package org.ggp.base.util.propnet.factory.converter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.ggp.base.util.gdl.grammar.GdlDistinct;
import org.ggp.base.util.gdl.grammar.GdlLiteral;
import org.ggp.base.util.gdl.grammar.GdlNot;
import org.ggp.base.util.gdl.grammar.GdlPool;
import org.ggp.base.util.gdl.grammar.GdlProposition;
import org.ggp.base.util.gdl.grammar.GdlRelation;
import org.ggp.base.util.gdl.grammar.GdlRule;
import org.ggp.base.util.gdl.grammar.GdlSentence;
import org.ggp.base.util.propnet.architecture.Component;
import org.ggp.base.util.propnet.architecture.PropNet;
import org.ggp.base.util.propnet.architecture.components.And;
import org.ggp.base.util.propnet.architecture.components.Constant;
import org.ggp.base.util.propnet.architecture.components.Not;
import org.ggp.base.util.propnet.architecture.components.Or;
import org.ggp.base.util.propnet.architecture.components.Proposition;
import org.ggp.base.util.propnet.architecture.components.Transition;
import org.ggp.base.util.statemachine.Role;
/**
* The PropNetConverter class defines PropNet conversion for the PropNetFactory
* class. This takes in a flattened game description, and converts it into an
* equivalent PropNet.
*/
public final class PropNetConverter
{
/** An archive of Propositions, indexed by name. */
private Map<GdlSentence, Proposition> propositions;
/** An archive of Components. */
private Set<Component> components;
/**
* Converts a game description to a PropNet using the following process
* (note that this method and all of the methods that it invokes assume that
* <tt>description</tt> has already been flattened by a PropNetFlattener):
* <ol>
* <li>Transforms each of the rules in <tt>description</tt> into
* equivalent PropNet Components.</li>
* <li>Adds or gates to Propositions with more than one input.</li>
* <li>Adds inputs that are implicitly specified by <tt>description</tt>.</li>
* </ol>
*
* @param description
* A game description.
* @return An equivalent PropNet.
*/
public PropNet convert(List<Role> roles, List<GdlRule> description)
{
propositions = new HashMap<GdlSentence, Proposition>();
components = new HashSet<Component>();
for ( GdlRule rule : description )
{
if ( rule.arity() > 0 )
{
convertRule(rule);
}
else
{
convertStatic(rule.getHead());
}
}
fixDisjunctions();
addMissingInputs();
return new PropNet(roles, components);
}
/**
* Creates an equivalent InputProposition for every LegalProposition where
* none already exists.
*/
private void addMissingInputs()
{
List<Proposition> addList = new ArrayList<Proposition>();
for ( Proposition proposition : propositions.values() )
{
if ( proposition.getName() instanceof GdlRelation )
{
GdlRelation relation = (GdlRelation) proposition.getName();
if ( relation.getName().getValue().equals("legal") )
{
addList.add(proposition);
}
}
}
for ( Proposition addItem : addList )
{
GdlRelation relation = (GdlRelation) addItem.getName();
components.add(getProposition(GdlPool.getRelation(GdlPool.getConstant("does"), relation.getBody())));
}
}
/**
* Converts a literal to equivalent PropNet Components and returns a
* reference to the last of those components.
*
* @param literal
* The literal to convert to equivalent PropNet Components.
* @return The last of those components.
*/
private Proposition convertConjunct(GdlLiteral literal)
{
if ( literal instanceof GdlDistinct )
{
GdlDistinct distinct = (GdlDistinct) literal;
Proposition proposition = new Proposition(GdlPool.getProposition(GdlPool.getConstant("anon")));
Constant constant = new Constant(!distinct.getArg1().equals(distinct.getArg2()));
link(constant, proposition);
components.add(proposition);
components.add(constant);
return proposition;
}
else if ( literal instanceof GdlNot )
{
GdlNot not = (GdlNot) literal;
Proposition input = convertConjunct(not.getBody());
Not no = new Not();
Proposition output = new Proposition(GdlPool.getProposition(GdlPool.getConstant("anon")));
link(input, no);
link(no, output);
components.add(input);
components.add(no);
components.add(output);
return output;
}
else
{
GdlSentence sentence = (GdlSentence) literal;
Proposition proposition = getProposition(sentence);
components.add(proposition);
return proposition;
}
}
/**
* Converts a sentence to equivalent PropNet Components and returns the
* first of those components.
*
* @param sentence
* The sentence to convert to equivalent PropNet Components.
* @return The first of those Components.
*/
private Proposition convertHead(GdlSentence sentence)
{
if ( sentence.getName().getValue().equals("next") )
{
Proposition head = getProposition(GdlPool.getRelation(GdlPool.getConstant("true"),
sentence.getBody()));
Transition transition = new Transition();
Proposition preTransition = new Proposition(GdlPool.getProposition(GdlPool.getConstant("anon")));
link(preTransition, transition);
link(transition, head);
components.add(head);
components.add(transition);
components.add(preTransition);
return preTransition;
}
else
{
Proposition proposition = getProposition(sentence);
components.add(proposition);
return proposition;
}
}
/**
* Converts a rule into equivalent PropNet Components by invoking the
* <tt>convertHead()</tt> method on the head, and the
* <tt>convertConjunct</tt> method on every literal in the body and
* joining the results by an and gate.
*
* @param rule
* The rule to convert.
*/
private void convertRule(GdlRule rule)
{
Proposition head = convertHead(rule.getHead());
And and = new And();
link(and, head);
components.add(head);
components.add(and);
for ( GdlLiteral literal : rule.getBody() )
{
Proposition conjunct = convertConjunct(literal);
link(conjunct, and);
}
}
/**
* Converts a sentence to equivalent PropNet Components.
*
* @param sentence
* The sentence to convert to equivalent PropNet Components.
*/
private void convertStatic(GdlSentence sentence)
{
if ( sentence.getName().getValue().equals("init") )
{
Proposition init = getProposition(GdlPool.getProposition(GdlPool.getConstant("INIT")));
Transition transition = new Transition();
Proposition proposition = getProposition(GdlPool.getRelation(GdlPool.getConstant("true"),
sentence.getBody()));
link(init, transition);
link(transition, proposition);
components.add(init);
components.add(transition);
components.add(proposition);
}
Constant constant = new Constant(true);
Proposition proposition = getProposition(sentence);
link(constant, proposition);
components.add(constant);
components.add(proposition);
}
/**
* Creates an or gate to combine the inputs to a Proposition wherever one
* has more than one input.
*/
private void fixDisjunctions()
{
List<Proposition> fixList = new ArrayList<Proposition>();
for ( Proposition proposition : propositions.values() )
{
if ( proposition.getInputs().size() > 1 )
{
fixList.add(proposition);
}
}
for ( Proposition fixItem : fixList )
{
Or or = new Or();
int i = 0;
for ( Component input : fixItem.getInputs() )
{
i++;
Proposition disjunct = null;
if ( fixItem.getName() instanceof GdlProposition )
{
GdlProposition proposition = (GdlProposition) fixItem.getName();
disjunct = new Proposition(GdlPool.getProposition(GdlPool.getConstant(proposition.getName().getValue() + "-" + i)));
}
else
{
GdlRelation relation = (GdlRelation) fixItem.getName();
disjunct = new Proposition(GdlPool.getRelation(GdlPool.getConstant(relation.getName().getValue() + "-" + i), relation.getBody()));
}
input.getOutputs().clear();
link(input, disjunct);
link(disjunct, or);
components.add(disjunct);
}
fixItem.getInputs().clear();
link(or, fixItem);
components.add(or);
}
}
/**
* Returns a Proposition with name <tt>term</tt>, creating one if none
* already exists.
*
* @param sentence
* The name of the Proposition.
* @return A Proposition with name <tt>term</tt>.
*/
private Proposition getProposition(GdlSentence sentence)
{
if ( !propositions.containsKey(sentence) )
{
propositions.put(sentence, new Proposition(sentence));
}
return propositions.get(sentence);
}
/**
* Adds inputs and outputs to <tt>source</tt> and <tt>target</tt> such
* that <tt>source becomes an input to <tt>target</tt>.
* @param source A component.
* @param target A second component.
*/
private void link(Component source, Component target)
{
source.addOutput(target);
target.addInput(source);
}
}