package org.ggp.base.util.propnet.factory.flattener;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.ggp.base.util.gdl.grammar.Gdl;
import org.ggp.base.util.gdl.grammar.GdlConstant;
import org.ggp.base.util.gdl.grammar.GdlFunction;
import org.ggp.base.util.gdl.grammar.GdlLiteral;
import org.ggp.base.util.gdl.grammar.GdlPool;
import org.ggp.base.util.gdl.grammar.GdlRule;
import org.ggp.base.util.gdl.grammar.GdlSentence;
import org.ggp.base.util.gdl.grammar.GdlTerm;
import org.ggp.base.util.gdl.transforms.DeORer;
import org.ggp.base.util.logging.GamerLogger;
import org.ggp.base.util.propnet.factory.annotater.PropNetAnnotater;
import org.ggp.base.util.prover.aima.substituter.Substituter;
import org.ggp.base.util.prover.aima.substitution.Substitution;
import org.ggp.base.util.prover.aima.unifier.Unifier;
/**
* PropNetAnnotatedFlattener is an implementation of a GDL flattener that needs
* the rules to contain ( base ?x ) propositions that explicitly specify domains
* for all of the base propositions.
*
* This flattener should work on all sizes of games, but requires these explicit
* annotations to be present in the game description; it cannot infer them.
*
* A separate PropNetAnnotater class is able to generate these annotations.
* Sadly, it can only annotate relatively simple games. If there are no base
* propositions in a game description, PropNetAnnotatedFlattener will call
* the annotater in an attempt to generate annotations.
*
* To use this class:
* PropNetAnnotatedFlattener AF = new PropNetAnnotatedFlattener(description);
* List<GdlRule> flatDescription = AF.flatten();
* return converter.convert(flatDescription);
*/
public final class PropNetAnnotatedFlattener
{
/** An archive of Rule instantiations, indexed by head name. */
private Map<GdlConstant, List<GdlRule>> instantiations;
/** An archive of the rules in a game description, indexed by head name. */
private Map<GdlConstant, List<GdlRule>> templates;
/**
* Construct a BasicPropNetFlattener for a given game.
*/
private List<Gdl> description;
public PropNetAnnotatedFlattener(List<Gdl> description) {
this.description = description;
}
/**
* Flattens a game description using the following process:
* <ol>
* <li>Records the rules in the description, and indexes them by head name.</li>
* <li>Creates an archive of rule instantiations, initialized with
* <tt>true</tt> rules.</li>
* <li>Creates every instantiation of each rule in the description and
* records the result.</li>
* </ol>
*
* @param description
* A game description.
* @return An equivalent description, without variables.
*/
public List<GdlRule> flatten()
{
description = DeORer.run(description);
if (noAnnotations()) {
GamerLogger.log("StateMachine", "Could not find 'base' annotations. Attempting to generate them...");
description = new PropNetAnnotater(description).getAugmentedDescription();
GamerLogger.log("StateMachine", "Annotations generated.");
}
templates = recordTemplates(description);
instantiations = initializeInstantiations(description);
List<GdlRule> flatDescription = new ArrayList<GdlRule>();
for ( GdlConstant constant : templates.keySet() )
{
flatDescription.addAll(getInstantiations(constant));
}
return flatDescription;
}
public boolean noAnnotations() {
for ( Gdl gdl : description ) {
if ( ! (gdl instanceof GdlSentence) ) continue;
GdlSentence sentence = (GdlSentence) gdl;
if (sentence.getName().getValue().equals("base"))
return false;
}
return true;
}
/**
* Recursive method that uses a <tt>base</tt> rule to build a set of
* <tt>true</tt> instantiations. Given a <tt>base</tt> rule of the form
* <tt>(base name (arg1 a11 a12 ... a1n) ... (argn an1 an2 ... ann))</tt>
* the method will return every possible combination of rules with name
* <tt>name</tt> and args <tt>arg1</tt> through <tt>argn</tt>.
*
* @param base
* A <tt>base</tt> rule.
* @param index
* The index of the rule being considered.
* @param workingSet
* The list of GdlTerms built up so far.
* @param results
* The list of results built up so far.
*/
private void expandTrue(GdlSentence base, int index, LinkedList<GdlTerm> workingSet, List<GdlRule> results)
{
if ( base.arity() == index )
{
GdlConstant name = (GdlConstant) base.get(0);
List<GdlTerm> body = new ArrayList<GdlTerm>(workingSet);
GdlFunction function = GdlPool.getFunction(name, body);
results.add(GdlPool.getRule(GdlPool.getRelation(GdlPool.getConstant("true"), new GdlTerm[] { function })));
}
else
{
for ( GdlTerm term : ((GdlFunction) base.get(index)).getBody() )
{
workingSet.addLast(term);
expandTrue(base, index + 1, workingSet, results);
workingSet.removeLast();
}
}
}
/**
* Returns the list of instantiations associated with the head name
* <tt>constant</tt>, building one first if necessary. Rules with heads
* named <tt>legal</tt> are generated by looking up the instantiation for
* rules with heads named <tt>does</tt> and renaming the results.
*
* @param constant
* The name of the head of the rule to instantiate.
* @return A list of instantiations.
*/
private List<GdlRule> getInstantiations(GdlConstant constant)
{
if ( !instantiations.containsKey(constant) )
{
instantiations.put(constant, new ArrayList<GdlRule>());
if ( constant.getValue().equals("does") )
{
for ( GdlRule rule : getInstantiations(GdlPool.getConstant("legal")) )
{
GdlSentence head = GdlPool.getRelation(GdlPool.getConstant("does"), rule.getHead().getBody());
GdlRule equivalentDoesRule = GdlPool.getRule(head);
instantiations.get(constant).add(equivalentDoesRule);
}
}
else
{
for ( GdlRule template : templates.get(constant) )
{
Set<GdlRule> results = new HashSet<GdlRule>();
instantiate(template, 0, new Substitution(), results);
instantiations.get(constant).addAll(results);
}
}
}
return instantiations.get(constant);
}
/**
* Creates an archive of rule instantiations from a game description,
* initialized with <tt>true</tt> rules, built using the reserved
* <tt>base</tt> keyword.
*
* @param description
* A game description.
* @return An archive of rule instantiations, indexed by head name.
*/
private Map<GdlConstant, List<GdlRule>> initializeInstantiations(List<Gdl> description)
{
List<GdlRule> trues = new ArrayList<GdlRule>();
for ( Gdl gdl : description )
{
if ( gdl instanceof GdlSentence )
{
GdlSentence sentence = (GdlSentence) gdl;
if ( sentence.getName().getValue().equals("base") )
{
if ( sentence.arity() == 1 )
{
GdlConstant constant = (GdlConstant) sentence.get(0);
trues.add(GdlPool.getRule(GdlPool.getRelation(GdlPool.getConstant("true"), new GdlTerm[] { constant })));
}
else
{
List<GdlRule> results = new ArrayList<GdlRule>();
expandTrue(sentence, 1, new LinkedList<GdlTerm>(), results);
trues.addAll(results);
}
}
}
}
Map<GdlConstant, List<GdlRule>> instantiations = new HashMap<GdlConstant, List<GdlRule>>();
instantiations.put(GdlPool.getConstant("true"), trues);
return instantiations;
}
/**
* A recursive method for generating every possible instantiation of a rule.
* Instantiations are generated by created every possible combination of
* instantiations to the literals in the body of the rule so long as those
* instantiations do not conflict with each other.
*
* @param template
* The rule to instantiate.
* @param index
* The literal in the body currently being considered.
* @param theta
* The substitution built up so far.
* @param results
* The list of results built up so far.
*/
private void instantiate(GdlRule template, int index, Substitution theta, Set<GdlRule> results)
{
if ( template.getBody().size() == index )
{
results.add(Substituter.substitute(template, theta));
}
else
{
GdlLiteral literal = template.getBody().get(index);
if ( literal instanceof GdlSentence )
{
GdlSentence sentence = (GdlSentence) Substituter.substitute(literal, theta);
for ( GdlRule instantiation : getInstantiations(sentence.getName()) )
{
Substitution thetaPrime = Unifier.unify(sentence, instantiation.getHead());
if ( thetaPrime!=null )
{
Substitution thetaCopy = theta.copy();
thetaCopy = thetaCopy.compose(thetaPrime);
instantiate(template, index + 1, thetaCopy, results);
}
}
}
else
{
instantiate(template, index + 1, theta, results);
}
}
}
/**
* Records the rules in a game description, indexed by head name. Ignores
* rules that begin with the reserved <tt>base</tt> keyword.
*
* @param description
* A game description.
* @return An archive of rules, indexed by head name.
*/
private Map<GdlConstant, List<GdlRule>> recordTemplates(List<Gdl> description)
{
Map<GdlConstant, List<GdlRule>> templates = new HashMap<GdlConstant, List<GdlRule>>();
for ( Gdl gdl : description )
{
GdlRule rule = (gdl instanceof GdlRule) ? (GdlRule) gdl : GdlPool.getRule((GdlSentence) gdl);
GdlConstant name = rule.getHead().getName();
if ( !name.getValue().equals("base") )
{
if ( !templates.containsKey(name) )
{
templates.put(name, new ArrayList<GdlRule>());
}
templates.get(name).add(rule);
}
}
return templates;
}
}