ICU msg format support with more than one arguments

base/i18n/message_formatter.h

Index: base/i18n/message_formatter.h
diff --git a/base/i18n/message_formatter.h b/base/i18n/message_formatter.h
new file mode 100644
index 0000000000000000000000000000000000000000..1044950c777b67253c33a786290eb78531affc1c
--- /dev/null
+++ b/base/i18n/message_formatter.h
@@ -0,0 +1,103 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+// Copied from i18n/localization/formatter.h with modifications.

[Ryan Sleevi, 2015/07/31 22:19:36]

Seems like there should at least be a newline between this and the copyright
declaration.

Is this path referencing an internal Google path? Do you need to confirm with
OSPO the acceptability of open-sourcing this? If so, and once done, it seems
like this comment should be deleted - there's plenty in //base that has history
in Google internal code but since stands alone.

[jungshik at Google, 2015/08/01 14:00:58]

Before making the CL, I talked to OSPO and the two authors of this class/api. I
also asked Brett what he did with string_piece. The authors greenlighted using
this. 

The line referring to the internal src file was patterned after the lines in
string_piece.{h,cc}, but I deleted per your suggestion. 

+
+#ifndef BASE_I18N_MESSAGE_FORMATTER_H_
+#define BASE_I18N_MESSAGE_FORMATTER_H_
+
+#include <string>
+
+#include "base/i18n/base_i18n_export.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string16.h"
+#include "base/strings/string_piece.h"
+#include "base/time/time.h"
+#include "third_party/icu/source/i18n/unicode/msgfmt.h"
+
+namespace base {
+namespace i18n {
+
+class MessageFormatter;
+
+namespace internal {
+
+class BASE_I18N_EXPORT MessageArg {
+ public:
+  MessageArg(const char* s);
+  MessageArg(StringPiece s);
+  MessageArg(const std::string& s);
+  MessageArg(const string16& s);
+  MessageArg(int i);
+  MessageArg(double d);
+  MessageArg(const Time& t);

[Ryan Sleevi, 2015/07/31 22:19:36]

You could forward declare base::Time and avoid the include.

[jungshik at Google, 2015/08/01 14:00:58]

Done.

+
+  ~MessageArg();
+
+ private:
+  friend class base::i18n::MessageFormatter;
+  MessageArg();

[Ryan Sleevi, 2015/07/31 22:19:36]

style nits: newline between 38 and 39, newline between 40 and 41, document 40?

[jungshik at Google, 2015/08/01 14:00:58]

Done.

+  bool has_value(int* count) const;
+  scoped_ptr<icu::Formattable> formattable;

[Ryan Sleevi, 2015/07/31 22:19:36]

You could forward declare this, but I'm guessing that's not idiomatic ICU usage?

[jungshik at Google, 2015/08/01 14:00:58]

Thanks for the suggestion. 
Nothing in ICU against that. The only thing is that I can't do

namespace icu {
class Formattable;
}

Instead, I need to do the following (which I did in an updated CL). I may look
for other headers in the cr tree (and perhaps ICU itself)  to see if others can
benefit from that (not in this CL). 

#Include "third_party/icu/source/common/unicode/uversion.h"  // to get renamed
icu namespace

U_NAMESPACE_BEGIN
class Formattable;
U_NAMESPACE_END

[Ryan Sleevi, 2015/08/03 08:01:41]

I guess the forward declaration doesn't really buy you much, since you have to
include uversion.h to get the U_NAMESPACE_BEGIN

Mostly, I mentioned it to see if there was a way to avoid including ICU headers
in these headers, which would let you avoid the build system issues. Since it
doesn't seem there is, it's not terribly beneficial for forward declarations, so
I wouldn't worry about it too much for existing code, and it may just make sense
to include formatter here. whatever you think is appropriate.

+  DISALLOW_COPY_AND_ASSIGN(MessageArg);
+};
+
+}  // namespace internal
+
+// Message Formatter with the ICU message format syntax support.
+// It can format strings (UTF-8 and UTF-16), numbers and base::Time with
+// plural, gender and other 'selectors' support. This is handy if you
+// have multiple parameters of differnt types and some of them require
+// plural or gender/selector support.
+//
+// To use this API for locale-sensitive formatting, retrieve a 'message
+// template' in the ICU message format from a message bundle (e.g. with
+// l10n_util::GetStringUTF16()) and pass it to FormatWith{Named,Numbered}Args.
+//
+// MessageFormat specs:
+//   http://icu-project.org/apiref/icu4j/com/ibm/icu/text/MessageFormat.html
+//   http://icu-project.org/apiref/icu4c/classicu_1_1DecimalFormat.html#details
+// Examples:
+//   http://userguide.icu-project.org/formatparse/messages
+//   message_formatter_unittest.cc
+//   go/plurals inside Google.
+//   TODO(jshin): Document this API at sites.chromium.org and add a reference
+//   here.
+
+class BASE_I18N_EXPORT MessageFormatter {
+ public:
+  static string16 FormatWithNamedArgs(
+      StringPiece16 msg,
+      StringPiece name0 = StringPiece(),
+      const internal::MessageArg& arg0 = internal::MessageArg(),
+      StringPiece name1 = StringPiece(),
+      const internal::MessageArg& arg1 = internal::MessageArg(),
+      StringPiece name2 = StringPiece(),
+      const internal::MessageArg& arg2 = internal::MessageArg(),
+      StringPiece name3 = StringPiece(),
+      const internal::MessageArg& arg3 = internal::MessageArg(),
+      StringPiece name4 = StringPiece(),
+      const internal::MessageArg& arg4 = internal::MessageArg(),
+      StringPiece name5 = StringPiece(),
+      const internal::MessageArg& arg5 = internal::MessageArg(),
+      StringPiece name6 = StringPiece(),
+      const internal::MessageArg& arg6 = internal::MessageArg());
+
+  static string16 FormatWithNumberedArgs(
+      StringPiece16 msg,
+      const internal::MessageArg& arg0 = internal::MessageArg(),
+      const internal::MessageArg& arg1 = internal::MessageArg(),
+      const internal::MessageArg& arg2 = internal::MessageArg(),
+      const internal::MessageArg& arg3 = internal::MessageArg(),
+      const internal::MessageArg& arg4 = internal::MessageArg(),
+      const internal::MessageArg& arg5 = internal::MessageArg(),
+      const internal::MessageArg& arg6 = internal::MessageArg());
+
+ private:
+  MessageFormatter() {}
+  DISALLOW_COPY_AND_ASSIGN(MessageFormatter);
+};
+
+}  // namespace i18n
+}  // namespace base
+#endif