add support for MAC_CLASSIC (\r only)

[DemonJun]

If you are submitting a bug, please include the following:

• summary of problem
  • spotless check can not checkout the file with cr(\r) lineSeparator
• gradle or maven version
  • maven with 3.8
• spotless version
  • 2.22.4
• operating system and version
  • macos
• copy-paste your full Spotless configuration block(s), and a link to a public git repo that reproduces the problem if possible

<plugin>
                <groupId>com.diffplug.spotless</groupId>
                <artifactId>spotless-maven-plugin</artifactId>
                <version>2.22.4</version>
                <configuration>
                    <formats>
                        <format>
                            <includes>
                                <include>*.java</include>
                                <include>*.xml</include>
                            </includes>
                            <trimTrailingWhitespace/>
                            <endWithNewline/>
                            <encoding>UTF-8</encoding>
                            <indent>
                                <spaces>true</spaces>
                                <spacesPerTab>4</spacesPerTab>
                            </indent>
                        </format>
                    </formats>
                    <java>
                        <encoding>UTF-8</encoding>
                        <googleJavaFormat>
                            <version>1.15.0</version>
                            <style>AOSP</style>
                        </googleJavaFormat>
                        <removeUnusedImports/>
                    </java>
                    <encoding>UTF-8</encoding>
                    <lineEndings>UNIX</lineEndings>
                </configuration>
</plugin>

[nedtwigg]

There are two standard line endings in use today:

• unix \n
• windows \r\n

On Mac OS Classic (last actively developed 20 years ago around Y2K) there was a \r only line ending convention. To my knowledge, that mode is completely unsupported by git.

If you want to add a MAC_CLASSIC line ending, I'd be happy to merge it.

The tricky part is that this method currently assumes it is getting \r\n or \n, and then it promises to return \n only. You'll have to update it to detect files with \r but no \n, and then replace \r with \n.

spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java

Lines 138 to 147 in 4230476

	/** Returns a string with exclusively unix line endings. */
	public static String toUnix(String input) {
	int firstNewline = input.lastIndexOf('\n');
	if (firstNewline == -1) {
	// fastest way to detect if a string is already unix-only
	return input;
	} else {
	return input.replace("\r", "");
	}
	}

Then these methods would need to get updated too (perhaps other places too, but I think this is most of it).

spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java

Lines 40 to 45 in 4230476

	/** {@code \n} on unix systems, {@code \r\n} on windows systems. */
	PLATFORM_NATIVE,
	/** {@code \r\n} */
	WINDOWS,
	/** {@code \n} */
	UNIX;

spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java

Lines 72 to 77 in 4230476

	/** Should use {@link #createPolicy(File, Supplier)} instead, but this will work iff its a path-independent LineEnding policy. */
	public Policy createPolicy() {
	switch (this) {
	case PLATFORM_NATIVE: return _platformNativePolicy;
	case WINDOWS: return WINDOWS_POLICY;
	case UNIX: return UNIX_POLICY;

spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java

Lines 97 to 98 in 4230476

	private static final Policy WINDOWS_POLICY = new ConstantLineEndingPolicy(WINDOWS.str());
	private static final Policy UNIX_POLICY = new ConstantLineEndingPolicy(UNIX.str());

spotless/lib/src/main/java/com/diffplug/spotless/LineEnding.java

Lines 114 to 120 in 4230476

	/** Returns the standard line ending for this policy. */
	public String str() {
	switch (this) {
	case PLATFORM_NATIVE: return _platformNative;
	case WINDOWS: return "\r\n";
	case UNIX: return "\n";
	default: throw new UnsupportedOperationException(this + " is a path-specific line ending.");

[DemonJun]

 /** Returns a string with exclusively unix line endings. */ 
 public static String toUnix(String input) { 
 	int firstNewline = input.lastIndexOf('\n'); 
 	if (firstNewline == -1) { 
 		// fastest way to detect if a string is already unix-only 
 		return input; 
 	} else { 
 		return input.replace("\r", ""); 
 	} 
 } 

Here I don't understand, if input is endWith '\n', it must go to the else block? Is this necessary?

[DemonJun]

/** Returns a string with exclusively unix line endings. */
public static String toUnix(String input) {
      if (input.lastIndexOf(WINDOWS.str()) > -1) {
          return input.replace('\r', '');
      } else if (input.lastIndexOf(MAC_CLASSIC.str()) > -1) {
          // replace mac classic '\r' with unix line endings '\n'
          return input.replace(MAC_CLASSIC.str(), UNIX.str());
      } else {
	// fastest way to detect if a string is already unix-only
	return input;
      }
}

After adding the MAC_CLASSIC conversion, I think it should look like this.

[nedtwigg]

Released in plugin-gradle 6.8.0 and plugin-maven 2.23.0, thanks to @DemonJun.