| 1 | package com.hammurapi.extract; |
| 2 | |
| 3 | import java.util.Collections; |
| 4 | import java.util.Map; |
| 5 | import java.util.Set; |
| 6 | |
| 7 | |
| 8 | /** |
| 9 | * Predicate which always evaluates to true. This predicate is primarily used for |
| 10 | * comparison |
| 11 | * @author Pavel Vlasov |
| 12 | * |
| 13 | * @param <T> |
| 14 | * @param <C> |
| 15 | */ |
| 16 | public class True<T, C> implements Predicate<T, C> { |
| 17 | |
| 18 | private True() { |
| 19 | // Singleton |
| 20 | } |
| 21 | |
| 22 | private static True<?, ?> INSTANCE = new True<Object, Object>(); |
| 23 | |
| 24 | @SuppressWarnings("unchecked") |
| 25 | public static <T, C> True<T, C> getInstance() { |
| 26 | return (True<T, C>) INSTANCE; |
| 27 | } |
| 28 | |
| 29 | public ComparisonResult compareTo(Extractor<T, Boolean, C> otherPredicate) { |
| 30 | if (otherPredicate instanceof True) { |
| 31 | return ComparisonResult.EQUAL_NM; |
| 32 | } |
| 33 | |
| 34 | if (otherPredicate instanceof False) { |
| 35 | return ComparisonResult.OPPOSITE_NM; |
| 36 | } |
| 37 | |
| 38 | |
| 39 | if (otherPredicate == null) { |
| 40 | return ComparisonResult.NOT_EQUAL_NM; |
| 41 | } |
| 42 | |
| 43 | if (otherPredicate instanceof Constant) { |
| 44 | if (Boolean.TRUE.equals(((Constant) otherPredicate).getValue())) { |
| 45 | return ComparisonResult.EQUAL_NM; |
| 46 | } |
| 47 | if (Boolean.FALSE.equals(((Constant) otherPredicate).getValue())) { |
| 48 | return ComparisonResult.OPPOSITE_NM; |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | ComparisonResult cr = otherPredicate.compareTo(this); |
| 53 | switch (cr.getType()) { |
| 54 | case EQUAL: |
| 55 | case NOT_EQUAL: |
| 56 | case OPPOSITE: |
| 57 | return cr; |
| 58 | case LESS_RESTRICTIVE: |
| 59 | return ComparisonResult.MORE_RESTRICTIVE_NM; |
| 60 | case MORE_RESTRICTIVE: |
| 61 | return ComparisonResult.LESS_RESTRICTIVE_NM; |
| 62 | case OPPOSITE_LESS_RESTRICTIVE: |
| 63 | return ComparisonResult.OPPOSITE_MORE_RESTRICTIVE_NM; |
| 64 | case OPPOSITE_MORE_RESTRICTIVE: |
| 65 | return ComparisonResult.OPPOSITE_LESS_RESTRICTIVE_NM; |
| 66 | default: |
| 67 | throw new IllegalArgumentException("Unexpected comparison type: "+cr.getType()); |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | public Boolean extract( |
| 72 | C context, |
| 73 | Map<C, Map<Extractor<T, ? super Boolean, C>, ? super Boolean>> cache, |
| 74 | T... obj) { |
| 75 | return Boolean.TRUE; |
| 76 | } |
| 77 | |
| 78 | public boolean isContextDependent() { |
| 79 | return false; |
| 80 | } |
| 81 | |
| 82 | public Set<Integer> parameterIndices() { |
| 83 | return Collections.emptySet(); |
| 84 | } |
| 85 | |
| 86 | @Override |
| 87 | public String toString() { |
| 88 | return getClass().getName(); |
| 89 | } |
| 90 | |
| 91 | @Override |
| 92 | public double getCost() { |
| 93 | return 0; |
| 94 | } |
| 95 | |
| 96 | } |