com.google.gerrit.server.fixes.StringModifier Maven / Gradle / Ivy
// Copyright (C) 2017 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.server.fixes;
import static java.util.Objects.requireNonNull;
/**
* A modifier of a string. It allows to replace multiple parts of a string by indicating those parts
* with indices based on the unmodified string. There is one limitation though: Replacements which
* affect lower indices of the string must be specified before replacements for higher indices.
*/
class StringModifier {
private final StringBuilder stringBuilder;
private int characterShift = 0;
private int previousEndOffset = Integer.MIN_VALUE;
StringModifier(String string) {
requireNonNull(string, "string must not be null");
stringBuilder = new StringBuilder(string);
}
/**
* Replaces part of the string with another content. When called multiple times, the calls must be
* ordered according to increasing start indices. Overlapping replacement regions aren't
* supported.
*
* @param startIndex the beginning index in the unmodified string (inclusive)
* @param endIndex the ending index in the unmodified string (exclusive)
* @param replacement the string which should be used instead of the original content
* @throws StringIndexOutOfBoundsException if the start index is smaller than the end index of a
* previous call of this method
*/
public void replace(int startIndex, int endIndex, String replacement) {
requireNonNull(replacement, "replacement string must not be null");
if (previousEndOffset > startIndex) {
throw new StringIndexOutOfBoundsException(
String.format(
"Not supported to replace the content starting at index %s after previous "
+ "replacement which ended at index %s",
startIndex, previousEndOffset));
}
int shiftedStartIndex = startIndex + characterShift;
int shiftedEndIndex = endIndex + characterShift;
if (shiftedEndIndex > stringBuilder.length()) {
throw new StringIndexOutOfBoundsException(
String.format("end %s > length %s", shiftedEndIndex, stringBuilder.length()));
}
stringBuilder.replace(shiftedStartIndex, shiftedEndIndex, replacement);
int replacedContentLength = endIndex - startIndex;
characterShift += replacement.length() - replacedContentLength;
previousEndOffset = endIndex;
}
/**
* Returns the modified string including all specified replacements.
*
* @return the modified string
*/
public String getResult() {
return stringBuilder.toString();
}
}