001 package aima.logic.fol;
002
003 import java.util.ArrayList;
004 import java.util.HashMap;
005 import java.util.List;
006 import java.util.Map;
007
008 import aima.logic.fol.kb.data.Chain;
009 import aima.logic.fol.kb.data.Clause;
010 import aima.logic.fol.kb.data.Literal;
011 import aima.logic.fol.parsing.FOLVisitor;
012 import aima.logic.fol.parsing.ast.ConnectedSentence;
013 import aima.logic.fol.parsing.ast.Constant;
014 import aima.logic.fol.parsing.ast.Function;
015 import aima.logic.fol.parsing.ast.NotSentence;
016 import aima.logic.fol.parsing.ast.Predicate;
017 import aima.logic.fol.parsing.ast.QuantifiedSentence;
018 import aima.logic.fol.parsing.ast.Sentence;
019 import aima.logic.fol.parsing.ast.Term;
020 import aima.logic.fol.parsing.ast.TermEquality;
021 import aima.logic.fol.parsing.ast.Variable;
022
023 /**
024 * @author Ciaran O'Reilly
025 *
026 */
027 public class StandardizeApartInPlace {
028 //
029 private static CollectAllVariables _collectAllVariables = new CollectAllVariables();
030
031 public static int standardizeApart(Chain c, int saIdx) {
032 List<Variable> variables = new ArrayList<Variable>();
033 for (Literal l : c.getLiterals()) {
034 collectAllVariables(l.getAtomicSentence(), variables);
035 }
036
037 return standardizeApart(variables, c, saIdx);
038 }
039
040 public static int standardizeApart(Clause c, int saIdx) {
041 List<Variable> variables = new ArrayList<Variable>();
042 for (Literal l : c.getLiterals()) {
043 collectAllVariables(l.getAtomicSentence(), variables);
044 }
045
046 return standardizeApart(variables, c, saIdx);
047 }
048
049 //
050 // PRIVATE METHODS
051 //
052 private static int standardizeApart(List<Variable> variables, Object expr, int saIdx) {
053 Map<String, Integer> indexicals = new HashMap<String, Integer>();
054 for (Variable v : variables) {
055 if (!indexicals.containsKey(v.getIndexedValue())) {
056 indexicals.put(v.getIndexedValue(), saIdx++);
057 }
058 }
059 for (Variable v : variables) {
060 Integer i = indexicals.get(v.getIndexedValue());
061 if (null == i) {
062 throw new RuntimeException("ERROR: duplicate var=" + v + ", expr=" + expr);
063 } else {
064 v.setIndexical(i);
065 }
066 }
067
068 return saIdx;
069 }
070
071 private static void collectAllVariables(Sentence s, List<Variable> vars) {
072 s.accept(_collectAllVariables, vars);
073 }
074 }
075
076 class CollectAllVariables implements FOLVisitor {
077 public CollectAllVariables() {
078
079 }
080
081 @SuppressWarnings("unchecked")
082 public Object visitVariable(Variable var, Object arg) {
083 List<Variable> variables = (List<Variable>) arg;
084 variables.add(var);
085 return var;
086 }
087
088 @SuppressWarnings("unchecked")
089 public Object visitQuantifiedSentence(QuantifiedSentence sentence,
090 Object arg) {
091 // Ensure I collect quantified variables too
092 List<Variable> variables = (List<Variable>) arg;
093 variables.addAll(sentence.getVariables());
094
095 sentence.getQuantified().accept(this, arg);
096
097 return sentence;
098 }
099
100 public Object visitPredicate(Predicate predicate, Object arg) {
101 for (Term t : predicate.getTerms()) {
102 t.accept(this, arg);
103 }
104 return predicate;
105 }
106
107 public Object visitTermEquality(TermEquality equality, Object arg) {
108 equality.getTerm1().accept(this, arg);
109 equality.getTerm2().accept(this, arg);
110 return equality;
111 }
112
113 public Object visitConstant(Constant constant, Object arg) {
114 return constant;
115 }
116
117 public Object visitFunction(Function function, Object arg) {
118 for (Term t : function.getTerms()) {
119 t.accept(this, arg);
120 }
121 return function;
122 }
123
124 public Object visitNotSentence(NotSentence sentence, Object arg) {
125 sentence.getNegated().accept(this, arg);
126 return sentence;
127 }
128
129 public Object visitConnectedSentence(ConnectedSentence sentence, Object arg) {
130 sentence.getFirst().accept(this, arg);
131 sentence.getSecond().accept(this, arg);
132 return sentence;
133 }
134 }