VariableRenamer.java

package org.ggp.base.util.prover.aima.renamer;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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;


public class VariableRenamer
{

    private int nextName;

    public VariableRenamer()
    {
        nextName = 0;
    }

    public GdlRule rename(GdlRule rule)
    {
        return renameRule(rule, new HashMap<GdlVariable, GdlVariable>());
    }

    public GdlSentence rename(GdlSentence sentence)
    {
        return renameSentence(sentence, new HashMap<GdlVariable, GdlVariable>());
    }

    private GdlConstant renameConstant(GdlConstant constant, Map<GdlVariable, GdlVariable> renamings)
    {
        return constant;
    }

    private GdlDistinct renameDistinct(GdlDistinct distinct, Map<GdlVariable, GdlVariable> renamings)
    {
        if (distinct.isGround())
        {
            return distinct;
        }
        else
        {
            GdlTerm arg1 = renameTerm(distinct.getArg1(), renamings);
            GdlTerm arg2 = renameTerm(distinct.getArg2(), renamings);

            return GdlPool.getDistinct(arg1, arg2);
        }
    }

    private GdlFunction renameFunction(GdlFunction function, Map<GdlVariable, GdlVariable> renamings)
    {
        if (function.isGround())
        {
            return function;
        }
        else
        {
            GdlConstant name = renameConstant(function.getName(), renamings);

            List<GdlTerm> body = new ArrayList<GdlTerm>();
            for (int i = 0; i < function.arity(); i++)
            {
                body.add(renameTerm(function.get(i), renamings));
            }

            return GdlPool.getFunction(name, body);
        }
    }

    private GdlLiteral renameLiteral(GdlLiteral literal, Map<GdlVariable, GdlVariable> renamings)
    {
        if (literal instanceof GdlDistinct)
        {
            return renameDistinct((GdlDistinct) literal, renamings);
        }
        else if (literal instanceof GdlNot)
        {
            return renameNot((GdlNot) literal, renamings);
        }
        else if (literal instanceof GdlOr)
        {
            return renameOr((GdlOr) literal, renamings);
        }
        else
        {
            return renameSentence((GdlSentence) literal, renamings);
        }
    }

    private GdlNot renameNot(GdlNot not, Map<GdlVariable, GdlVariable> renamings)
    {
        if (not.isGround())
        {
            return not;
        }
        else
        {
            GdlLiteral body = renameLiteral(not.getBody(), renamings);
            return GdlPool.getNot(body);
        }
    }

    private GdlOr renameOr(GdlOr or, Map<GdlVariable, GdlVariable> renamings)
    {
        if (or.isGround())
        {
            return or;
        }
        else
        {
            List<GdlLiteral> disjuncts = new ArrayList<GdlLiteral>();
            for (int i = 0; i < or.arity(); i++)
            {
                disjuncts.add(renameLiteral(or.get(i), renamings));
            }

            return GdlPool.getOr(disjuncts);
        }
    }

    private GdlProposition renameProposition(GdlProposition proposition, Map<GdlVariable, GdlVariable> renamings)
    {
        return proposition;
    }

    private GdlRelation renameRelation(GdlRelation relation, Map<GdlVariable, GdlVariable> renamings)
    {
        if (relation.isGround())
        {
            return relation;
        }
        else
        {
            GdlConstant name = renameConstant(relation.getName(), renamings);

            List<GdlTerm> body = new ArrayList<GdlTerm>();
            for (int i = 0; i < relation.arity(); i++)
            {
                body.add(renameTerm(relation.get(i), renamings));
            }

            return GdlPool.getRelation(name, body);
        }
    }

    private GdlRule renameRule(GdlRule rule, Map<GdlVariable, GdlVariable> renamings)
    {
        if (rule.isGround())
        {
            return rule;
        }
        else
        {
            GdlSentence head = renameSentence(rule.getHead(), renamings);

            List<GdlLiteral> body = new ArrayList<GdlLiteral>();
            for (int i = 0; i < rule.arity(); i++)
            {
                body.add(renameLiteral(rule.get(i), renamings));
            }

            return GdlPool.getRule(head, body);
        }
    }

    private GdlSentence renameSentence(GdlSentence sentence, Map<GdlVariable, GdlVariable> renamings)
    {
        if (sentence instanceof GdlProposition)
        {
            return renameProposition((GdlProposition) sentence, renamings);
        }
        else
        {
            return renameRelation((GdlRelation) sentence, renamings);
        }
    }

    private GdlTerm renameTerm(GdlTerm term, Map<GdlVariable, GdlVariable> renamings)
    {
        if (term instanceof GdlConstant)
        {
            return renameConstant((GdlConstant) term, renamings);
        }
        else if (term instanceof GdlVariable)
        {
            return renameVariable((GdlVariable) term, renamings);
        }
        else
        {
            return renameFunction((GdlFunction) term, renamings);
        }
    }

    private GdlVariable renameVariable(GdlVariable variable, Map<GdlVariable, GdlVariable> renamings)
    {
        if (!renamings.containsKey(variable))
        {
            GdlVariable newName = GdlPool.getVariable("?R" + (nextName++));
            renamings.put(variable, newName);
        }

        return renamings.get(variable);
    }

}