Line data    Source code

       1             : // Copyright (C) 2019 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : 
      15             : package com.google.gerrit.git;
      16             : 
      17             : import static com.google.common.base.Preconditions.checkArgument;
      18             : import static java.util.Objects.requireNonNull;
      19             : 
      20             : import com.google.gerrit.common.Nullable;
      21             : import java.io.IOException;
      22             : import org.eclipse.jgit.lib.AnyObjectId;
      23             : import org.eclipse.jgit.lib.Constants;
      24             : import org.eclipse.jgit.lib.ObjectId;
      25             : import org.eclipse.jgit.lib.ObjectReader;
      26             : 
      27             : /** Static utilities for working with {@code ObjectId}s. */
      28             : public class ObjectIds {
      29             :   /** Length of a binary SHA-1 byte array. */
      30             :   public static final int LEN = Constants.OBJECT_ID_LENGTH;
      31             : 
      32             :   /** Length of a hex SHA-1 string. */
      33             :   public static final int STR_LEN = Constants.OBJECT_ID_STRING_LENGTH;
      34             : 
      35             :   /** Default abbreviated length of a hex SHA-1 string. */
      36             :   public static final int ABBREV_STR_LEN = 7;
      37             : 
      38             :   /**
      39             :    * Abbreviate an ID's hex string representation to 7 chars.
      40             :    *
      41             :    * @param id object ID.
      42             :    * @return abbreviated hex string representation, exactly 7 chars.
      43             :    */
      44             :   public static String abbreviateName(AnyObjectId id) {
      45          19 :     return abbreviateName(id, ABBREV_STR_LEN);
      46             :   }
      47             : 
      48             :   /**
      49             :    * Abbreviate an ID's hex string representation to {@code n} chars.
      50             :    *
      51             :    * @param id object ID.
      52             :    * @param n number of hex chars, 1 to 40.
      53             :    * @return abbreviated hex string representation, exactly {@code n} chars.
      54             :    */
      55             :   public static String abbreviateName(AnyObjectId id, int n) {
      56          31 :     checkValidLength(n);
      57          31 :     return requireNonNull(id).abbreviate(n).name();
      58             :   }
      59             : 
      60             :   /**
      61             :    * Abbreviate an ID's hex string representation uniquely to at least 7 chars.
      62             :    *
      63             :    * @param id object ID.
      64             :    * @param reader object reader for determining uniqueness.
      65             :    * @return abbreviated hex string representation, unique according to {@code reader} at least 7
      66             :    *     chars.
      67             :    * @throws IOException if an error occurs while looking for ambiguous objects.
      68             :    */
      69             :   public static String abbreviateName(AnyObjectId id, ObjectReader reader) throws IOException {
      70          22 :     return abbreviateName(id, ABBREV_STR_LEN, reader);
      71             :   }
      72             : 
      73             :   /**
      74             :    * Abbreviate an ID's hex string representation uniquely to at least {@code n} chars.
      75             :    *
      76             :    * @param id object ID.
      77             :    * @param n minimum number of hex chars, 1 to 40.
      78             :    * @param reader object reader for determining uniqueness.
      79             :    * @return abbreviated hex string representation, unique according to {@code reader} at least
      80             :    *     {@code n} chars.
      81             :    * @throws IOException if an error occurs while looking for ambiguous objects.
      82             :    */
      83             :   public static String abbreviateName(AnyObjectId id, int n, ObjectReader reader)
      84             :       throws IOException {
      85         103 :     checkValidLength(n);
      86         103 :     return reader.abbreviate(id, n).name();
      87             :   }
      88             : 
      89             :   /**
      90             :    * Copy a nullable ID, preserving null.
      91             :    *
      92             :    * @param id object ID.
      93             :    * @return {@link AnyObjectId#copy} of {@code id}, or {@code null} if {@code id} is null.
      94             :    */
      95             :   @Nullable
      96             :   public static ObjectId copyOrNull(@Nullable AnyObjectId id) {
      97         152 :     return id != null ? id.copy() : null;
      98             :   }
      99             : 
     100             :   /**
     101             :    * Copy a nullable ID, converting null to {@code zeroId}.
     102             :    *
     103             :    * @param id object ID.
     104             :    * @return {@link AnyObjectId#copy} of {@code id}, or {@link ObjectId#zeroId} if {@code id} is
     105             :    *     null.
     106             :    */
     107             :   public static ObjectId copyOrZero(@Nullable AnyObjectId id) {
     108         153 :     return id != null ? id.copy() : ObjectId.zeroId();
     109             :   }
     110             : 
     111             :   /**
     112             :    * Return whether the given ID matches the given abbreviation.
     113             :    *
     114             :    * @param id object ID.
     115             :    * @param abbreviation abbreviated hex object ID. May not be null, but may be an invalid hex SHA-1
     116             :    *     abbreviation string.
     117             :    * @return true if {@code id} is not null and {@code abbreviation} is a valid hex SHA-1
     118             :    *     abbreviation that matches {@code id}, false otherwise.
     119             :    */
     120             :   public static boolean matchesAbbreviation(@Nullable AnyObjectId id, String abbreviation) {
     121          30 :     requireNonNull(abbreviation);
     122          30 :     return id != null && id.name().startsWith(abbreviation);
     123             :   }
     124             : 
     125             :   private static void checkValidLength(int n) {
     126         103 :     checkArgument(n > 0);
     127         103 :     checkArgument(n <= STR_LEN);
     128         103 :   }
     129             : 
     130             :   private ObjectIds() {}
     131             : }