package org.ggp.base.util.gdl.transforms;
import java.util.ArrayList;
import java.util.List;
import org.ggp.base.util.gdl.grammar.Gdl;
import org.ggp.base.util.gdl.grammar.GdlConstant;
import org.ggp.base.util.gdl.grammar.GdlDistinct;
import org.ggp.base.util.gdl.grammar.GdlFunction;
import org.ggp.base.util.gdl.grammar.GdlLiteral;
import org.ggp.base.util.gdl.grammar.GdlNot;
import org.ggp.base.util.gdl.grammar.GdlOr;
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.gdl.grammar.GdlTerm;
import org.ggp.base.util.gdl.grammar.GdlVariable;
//Cleans up various issues with games to make them more standardized.
public class GdlCleaner {
private static final int MAX_ITERATIONS = 100;
private GdlCleaner() {
}
public static List<Gdl> run(List<Gdl> description) {
for (int i = 0; i < MAX_ITERATIONS; i++) {
List<Gdl> newDescription = runOnce(description);
if (newDescription.equals(description)) {
break;
}
description = newDescription;
}
return description;
}
private static List<Gdl> runOnce(List<Gdl> description) {
List<Gdl> newDescription = new ArrayList<Gdl>();
//First: Clean up all rules with zero-element bodies
for(Gdl gdl : description) {
if(gdl instanceof GdlRule) {
GdlRule rule = (GdlRule) gdl;
if(rule.getBody().size() == 0) {
newDescription.add(rule.getHead());
} else {
newDescription.add(gdl);
}
} else {
newDescription.add(gdl);
}
}
//TODO: Add (role ?player) where appropriate, i.e. in rules for
//"legal" or "input" where the first argument is an undefined
//variable
//Get rid of "extra parentheses", i.e. zero-arity functions
description = newDescription;
newDescription = new ArrayList<Gdl>();
for(Gdl gdl : description) {
if(gdl instanceof GdlRelation) {
newDescription.add(cleanParentheses((GdlRelation)gdl));
} else if(gdl instanceof GdlRule) {
newDescription.add(cleanParentheses((GdlRule)gdl));
} else {
newDescription.add(gdl);
}
}
//TODO: Get rid of GdlPropositions in the description
//TODO: Get rid of (not (or ...))
//Get rid of (not (distinct _ _)) literals in rules
//TODO: Expand to functions
description = newDescription;
newDescription = new ArrayList<Gdl>();
for(Gdl gdl : description) {
if(gdl instanceof GdlRule) {
GdlRule cleaned = removeNotDistinctLiterals((GdlRule)gdl);
if(cleaned != null)
newDescription.add(cleaned);
} else {
newDescription.add(gdl);
}
}
//Get rid of the old style of "base" sentences (with arity more than 1, not in rules)
//See e.g. current version of Qyshinsu on the Dresden server
description = newDescription;
newDescription = new ArrayList<Gdl>();
boolean removeBaseSentences = false;
for (Gdl gdl : description) {
if (gdl instanceof GdlRelation) {
GdlRelation relation = (GdlRelation) gdl;
if (relation.getName() == GdlPool.BASE && relation.arity() != 1) {
removeBaseSentences = true;
break;
}
}
}
//Note that in this case, we have to remove ALL of them or we might
//misinterpret this as being the new kind of "base" relation
for (Gdl gdl : description) {
if (gdl instanceof GdlRelation) {
GdlRelation relation = (GdlRelation) gdl;
if (removeBaseSentences && relation.getName() == GdlPool.BASE) {
//Leave out the relation
} else {
newDescription.add(gdl);
}
} else {
newDescription.add(gdl);
}
}
return newDescription;
}
private static GdlRule removeNotDistinctLiterals(GdlRule rule) {
while(rule != null && getNotDistinctLiteral(rule) != null) {
rule = removeNotDistinctLiteral(rule, getNotDistinctLiteral(rule));
}
return rule;
}
private static GdlNot getNotDistinctLiteral(GdlRule rule) {
for(GdlLiteral literal : rule.getBody()) {
if(literal instanceof GdlNot) {
GdlNot not = (GdlNot) literal;
if(not.getBody() instanceof GdlDistinct) {
//For now, we can only deal with this if not both are functions.
//That means we have to skip that case at this point.
GdlDistinct distinct = (GdlDistinct) not.getBody();
if(!(distinct.getArg1() instanceof GdlFunction)
|| !(distinct.getArg2() instanceof GdlFunction))
return not;
}
}
}
return null;
}
//Returns null if the rule is useless.
private static GdlRule removeNotDistinctLiteral(GdlRule rule, GdlNot notDistinctLiteral) {
//Figure out the substitution we want...
//If we have two constants: Either remove one or
//maybe get rid of the ___?
//One is a variable: Replace the variable with the other thing
//throughout the rule
GdlDistinct distinct = (GdlDistinct) notDistinctLiteral.getBody();
GdlTerm arg1 = distinct.getArg1();
GdlTerm arg2 = distinct.getArg2();
if(arg1 == arg2) {
//Just remove that literal
List<GdlLiteral> newBody = new ArrayList<GdlLiteral>();
newBody.addAll(rule.getBody());
newBody.remove(notDistinctLiteral);
return GdlPool.getRule(rule.getHead(), newBody);
}
if(arg1 instanceof GdlVariable) {
//What we return will still have the not-distinct literal,
//but it will get replaced in the next pass.
//(Even if we have two variables, they will be equal next time through.)
return CommonTransforms.replaceVariable(rule, (GdlVariable)arg1, arg2);
}
if(arg2 instanceof GdlVariable) {
return CommonTransforms.replaceVariable(rule, (GdlVariable)arg2, arg1);
}
if(arg1 instanceof GdlConstant || arg2 instanceof GdlConstant) {
//We have two non-equal constants, or a constant and a function.
//The rule should have no effect.
return null;
}
//We have two functions. Complicated! (Have to replace them with unified version.)
//We pass on this case for now.
//TODO: Implement correctly.
throw new UnsupportedOperationException("We can't currently handle (not (distinct <function> <function>)).");
}
private static GdlRule cleanParentheses(GdlRule rule) {
GdlSentence cleanedHead = cleanParentheses(rule.getHead());
List<GdlLiteral> cleanedBody = new ArrayList<GdlLiteral>();
for(GdlLiteral literal : rule.getBody())
cleanedBody.add(cleanParentheses(literal));
return GdlPool.getRule(cleanedHead, cleanedBody);
}
private static GdlLiteral cleanParentheses(GdlLiteral literal) {
if(literal instanceof GdlSentence) {
return cleanParentheses((GdlSentence)literal);
} else if(literal instanceof GdlDistinct) {
GdlDistinct distinct = (GdlDistinct) literal;
GdlTerm term1 = cleanParentheses(distinct.getArg1());
GdlTerm term2 = cleanParentheses(distinct.getArg2());
return GdlPool.getDistinct(term1, term2);
} else if(literal instanceof GdlNot) {
GdlLiteral body = ((GdlNot) literal).getBody();
return GdlPool.getNot(cleanParentheses(body));
} else if(literal instanceof GdlOr) {
GdlOr or = (GdlOr) literal;
List<GdlLiteral> disjuncts = new ArrayList<GdlLiteral>();
for(int i = 0; i < or.arity(); i++)
disjuncts.add(cleanParentheses(or.get(i)));
return GdlPool.getOr(disjuncts);
}
throw new RuntimeException("Unexpected literal type in GdlCleaner");
}
private static GdlSentence cleanParentheses(GdlSentence sentence) {
if(sentence instanceof GdlProposition)
return sentence;
List<GdlTerm> cleanedBody = new ArrayList<GdlTerm>();
for(GdlTerm term : sentence.getBody())
cleanedBody.add(cleanParentheses(term));
if (cleanedBody.isEmpty()) {
return GdlPool.getProposition(sentence.getName());
} else {
return GdlPool.getRelation(sentence.getName(), cleanedBody);
}
}
private static GdlTerm cleanParentheses(GdlTerm term) {
if(term instanceof GdlConstant || term instanceof GdlVariable)
return term;
if(term instanceof GdlFunction) {
GdlFunction function = (GdlFunction) term;
//The whole point of the function
if(function.arity() == 0)
return function.getName();
List<GdlTerm> cleanedBody = new ArrayList<GdlTerm>();
for(GdlTerm functionTerm : function.getBody())
cleanedBody.add(cleanParentheses(functionTerm));
return GdlPool.getFunction(function.getName(), cleanedBody);
}
throw new RuntimeException("Unexpected term type in GdlCleaner");
}
}