UnifiedDiffWriter.java
/*
* Copyright 2019 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.unifieddiff;
import com.github.difflib.patch.AbstractDelta;
import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* @todo use an instance to store contextSize and originalLinesProvider.
* @author Tobias Warneke (t.warneke@gmx.net)
*/
public class UnifiedDiffWriter {
private static final Logger LOG = Logger.getLogger(UnifiedDiffWriter.class.getName());
public static void write(UnifiedDiff diff, Function<String, List<String>> originalLinesProvider, Writer writer, int contextSize) throws IOException {
Objects.requireNonNull(originalLinesProvider, "original lines provider needs to be specified");
write(diff, originalLinesProvider, line -> {
try {
writer.append(line).append("\n");
} catch (IOException ex) {
LOG.log(Level.SEVERE, null, ex);
}
}, contextSize);
}
public static void write(UnifiedDiff diff, Function<String, List<String>> originalLinesProvider, Consumer<String> writer, int contextSize) throws IOException {
if (diff.getHeader() != null) {
writer.accept(diff.getHeader());
}
for (UnifiedDiffFile file : diff.getFiles()) {
List<AbstractDelta<String>> patchDeltas = new ArrayList<>(
file.getPatch().getDeltas());
if (!patchDeltas.isEmpty()) {
writeOrNothing(writer, file.getDiffCommand());
if (file.getIndex() != null) {
writer.accept("index " + file.getIndex());
}
writer.accept("--- " + (file.getFromFile() == null ? "/dev/null" : file.getFromFile()));
if (file.getToFile() != null) {
writer.accept("+++ " + file.getToFile());
}
List<String> originalLines = originalLinesProvider.apply(file.getFromFile());
List<AbstractDelta<String>> deltas = new ArrayList<>();
AbstractDelta<String> delta = patchDeltas.get(0);
deltas.add(delta); // add the first Delta to the current set
// if there's more than 1 Delta, we may need to output them together
if (patchDeltas.size() > 1) {
for (int i = 1; i < patchDeltas.size(); i++) {
int position = delta.getSource().getPosition();
// Check if the next Delta is too close to the current
// position.
// And if it is, add it to the current set
AbstractDelta<String> nextDelta = patchDeltas.get(i);
if ((position + delta.getSource().size() + contextSize) >= (nextDelta
.getSource().getPosition() - contextSize)) {
deltas.add(nextDelta);
} else {
// if it isn't, output the current set,
// then create a new set and add the current Delta to
// it.
processDeltas(writer, originalLines, deltas, contextSize, false);
deltas.clear();
deltas.add(nextDelta);
}
delta = nextDelta;
}
}
// don't forget to process the last set of Deltas
processDeltas(writer, originalLines, deltas, contextSize,
patchDeltas.size() == 1 && file.getFromFile() == null);
}
}
if (diff.getTail() != null) {
writer.accept("--");
writer.accept(diff.getTail());
}
}
private static void processDeltas(Consumer<String> writer,
List<String> origLines, List<AbstractDelta<String>> deltas,
int contextSize, boolean newFile) {
List<String> buffer = new ArrayList<>();
int origTotal = 0; // counter for total lines output from Original
int revTotal = 0; // counter for total lines output from Original
int line;
AbstractDelta<String> curDelta = deltas.get(0);
int origStart;
if (newFile) {
origStart = 0;
} else {
// NOTE: +1 to overcome the 0-offset Position
origStart = curDelta.getSource().getPosition() + 1 - contextSize;
if (origStart < 1) {
origStart = 1;
}
}
int revStart = curDelta.getTarget().getPosition() + 1 - contextSize;
if (revStart < 1) {
revStart = 1;
}
// find the start of the wrapper context code
int contextStart = curDelta.getSource().getPosition() - contextSize;
if (contextStart < 0) {
contextStart = 0; // clamp to the start of the file
}
// output the context before the first Delta
for (line = contextStart; line < curDelta.getSource().getPosition()
&& line < origLines.size(); line++) { //
buffer.add(" " + origLines.get(line));
origTotal++;
revTotal++;
}
// output the first Delta
getDeltaText(txt -> buffer.add(txt), curDelta);
origTotal += curDelta.getSource().getLines().size();
revTotal += curDelta.getTarget().getLines().size();
int deltaIndex = 1;
while (deltaIndex < deltas.size()) { // for each of the other Deltas
AbstractDelta<String> nextDelta = deltas.get(deltaIndex);
int intermediateStart = curDelta.getSource().getPosition()
+ curDelta.getSource().getLines().size();
for (line = intermediateStart; line < nextDelta.getSource().getPosition()
&& line < origLines.size(); line++) {
// output the code between the last Delta and this one
buffer.add(" " + origLines.get(line));
origTotal++;
revTotal++;
}
getDeltaText(txt -> buffer.add(txt), nextDelta); // output the Delta
origTotal += nextDelta.getSource().getLines().size();
revTotal += nextDelta.getTarget().getLines().size();
curDelta = nextDelta;
deltaIndex++;
}
// Now output the post-Delta context code, clamping the end of the file
contextStart = curDelta.getSource().getPosition()
+ curDelta.getSource().getLines().size();
for (line = contextStart; (line < (contextStart + contextSize))
&& (line < origLines.size()); line++) {
buffer.add(" " + origLines.get(line));
origTotal++;
revTotal++;
}
// Create and insert the block header, conforming to the Unified Diff
// standard
writer.accept("@@ -" + origStart + "," + origTotal + " +" + revStart + "," + revTotal + " @@");
buffer.forEach(txt -> {
writer.accept(txt);
});
}
/**
* getDeltaText returns the lines to be added to the Unified Diff text from the Delta parameter.
*
* @param writer consumer for the list of String lines of code
* @param delta the Delta to output
*/
private static void getDeltaText(Consumer<String> writer, AbstractDelta<String> delta) {
for (String line : delta.getSource().getLines()) {
writer.accept("-" + line);
}
for (String line : delta.getTarget().getLines()) {
writer.accept("+" + line);
}
}
private static void writeOrNothing(Consumer<String> writer, String str) throws IOException {
if (str != null) {
writer.accept(str);
}
}
}