KT-5927 Join Lines could merge nested if's

#KT-5927 Fixed

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiFactory.kt

@@ -300,12 +300,11 @@ public class JetPsiFactory(private val project: Project) {
         return createExpression("$" + fieldName)
     }
 
-    public fun createBinaryExpression(lhs: String, op: String, rhs: String): JetBinaryExpression {
-        return createExpression(lhs + " " + op + " " + rhs) as JetBinaryExpression
-    }
-
-    public fun createBinaryExpression(lhs: JetExpression?, op: String, rhs: JetExpression?): JetBinaryExpression {
-        return createBinaryExpression(JetPsiUtil.getText(lhs), op, JetPsiUtil.getText(rhs))
+    public fun createBinaryExpression(lhs: JetExpression, op: String, rhs: JetExpression): JetBinaryExpression {
+        val expression = createExpression("a $op b") as JetBinaryExpression
+        expression.getLeft().replace(lhs)
+        expression.getRight().replace(rhs)
+        return expression
     }
 
     public fun createTypeCodeFragment(text: String, context: PsiElement?): JetTypeCodeFragment {

idea/src/org/jetbrains/jet/plugin/joinLines/JoinBlockIntoSingleStatementHandler.kt

@@ -24,6 +24,8 @@ import org.jetbrains.jet.lexer.JetTokens
 import org.jetbrains.jet.lang.psi.JetBlockExpression
 import org.jetbrains.jet.lang.psi.JetContainerNode
 import org.jetbrains.jet.lang.psi.JetWhenEntry
+import org.jetbrains.jet.lang.psi.JetIfExpression
+import org.jetbrains.jet.lang.psi.JetPsiFactory
 
 public class JoinBlockIntoSingleStatementHandler : JoinRawLinesHandlerDelegate {
     override fun tryJoinRawLines(document: Document, file: PsiFile, start: Int, end: Int): Int {
@@ -42,6 +44,20 @@ public class JoinBlockIntoSingleStatementHandler : JoinRawLinesHandlerDelegate {
         if (parent !is JetContainerNode && parent !is JetWhenEntry) return -1
         if (block.getNode().getChildren(JetTokens.COMMENTS).isNotEmpty()) return -1 // otherwise we will loose comments
 
+        // handle nested if's
+        val pparent = parent.getParent()
+        if (pparent is JetIfExpression && block == pparent.getThen() && statement is JetIfExpression && statement.getElse() == null) {
+            val condition1 = pparent.getCondition()
+            val condition2 = statement.getCondition()
+            val body = statement.getThen()
+            if (condition1 != null && condition2 != null && body != null) {
+                val newCondition = JetPsiFactory(pparent).createBinaryExpression(condition1, "&&", condition2)
+                condition1.replace(newCondition)
+                val newBody = block.replace(body)
+                return newBody.getTextRange()!!.getStartOffset()
+            }
+        }
+
         val newStatement = block.replace(statement)
         return newStatement.getTextRange()!!.getStartOffset()
     }

idea/testData/joinLines/nestedIfs/BlockBody.kt

@@ -0,0 +1,7 @@
+fun foo() {
+    <caret>if (a) {
+        if (b) {
+            foo()
+        }
+    }
+}

idea/testData/joinLines/nestedIfs/BlockBody.kt.after

@@ -0,0 +1,5 @@
+fun foo() {
+    if (a && b) <caret>{
+        foo()
+    }
+}

idea/testData/joinLines/nestedIfs/ComplexCondition1.kt

@@ -0,0 +1,5 @@
+fun foo() {
+    <caret>if (a && b) {
+        if (c && d) foo()
+    }
+}

idea/testData/joinLines/nestedIfs/ComplexCondition1.kt.after

@@ -0,0 +1,3 @@
+fun foo() {
+    if (a && b && c && d) <caret>foo()
+}

idea/testData/joinLines/nestedIfs/ComplexCondition2.kt

@@ -0,0 +1,5 @@
+fun foo() {
+    <caret>if (a && b) {
+        if (c || d) foo()
+    }
+}

idea/testData/joinLines/nestedIfs/ComplexCondition2.kt.after

@@ -0,0 +1,3 @@
+fun foo() {
+    if (a && b && (c || d)) <caret>foo()
+}

idea/testData/joinLines/nestedIfs/Simple.kt

@@ -0,0 +1,5 @@
+fun foo() {
+    <caret>if (a) {
+        if (b) foo()
+    }
+}

idea/testData/joinLines/nestedIfs/Simple.kt.after

@@ -0,0 +1,3 @@
+fun foo() {
+    if (a && b) <caret>foo()
+}

idea/tests/org/jetbrains/jet/plugin/intentions/declarations/JoinLinesTestGenerated.java

@@ -30,7 +30,7 @@ import java.util.regex.Pattern;
 @SuppressWarnings("all")
 @TestMetadata("idea/testData/joinLines")
 @TestDataPath("$PROJECT_ROOT")
-@InnerTestClasses({JoinLinesTestGenerated.DeclarationAndAssignment.class, JoinLinesTestGenerated.RemoveBraces.class})
+@InnerTestClasses({JoinLinesTestGenerated.DeclarationAndAssignment.class, JoinLinesTestGenerated.NestedIfs.class, JoinLinesTestGenerated.RemoveBraces.class})
 @RunWith(JUnit3RunnerWithInners.class)
 public class JoinLinesTestGenerated extends AbstractJoinLinesTest {
     public void testAllFilesPresentInJoinLines() throws Exception {
@@ -148,6 +148,39 @@ public class JoinLinesTestGenerated extends AbstractJoinLinesTest {
         }
     }
 
+    @TestMetadata("idea/testData/joinLines/nestedIfs")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class NestedIfs extends AbstractJoinLinesTest {
+        public void testAllFilesPresentInNestedIfs() throws Exception {
+            JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/joinLines/nestedIfs"), Pattern.compile("^(.+)\\.kt$"), true);
+        }
+
+        @TestMetadata("BlockBody.kt")
+        public void testBlockBody() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/joinLines/nestedIfs/BlockBody.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("ComplexCondition1.kt")
+        public void testComplexCondition1() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/joinLines/nestedIfs/ComplexCondition1.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("ComplexCondition2.kt")
+        public void testComplexCondition2() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/joinLines/nestedIfs/ComplexCondition2.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("Simple.kt")
+        public void testSimple() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/joinLines/nestedIfs/Simple.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("idea/testData/joinLines/removeBraces")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)