Don't call redundant toString for variables of type Int

Refactor StringTemplateTranslator a little

js/js.tests/test/org/jetbrains/k2js/test/semantics/StringTest.java

@@ -71,6 +71,10 @@ public final class StringTest extends AbstractExpressionTest {
         fooBoxTest();
     }
 
+    public void testNumbersInTemplate() throws Exception {
+        fooBoxIsValue("2354");
+    }
+
     private void checkHasNoToStringCalls() throws IOException {
         for (EcmaVersion ecmaVersion : DEFAULT_ECMA_VERSIONS) {
             String filePath = getOutputFilePath(getTestName(true) + ".kt", ecmaVersion);

js/js.translator/src/org/jetbrains/k2js/translate/expression/StringTemplateTranslator.java

@@ -27,15 +27,14 @@ import org.jetbrains.jet.lang.resolve.name.Name;
 import org.jetbrains.k2js.translate.context.TranslationContext;
 import org.jetbrains.k2js.translate.general.AbstractTranslator;
 import org.jetbrains.k2js.translate.general.Translation;
-import org.jetbrains.k2js.translate.utils.JsDescriptorUtils;
 
 import static org.jetbrains.k2js.translate.utils.JsAstUtils.sum;
+import static org.jetbrains.k2js.translate.utils.JsDescriptorUtils.getNameIfStandardType;
 
 
 /**
  * @author Pavel Talanov
  */
-//TODO: add toString call for non-primitive object
 public final class StringTemplateTranslator extends AbstractTranslator {
 
     @NotNull
@@ -85,18 +84,30 @@ public final class StringTemplateTranslator extends AbstractTranslator {
             JsExpression translatedExpression = Translation.translateAsExpression(entryExpression, context());
             if (translatedExpression instanceof JsNumberLiteral) {
                 append(context().program().getStringLiteral(translatedExpression.toString()));
+                return;
             }
-            else {
-                Name typeName = JsDescriptorUtils.getNameIfStandardType(entryExpression, context());
-                if (typeName != null && typeName.getName().equals("String")) {
-                    append(translatedExpression);
-                    return;
-                }
-
+            if (mustCallToString(entryExpression)) {
                 append(new JsInvocation(new JsNameRef("toString", translatedExpression)));
+            } else {
+                append(translatedExpression);
             }
         }
 
+        private boolean mustCallToString(@NotNull JetExpression entryExpression) {
+            Name typeName = getNameIfStandardType(entryExpression, context());
+            if (typeName == null) {
+                return true;
+            }
+            //TODO: this is a hacky optimization, should use some generic approach
+            if (typeName.getName().equals("String")) {
+                return false;
+            }
+            if (typeName.getName().equals("Int") && resultingExpression != null) {
+                return false;
+            }
+            return true;
+        }
+
         @Override
         public void visitLiteralStringTemplateEntry(@NotNull JetLiteralStringTemplateEntry entry) {
             appendText(entry.getText());

js/js.translator/testFiles/expression/string/cases/numbersInTemplate.kt

@@ -0,0 +1,9 @@
+package foo
+
+fun box() : String {
+    val number = 3
+    val s1 = "${number-1}${number}"
+    val s2 = "${5}${4}"
+    return "${s1}${s2}"
+}
+