grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals

generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"
import "http://www.eclipse.org/emf/2002/Ecore" as ecore

Model:
	definitions+=VariableDefinition*
	eval=Expression;

VariableDefinition:
	name=ID ('(' parameter=ID ')')? '=' value=Expression;

Expression:
	FeatureCall | Literal;

Literal:
	literal=Boolean;

FeatureCall:
	target=[ecore::EObject|ID] ('(' argument=ID ')')?;

Boolean returns ecore::EString:
	'true' | 'false'

class MyDslFormatter extends AbstractFormatter2 {
	
	@Inject extension MyDslGrammarAccess

	def dispatch void format(Model model, extension IFormattableDocument document) {
		model.definitions.forEach[format]
	}
	
	def dispatch void format(VariableDefinition it, extension IFormattableDocument document){
		val extension access = variableDefinitionAccess
		regionFor.keyword(equalsSignKeyword_2).prepend[oneSpace].append[oneSpace autowrap]
	}
}

@RunWith(XtextRunner)
@InjectWith(MyDslInjectorProvider)
class MyDslFormattingTest {
	@Inject
	extension FormatterTestHelper

	@Test
	def void loadModel() {
		assertFormatted[
			request.preferences = new MapBasedPreferenceValues => [
				put(FormatterPreferenceKeys.maxLineWidth, 31)
			]
			toBeFormatted = '''
				myThing = longggggggggggggggggggggggggg
				myThing
			'''
			expectation = '''
				myThing =
				longggggggggggggggggggggggggg
				myThing
			'''
		]
	}
}

Expression:
	Addition;

Addition:
	Primary ({Addition.left=current} '+' right=Primary)*;

Primary:
	FeatureCall | Literal;

def dispatch void format(VariableDefinition it, extension IFormattableDocument document){
	val extension access = variableDefinitionAccess
	regionFor.keyword(equalsSignKeyword_2).prepend[oneSpace].append[oneSpace autowrap]
	append[newLine]
}
	
def dispatch void format(Addition it, extension IFormattableDocument document) {
	val extension access = additionAccess
	regionFor.keyword(plusSignKeyword_1_1).prepend[oneSpace autowrap].append[oneSpace]
	append[newLine]
}

assertFormatted[
	request.preferences = new MapBasedPreferenceValues => [
		put(FormatterPreferenceKeys.maxLineWidth, 31)
	]
	toBeFormatted = '''
		myThing = thing + longggggggggggggggggggggggggg + another
		myThing
	'''
	expectation = '''
		myThing =
		thing
		+ longggggggggggggggggggggggggg
		+ another
		myThing
	'''
]

def dispatch void format(Model model, extension IFormattableDocument document) {
	model.definitions.forEach[format]
	append[lowPriority noSpace] // this is the workaround
}