ICU msg format support with more than one arguments

base/i18n/message_formatter.h

+// 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.
+
+#ifndef BASE_I18N_MESSAGE_FORMATTER_H_
+#define BASE_I18N_MESSAGE_FORMATTER_H_
+
+#include <string>
+
+#include "base/i18n/base_i18n_export.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);
+
+  ~MessageArg();
+
+ private:
+  friend class base::i18n::MessageFormatter;
+  MessageArg() : f(NULL) {}  // for "no argument"

[Avi (use Gerrit), 2015/07/30 19:19:48]

nullptr

[jungshik at Google, 2015/07/31 21:36:15]

Done. Had to move to cc when I also switched to using scoped_ptr because clang
chrome style checker does not want a 'complex ctor' inlined. 

It's also renamed 'formattable'. 

+  bool def(int *count) const;

[Ryan Sleevi, 2015/07/30 23:21:51]

Seems like this should be documented, and perhaps renamed?

[jungshik at Google, 2015/07/31 21:36:15]

Changed it to has_value(). 

+  icu::Formattable *f;

[Avi (use Gerrit), 2015/07/30 19:19:48]

Previous two lines, * goes on the type, not the variable.

[jungshik at Google, 2015/07/31 21:36:15]

Done.

+  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(),

[Ryan Sleevi, 2015/07/30 23:21:51]

I'm somewhat surprised this compiles. I thought the friend decl would allow
MessageFormatter to create internal::MessageArg(), but the default arguments are
expanded at the call site in the context of the caller, and they
wouldn't/shouldn't be allowed to call this method, right?

[jungshik at Google, 2015/07/31 21:36:15]

I guess it's compiled because I have 'friend class MessageFormatter' instead of
'friend <stand-alone function>'. I tried to use standalone functions instead,
but never succeeded always getting complaints about a private member function
not accessible.  

+      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