From 8d290ee127d039ad0238dc65325fb33670967fe4 Mon Sep 17 00:00:00 2001
From: Valentin Kipyatkov <valentin@jetbrains.com>
Date: Mon, 7 Jul 2014 20:02:32 +0400
Subject: [PATCH] Java to Kotlin converter: better switch conversion in case of
 code block in case

---
 .../jet/j2k/visitors/StatementVisitor.kt      | 30 +++++++++++++++----
 .../JavaToKotlinConverterTestGenerated.java   |  5 ++++
 .../testData/ast/switch/caseWithBlock.java    | 20 +++++++++++++
 .../testData/ast/switch/caseWithBlock.kt      | 17 +++++++++++
 4 files changed, 66 insertions(+), 6 deletions(-)
 create mode 100644 j2k/tests/testData/ast/switch/caseWithBlock.java
 create mode 100644 j2k/tests/testData/ast/switch/caseWithBlock.kt

diff --git a/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt b/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt
index 09fd606fa23..027686d7d3d 100644
--- a/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt
@@ -216,18 +216,33 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
 
         fun isSwitchBreak(statement: PsiStatement) = statement is PsiBreakStatement && statement.getLabelIdentifier() == null
 
-        fun convertStatements(statements: List<PsiStatement>): List<Statement>
-                = statements.filterNot(::isSwitchBreak).map { converter.convertStatement(it) }
+        fun convertStatements(statements: List<PsiStatement>): List<Statement> {
+            val statementsToKeep = statements.filterNot(::isSwitchBreak)
+            if (statementsToKeep.size == 1) {
+                val block = statementsToKeep.single() as? PsiBlockStatement
+                if (block != null) {
+                    return listOf(converter.convertBlock(block.getCodeBlock(), true, { !isSwitchBreak(it) }))
+                }
+            }
+            return statementsToKeep.map { converter.convertStatement(it) }
+        }
 
         fun convertCaseStatements(caseIndex: Int): List<Statement> {
             val case = cases[caseIndex]
-            return if (case.statements.any { it is PsiBreakStatement || it is PsiContinueStatement || it is PsiReturnStatement || it is PsiThrowStatement } ||
-                    caseIndex == cases.lastIndex) {
-                convertStatements(case.statements)
+            val fallsThrough = if (caseIndex == cases.lastIndex) {
+                false
             }
-            else { // otherwise we fall through into the next case
+            else {
+                val block = case.statements.singleOrNull2() as? PsiBlockStatement
+                val statements = if (block != null) block.getCodeBlock().getStatements().toList() else case.statements
+                !statements.any { it is PsiBreakStatement || it is PsiContinueStatement || it is PsiReturnStatement || it is PsiThrowStatement }
+            }
+            return if (fallsThrough) { // we fall through into the next case
                 convertStatements(case.statements) + convertCaseStatements(caseIndex + 1)
             }
+            else {
+                convertStatements(case.statements)
+            }
         }
 
         fun convertCaseStatementsToBody(caseIndex: Int): Statement {
@@ -399,4 +414,7 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
         else
             converter.convertStatement(statement)
     }
+
+    private fun <T: Any> List<T>.singleOrNull2(): T?
+            = if (size == 1) this[0] else null
 }
diff --git a/j2k/tests/test/org/jetbrains/jet/j2k/test/JavaToKotlinConverterTestGenerated.java b/j2k/tests/test/org/jetbrains/jet/j2k/test/JavaToKotlinConverterTestGenerated.java
index 26afc5a999e..fec40a87653 100644
--- a/j2k/tests/test/org/jetbrains/jet/j2k/test/JavaToKotlinConverterTestGenerated.java
+++ b/j2k/tests/test/org/jetbrains/jet/j2k/test/JavaToKotlinConverterTestGenerated.java
@@ -2596,6 +2596,11 @@ public class JavaToKotlinConverterTestGenerated extends AbstractJavaToKotlinConv
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.TestsPackage", new File("j2k/tests/testData/ast/switch"), Pattern.compile("^(.+)\\.java$"), true);
         }
         
+        @TestMetadata("caseWithBlock.java")
+        public void testCaseWithBlock() throws Exception {
+            doTest("j2k/tests/testData/ast/switch/caseWithBlock.java");
+        }
+        
         @TestMetadata("comlicatedFallDown.java")
         public void testComlicatedFallDown() throws Exception {
             doTest("j2k/tests/testData/ast/switch/comlicatedFallDown.java");
diff --git a/j2k/tests/testData/ast/switch/caseWithBlock.java b/j2k/tests/testData/ast/switch/caseWithBlock.java
new file mode 100644
index 00000000000..4e201677698
--- /dev/null
+++ b/j2k/tests/testData/ast/switch/caseWithBlock.java
@@ -0,0 +1,20 @@
+//method
+void foo() {
+  switch(a) {
+    case 1: {
+      int x = 1;
+      System.out.println(x);
+      break;
+    }
+
+    case 2: {
+      int x = 2;
+      System.out.println(x);
+    }
+    break;
+
+    case 3: {
+        System.out.println(3);
+    }
+  }
+}
\ No newline at end of file
diff --git a/j2k/tests/testData/ast/switch/caseWithBlock.kt b/j2k/tests/testData/ast/switch/caseWithBlock.kt
new file mode 100644
index 00000000000..81ce65fdae5
--- /dev/null
+++ b/j2k/tests/testData/ast/switch/caseWithBlock.kt
@@ -0,0 +1,17 @@
+fun foo() {
+    when (a) {
+        1 -> {
+            val x = 1
+            System.out.println(x)
+        }
+
+        2 -> {
+            val x = 2
+            System.out.println(x)
+        }
+
+        3 -> {
+            System.out.println(3)
+        }
+    }
+}
\ No newline at end of file