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/*
Copyright (C) 2011 Brazil
Copyright (C) 2022 Sutou Kouhei <kou@clear-code.com>
This library 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 2.1 of the License, or (at your option) any later version.
This library 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 library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "predictive-cursor.hpp"
#include <algorithm>
#include <cstring>
#include "trie.hpp"
namespace grn {
namespace dat {
PredictiveCursor::PredictiveCursor()
: trie_(NULL),
offset_(0),
limit_(MAX_UINT32),
flags_(PREDICTIVE_CURSOR),
buf_(),
cur_(0),
end_(0),
min_length_(0) {}
PredictiveCursor::~PredictiveCursor() {}
void PredictiveCursor::open(const Trie &trie,
const String &str,
UInt32 offset,
UInt32 limit,
UInt32 flags) {
GRN_DAT_THROW_IF(PARAM_ERROR, (str.ptr() == NULL) && (str.length() != 0));
flags = fix_flags(flags);
PredictiveCursor new_cursor(trie, offset, limit, flags);
new_cursor.init(str);
new_cursor.swap(this);
}
void PredictiveCursor::close() {
PredictiveCursor new_cursor;
new_cursor.swap(this);
}
const Key &PredictiveCursor::next() {
if (cur_ == end_) {
return Key::invalid_key();
}
if ((flags_ & ASCENDING_CURSOR) == ASCENDING_CURSOR) {
return ascending_next();
} else {
return descending_next();
}
}
PredictiveCursor::PredictiveCursor(const Trie &trie,
UInt32 offset, UInt32 limit, UInt32 flags)
: trie_(&trie),
offset_(offset),
limit_(limit),
flags_(flags),
buf_(),
cur_(0),
end_(0),
min_length_(0) {}
UInt32 PredictiveCursor::fix_flags(UInt32 flags) const {
const UInt32 cursor_type = flags & CURSOR_TYPE_MASK;
GRN_DAT_THROW_IF(PARAM_ERROR, (cursor_type != 0) &&
(cursor_type != PREDICTIVE_CURSOR));
flags |= PREDICTIVE_CURSOR;
const UInt32 cursor_order = flags & CURSOR_ORDER_MASK;
GRN_DAT_THROW_IF(PARAM_ERROR, (cursor_order != 0) &&
(cursor_order != ASCENDING_CURSOR) &&
(cursor_order != DESCENDING_CURSOR));
if (cursor_order == 0) {
flags |= ASCENDING_CURSOR;
}
const UInt32 cursor_options = flags & CURSOR_OPTIONS_MASK;
GRN_DAT_THROW_IF(PARAM_ERROR, cursor_options & ~(EXCEPT_EXACT_MATCH));
return flags;
}
void PredictiveCursor::init(const String &str) {
if (limit_ == 0) {
return;
}
min_length_ = str.length();
if ((flags_ & EXCEPT_EXACT_MATCH) == EXCEPT_EXACT_MATCH) {
++min_length_;
}
end_ = (offset_ > (MAX_UINT32 - limit_)) ? MAX_UINT32 : (offset_ + limit_);
UInt32 node_id = ROOT_NODE_ID;
for (UInt32 i = 0; i < str.length(); ++i) {
const Base base = trie_->ith_node(node_id).base();
if (base.is_linker()) {
if (offset_ == 0) {
const Key &key = trie_->get_key(base.key_pos());
if ((key.length() >= str.length()) &&
(key.str().substr(0, str.length()).compare(str, i) == 0)) {
if ((flags_ & ASCENDING_CURSOR) == ASCENDING_CURSOR) {
node_id |= IS_ROOT_FLAG;
}
buf_.push_back(node_id);
}
}
return;
}
node_id = base.offset() ^ str[i];
if (trie_->ith_node(node_id).label() != str[i]) {
return;
}
}
if ((flags_ & ASCENDING_CURSOR) == ASCENDING_CURSOR) {
node_id |= IS_ROOT_FLAG;
}
buf_.push_back(node_id);
}
void PredictiveCursor::swap(PredictiveCursor *cursor) {
std::swap(trie_, cursor->trie_);
std::swap(offset_, cursor->offset_);
std::swap(limit_, cursor->limit_);
std::swap(flags_, cursor->flags_);
buf_.swap(&cursor->buf_);
std::swap(cur_, cursor->cur_);
std::swap(end_, cursor->end_);
std::swap(min_length_, cursor->min_length_);
}
const Key &PredictiveCursor::ascending_next() {
while (!buf_.empty()) {
const bool is_root = (buf_.back() & IS_ROOT_FLAG) == IS_ROOT_FLAG;
const UInt32 node_id = buf_.back() & ~IS_ROOT_FLAG;
buf_.pop_back();
const Node node = trie_->ith_node(node_id);
if (!is_root && (node.sibling() != INVALID_LABEL)) {
buf_.push_back(node_id ^ node.label() ^ node.sibling());
}
if (node.is_linker()) {
const Key &key = trie_->get_key(node.key_pos());
if (key.length() >= min_length_) {
if (cur_++ >= offset_) {
return key;
}
}
} else if (node.child() != INVALID_LABEL) {
buf_.push_back(node.offset() ^ node.child());
}
}
return Key::invalid_key();
}
const Key &PredictiveCursor::descending_next() {
while (!buf_.empty()) {
const bool post_order = (buf_.back() & POST_ORDER_FLAG) == POST_ORDER_FLAG;
const UInt32 node_id = buf_.back() & ~POST_ORDER_FLAG;
const Base base = trie_->ith_node(node_id).base();
if (post_order) {
buf_.pop_back();
if (base.is_linker()) {
const Key &key = trie_->get_key(base.key_pos());
if (key.length() >= min_length_) {
if (cur_++ >= offset_) {
return key;
}
}
}
} else {
buf_.back() |= POST_ORDER_FLAG;
UInt32 label = trie_->ith_node(node_id).child();
while (label != INVALID_LABEL) {
buf_.push_back(base.offset() ^ label);
label = trie_->ith_node(base.offset() ^ label).sibling();
}
}
}
return Key::invalid_key();
}
} // namespace dat
} // namespace grn
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