Line data    Source code

       1             : // Copyright (C) 2017 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.server.fixes;
      16             : 
      17             : import static java.util.Objects.requireNonNull;
      18             : 
      19             : /**
      20             :  * A modifier of a string. It allows to replace multiple parts of a string by indicating those parts
      21             :  * with indices based on the unmodified string. There is one limitation though: Replacements which
      22             :  * affect lower indices of the string must be specified before replacements for higher indices.
      23             :  */
      24             : class StringModifier {
      25             : 
      26             :   private final StringBuilder stringBuilder;
      27             : 
      28           1 :   private int characterShift = 0;
      29           1 :   private int previousEndOffset = Integer.MIN_VALUE;
      30             : 
      31           1 :   StringModifier(String string) {
      32           1 :     requireNonNull(string, "string must not be null");
      33           1 :     stringBuilder = new StringBuilder(string);
      34           1 :   }
      35             : 
      36             :   /**
      37             :    * Replaces part of the string with another content. When called multiple times, the calls must be
      38             :    * ordered according to increasing start indices. Overlapping replacement regions aren't
      39             :    * supported.
      40             :    *
      41             :    * @param startIndex the beginning index in the unmodified string (inclusive)
      42             :    * @param endIndex the ending index in the unmodified string (exclusive)
      43             :    * @param replacement the string which should be used instead of the original content
      44             :    * @throws StringIndexOutOfBoundsException if the start index is smaller than the end index of a
      45             :    *     previous call of this method
      46             :    */
      47             :   public void replace(int startIndex, int endIndex, String replacement) {
      48           1 :     requireNonNull(replacement, "replacement string must not be null");
      49           1 :     if (previousEndOffset > startIndex) {
      50           1 :       throw new StringIndexOutOfBoundsException(
      51           1 :           String.format(
      52             :               "Not supported to replace the content starting at index %s after previous "
      53             :                   + "replacement which ended at index %s",
      54           1 :               startIndex, previousEndOffset));
      55             :     }
      56           1 :     int shiftedStartIndex = startIndex + characterShift;
      57           1 :     int shiftedEndIndex = endIndex + characterShift;
      58           1 :     if (shiftedEndIndex > stringBuilder.length()) {
      59           1 :       throw new StringIndexOutOfBoundsException(
      60           1 :           String.format("end %s > length %s", shiftedEndIndex, stringBuilder.length()));
      61             :     }
      62           1 :     stringBuilder.replace(shiftedStartIndex, shiftedEndIndex, replacement);
      63             : 
      64           1 :     int replacedContentLength = endIndex - startIndex;
      65           1 :     characterShift += replacement.length() - replacedContentLength;
      66           1 :     previousEndOffset = endIndex;
      67           1 :   }
      68             : 
      69             :   /**
      70             :    * Returns the modified string including all specified replacements.
      71             :    *
      72             :    * @return the modified string
      73             :    */
      74             :   public String getResult() {
      75           1 :     return stringBuilder.toString();
      76             :   }
      77             : }