Insert final newline depending on lsp4j formatting settings

[xorye]

First step to fix redhat-developer/vscode-xml#196

Signed-off-by: David Kwon dakwon@redhat.com

[xorye]

In my latest commit, the code now trims the final newline only if the lsp4j trimFinalNewlines option is true. With vscode-xml, the option is currently null, so FormattingOptions#isTrimFinalNewlines returns false.

Some tests are failing right now, partly because the current code does not trim final spaces. (I think the code should always trim final spaces? If yes, I will go ahead and implement that)

For example, if _ were spaces:
before formatting

<a           ></a>_____

after formatting

<a></a>

[xorye]

And for cases where FormattingOptions#isTrimFinalNewlines is false, I think we should make sure to only trim final spaces, not final newlines.

Like so:

before formatting

<a      ></a>
__________\n
____\n
_____\n

before formatting

<a></a>
\n
\n
\n

[xorye]

The latest commit makes the formatting settings/behaviour be more consistent with HTML's

HTML's "preserve new lines" settings preserve newlines in between tags, therefore does not affect the newlines at the end of the document whatsoever. This PR implements that behaviour, the xml.format.preservedNewlines preference now only applies to newlines in between tags.

In HTML, there is no HTML setting to keep more than 1 newline at the end of the document after formatting. Either there are no newlines, or there are only one.
This can be configured using the html.format.endWithNewline setting.

To have this in vscode-xml, we should introduce a xml.format.endWithNewline preference, and maybe have the setting be passed into the formatting request, so that it is accessible from the lsp4j FormattingOptions.

So as it stands right now, to keep consistency with HTML, I think it makes sense to always trim final lines at the end, and only add the newline if xml.format.endWithNewline is true.

All of this is (with the exception of the vscode-xml preference, this would be handled in a PR in vscode-xml) implemented in the latest commit of this PR

[xorye]

With this vscode-xml PR: redhat-developer/vscode-xml#248 the files.trimFinalNewlines and files.insertFinalNewline vscode settings get mapped to xml.format.trimFinalNewlines and xml.format.insertFinalNewline respectively.

Because of this line: https://github.com/xorye/lsp4xml/blob/ea1669063effe5d842abcc11405b4613354c7179/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/settings/XMLFormattingOptions.java#L354

If the formatting options from the formatting request has the insertFinalNewlineor trimFinalNewlines setting, they will override xml.format.insertFinalNewline/xml.format.trimFinalLines.

[xorye]

I did this because since initializeDefaultSettings calls super.setTabSize(DEFAULT_TAB_SIZE);. When merging formattingOptions, the tabSize will not get updated because it has already been set:

lemminx/org.eclipse.lemminx/src/main/java/org/eclipse/lemminx/settings/XMLFormattingOptions.java

Lines 346 to 356 in 55e92f3

	public XMLFormattingOptions merge(FormattingOptions formattingOptions) {
	formattingOptions.entrySet().stream().forEach(entry -> {
	String key = entry.getKey();
	if (!key.equals("tabSize") && !key.equals("insertSpaces")) {
	this.put(entry.getKey(), entry.getValue());
	} else {
	this.putIfAbsent(entry.getKey(), entry.getValue());
	}
	});
	return this;
	}

[angelozerr]

Great job @xorye ! Could you add a section which explains those 2 settings (bound with vscode-xml) in https://github.com/redhat-developer/vscode-xml/wiki/Formatting please