Add Shell::PrintErr and expose it in the d8 shell as printErr

This function is implemented in other JavaScript shells

BUG=None

R=titzer

Review-Url: https://codereview.chromium.org/2458963003
Cr-Commit-Position: refs/heads/master@{#40677}

src/d8.cc

@@ -934,19 +934,11 @@ void Shell::RealmSharedSet(Local<String> property,
   data->realm_shared_.Reset(isolate, value);
 }
 
-
-void Shell::Print(const v8::FunctionCallbackInfo<v8::Value>& args) {
-  Write(args);
-  printf("\n");
-  fflush(stdout);
-}
-
-
-void Shell::Write(const v8::FunctionCallbackInfo<v8::Value>& args) {
+void WriteToFile(FILE* file, const v8::FunctionCallbackInfo<v8::Value>& args) {
   for (int i = 0; i < args.Length(); i++) {
     HandleScope handle_scope(args.GetIsolate());
     if (i != 0) {
-      printf(" ");
+      fprintf(file, " ");
     }
 
     // Explicitly catch potential exceptions in toString().
@@ -964,14 +956,32 @@ void Shell::Write(const v8::FunctionCallbackInfo<v8::Value>& args) {
     }
 
     v8::String::Utf8Value str(str_obj);
-    int n = static_cast<int>(fwrite(*str, sizeof(**str), str.length(), stdout));
+    int n = static_cast<int>(fwrite(*str, sizeof(**str), str.length(), file));
     if (n != str.length()) {
       printf("Error in fwrite\n");
-      Exit(1);
+      Shell::Exit(1);
     }
   }
 }
 
+void WriteAndFlush(FILE* file,
+                   const v8::FunctionCallbackInfo<v8::Value>& args) {
+  WriteToFile(file, args);
+  fprintf(file, "\n");
+  fflush(file);
+}
+
+void Shell::Print(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  WriteAndFlush(stdout, args);
+}
+
+void Shell::PrintErr(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  WriteAndFlush(stderr, args);
+}
+
+void Shell::Write(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  WriteToFile(stdout, args);
+}
 
 void Shell::Read(const v8::FunctionCallbackInfo<v8::Value>& args) {
   String::Utf8Value file(args[0]);
@@ -1387,6 +1397,10 @@ Local<ObjectTemplate> Shell::CreateGlobalTemplate(Isolate* isolate) {
       String::NewFromUtf8(isolate, "print", NewStringType::kNormal)
           .ToLocalChecked(),
       FunctionTemplate::New(isolate, Print));
+  global_template->Set(
+      String::NewFromUtf8(isolate, "printErr", NewStringType::kNormal)
+          .ToLocalChecked(),
+      FunctionTemplate::New(isolate, PrintErr));
   global_template->Set(
       String::NewFromUtf8(isolate, "write", NewStringType::kNormal)
           .ToLocalChecked(),

src/d8.h

@@ -372,6 +372,7 @@ class Shell : public i::AllStatic {
                              const  PropertyCallbackInfo<void>& info);
 
   static void Print(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void PrintErr(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void Write(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void QuitOnce(v8::FunctionCallbackInfo<v8::Value>* args);
   static void Quit(const v8::FunctionCallbackInfo<v8::Value>& args);

test/mjsunit/print.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+assertEquals("function", typeof print, "print should be defined");
+assertEquals("function", typeof printErr, "printErr should be defined");