Add configurable EOL specifier (#27)

* Add configurable EOL specifier
* Document where LineEnding.java and LineEndingTest.java come from

This closes #2

.gitignore

@@ -7,3 +7,5 @@
 /.classpath
 /.project
 /.settings/
+/.idea/
+/*.iml

src/main/java/net/revelc/code/impsort/Grouper.java

@@ -124,7 +124,7 @@ public boolean getJoinStaticWithNonStatic() {
     return joinStaticWithNonStatic;
   }
 
-  public String groupedImports(Collection<Import> allImports) {
+  public String groupedImports(Collection<Import> allImports, String eol) {
     StringBuilder sb = new StringBuilder();
     Map<Integer, ArrayList<Import>> staticImports = groupStatic(allImports);
     Map<Integer, ArrayList<Import>> nonStaticImports = groupNonStatic(allImports);
@@ -135,13 +135,13 @@ public String groupedImports(Collection<Import> allImports) {
     AtomicBoolean firstGroup = new AtomicBoolean(true);
     Consumer<ArrayList<Import>> consumer = grouping -> {
       if (!firstGroup.getAndSet(false)) {
-        sb.append("\n");
+        sb.append(eol);
       }
-      grouping.forEach(imp -> sb.append(imp).append("\n"));
+      grouping.forEach(imp -> sb.append(imp).append(eol));
     };
     first.values().forEach(consumer);
     if (!getJoinStaticWithNonStatic() && !first.isEmpty() && !second.isEmpty()) {
-      sb.append("\n");
+      sb.append(eol);
     }
     firstGroup.set(true);
     second.values().forEach(consumer);

src/main/java/net/revelc/code/impsort/ImpSort.java

@@ -22,6 +22,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.EnumSet;
@@ -55,33 +56,42 @@
 
 public class ImpSort {
 
-  private static final Comparator<Node> BY_POSITION =
-      (a, b) -> a.getBegin().get().compareTo(b.getBegin().get());
+  private static final Comparator<Node> BY_POSITION = Comparator.comparing(a -> a.getBegin().get());
 
   private final Charset sourceEncoding;
   private final Grouper grouper;
   private final boolean removeUnused;
   private final boolean treatSamePackageAsUnused;
+  private final LineEnding lineEnding;
 
   public ImpSort(final Charset sourceEncoding, final Grouper grouper, final boolean removeUnused,
-      final boolean treatSamePackageAsUnused) {
+      final boolean treatSamePackageAsUnused, final LineEnding lineEnding) {
     this.sourceEncoding = sourceEncoding;
     this.grouper = grouper;
     this.removeUnused = removeUnused;
     this.treatSamePackageAsUnused = treatSamePackageAsUnused;
+    this.lineEnding = lineEnding;
   }
 
   public Result parseFile(final Path path) throws IOException {
-    List<String> fileLines = Files.readAllLines(path, sourceEncoding);
-    ParseResult<CompilationUnit> parseResult = new JavaParser().parse(String.join("\n", fileLines));
+    String file = new String(Files.readAllBytes(path), sourceEncoding);
+    LineEnding fileLineEnding = LineEnding.determineLineEnding(file);
+    LineEnding impLineEnding;
+    if (lineEnding == LineEnding.KEEP) {
+      impLineEnding = fileLineEnding;
+    } else {
+      impLineEnding = lineEnding;
+    }
+    List<String> fileLines = Arrays.asList(file.split(fileLineEnding.getChars()));
+    ParseResult<CompilationUnit> parseResult = new JavaParser().parse(file);
     CompilationUnit unit =
         parseResult.getResult().orElseThrow(() -> new IOException("Unable to parse " + path));
     Position packagePosition =
         unit.getPackageDeclaration().map(p -> p.getEnd().get()).orElse(unit.getBegin().get());
     NodeList<ImportDeclaration> importDeclarations = unit.getImports();
     if (importDeclarations.isEmpty()) {
       return new Result(path, sourceEncoding, fileLines, 0, fileLines.size(), "", "",
-          Collections.emptyList());
+          Collections.emptyList(), impLineEnding);
     }
 
     // find orphaned comments before between package and last import
@@ -107,9 +117,10 @@ public Result parseFile(final Path path) throws IOException {
     while (stop < fileLines.size() && fileLines.get(stop).trim().isEmpty()) {
       ++stop;
     }
-    String originalSection = String.join("\n", fileLines.subList(start, stop)) + "\n";
+    String originalSection = String.join(impLineEnding.getChars(), fileLines.subList(start, stop))
+        + impLineEnding.getChars();
 
-    Set<Import> allImports = convertImportSection(importSectionNodes);
+    Set<Import> allImports = convertImportSection(importSectionNodes, impLineEnding.getChars());
 
     if (removeUnused) {
       removeUnusedImports(allImports, tokensInUse(unit));
@@ -118,22 +129,22 @@ public Result parseFile(final Path path) throws IOException {
       }
     }
 
-    String newSection = grouper.groupedImports(allImports);
+    String newSection = grouper.groupedImports(allImports, impLineEnding.getChars());
     if (start > 0) {
       // add newline before imports, as long as imports not at start of file
-      newSection = "\n" + newSection;
+      newSection = impLineEnding.getChars() + newSection;
     }
     if (stop < fileLines.size()) {
       // add newline after imports, as long as there's more in file
-      newSection += "\n";
+      newSection += impLineEnding.getChars();
     }
 
     return new Result(path, sourceEncoding, fileLines, start, stop, originalSection, newSection,
-        allImports);
+        allImports, impLineEnding);
   }
 
   // return imports, with associated comments, in order found in the file
-  private static Set<Import> convertImportSection(List<Node> importSectionNodes) {
+  private static Set<Import> convertImportSection(List<Node> importSectionNodes, String eol) {
     List<Comment> recentComments = new ArrayList<>();
     LinkedHashSet<Import> allImports = new LinkedHashSet<>(importSectionNodes.size() / 2);
     for (Node node : importSectionNodes) {
@@ -159,7 +170,7 @@ private static Set<Import> convertImportSection(List<Node> importSectionNodes) {
         }
 
         recentComments.clear();
-        convertAndAddImport(allImports, thisImport);
+        convertAndAddImport(allImports, thisImport, eol);
       } else {
         throw new IllegalStateException("Unknown node: " + node);
       }
@@ -171,7 +182,8 @@ private static Set<Import> convertImportSection(List<Node> importSectionNodes) {
     return allImports;
   }
 
-  private static void convertAndAddImport(LinkedHashSet<Import> allImports, List<Node> thisImport) {
+  private static void convertAndAddImport(LinkedHashSet<Import> allImports, List<Node> thisImport,
+      String eol) {
     boolean isStatic = false;
     String importItem = null;
     String prefix = "";
@@ -194,7 +206,7 @@ private static void convertAndAddImport(LinkedHashSet<Import> allImports, List<N
     if (!suffix.isEmpty()) {
       suffix = " " + suffix;
     }
-    Import imp = new Import(isStatic, importItem, prefix.trim(), suffix);
+    Import imp = new Import(isStatic, importItem, prefix.trim(), suffix, eol);
     Iterator<Import> iter = allImports.iterator();
     // this de-duplication can probably be made more efficient by doing it all at the end
     while (iter.hasNext()) {

src/main/java/net/revelc/code/impsort/Import.java

@@ -22,12 +22,15 @@ public class Import {
   private final String imp;
   private final String prefix;
   private final String suffix;
+  private final String eol;
 
-  Import(final boolean isStatic, final String imp, final String prefix, final String suffix) {
+  Import(final boolean isStatic, final String imp, final String prefix, final String suffix,
+      final String eol) {
     this.isStatic = isStatic;
     this.imp = Objects.requireNonNull(imp);
     this.prefix = Objects.requireNonNull(prefix);
     this.suffix = Objects.requireNonNull(suffix);
+    this.eol = eol;
   }
 
   public boolean isStatic() {
@@ -48,7 +51,7 @@ public String getSuffix() {
 
   @Override
   public String toString() {
-    return prefix + (prefix.isEmpty() ? "" : "\n") + "import" + (isStatic() ? " static" : "") + " "
+    return prefix + (prefix.isEmpty() ? "" : eol) + "import" + (isStatic() ? " static" : "") + " "
         + getImport() + ";" + suffix;
   }
 
@@ -83,7 +86,7 @@ public Import combineWith(Import duplicate) {
     } else if (duplicate.getPrefix().isEmpty()) {
       newPrefix = getPrefix();
     } else {
-      newPrefix = getPrefix() + "\n" + duplicate.getPrefix();
+      newPrefix = getPrefix() + eol + duplicate.getPrefix();
     }
     if (getSuffix().isEmpty()) {
       newSuffix = duplicate.getSuffix();
@@ -92,7 +95,7 @@ public Import combineWith(Import duplicate) {
     } else {
       newSuffix = getSuffix() + duplicate.getSuffix();
     }
-    return new Import(isStatic(), getImport(), newPrefix, newSuffix);
+    return new Import(isStatic(), getImport(), newPrefix, newSuffix, eol);
   }
 
 }

src/main/java/net/revelc/code/impsort/LineEnding.java

@@ -0,0 +1,66 @@
+/*
+ * 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 net.revelc.code.impsort;
+
+/**
+ * This file is taken from <a href="https://github.com/revelc/formatter-maven-plugin/blob/46b15ca42db50cb91e2edad79dd40882ccb2af4c/src/main/java/net/revelc/code/formatter/LineEnding.java">formatter-maven-plugin</a>.
+ */
+public enum LineEnding {
+
+  AUTO(System.lineSeparator()), KEEP(null), LF("\n"), CRLF("\r\n"), CR("\r"), UNKNOWN(null);
+
+  private final String chars;
+
+  LineEnding(String value) {
+    this.chars = value;
+  }
+
+  public String getChars() {
+    return this.chars;
+  }
+
+  /**
+   * Returns the most occurring line-ending characters in the file text or null if no line-ending
+   * occurs the most.
+   */
+  public static LineEnding determineLineEnding(String fileDataString) {
+    int lfCount = 0;
+    int crCount = 0;
+    int crlfCount = 0;
+
+    for (int i = 0; i < fileDataString.length(); i++) {
+      char c = fileDataString.charAt(i);
+      if (c == '\r') {
+        if ((i + 1) < fileDataString.length() && fileDataString.charAt(i + 1) == '\n') {
+          crlfCount++;
+          i++;
+        } else {
+          crCount++;
+        }
+      } else if (c == '\n') {
+        lfCount++;
+      }
+    }
+
+    if (lfCount > crCount && lfCount > crlfCount) {
+      return LF;
+    } else if (crlfCount > lfCount && crlfCount > crCount) {
+      return CRLF;
+    } else if (crCount > lfCount && crCount > crlfCount) {
+      return CR;
+    }
+    return UNKNOWN;
+  }
+
+}

src/main/java/net/revelc/code/impsort/Result.java

@@ -14,7 +14,12 @@
 
 package net.revelc.code.impsort;
 
+import static java.nio.file.Files.newOutputStream;
+
+import java.io.BufferedWriter;
 import java.io.IOException;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -36,9 +41,11 @@ public class Result {
   private final List<String> fileLines;
   private final int start;
   private final int stop;
+  private final LineEnding lineEnding;
 
   Result(Path path, Charset sourceEncoding, List<String> fileLines, int start, int stop,
-      String originalSection, String newSection, Collection<Import> allImports) {
+      String originalSection, String newSection, Collection<Import> allImports,
+      LineEnding lineEnding) {
     this.path = path;
     this.sourceEncoding = sourceEncoding;
     this.originalSection = originalSection;
@@ -47,6 +54,7 @@ public class Result {
     this.fileLines = fileLines;
     this.start = start;
     this.stop = stop;
+    this.lineEnding = lineEnding;
   }
 
   public boolean isSorted() {
@@ -72,17 +80,30 @@ public void saveSorted(Path destination) throws IOException {
       return;
     }
     List<String> beforeImports = fileLines.subList(0, start);
-    List<String> importLines = Arrays.asList(newSection.split("\\n"));
+    List<String> importLines = Arrays.asList(newSection.split(lineEnding.getChars()));
     List<String> afterImports = fileLines.subList(stop, fileLines.size());
     List<String> allLines =
         new ArrayList<>(beforeImports.size() + importLines.size() + afterImports.size() + 1);
     allLines.addAll(beforeImports);
     allLines.addAll(importLines);
     if (afterImports.size() > 0) {
-      allLines.add(""); // restore blank line lost by split("\\n")
+      allLines.add(""); // restore blank line lost by split
     }
     allLines.addAll(afterImports);
-    Files.write(destination, allLines, sourceEncoding);
+    writeLines(destination, allLines, sourceEncoding);
+  }
+
+  private Path writeLines(Path destination, List<String> lines, Charset sourceEncoding)
+      throws IOException {
+    try (OutputStream out = newOutputStream(destination);
+        BufferedWriter writer =
+            new BufferedWriter(new OutputStreamWriter(out, sourceEncoding.newEncoder()))) {
+      for (String line : lines) {
+        writer.write(line);
+        writer.write(lineEnding.getChars());
+      }
+    }
+    return destination;
   }
 
 }

src/main/java/net/revelc/code/impsort/maven/plugin/AbstractImpSortMojo.java

@@ -36,6 +36,7 @@
 
 import net.revelc.code.impsort.Grouper;
 import net.revelc.code.impsort.ImpSort;
+import net.revelc.code.impsort.LineEnding;
 import net.revelc.code.impsort.Result;
 
 abstract class AbstractImpSortMojo extends AbstractMojo {
@@ -174,6 +175,21 @@ abstract class AbstractImpSortMojo extends AbstractMojo {
       defaultValue = "true")
   private boolean breadthFirstComparator;
 
+  /**
+   * Sets the line-ending of files after formatting. Valid values are:
+   * <ul>
+   * <li><b>"AUTO"</b> - Use line endings of current system</li>
+   * <li><b>"KEEP"</b> - Preserve line endings of files, default to AUTO if ambiguous</li>
+   * <li><b>"LF"</b> - Use Unix and Mac style line endings</li>
+   * <li><b>"CRLF"</b> - Use DOS and Windows style line endings</li>
+   * <li><b>"CR"</b> - Use early Mac style line endings</li>
+   * </ul>
+   *
+   * @since 1.4.0
+   */
+  @Parameter(defaultValue = "AUTO", property = "lineending", required = true)
+  private LineEnding lineEnding;
+
   abstract void processResult(Path path, Result results) throws MojoFailureException;
 
   @Override
@@ -199,7 +215,8 @@ public final void execute() throws MojoExecutionException, MojoFailureException
     Grouper grouper = new Grouper(groups, staticGroups, staticAfter, joinStaticWithNonStatic,
         breadthFirstComparator);
     Charset encoding = Charset.forName(sourceEncoding);
-    ImpSort impSort = new ImpSort(encoding, grouper, removeUnused, treatSamePackageAsUnused);
+    ImpSort impSort =
+        new ImpSort(encoding, grouper, removeUnused, treatSamePackageAsUnused, lineEnding);
     AtomicLong numAlreadySorted = new AtomicLong(0);
     AtomicLong numProcessed = new AtomicLong(0);