Implement Double.{toString, toStringAsExponential, toStringAsPrecision}

runtime/lib/double.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <math.h>
 
 #include "vm/bootstrap_natives.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/double_conversion.h"
@@ skipping 185 matching lines @@
     GrowableArray<const Object*> args;
     args.Add(&String::ZoneHandle(String::New(
         "Illegal arguments to double.toStringAsFixed")));
     Exceptions::ThrowByType(Exceptions::kIllegalArgument, args);
   }
   arguments->SetReturn(result);
 }
 
 
 DEFINE_NATIVE_ENTRY(Double_toStringAsExponential, 2) {
-  UNIMPLEMENTED();
+  const Double& arg = Double::CheckedHandle(arguments->At(0));
+  GET_NATIVE_ARGUMENT(Smi, fraction_digits, arguments->At(1));
+  double d = arg.value();
+  int fraction_digits_value = fraction_digits.Value();
+  String& result = String::Handle();
+  bool succeeded =
+      DoubleToStringAsExponential(d, fraction_digits_value, result);
+  if (!succeeded) {
+    GrowableArray<const Object*> args;
+    args.Add(&String::ZoneHandle(String::New(
+        "Illegal arguments to double.toStringAsExponential")));
+    Exceptions::ThrowByType(Exceptions::kIllegalArgument, args);
+  }
+  arguments->SetReturn(result);
 }
 
 
 DEFINE_NATIVE_ENTRY(Double_toStringAsPrecision, 2) {
-  UNIMPLEMENTED();
+  const Double& arg = Double::CheckedHandle(arguments->At(0));
+  GET_NATIVE_ARGUMENT(Smi, precision, arguments->At(1));
+  double d = arg.value();
+  int precision_value = precision.Value();
+  String& result = String::Handle();
+  bool succeeded = DoubleToStringAsPrecision(d, precision_value, result);
+  if (!succeeded) {
+    GrowableArray<const Object*> args;
+    args.Add(&String::ZoneHandle(String::New(
+        "Illegal arguments to double.toStringAsPrecision")));
+    Exceptions::ThrowByType(Exceptions::kIllegalArgument, args);
+  }
+  arguments->SetReturn(result);
 }
 
 
 DEFINE_NATIVE_ENTRY(Double_isInfinite, 1) {
   const Double& arg = Double::CheckedHandle(arguments->At(0));
   if (isinf(arg.value())) {
     arguments->SetReturn(Bool::Handle(Bool::True()));
   } else {
     arguments->SetReturn(Bool::Handle(Bool::False()));
   }
@@ skipping 17 matching lines @@
     arguments->SetReturn(Bool::Handle(Bool::True()));
   } else {
     arguments->SetReturn(Bool::Handle(Bool::False()));
   }
 }
 
 // Add here only functions using/referring to old-style casts.
 
 }  // namespace dart