Implement Double.{toString, toStringAsExponential, toStringAsPrecision}

runtime/vm/object.cc

 // Copyright (c) 2012, 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 "vm/object.h"
 
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/bootstrap.h"
 #include "vm/code_generator.h"
 #include "vm/code_index_table.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/compiler_stats.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_entry.h"
 #include "vm/debuginfo.h"
+#include "vm/double_conversion.h"
 #include "vm/exceptions.h"
 #include "vm/growable_array.h"
 #include "vm/heap.h"
 #include "vm/ic_data.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/runtime_entry.h"
 #include "vm/scopes.h"
 #include "vm/timer.h"
 #include "vm/unicode.h"
@@ skipping 5930 matching lines @@
 }
 
 
 const char* Double::ToCString() const {
   if (isnan(value())) {
     return "NaN";
   }
   if (isinf(value())) {
     return value() < 0 ? "-Infinity" : "Infinity";
   }
-  const char* kFormat = "%f";
-  // Calculate the size of the string.
-  intptr_t len = OS::SNPrint(NULL, 0, kFormat, value()) + 1;
+  const int kBufferSize = 128;
+  char buffer[kBufferSize];
+  int len;
+  bool status = DoubleToCString(value(), buffer, kBufferSize, &len);
+  ASSERT(status);
+
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len));
-  OS::SNPrint(chars, len, kFormat, value());
-  // Eliminate trailing 0s, but leave one digit after '.'.
-  // 'chars' is null terminated.
-  for (intptr_t i = len - 2; i >= 1; i--) {
-    if ((chars[i] == '0') && (chars[i - 1] != '.')) {
-      chars[i] = '\0';
-    } else {
-      break;
-    }
-  }
+  memmove(chars, buffer, len);
   return chars;
 }
 
 
 bool Bigint::Equals(const Instance& other) const {
   if (this->raw() == other.raw()) {
     // Both handles point to the same raw instance.
     return true;
   }
 
@@ skipping 1787 matching lines @@
   const String& str = String::Handle(pattern());
   const char* format = "JSRegExp: pattern=%s flags=%s";
   intptr_t len = OS::SNPrint(NULL, 0, format, str.ToCString(), Flags());
   char* chars = reinterpret_cast<char*>(
       Isolate::Current()->current_zone()->Allocate(len + 1));
   OS::SNPrint(chars, (len + 1), format, str.ToCString(), Flags());
   return chars;
 }
 
 }  // namespace dart