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  • Committer: Jonas Finnemann Jensen
  • Date: 2011-09-15 13:30:00 UTC
  • Revision ID: jopsen@gmail.com-20110915133000-wnywm1odf82emiuw
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PetriEngine/Structures/BlockStack.h
 
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/* PeTe - Petri Engine exTremE
 
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 * Copyright (C) 2011  Jonas Finnemann Jensen <jopsen@gmail.com>,
 
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 *                     Thomas Søndersø Nielsen <primogens@gmail.com>,
 
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 *                     Lars Kærlund Østergaard <larsko@gmail.com>,
 
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 * 
 
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 * This program is free software: you can redistribute it and/or modify
 
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 * it under the terms of the GNU General Public License as published by
 
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 * the Free Software Foundation, either version 3 of the License, or
 
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 * (at your option) any later version.
 
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 * 
 
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 * This program is distributed in the hope that it will be useful,
 
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 
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 * GNU General Public License for more details.
 
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 * 
 
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 * You should have received a copy of the GNU General Public License
 
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 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
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 */
 
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#ifndef BLOCKSTACK_H
 
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#define BLOCKSTACK_H
 
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#include <assert.h>
 
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namespace PetriEngine{
 
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namespace Structures{
 
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/** Block allocating stack */
 
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template<class Item, size_t blocksize>
 
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class BlockStack{
 
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        /** Internal block */
 
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        struct Block{
 
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                Block* parent;
 
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                Item items[blocksize];
 
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        };
 
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public:
 
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        /** Allocate block stack */
 
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        BlockStack(){
 
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                assert(blocksize > 0);
 
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                offset = 0;
 
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                block = new Block;
 
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                block->parent = NULL;
 
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        }
 
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        /** Release allocated memory */
 
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        ~BlockStack(){
 
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                while(block){
 
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                        Block* b = block;
 
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                        block = block->parent;
 
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                        delete b;
 
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                }
 
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        }
 
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        /** Get the top, NULL if none */
 
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        Item* top(){
 
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                if(offset)
 
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                        return &block->items[offset-1];
 
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                return NULL;
 
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        }
 
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        /** Pop item of stack, true if successful */
 
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        bool pop(){
 
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                if(offset > 1){
 
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                        offset--;
 
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                        return true;
 
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                }else if(block->parent){
 
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                        offset = blocksize;
 
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                        Block* b = block;
 
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                        block = block->parent;
 
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                        delete b;
 
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                        return true;
 
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                }else if(offset == 1){
 
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                        offset = 0;
 
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                        return true;
 
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                }
 
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                return false;
 
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        }
 
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        /** Push item onto the stack */
 
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        void push(const Item& item){
 
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                if(offset == blocksize){
 
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                        offset = 0;
 
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                        Block* parent = block;
 
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                        block = new Block;
 
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                        block->parent = parent;
 
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                }
 
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                block->items[offset++] = item;
 
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        }
 
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private:
 
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        size_t offset;
 
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        Block* block;
 
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};
 
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}
 
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}
 
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#endif /* BLOCKSTACK_H */