t*) * count); + zmq_assert (next.table); + memmove (next.table + min - c, next.table, + old_count * sizeof (prefix_tree_t*)); + for (unsigned char 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) prefix_tree_t; + zmq_assert (next.node); + } + next.node->add (prefix_ + 1, size_ - 1); + } + else { + if (!next.table [c - min]) { + next.table [c - min] = new (std::nothrow) prefix_tree_t; + zmq_assert (next.table [c - min]); + } + next.table [c - min]->add (prefix_ + 1, size_ - 1); + } +} + +bool zmq::prefix_tree_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; + + prefix_tree_t *next_node = + count == 1 ? next.node : next.table [c - min]; + + if (!next_node) + return false; + + return next_node->rm (prefix_ + 1, size_ - 1); +} + +bool zmq::prefix_tree_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. + prefix_tree_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_--; + } +} |