New J2K: Add import statement conversion

j2k/newSrc/org/jetbrains/kotlin/j2k/ConversionsRunner.kt

@@ -61,6 +61,7 @@ object ConversionsRunner {
             +StaticsToCompanionExtractConversion()
             +ClassToObjectPromotionConversion(context)
             +LabeledStatementConversion()
+            +ImportStatementConversion()
             +SortClassMembersConversion()
         }
 

j2k/newSrc/org/jetbrains/kotlin/j2k/conversions/ImportStatementConversion.kt

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.j2k.conversions
+
+import org.jetbrains.kotlin.j2k.tree.*
+import org.jetbrains.kotlin.j2k.tree.impl.JKImportStatementImpl
+import org.jetbrains.kotlin.j2k.tree.impl.JKNameIdentifierImpl
+import org.jetbrains.kotlin.j2k.tree.visitors.JKVisitorVoid
+
+
+class ImportStatementConversion : RecursiveApplicableConversionBase() {
+    override fun applyToElement(element: JKTreeElement): JKTreeElement {
+        if (element !is JKFile) return recurse(element)
+
+        for (import in element.declarationList.collectImports()) {
+            if (!element.importList.containsImport(import)) {
+                element.importList += JKImportStatementImpl(JKNameIdentifierImpl(import))
+            }
+        }
+        return recurse(element)
+    }
+
+    private fun List<JKImportStatement>.containsImport(import: String) =
+        asSequence()
+            .map { it.name.value }
+            .any {
+                it == import ||
+                        it.endsWith("*") && import.substringBeforeLast(".") == it.substringBeforeLast(".*")
+            }
+
+    private fun List<JKDeclaration>.collectImports(): List<String> {
+        val collectImportsVisitor = CollectImportsVisitor()
+        forEach {
+            it.accept(collectImportsVisitor)
+        }
+        return collectImportsVisitor.collectedFqNames
+    }
+
+
+    private class CollectImportsVisitor : JKVisitorVoid {
+        private val unfilteredCollectedFqNames = mutableSetOf<String>()
+
+        private val defaultImports =
+            listOf(
+                "kotlin",
+                "kotlin.annotation",
+                "kotlin.collections",
+                "kotlin.comparisons",
+                "kotlin.io",
+                "kotlin.ranges",
+                "kotlin.sequences",
+                "kotlin.text",
+                "java.lang",
+                "kotlin.jvm"
+            )
+
+        val collectedFqNames
+            get() = unfilteredCollectedFqNames.filter {
+                it.substringBeforeLast(".") !in defaultImports && it.contains(".")
+            }
+
+        override fun visitTreeElement(treeElement: JKTreeElement) {
+            treeElement.acceptChildren(this)
+        }
+
+        override fun visitJavaNewExpression(javaNewExpression: JKJavaNewExpression) {
+            unfilteredCollectedFqNames += javaNewExpression.classSymbol.fqName!!
+            javaNewExpression.acceptChildren(this)
+        }
+
+        override fun visitTypeElement(typeElement: JKTypeElement, data: Nothing?) {
+            val classType = typeElement.type as? JKClassType ?: return
+            unfilteredCollectedFqNames += classType.classReference.fqName!!
+        }
+
+        override fun visitClassLiteralExpression(classLiteralExpression: JKClassLiteralExpression) {
+            val type = classLiteralExpression.classType.type
+            if (type is JKClassType) {
+                unfilteredCollectedFqNames += type.classReference.fqName!!
+            }
+            classLiteralExpression.acceptChildren(this)
+        }
+    }
+}