Option to wrap elvis expressions

#KT-21720 Fixed

idea/formatter/src/org/jetbrains/kotlin/idea/core/formatter/KotlinCodeStyleSettings.java

@@ -47,6 +47,7 @@ public class KotlinCodeStyleSettings extends CustomCodeStyleSettings {
     public boolean CONTINUATION_INDENT_IN_SUPERTYPE_LISTS = true;
     public int BLANK_LINES_AROUND_BLOCK_WHEN_BRANCHES = 0;
     public int WRAP_EXPRESSION_BODY_FUNCTIONS = 0;
+    public int WRAP_ELVIS_EXPRESSIONS = 1;
 
     public KotlinCodeStyleSettings(CodeStyleSettings container) {
         super("JetCodeStyleSettings", container);

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/KotlinCommonBlock.kt

@@ -439,6 +439,16 @@ abstract class KotlinCommonBlock(
                         }
                     }
                 }
+                if (nodePsi.operationToken == KtTokens.ELVIS) {
+                    return object : WrappingStrategy {
+                        override fun getWrap(childElement: ASTNode): Wrap? {
+                            if (childElement.elementType == KtNodeTypes.OPERATION_REFERENCE) {
+                                return Wrap.createWrap(settings.kotlinCustomSettings.WRAP_ELVIS_EXPRESSIONS, true)
+                            }
+                            return null
+                        }
+                    }
+                }
                 return WrappingStrategy.NoWrapping
             }
         }

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt

@@ -50,6 +50,9 @@ fun SpacingBuilder.afterInside(element: IElementType, tokenSet: TokenSet, spacin
     tokenSet.types.forEach { inType -> afterInside(element, inType).spacingFun() }
 }
 
+fun SpacingBuilder.RuleBuilder.spacesNoLineBreak(spaces: Int) =
+        spacing(spaces, spaces, 0, false, 0)
+
 fun createSpacingBuilder(settings: CodeStyleSettings, builderUtil: KotlinSpacingBuilderUtil): KotlinSpacingBuilder {
     val kotlinCommonSettings = settings.kotlinCommonSettings
     val kotlinCustomSettings = settings.kotlinCustomSettings
@@ -199,7 +202,7 @@ fun createSpacingBuilder(settings: CodeStyleSettings, builderUtil: KotlinSpacing
 
 
             val spacesAroundAssignment = if (kotlinCommonSettings.SPACE_AROUND_ASSIGNMENT_OPERATORS) 1 else 0
-            beforeInside(EQ, PROPERTY).spacing(spacesAroundAssignment, spacesAroundAssignment, 0, false, 0)
+            beforeInside(EQ, PROPERTY).spacesNoLineBreak(spacesAroundAssignment)
             beforeInside(EQ, FUN).spacing(spacesAroundAssignment, spacesAroundAssignment, 0, false, 0)
 
             around(TokenSet.create(EQ, MULTEQ, DIVEQ, PLUSEQ, MINUSEQ, PERCEQ)).spaceIf(kotlinCommonSettings.SPACE_AROUND_ASSIGNMENT_OPERATORS)
@@ -209,7 +212,8 @@ fun createSpacingBuilder(settings: CodeStyleSettings, builderUtil: KotlinSpacing
             aroundInside(TokenSet.create(PLUS, MINUS), BINARY_EXPRESSION).spaceIf(kotlinCommonSettings.SPACE_AROUND_ADDITIVE_OPERATORS)
             aroundInside(TokenSet.create(MUL, DIV, PERC), BINARY_EXPRESSION).spaceIf(kotlinCommonSettings.SPACE_AROUND_MULTIPLICATIVE_OPERATORS)
             around(TokenSet.create(PLUSPLUS, MINUSMINUS, EXCLEXCL, MINUS, PLUS, EXCL)).spaceIf(kotlinCommonSettings.SPACE_AROUND_UNARY_OPERATOR)
-            around(ELVIS).spaces(1)
+            before(ELVIS).spaces(1)
+            after(ELVIS).spacesNoLineBreak(1)
             around(RANGE).spaceIf(kotlinCustomSettings.SPACE_AROUND_RANGE)
 
             after(MODIFIER_LIST).spaces(1)

idea/src/org/jetbrains/kotlin/idea/formatter/KotlinLanguageCodeStyleSettingsProvider.kt

@@ -55,10 +55,12 @@ class KotlinLanguageCodeStyleSettingsProvider : LanguageCodeStyleSettingsProvide
 
                    fun multilineMethod(
                            foo: String,
-                           bar: String
+                           bar: String?,
+                           x: Int?
                        ) {
                        foo.toUpperCase().trim()
                            .length
+                       val barLen = bar?.length() ?: x ?: -1
                    }
                }
 
@@ -300,6 +302,11 @@ class KotlinLanguageCodeStyleSettingsProvider : LanguageCodeStyleSettingsProvide
                         "Use continuation indent",
                         "Expression body functions"
                 )
+                showCustomOption(
+                        KotlinCodeStyleSettings::WRAP_ELVIS_EXPRESSIONS,
+                        "Elvis expressions",
+                        options = *arrayOf(CodeStyleSettingsCustomizable.WRAP_OPTIONS_FOR_SINGLETON, CodeStyleSettingsCustomizable.WRAP_VALUES_FOR_SINGLETON)
+                )
             }
             LanguageCodeStyleSettingsProvider.SettingsType.BLANK_LINES_SETTINGS -> {
                 consumer.showStandardOptions(

idea/testData/formatter/Elvis.after.inv.kt

@@ -3,15 +3,14 @@ fun test(a: Int?) {
 
     a ?: 42
 
-    a ?:
+    a ?: 42
-            42
 
     a
             ?: 42
 
-    val some = a ?:
+    val some = a
-            b ?:
+            ?: b
-            12
+            ?: 12
 }
 
 // SET_TRUE: ALIGN_MULTILINE_BINARY_OPERATION

idea/testData/formatter/Elvis.after.kt

@@ -3,15 +3,14 @@ fun test(a: Int?) {
 
     a ?: 42
 
-    a ?:
+    a ?: 42
-    42
 
     a
     ?: 42
 
-    val some = a ?:
+    val some = a
-               b ?:
+               ?: b
-               12
+               ?: 12
 }
 
 // SET_TRUE: ALIGN_MULTILINE_BINARY_OPERATION

idea/testData/formatter/Elvis.kt

@@ -9,9 +9,9 @@ fun test(a: Int?) {
     a
     ?: 42
 
-    val some = a ?:
+    val some = a
-    b ?:
+?: b
-    12
+?: 12
 }
 
 // SET_TRUE: ALIGN_MULTILINE_BINARY_OPERATION

idea/testData/formatter/ElvisWrap.after.kt

@@ -0,0 +1,4 @@
+val x = "abc"
+        ?: "def"
+
+// SET_INT: WRAP_ELVIS_EXPRESSIONS = 2

idea/testData/formatter/ElvisWrap.kt

@@ -0,0 +1,3 @@
+val x = "abc" ?: "def"
+
+// SET_INT: WRAP_ELVIS_EXPRESSIONS = 2

idea/tests/org/jetbrains/kotlin/formatter/FormatterTestGenerated.java

@@ -284,6 +284,12 @@ public class FormatterTestGenerated extends AbstractFormatterTest {
             doTest(fileName);
         }
 
+        @TestMetadata("ElvisWrap.after.kt")
+        public void testElvisWrap() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/formatter/ElvisWrap.after.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("EmptyLineAfterObjectDeclaration.after.kt")
         public void testEmptyLineAfterObjectDeclaration() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/formatter/EmptyLineAfterObjectDeclaration.after.kt");