DiffUtils.java
/*
* Copyright 2009-2017 java-diff-utils.
*
* 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.github.difflib;
import com.github.difflib.algorithm.DiffAlgorithmFactory;
import com.github.difflib.algorithm.DiffAlgorithmI;
import com.github.difflib.algorithm.DiffAlgorithmListener;
import com.github.difflib.algorithm.myers.MyersDiff;
import com.github.difflib.patch.AbstractDelta;
import com.github.difflib.patch.Patch;
import com.github.difflib.patch.PatchFailedException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.function.BiPredicate;
/**
* Utility class to implement the difference and patching engine.
*/
public final class DiffUtils {
/**
* This factory generates the DEFAULT_DIFF algorithm for all these routines.
*/
static DiffAlgorithmFactory DEFAULT_DIFF = MyersDiff.factory();
/**
* Sets the default diff algorithm factory to be used by all diff routines.
*
* @param factory a {@link DiffAlgorithmFactory} representing the new default diff algorithm factory.
*/
public static void withDefaultDiffAlgorithmFactory(DiffAlgorithmFactory factory) {
DEFAULT_DIFF = factory;
}
/**
* Computes the difference between two sequences of elements using the default diff algorithm.
*
* @param <T> a generic representing the type of the elements to be compared.
* @param original a {@link List} representing the original sequence of elements. Must not be {@code null}.
* @param revised a {@link List} representing the revised sequence of elements. Must not be {@code null}.
* @param progress a {@link DiffAlgorithmListener} representing the progress listener. Can be {@code null}.
* @return The patch describing the difference between the original and revised sequences. Never {@code null}.
*/
public static <T> Patch<T> diff(List<T> original, List<T> revised, DiffAlgorithmListener progress) {
return DiffUtils.diff(original, revised, DEFAULT_DIFF.create(), progress);
}
/**
* Computes the difference between two sequences of elements using the default diff algorithm.
*
* @param <T> a generic representing the type of the elements to be compared.
* @param original a {@link List} representing the original sequence of elements. Must not be {@code null}.
* @param revised a {@link List} representing the revised sequence of elements. Must not be {@code null}.
* @return The patch describing the difference between the original and revised sequences. Never {@code null}.
*/
public static <T> Patch<T> diff(List<T> original, List<T> revised) {
return DiffUtils.diff(original, revised, DEFAULT_DIFF.create(), null);
}
/**
* Computes the difference between two sequences of elements using the default diff algorithm.
*
* @param <T> a generic representing the type of the elements to be compared.
* @param original a {@link List} representing the original sequence of elements. Must not be {@code null}.
* @param revised a {@link List} representing the revised sequence of elements. Must not be {@code null}.
* @param includeEqualParts a {@link boolean} representing whether to include equal parts in the resulting patch.
* @return The patch describing the difference between the original and revised sequences. Never {@code null}.
*/
public static <T> Patch<T> diff(List<T> original, List<T> revised, boolean includeEqualParts) {
return DiffUtils.diff(original, revised, DEFAULT_DIFF.create(), null, includeEqualParts);
}
/**
* Computes the difference between two strings using the default diff algorithm.
*
* @param sourceText a {@link String} representing the original string. Must not be {@code null}.
* @param targetText a {@link String} representing the revised string. Must not be {@code null}.
* @param progress a {@link DiffAlgorithmListener} representing the progress listener. Can be {@code null}.
* @return The patch describing the difference between the original and revised strings. Never {@code null}.
*/
public static Patch<String> diff(String sourceText, String targetText, DiffAlgorithmListener progress) {
return DiffUtils.diff(Arrays.asList(sourceText.split("\n")), Arrays.asList(targetText.split("\n")), progress);
}
/**
* Computes the difference between the original and revised list of elements
* with default diff algorithm
*
* @param source a {@link List} representing the original text. Must not be {@code null}.
* @param target a {@link List} representing the revised text. Must not be {@code null}.
* @param equalizer a {@link BiPredicate} representing the equalizer object to replace the default compare
* algorithm (Object.equals). If {@code null} the default equalizer of the
* default algorithm is used.
* @return The patch describing the difference between the original and
* revised sequences. Never {@code null}.
*/
public static <T> Patch<T> diff(List<T> source, List<T> target, BiPredicate<T, T> equalizer) {
if (equalizer != null) {
return DiffUtils.diff(source, target, DEFAULT_DIFF.create(equalizer));
}
return DiffUtils.diff(source, target, new MyersDiff<>());
}
public static <T> Patch<T> diff(
List<T> original, List<T> revised, DiffAlgorithmI<T> algorithm, DiffAlgorithmListener progress) {
return diff(original, revised, algorithm, progress, false);
}
/**
* Computes the difference between the original and revised list of elements
* with default diff algorithm
*
* @param original a {@link List} representing the original text. Must not be {@code null}.
* @param revised a {@link List} representing the revised text. Must not be {@code null}.
* @param algorithm a {@link DiffAlgorithmI} representing the diff algorithm. Must not be {@code null}.
* @param progress a {@link DiffAlgorithmListener} representing the diff algorithm listener.
* @param includeEqualParts Include equal data parts into the patch.
* @return The patch describing the difference between the original and
* revised sequences. Never {@code null}.
*/
public static <T> Patch<T> diff(
List<T> original,
List<T> revised,
DiffAlgorithmI<T> algorithm,
DiffAlgorithmListener progress,
boolean includeEqualParts) {
Objects.requireNonNull(original, "original must not be null");
Objects.requireNonNull(revised, "revised must not be null");
Objects.requireNonNull(algorithm, "algorithm must not be null");
return Patch.generate(original, revised, algorithm.computeDiff(original, revised, progress), includeEqualParts);
}
/**
* Computes the difference between the original and revised list of elements
* with default diff algorithm
*
* @param original a {@link List} representing the original text. Must not be {@code null}.
* @param revised a {@link List} representing the revised text. Must not be {@code null}.
* @param algorithm a {@link DiffAlgorithmI} representing the diff algorithm. Must not be {@code null}.
* @return The patch describing the difference between the original and
* revised sequences. Never {@code null}.
*/
public static <T> Patch<T> diff(List<T> original, List<T> revised, DiffAlgorithmI<T> algorithm) {
return diff(original, revised, algorithm, null);
}
/**
* Computes the difference between the given texts inline. This one uses the
* "trick" to make out of texts lists of characters, like DiffRowGenerator
* does and merges those changes at the end together again.
*
* @param original a {@link String} representing the original text. Must not be {@code null}.
* @param revised a {@link String} representing the revised text. Must not be {@code null}.
* @return The patch describing the difference between the original and
* revised sequences. Never {@code null}.
*/
public static Patch<String> diffInline(String original, String revised) {
List<String> origList = new ArrayList<>();
List<String> revList = new ArrayList<>();
for (Character character : original.toCharArray()) {
origList.add(character.toString());
}
for (Character character : revised.toCharArray()) {
revList.add(character.toString());
}
Patch<String> patch = DiffUtils.diff(origList, revList);
for (AbstractDelta<String> delta : patch.getDeltas()) {
delta.getSource().setLines(compressLines(delta.getSource().getLines(), ""));
delta.getTarget().setLines(compressLines(delta.getTarget().getLines(), ""));
}
return patch;
}
/**
* Applies the given patch to the original list and returns the revised list.
*
* @param original a {@link List} representing the original list.
* @param patch a {@link List} representing the patch to apply.
* @return the revised list.
* @throws PatchFailedException if the patch cannot be applied.
*/
public static <T> List<T> patch(List<T> original, Patch<T> patch) throws PatchFailedException {
return patch.applyTo(original);
}
/**
* Applies the given patch to the revised list and returns the original list.
*
* @param revised a {@link List} representing the revised list.
* @param patch a {@link Patch} representing the patch to apply.
* @return the original list.
* @throws PatchFailedException if the patch cannot be applied.
*/
public static <T> List<T> unpatch(List<T> revised, Patch<T> patch) {
return patch.restore(revised);
}
private static List<String> compressLines(List<String> lines, String delimiter) {
if (lines.isEmpty()) {
return Collections.emptyList();
}
return Collections.singletonList(String.join(delimiter, lines));
}
private DiffUtils() {}
}