lambda: spaces around arrow

java/java-impl/src/com/intellij/ide/JavaLanguageCodeStyleSettingsProvider.java

@@ -188,7 +188,8 @@ public class JavaLanguageCodeStyleSettingsProvider extends LanguageCodeStyleSett
     "public class Foo<T, U> {\n" +
     "  int[] X = new int[]{1, 3, 5, 6, 7, 87, 1213, 2};\n" +
     "\n" +
-    "  public void foo(int x, int y) {\n" +
+    "  public void foo(int x, int y) {" +
+    "    Runnable r = () -> {};\n" +
     "    for (int i = 0; i < x; i++) {\n" +
     "      y += (y ^ 0x123) << 2;\n" +
     "    }\n" +

java/java-impl/src/com/intellij/psi/formatter/java/JavaSpacePropertyProcessor.java

@@ -1168,6 +1168,14 @@ public class JavaSpacePropertyProcessor extends JavaElementVisitor {
 
   }
 
+  @Override
+  public void visitLambdaExpression(PsiLambdaExpression expression) {
+    if ((myRole1 == ChildRole.ARROW && (myRole2 == ChildRole.LBRACE || myRole2 == ChildRole.EXPRESSION)) || 
+        (myRole1 == ChildRole.PARAMETER_LIST && myRole2 == ChildRole.ARROW)) {
+      createSpaceInCode(mySettings.SPACE_AROUND_LAMBDA_ARROW);
+    }
+  }
+
   @Override public void visitForStatement(PsiForStatement statement) {
     if (myRole2 == ChildRole.LPARENTH) {
       createSpaceInCode(mySettings.SPACE_BEFORE_FOR_PARENTHESES);

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/ChildRole.java

@@ -156,6 +156,7 @@ public class ChildRole {
   public static final int ANNOTATION_VALUE = 249;  // in NAME_VALUE_PAIR, ANNOTATION_ARRAY_INITIALIZER
   public static final int ANNOTATION = 250;  // in MODIFIER_LIST
   public static final int CATCH_SECTION = 251; // in TRY_STATEMENT
+  public static final int ARROW = 252; // in LAMBDA STATEMENT
 
   private ChildRole() {
   }

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiLambdaExpressionImpl.java

@@ -15,11 +15,14 @@
  */
 package com.intellij.psi.impl.source.tree.java;
 
+import com.intellij.lang.ASTNode;
 import com.intellij.psi.*;
 import com.intellij.psi.controlFlow.*;
 import com.intellij.psi.impl.PsiImplUtil;
+import com.intellij.psi.impl.source.tree.ChildRole;
 import com.intellij.psi.impl.source.tree.JavaElementType;
 import com.intellij.psi.scope.PsiScopeProcessor;
+import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -40,6 +43,20 @@ public class PsiLambdaExpressionImpl extends ExpressionPsiElement implements Psi
     return PsiTreeUtil.getRequiredChildOfType(this, PsiParameterList.class);
   }
 
+  @Override
+  public int getChildRole(ASTNode child) {
+    final IElementType elType = child.getElementType();
+    if (elType == JavaTokenType.ARROW) {
+      return ChildRole.ARROW;
+    } else if (elType == JavaElementType.PARAMETER_LIST) {
+      return ChildRole.PARAMETER_LIST;
+    } else if (elType == JavaElementType.CODE_BLOCK) {
+      return ChildRole.LBRACE;
+    } else {
+      return ChildRole.EXPRESSION;
+    }
+  }
+
   @Override
   public PsiElement getBody() {
     final PsiElement element = getLastChild();

java/java-tests/testSrc/com/intellij/psi/formatter/java/JavaFormatterSpaceTest.java

@@ -301,6 +301,18 @@ public class JavaFormatterSpaceTest extends AbstractJavaFormatterTest {
                  "try { } catch (E1|E2 e) { }");
   }
 
+  public void testSpacesInsideLambda() throws Exception {
+    getSettings().KEEP_SIMPLE_BLOCKS_IN_ONE_LINE = true;
+    getSettings().SPACE_AROUND_LAMBDA_ARROW = true;
+
+    doMethodTest("()->{}",
+                 "() -> {}");
+
+    getSettings().SPACE_AROUND_LAMBDA_ARROW = false;
+    doMethodTest("() -> {}",
+                 "()->{}");
+  }
+
   public void testSpacesBeforeResourceList() throws Exception {
     getSettings().KEEP_SIMPLE_BLOCKS_IN_ONE_LINE = true;
     getSettings().BRACE_STYLE = CommonCodeStyleSettings.NEXT_LINE;

platform/lang-api/src/com/intellij/psi/codeStyle/CodeStyleSettingsCustomizable.java

@@ -32,6 +32,7 @@ public interface CodeStyleSettingsCustomizable {
     SPACE_AROUND_MULTIPLICATIVE_OPERATORS,
     SPACE_AROUND_SHIFT_OPERATORS,
     SPACE_AROUND_UNARY_OPERATOR,
+    SPACE_AROUND_LAMBDA_ARROW,
     SPACE_AFTER_COMMA,
     SPACE_AFTER_COMMA_IN_TYPE_ARGUMENTS,
     SPACE_BEFORE_COMMA,

platform/lang-api/src/com/intellij/psi/codeStyle/CommonCodeStyleSettings.java

@@ -517,6 +517,8 @@ public class CommonCodeStyleSettings {
 
   public boolean SPACE_AROUND_UNARY_OPERATOR = false;
 
+  public boolean SPACE_AROUND_LAMBDA_ARROW = true;
+
   public boolean SPACE_AFTER_COMMA = true;
   public boolean SPACE_AFTER_COMMA_IN_TYPE_ARGUMENTS = true;
   public boolean SPACE_BEFORE_COMMA = false;

platform/lang-impl/src/com/intellij/application/options/codeStyle/CodeStyleSpacesPanel.java

@@ -53,6 +53,7 @@ public class CodeStyleSpacesPanel extends OptionTreeWithPreviewPanel {
     initBooleanField("SPACE_AROUND_MULTIPLICATIVE_OPERATORS", ApplicationBundle.message("checkbox.spaces.multiplicative.operators"), SPACES_AROUND_OPERATORS);
     initBooleanField("SPACE_AROUND_SHIFT_OPERATORS", ApplicationBundle.message("checkbox.spaces.shift.operators"), SPACES_AROUND_OPERATORS);
     initBooleanField("SPACE_AROUND_UNARY_OPERATOR", ApplicationBundle.message("checkbox.spaces.around.unary.operator"), SPACES_AROUND_OPERATORS);
+    initBooleanField("SPACE_AROUND_LAMBDA_ARROW", ApplicationBundle.message("checkbox.spaces.around.lambda.arrow"), SPACES_AROUND_OPERATORS);
     initCustomOptions(SPACES_AROUND_OPERATORS);
 
     initBooleanField("SPACE_BEFORE_CLASS_LBRACE", ApplicationBundle.message("checkbox.spaces.class.left.brace"), SPACES_BEFORE_LEFT_BRACE);

platform/platform-resources-en/src/messages/ApplicationBundle.properties

@@ -558,4 +558,5 @@ arrangement.text.negate=Negate
 arrangement.action.rule.add.text=Add rule
 arrangement.action.rule.add.description=Add new arrangement rule
 arrangement.action.rule.remove.text=Remove rule
-arrangement.action.rule.remove.description=Remove selected arrangement rule
+arrangement.action.rule.remove.description=Remove selected arrangement rule
+checkbox.spaces.around.lambda.arrow=Lambda arrow