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Add generateOriginalAndDiff method and test class (#164)
* Add generateOriginalAndDiff method and test class * Add generateOriginalAndDiff method and test class.I split long code into short methods, changed ambiguous variable names to explicit variable names * fixes #164 * fix build issues
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‎java-diff-utils/src/main/java/com/github/difflib/UnifiedDiffUtils.java

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import com.github.difflib.patch.Chunk;
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import com.github.difflib.patch.AbstractDelta;
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import com.github.difflib.patch.Patch;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.Optional;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import java.util.stream.Collectors;
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/**
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*
@@ -313,4 +317,151 @@ private static List<String> getDeltaText(AbstractDelta<String> delta) {
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private UnifiedDiffUtils() {
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}
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/**
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* Compare the differences between two files and return to the original file and diff format
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*
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* (This method compares the original file with the comparison file to obtain a diff, and inserts the diff into the corresponding position of the original file.
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* You can see all the differences and unmodified places from the original file.
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* Also, this will be very easy and useful for making side-by-side comparison display applications,
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* for example, if you use diff2html (https://github.com/rtfpessoa/diff2html#usage)
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* Wait for tools to display your differences on html pages, you only need to insert the return value into your js code)
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*
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* @param original Original file content
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* @param revised revised file content
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*
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*/
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public static List<String> generateOriginalAndDiff(List<String> original, List<String> revised) {
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return generateOriginalAndDiff(original, revised, null, null);
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}
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/**
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* Compare the differences between two files and return to the original file and diff format
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*
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* (This method compares the original file with the comparison file to obtain a diff, and inserts the diff into the corresponding position of the original file.
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* You can see all the differences and unmodified places from the original file.
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* Also, this will be very easy and useful for making side-by-side comparison display applications,
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* for example, if you use diff2html (https://github.com/rtfpessoa/diff2html#usage)
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* Wait for tools to display your differences on html pages, you only need to insert the return value into your js code)
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*
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* @param original Original file content
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* @param revised revised file content
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* @param originalFileName Original file name
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* @param revisedFileName revised file name
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*/
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public static List<String> generateOriginalAndDiff(List<String> original, List<String> revised, String originalFileName, String revisedFileName) {
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String originalFileNameTemp = originalFileName;
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String revisedFileNameTemp = originalFileName;
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if (originalFileNameTemp == null) {
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originalFileNameTemp = "original";
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}
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if (revisedFileNameTemp == null) {
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revisedFileNameTemp = "revised";
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}
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Patch<String> patch = DiffUtils.diff(original, revised);
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List<String> unifiedDiff = generateUnifiedDiff(originalFileNameTemp, revisedFileNameTemp, original, patch, 0);
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if (unifiedDiff.isEmpty()) {
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unifiedDiff.add("--- " + originalFileNameTemp);
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unifiedDiff.add("+++ " + revisedFileNameTemp);
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unifiedDiff.add("@@ -0,0 +0,0 @@");
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} else if (unifiedDiff.size() >= 3 && !unifiedDiff.get(2).contains("@@ -1,")) {
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unifiedDiff.set(1, unifiedDiff.get(1));
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unifiedDiff.add(2, "@@ -0,0 +0,0 @@");
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}
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List<String> originalWithPrefix = original.stream().map(v -> " " + v).collect(Collectors.toList());
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return insertOrig(originalWithPrefix, unifiedDiff);
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}
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//Insert the diff format to the original file
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private static List<String> insertOrig(List<String> original, List<String> unifiedDiff) {
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List<String> result = new ArrayList<>();
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List<List<String>> diffList = new ArrayList<>();
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List<String> diff = new ArrayList<>();
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for (int i = 0; i < unifiedDiff.size(); i++) {
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String u = unifiedDiff.get(i);
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if (u.startsWith("@@") && !"@@ -0,0 +0,0 @@".equals(u) && !u.contains("@@ -1,")) {
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List<String> twoList = new ArrayList<>();
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twoList.addAll(diff);
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diffList.add(twoList);
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diff.clear();
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diff.add(u);
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continue;
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}
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if (i == unifiedDiff.size() - 1) {
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diff.add(u);
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List<String> twoList = new ArrayList<>();
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twoList.addAll(diff);
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diffList.add(twoList);
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diff.clear();
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break;
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}
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diff.add(u);
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}
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insertOrig(diffList, result, original);
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return result;
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}
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//Insert the diff format to the original file
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private static void insertOrig(List<List<String>> diffList, List<String> result, List<String> original) {
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for (int i = 0; i < diffList.size(); i++) {
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List<String> diff = diffList.get(i);
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List<String> nexDiff = i == diffList.size() - 1 ? null : diffList.get(i + 1);
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String simb = i == 0 ? diff.get(2) : diff.get(0);
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String nexSimb = nexDiff == null ? null : nexDiff.get(0);
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insert(result, diff);
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Map<String, Integer> map = getRowMap(simb);
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if (null != nexSimb) {
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Map<String, Integer> nexMap = getRowMap(nexSimb);
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int start = 0;
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if (map.get("orgRow") != 0) {
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start = map.get("orgRow") + map.get("orgDel") - 1;
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}
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int end = nexMap.get("revRow") - 2;
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insert(result, getOrigList(original, start, end));
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}
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if (simb.contains("@@ -1,") && null == nexSimb && map.get("orgDel") != original.size()) {
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insert(result, getOrigList(original, 0, original.size() - 1));
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} else if (null == nexSimb && (map.get("orgRow") + map.get("orgDel") - 1) < original.size()) {
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int start = map.get("orgRow") + map.get("orgDel") - 1;
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start = start == -1 ? 0 : start;
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insert(result, getOrigList(original, start, original.size() - 1));
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}
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}
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}
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//Insert the unchanged content in the source file into result
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private static void insert(List<String> result, List<String> noChangeContent) {
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for (String ins : noChangeContent) {
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result.add(ins);
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}
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}
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//Parse the line containing @@ to get the modified line number to delete or add a few lines
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private static Map<String, Integer> getRowMap(String str) {
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Map<String, Integer> map = new HashMap<>();
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if (str.startsWith("@@")) {
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String[] sp = str.split(" ");
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String org = sp[1];
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String[] orgSp = org.split(",");
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map.put("orgRow", Integer.valueOf(orgSp[0].substring(1)));
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map.put("orgDel", Integer.valueOf(orgSp[1]));
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String[] revSp = org.split(",");
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map.put("revRow", Integer.valueOf(revSp[0].substring(1)));
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map.put("revAdd", Integer.valueOf(revSp[1]));
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}
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return map;
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}
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//Get the specified part of the line from the original file
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private static List<String> getOrigList(List<String> originalWithPrefix, int start, int end) {
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List<String> list = new ArrayList<>();
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if (originalWithPrefix.size() >= 1 && start <= end && end < originalWithPrefix.size()) {
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int startTemp = start;
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for (; startTemp <= end; startTemp++) {
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list.add(originalWithPrefix.get(startTemp));
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}
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}
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return list;
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}
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}

‎java-diff-utils/src/test/java/com/github/difflib/examples/OriginalAndDiffTest.java

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package com.github.difflib.examples;
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import com.github.difflib.TestConstants;
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import com.github.difflib.UnifiedDiffUtils;
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import org.junit.jupiter.api.Test;
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import java.io.BufferedReader;
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import java.io.FileNotFoundException;
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import java.io.FileReader;
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import java.io.IOException;
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import java.util.ArrayList;
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import java.util.List;
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import static java.util.stream.Collectors.joining;
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import static org.junit.jupiter.api.Assertions.fail;
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public class OriginalAndDiffTest {
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@Test
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public void testGenerateOriginalAndDiff() {
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List<String> origLines = null;
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List<String> revLines = null;
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try {
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origLines = fileToLines(TestConstants.MOCK_FOLDER + "original.txt");
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revLines = fileToLines(TestConstants.MOCK_FOLDER + "revised.txt");
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} catch (IOException e) {
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fail(e.getMessage());
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}
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List<String> originalAndDiff = UnifiedDiffUtils.generateOriginalAndDiff(origLines, revLines);
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System.out.println(originalAndDiff.stream().collect(joining("\n")));
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}
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public static List<String> fileToLines(String filename) throws FileNotFoundException, IOException {
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List<String> lines = new ArrayList<>();
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String line = "";
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try (BufferedReader in = new BufferedReader(new FileReader(filename))) {
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while ((line = in.readLine()) != null) {
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lines.add(line);
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}
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}
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return lines;
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}
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}

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