JS/RTTI: support safe casts

js/js.dart-ast/src/com/google/dart/compiler/backend/js/ast/metadata/metadataProperties.kt

@@ -36,7 +36,7 @@ var JsFunction.isLocal: Boolean by MetadataProperty(default = false)
 
 var JsParameter.hasDefaultValue: Boolean by MetadataProperty(default = false)
 
-var JsConditional.isUnsafeCast: Boolean by MetadataProperty(default = false)
+var JsConditional.isCastExpression: Boolean by MetadataProperty(default = false)
 
 var JsInvocation.typeCheck: TypeCheck? by MetadataProperty(default = null)
 

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/CastTestGenerated.java

@@ -65,6 +65,30 @@ public class CastTestGenerated extends AbstractCastTest {
         doTest(fileName);
     }
 
+    @TestMetadata("safeCastToNotNull.kt")
+    public void testSafeCastToNotNull() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/expression/cast/cases/safeCastToNotNull.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("safeCastToNullable.kt")
+    public void testSafeCastToNullable() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/expression/cast/cases/safeCastToNullable.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("safeCastToReifiedNotNull.kt")
+    public void testSafeCastToReifiedNotNull() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/expression/cast/cases/safeCastToReifiedNotNull.kt");
+        doTest(fileName);
+    }
+
+    @TestMetadata("safeCastToReifiedNullable.kt")
+    public void testSafeCastToReifiedNullable() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/expression/cast/cases/safeCastToReifiedNullable.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("smartCastInExtensionFunction.kt")
     public void testSmartCastInExtensionFunction() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("js/js.translator/testData/expression/cast/cases/smartCastInExtensionFunction.kt");

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/ExpressionVisitor.java

@@ -396,8 +396,8 @@ public final class ExpressionVisitor extends TranslatorVisitor<JsNode> {
     ) {
         JsExpression jsExpression;
 
-        if (PatternTranslator.isUnsafeCast(expression)) {
+        if (PatternTranslator.isCastExpression(expression)) {
-            jsExpression = PatternTranslator.newInstance(context).translateUnsafeCast(expression);
+            jsExpression = PatternTranslator.newInstance(context).translateCastExpression(expression);
         }
         else {
             jsExpression = Translation.translateAsExpression(expression.getLeft(), context);

js/js.translator/src/org/jetbrains/kotlin/js/translate/expression/PatternTranslator.java

@@ -21,6 +21,8 @@ import com.google.dart.compiler.backend.js.ast.JsExpression;
 import com.google.dart.compiler.backend.js.ast.JsInvocation;
 import com.google.dart.compiler.backend.js.ast.JsNameRef;
 import com.google.dart.compiler.backend.js.ast.metadata.MetadataProperties;
+import com.google.dart.compiler.backend.js.ast.*;
+import com.google.dart.compiler.backend.js.ast.metadata.MetadataPackage;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.descriptors.*;
@@ -55,26 +57,32 @@ public final class PatternTranslator extends AbstractTranslator {
         super(context);
     }
 
-    public static boolean isUnsafeCast(@NotNull KtBinaryExpressionWithTypeRHS expression) {
+    public static boolean isCastExpression(@NotNull KtBinaryExpressionWithTypeRHS expression) {
-        return expression.getOperationReference().getReferencedNameElementType() == KtTokens.AS_KEYWORD;
+        return isSafeCast(expression) || isUnsafeCast(expression);
     }
 
     @NotNull
-    public JsExpression translateUnsafeCast(@NotNull KtBinaryExpressionWithTypeRHS expression) {
+    public JsExpression translateCastExpression(@NotNull JetBinaryExpressionWithTypeRHS expression) {
-        assert isUnsafeCast(expression): "Expected unsafe cast expression, got " + expression;
+        assert isCastExpression(expression): "Expected cast expression, got " + expression;
-        KtExpression left = expression.getLeft();
+        JetExpression left = expression.getLeft();
         JsExpression expressionToCast = Translation.translateAsExpression(left, context());
         TemporaryVariable temporary = context().declareTemporary(expressionToCast);
 
-        KtTypeReference typeReference = expression.getRight();
+        JetTypeReference typeReference = expression.getRight();
-        assert typeReference != null: "Unsafe cast must have type reference";
+        assert typeReference != null: "Cast expression must have type reference";
         JsExpression isCheck = translateIsCheck(temporary.assignmentExpression(), typeReference);
+        JsExpression onFail;
 
-        Namer namer = context().namer();
+        if (isSafeCast(expression)) {
-        JsExpression throwCCEFunRef = namer.throwClassCastExceptionFunRef();
+            onFail = JsLiteral.NULL;
-        JsExpression throwCCE = new JsInvocation(throwCCEFunRef);
+        }
-        JsConditional conditional = new JsConditional(isCheck, temporary.reference(), throwCCE);
+        else {
-        MetadataProperties.setUnsafeCast(conditional, true);
+            JsExpression throwCCEFunRef = context().namer().throwClassCastExceptionFunRef();
+            onFail = new JsInvocation(throwCCEFunRef);
+        }
+
+        JsConditional conditional = new JsConditional(isCheck, temporary.reference(), onFail);
+        MetadataPackage.setIsCastExpression(conditional, true);
         return conditional;
     }
 
@@ -185,4 +193,12 @@ public final class PatternTranslator extends AbstractTranslator {
     public JsExpression translateExpressionForExpressionPattern(@NotNull KtExpression patternExpression) {
         return Translation.translateAsExpression(patternExpression, context());
     }
+
+    private static boolean isSafeCast(@NotNull JetBinaryExpressionWithTypeRHS expression) {
+        return expression.getOperationReference().getReferencedNameElementType() == JetTokens.AS_SAFE;
+    }
+
+    private static boolean isUnsafeCast(@NotNull JetBinaryExpressionWithTypeRHS expression) {
+        return expression.getOperationReference().getReferencedNameElementType() == JetTokens.AS_KEYWORD;
+    }
 }

js/js.translator/src/org/jetbrains/kotlin/js/translate/utils/expandIsCalls.kt

@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.js.translate.utils
 
 import com.google.dart.compiler.backend.js.ast.*
 import com.google.dart.compiler.backend.js.ast.metadata.TypeCheck
-import com.google.dart.compiler.backend.js.ast.metadata.isUnsafeCast
+import com.google.dart.compiler.backend.js.ast.metadata.isCastExpression
 import com.google.dart.compiler.backend.js.ast.metadata.typeCheck
 import org.jetbrains.kotlin.js.inline.util.IdentitySet
 import org.jetbrains.kotlin.js.translate.context.TranslationContext
@@ -54,7 +54,7 @@ private class TypeCheckRewritingVisitor(private val context: TranslationContext)
     override fun endVisit(x: JsConditional, ctx: JsContext<JsNode>) {
         val test = x.testExpression
 
-        if (x.isUnsafeCast &&
+        if (x.isCastExpression &&
             test is JsBinaryOperation &&
             test.operator == JsBinaryOperator.ASG
         ) {

js/js.translator/testData/expression/cast/cases/safeCastToNotNull.kt

@@ -0,0 +1,16 @@
+package foo
+
+class A
+class B
+
+fun box(): String {
+    val a: Any? = A()
+    val nil: Any? = null
+    val b: Any? = B()
+
+    assertEquals(a, a as? A, "a")
+    assertEquals(null, nil as? A, "nil")
+    assertEquals(null, b as? A, "b")
+
+    return "OK"
+}

js/js.translator/testData/expression/cast/cases/safeCastToNullable.kt

@@ -0,0 +1,16 @@
+package foo
+
+class A
+class B
+
+fun box(): String {
+    val a: Any? = A()
+    val nil: Any? = null
+    val b: Any? = B()
+
+    assertEquals(a, a as? A?, "a")
+    assertEquals(null, nil as? A?, "nil")
+    assertEquals(null, b as? A?, "b")
+
+    return "OK"
+}

js/js.translator/testData/expression/cast/cases/safeCastToReifiedNotNull.kt

@@ -0,0 +1,21 @@
+package foo
+
+// CHECK_NOT_CALLED: castTo
+
+class A
+class B
+
+inline
+fun Any?.castTo<reified T>(): T? = this as? T
+
+fun box(): String {
+    val a: Any? = A()
+    val nil: Any? = null
+    val b: Any? = B()
+
+    assertEquals(a, a.castTo<A>(), "a")
+    assertEquals(null, nil.castTo<A>(), "nil")
+    assertEquals(null, b.castTo<A>(), "b")
+
+    return "OK"
+}

js/js.translator/testData/expression/cast/cases/safeCastToReifiedNullable.kt

@@ -0,0 +1,21 @@
+package foo
+
+// CHECK_NOT_CALLED: castTo
+
+class A
+class B
+
+inline
+fun Any?.castTo<reified T>(): T? = this as? T?
+
+fun box(): String {
+    val a: Any? = A()
+    val nil: Any? = null
+    val b: Any? = B()
+
+    assertEquals(a, a.castTo<A>(), "a")
+    assertEquals(null, nil.castTo<A>(), "nil")
+    assertEquals(null, b.castTo<A>(), "b")
+
+    return "OK"
+}