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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.statementservice.retriever;
     18 
     19 import android.annotation.NonNull;
     20 
     21 import java.util.regex.Pattern;
     22 
     23 /**
     24  * An immutable value type representing a statement relation with "kind" and "detail".
     25  *
     26  * <p> The set of kinds is enumerated by the API: <ul> <li> <b>delegate_permission</b>: The detail
     27  * field specifies which permission to delegate. A statement involving this relation does not
     28  * constitute a requirement to do the delegation, just a permission to do so. </ul>
     29  *
     30  * <p> We may add other kinds in the future.
     31  *
     32  * <p> The detail field is a lowercase alphanumeric string with underscores and periods allowed
     33  * (matching the regex [a-z0-9_.]+), but otherwise unstructured.
     34  */
     35 public final class Relation {
     36 
     37     private static final Pattern KIND_PATTERN = Pattern.compile("^[a-z0-9_.]+$");
     38     private static final Pattern DETAIL_PATTERN = Pattern.compile("^([a-z0-9_.]+)$");
     39 
     40     private final String mKind;
     41     private final String mDetail;
     42 
     43     private Relation(String kind, String detail) {
     44         mKind = kind;
     45         mDetail = detail;
     46     }
     47 
     48     /**
     49      * Returns the relation's kind.
     50      */
     51     @NonNull
     52     public String getKind() {
     53         return mKind;
     54     }
     55 
     56     /**
     57      * Returns the relation's detail.
     58      */
     59     @NonNull
     60     public String getDetail() {
     61         return mDetail;
     62     }
     63 
     64     /**
     65      * Creates a new Relation object for the specified {@code kind} and {@code detail}.
     66      *
     67      * @throws AssociationServiceException if {@code kind} or {@code detail} is not well formatted.
     68      */
     69     public static Relation create(@NonNull String kind, @NonNull String detail)
     70             throws AssociationServiceException {
     71         if (!KIND_PATTERN.matcher(kind).matches() || !DETAIL_PATTERN.matcher(detail).matches()) {
     72             throw new AssociationServiceException("Relation not well formatted.");
     73         }
     74         return new Relation(kind, detail);
     75     }
     76 
     77     /**
     78      * Creates a new Relation object from its string representation.
     79      *
     80      * @throws AssociationServiceException if the relation is not well formatted.
     81      */
     82     public static Relation create(@NonNull String relation) throws AssociationServiceException {
     83         String[] r = relation.split("/", 2);
     84         if (r.length != 2) {
     85             throw new AssociationServiceException("Relation not well formatted.");
     86         }
     87         return create(r[0], r[1]);
     88     }
     89 
     90     /**
     91      * Returns true if {@code relation} has the same kind and detail.
     92      */
     93     public boolean matches(Relation relation) {
     94         return getKind().equals(relation.getKind()) && getDetail().equals(relation.getDetail());
     95     }
     96 
     97     /**
     98      * Returns a string representation of this relation.
     99      */
    100     @Override
    101     public String toString() {
    102         StringBuilder relation = new StringBuilder();
    103         relation.append(getKind());
    104         relation.append("/");
    105         relation.append(getDetail());
    106         return relation.toString();
    107     }
    108 
    109     // equals() and hashCode() are generated by Android Studio.
    110     @Override
    111     public boolean equals(Object o) {
    112         if (this == o) {
    113             return true;
    114         }
    115         if (o == null || getClass() != o.getClass()) {
    116             return false;
    117         }
    118 
    119         Relation relation = (Relation) o;
    120 
    121         if (mDetail != null ? !mDetail.equals(relation.mDetail) : relation.mDetail != null) {
    122             return false;
    123         }
    124         if (mKind != null ? !mKind.equals(relation.mKind) : relation.mKind != null) {
    125             return false;
    126         }
    127 
    128         return true;
    129     }
    130 
    131     @Override
    132     public int hashCode() {
    133         int result = mKind != null ? mKind.hashCode() : 0;
    134         result = 31 * result + (mDetail != null ? mDetail.hashCode() : 0);
    135         return result;
    136     }
    137 }
    138