Make NumberFormat use the ICU currency data, fix bug in NumberFormat

src/i18n.cc

Index: src/i18n.cc
diff --git a/src/i18n.cc b/src/i18n.cc
index 1d735c97f1f04876c1adc250be22e214c55ead54..c10890e89e5937928930963a8c27367f937c177d 100644
--- a/src/i18n.cc
+++ b/src/i18n.cc
@@ -258,7 +258,24 @@ icu::DecimalFormat* CreateICUNumberFormat(
 #endif
 
       number_format = static_cast<icu::DecimalFormat*>(
-          icu::NumberFormat::createInstance(icu_locale, format_style,  status));
+          icu::NumberFormat::createInstance(icu_locale, format_style, status));
+
+      if (U_FAILURE(status)) {
+        delete number_format;
+        return NULL;
+      }
+

[mnita, 2015/07/17 15:48:53]

Two main worries:

1. Looks like the code uses the ICU defaults no matter if the javascript code
specified min/max fraction digits or not.

2. It is not OK to use the currency defaults for all number formatting types.

  2.1 There are currencies that use zero fraction digits by default, because the
currency does not have sub-units.
Example for ja_JP:
   currency: ￥54,306
   number: 54,306.405
   percent: 64%
   scientific: 5.4306404797E4

  2.2 The currency precision is not only locale-dependent, but also currency
dependent. For instance all locales will format the Japanese Yen with not
fractional part. So ucurr_getDefaultFractionDigits, which does not look at the
currency code, will not do the right thing.

Why not just use what ICU returns, "as is", unless caller of the Javascript API
specified the min / max fraction digits?

+      UErrorCode status_digits = U_ZERO_ERROR;
+      uint32_t fraction_digits = ucurr_getDefaultFractionDigits(
+        currency.getTerminatedBuffer(), &status_digits);
+      if (U_SUCCESS(status_digits)) {
+        number_format->setMinimumFractionDigits(fraction_digits);
+        number_format->setMaximumFractionDigits(fraction_digits);
+      } else {
+        // Set min & max to default values (previously in i18n.js)
+        number_format->setMinimumFractionDigits(0);
+        number_format->setMaximumFractionDigits(3);
+      }
     } else if (style == UNICODE_STRING_SIMPLE("percent")) {
       number_format = static_cast<icu::DecimalFormat*>(
           icu::NumberFormat::createPercentInstance(icu_locale, status));