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/* Copyright (C) 2013-2014 TU Dortmund
* This file is part of AutomataLib, http://www.automatalib.net/.
*
* AutomataLib is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 3.0 as published by the Free Software Foundation.
*
* AutomataLib 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 AutomataLib; if not, see
* http://www.gnu.de/documents/lgpl.en.html.
*/
/**
*
*/
package net.automatalib.util.minimizer;
import java.util.ArrayList;
import java.util.List;
import net.automatalib.commons.smartcollections.BasicLinkedListEntry;
import net.automatalib.commons.smartcollections.ElementReference;
import net.automatalib.commons.smartcollections.IntrusiveLinkedList;
import net.automatalib.commons.smartcollections.UnorderedCollection;
/**
* A block in the partition calculated during minimization.
*
* At the end of the minimization process, all states in the same block may
* be identified.
*
* @author Malte Isberner
*
* @param state class.
* @param transition label class.
*/
public final class Block extends BasicLinkedListEntry,Block> {
// The states contained in this block
private final UnorderedCollection> states;
// The references for both the partition and splitter collection.
private ElementReference partitionReference,
splitterQueueReference;
// The bucket of this block, used for initially arranging the
// states ordered by their respective blocks during the weak sort.
private IntrusiveLinkedList> bucket
= new IntrusiveLinkedList>();
// The sub blocks, i.e., the new blocks that result from
// splitting this block.
private List>>
subBlocks = new ArrayList>>();
// The total number of elements in all sub blocks, this is used
// to detect whether an actual split has to be performed.
private int elementsInSubBlocks;
// The sub block currently being created.
private UnorderedCollection> currSubBlock;
private final int id;
/**
* Constructor.
*/
Block(int id) {
this.id = id;
this.states = new UnorderedCollection>();
}
/**
* Constructor.
* @param states creates a block for the given collection of states.
* Ownership of this collection is assumed.
*/
Block(int id, UnorderedCollection> states) {
this.id = id;
this.states = states;
for(State state : states)
state.setBlock(this);
}
/**
* Adds a state to this block.
* @param state the state to add.
*/
void addState(State state) {
ElementReference ref = states.referencedAdd(state);
state.setBlockReference(ref);
state.setBlock(this);
}
/**
* Retrieves the collection of states in this block.
* @return the states in this block.
*/
UnorderedCollection> getStates() {
return states;
}
/**
* Retrieves the bucket of this block.
* @return this blocks bucket.
*/
IntrusiveLinkedList> getBucket() {
return bucket;
}
/**
* Adds a state to this blocks bucket.
* @param state the state to add.
* @return true iff this was the first state to be added
* to the bucket, false otherwise.
*/
boolean addToBucket(State state) {
boolean first = bucket.isEmpty();
bucket.pushBack(state);
return first;
}
/**
* Initializes a new sub block.
*/
void createSubBlock() {
currSubBlock = new UnorderedCollection>();
subBlocks.add(currSubBlock);
}
/**
* Adds a state to the current sub block.
* @param state the state to be added.
*/
void addToSubBlock(State state) {
if(currSubBlock == null) {
throw new IllegalStateException("No current sub block");
}
currSubBlock.referencedAdd(state);
elementsInSubBlocks++;
}
/**
* Retrieves the size of this block, i.e., the number of states it
* contains.
* @return the size of this block.
*/
public int size() {
return states.size();
}
/**
* Retrieves the number of elements contained in sub blocks.
* @return the number of elements in sub blocks.
*/
int getElementsInSubBlocks() {
return elementsInSubBlocks;
}
/**
* Retrieves the {@link ElementReference} that references this block
* in the partition collection, for efficient removal.
* @return the reference.
*/
ElementReference getPartitionReference() {
return partitionReference;
}
/**
* Sets the partition reference.
* @param partitionReference the reference.
*/
void setPartitionReference(
ElementReference partitionReference) {
this.partitionReference = partitionReference;
}
/**
* Retrieves the {@link ElementReference} referencing this block in the
* splitter collection, for efficient removal. If this block is no
* potential splitter, null is returned.
* @return the reference or null.
*/
ElementReference getSplitterQueueReference() {
return splitterQueueReference;
}
/**
* Sets the splitter queue reference.
* @param splitterQueueReference the reference
*/
void setSplitterQueueReference(
ElementReference splitterQueueReference) {
this.splitterQueueReference = splitterQueueReference;
}
/**
* Removes a state from this block.
* @param ref the reference for this state.
*/
void removeState(ElementReference ref) {
states.remove(ref);
}
/**
* Retrieves the list of sub blocks, if any.
* @return the sub blocks.
*/
List>> getSubBlocks() {
return subBlocks;
}
/**
* Resets all sub block information.
*/
void clearSubBlocks() {
subBlocks.clear();
elementsInSubBlocks = 0;
}
/**
* Checks whether or not this block is empty, i.e., contains no states.
* @return true iff the block is empty, false
* otherwise.
*/
public boolean isEmpty() {
return states.isEmpty();
}
/**
* Checks whether or not this block is a singleton, i.e., contains only
* a single state.
* @return true iff this block is a singleton,
* false otherwise.
*/
public boolean isSingleton() {
return (states.size() == 1);
}
/**
* Retrieves the ID of this block.
* @return the id of this block.
*/
public int getId() {
return id;
}
/*
* (non-Javadoc)
* @see de.ls5.smartcollections.LinkedListEntry#getElement()
*/
@Override
public Block getElement() {
return this;
}
}