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/*
This file is part of the Maude 2 interpreter.
Copyright 1997-2006 SRI International, Menlo Park, CA 94025, USA.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*/
//
// Class for managing a collection of persistent stacks of strategies with sharing.
//
#ifndef _strategyStackManager_hh_
#define _strategyStackManager_hh_
class StrategyStackManager
{
public:
typedef int StackId;
enum Constants
{
EMPTY_STACK = 0
};
StrategyStackManager();
static StackId emptyStack();
bool empty(StackId stackId) const;
StrategyExpression* top(StackId stackId) const;
StackId pop(StackId stackId) const;
StackId push(StackId stackId, StrategyExpression* strategy);
private:
struct Entry
{
StrategyExpression* strategy;
StackId restOfStack;
//
// This fields are use solelyto keep a linked list of entries having
// the same restOfStack so we can minimize the creation of duplicate
// entries.
//
StackId firstSuccessor; // first stack that has us as restOfStack
StackId nextPeer; // next stack that shares our restOfStack
};
Vector<Entry> stackTable;
};
inline bool
StrategyStackManager::empty(StackId stackId) const
{
return stackId == EMPTY_STACK;
}
inline StrategyExpression*
StrategyStackManager::top(StackId stackId) const
{
return stackTable[stackId].strategy;
}
inline StrategyStackManager::StackId
StrategyStackManager::pop(StackId stackId) const
{
return stackTable[stackId].restOfStack;
}
#endif
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