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/* Copyright(C) 2011 Brazil
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 "prefix-cursor.hpp"
#include <algorithm>
#include "trie.hpp"
namespace grn {
namespace dat {
PrefixCursor::PrefixCursor()
: trie_(NULL),
offset_(0),
limit_(MAX_UINT32),
flags_(PREFIX_CURSOR),
buf_(),
cur_(0),
end_(0) {}
PrefixCursor::~PrefixCursor() {}
void PrefixCursor::open(const Trie &trie,
const String &str,
UInt32 min_length,
UInt32 offset,
UInt32 limit,
UInt32 flags) {
GRN_DAT_THROW_IF(PARAM_ERROR, (str.ptr() == NULL) && (str.length() != 0));
GRN_DAT_THROW_IF(PARAM_ERROR, min_length > str.length());
flags = fix_flags(flags);
PrefixCursor new_cursor(trie, offset, limit, flags);
new_cursor.init(str, min_length);
new_cursor.swap(this);
}
void PrefixCursor::close() {
PrefixCursor new_cursor;
new_cursor.swap(this);
}
const Key &PrefixCursor::next() {
if (cur_ == end_) {
return Key::invalid_key();
}
if ((flags_ & ASCENDING_CURSOR) == ASCENDING_CURSOR) {
return trie_->get_key(buf_[cur_++]);
} else {
return trie_->get_key(buf_[--cur_]);
}
}
PrefixCursor::PrefixCursor(const Trie &trie,
UInt32 offset, UInt32 limit, UInt32 flags)
: trie_(&trie),
offset_(offset),
limit_(limit),
flags_(flags),
buf_(),
cur_(0),
end_(0) {}
UInt32 PrefixCursor::fix_flags(UInt32 flags) const {
const UInt32 cursor_type = flags & CURSOR_TYPE_MASK;
GRN_DAT_THROW_IF(PARAM_ERROR, (cursor_type != 0) &&
(cursor_type != PREFIX_CURSOR));
flags |= PREFIX_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 PrefixCursor::init(const String &str, UInt32 min_length) {
if ((limit_ == 0) || (offset_ > (str.length() - min_length))) {
return;
}
UInt32 node_id = ROOT_NODE_ID;
UInt32 i;
for (i = 0; i < str.length(); ++i) {
const Base base = trie_->ith_node(node_id).base();
if (base.is_linker()) {
const Key &key = trie_->get_key(base.key_pos());
if ((key.length() >= min_length) && (key.length() <= str.length()) &&
(str.substr(0, key.length()).compare(key.str(), i) == 0) &&
((key.length() < str.length()) ||
((flags_ & EXCEPT_EXACT_MATCH) != EXCEPT_EXACT_MATCH))) {
buf_.push_back(base.key_pos());
}
break;
}
if ((i >= min_length) &&
(trie_->ith_node(node_id).child() == TERMINAL_LABEL)) {
const Base linker_base =
trie_->ith_node(base.offset() ^ TERMINAL_LABEL).base();
if (linker_base.is_linker()) {
buf_.push_back(linker_base.key_pos());
}
}
node_id = base.offset() ^ str[i];
if (trie_->ith_node(node_id).label() != str[i]) {
break;
}
}
if ((i == str.length()) &&
((flags_ & EXCEPT_EXACT_MATCH) != EXCEPT_EXACT_MATCH)) {
const Base base = trie_->ith_node(node_id).base();
if (base.is_linker()) {
const Key &key = trie_->get_key(base.key_pos());
if ((key.length() >= min_length) && (key.length() <= str.length())) {
buf_.push_back(base.key_pos());
}
} else if (trie_->ith_node(node_id).child() == TERMINAL_LABEL) {
const Base linker_base =
trie_->ith_node(base.offset() ^ TERMINAL_LABEL).base();
if (linker_base.is_linker()) {
buf_.push_back(linker_base.key_pos());
}
}
}
if (buf_.size() <= offset_) {
return;
}
if ((flags_ & ASCENDING_CURSOR) == ASCENDING_CURSOR) {
cur_ = offset_;
end_ = (limit_ < (buf_.size() - cur_)) ? (cur_ + limit_) : buf_.size();
} else {
cur_ = buf_.size() - offset_;
end_ = (limit_ < cur_) ? (cur_ - limit_) : 0;
}
}
void PrefixCursor::swap(PrefixCursor *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_);
}
} // namespace dat
} // namespace grn
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