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/* This file is part of Strigi Desktop Search
*
* Copyright (C) 2006 Jos van den Oever <jos@vandenoever.info>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include <strigi/stringterminatedsubstream.h>
#include <strigi/strigiconfig.h>
#include <strigi/kmpsearcher.h>
#include <cassert>
#include <iostream>
using namespace std;
using namespace Strigi;
// TODO add a mechanism that avoid searching for a stop point again after a
// reset
class StringTerminatedSubStream::Private {
public:
KmpSearcher m_searcher;
const int64_t m_offset;
int64_t furthest;
InputStream* m_input;
Private(InputStream* i, const std::string& terminator)
: m_offset(i->position()), furthest(0), m_input(i) {
m_searcher.setQuery(terminator);
}
};
StringTerminatedSubStream::StringTerminatedSubStream(InputStream* i,
const std::string& terminator) :p(new Private(i, terminator)) {
}
StringTerminatedSubStream::~StringTerminatedSubStream() {
delete p;
}
int64_t
StringTerminatedSubStream::offset() const {
return p->m_offset;
}
int32_t
StringTerminatedSubStream::read(const char*& start, int32_t min, int32_t max) {
if (m_status == Eof) return -1;
if (m_status == Error) return -2;
int32_t nread;
// check if we already read enough
const int64_t pos = p->m_input->position();
nread = (int32_t)(p->furthest - pos);
if (min <= nread) {
if (max <= 0 || max > nread) {
max = nread;
}
nread = p->m_input->read(start, min, max);
assert(nread >= -1);
if (nread > 0) {
m_position += nread;
if (m_position == m_size) {
m_status = Eof;
}
}
return nread;
}
// convenience parameter
int32_t tl = p->m_searcher.queryLength();
// increase min and max to accommodate for the length of the terminator
int32_t tlmin = min;
int32_t tlmax = max;
if (tlmin == 0) {
tlmin = 1 + tl;
} else {
tlmin += tl;
}
if (tlmax > 0 && tlmax < tlmin) tlmax = tlmin;
nread = p->m_input->read(start, tlmin, tlmax);
if (nread == -1) {
m_status = Eof;
return nread;
}
if (nread < -1) {
m_status = Error;
m_error = p->m_input->error();
return nread;
}
const char* end = p->m_searcher.search(start, nread);
if (end) {
// the end signature was found
nread = (int32_t)(end - start);
// signal the end of stream at the next call
m_status = Eof;
// set input stream to point after the terminator
p->m_input->reset(pos + nread + tl);
} else if (nread >= tlmin) {
// we are not at or near the end and read the required amount
// reserve the last bit of buffer for rereading to match the terminator
// in the next call
nread -= tl;
p->furthest = pos + nread;
// we rewind, but the pointer 'start' will stay valid nontheless
p->m_input->reset(pos + nread);
} else if (max != 0 && nread > max) {
// we are near the end of the stream but cannot pass all data
// at once because the amount read is larger than the amount to pass
p->furthest = pos + nread;
p->m_input->reset(pos + max);
nread = max;
} else {
// we are at the end of the stream, so no need to rewind
// signal the end of stream at the next call
m_status = Eof;
}
if (nread > 0) m_position += nread;
if (m_status == Eof) {
m_size = m_position;
}
return nread;
}
int64_t
StringTerminatedSubStream::reset(int64_t newpos) {
m_position = p->m_input->reset(newpos + p->m_offset);
if (m_position >= p->m_offset) {
m_position -= p->m_offset;
if (m_position != m_size) m_status = Ok;
} else {
// the stream is not positioned at a valid m_position
m_status = Error;
m_position = -1;
}
return m_position;
}
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