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/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QLALR module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QPARSER_H
#define QPARSER_H
#include <QtCore/QSharedDataPointer>
#include <QtCore/QVarLengthArray>
template <typename _Parser, typename _Table, typename _Value = int>
class QParser: protected _Table
{
public:
QParser();
~QParser();
bool parse();
inline _Value &sym(int index);
private:
inline int nextToken()
{
return static_cast<_Parser*> (this)->nextToken();
}
inline void consumeRule(int rule)
{
static_cast<_Parser*> (this)->consumeRule(rule);
}
enum { DefaultStackSize = 128 };
struct Data: public QSharedData
{
Data(): stackSize (DefaultStackSize), tos (0) {}
QVarLengthArray<int, DefaultStackSize> stateStack;
QVarLengthArray<_Value, DefaultStackSize> parseStack;
int stackSize;
int tos;
void reallocateStack() {
stackSize <<= 1;
stateStack.resize(stackSize);
parseStack.resize(stackSize);
}
};
QSharedDataPointer<Data> d;
};
template <typename _Parser, typename _Table, typename _Value>
inline _Value &QParser<_Parser, _Table, _Value>::sym(int n)
{
return d->parseStack [d->tos + n - 1];
}
template <typename _Parser, typename _Table, typename _Value>
QParser<_Parser, _Table, _Value>::QParser():
d(new Data())
{
}
template <typename _Parser, typename _Table, typename _Value>
QParser<_Parser, _Table, _Value>::~QParser()
{
}
template <typename _Parser, typename _Table, typename _Value>
bool QParser<_Parser, _Table, _Value>::parse()
{
const int INITIAL_STATE = 0;
d->tos = 0;
d->reallocateStack();
int act = d->stateStack[++d->tos] = INITIAL_STATE;
int token = -1;
forever {
if (token == -1 && - _Table::TERMINAL_COUNT != _Table::action_index[act])
token = nextToken();
act = _Table::t_action(act, token);
if (d->stateStack[d->tos] == _Table::ACCEPT_STATE)
return true;
else if (act > 0) {
if (++d->tos == d->stackSize)
d->reallocateStack();
d->parseStack[d->tos] = d->parseStack[d->tos - 1];
d->stateStack[d->tos] = act;
token = -1;
}
else if (act < 0) {
int r = - act - 1;
d->tos -= _Table::rhs[r];
act = d->stateStack[d->tos++];
consumeRule(r);
act = d->stateStack[d->tos] = _Table::nt_action(act, _Table::lhs[r] - _Table::TERMINAL_COUNT);
}
else break;
}
return false;
}
#endif // QPARSER_H
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