ICU-3383 add utility to 'autoquote' unquoted apostrophes in message format

X-SVN-Rev: 17829

icu4c/source/i18n/unicode/msgfmt.h

@@ -179,6 +179,21 @@ class DateFormat;
  * If a pattern is used, then unquoted braces in the pattern, if any,
  * must match: that is, "ab {0} de" and "ab '}' de" are ok, but "ab
  * {0'}' de" and "ab } de" are not.
+ * <p>
+ * <dl><dt><b>Warning:</b><dd>The rules for using quotes within message
+ * format patterns unfortunately have shown to be somewhat confusing.
+ * In particular, it isn't always obvious to localizers whether single
+ * quotes need to be doubled or not. Make sure to inform localizers about
+ * the rules, and tell them (for example, by using comments in resource
+ * bundle source files) which strings will be processed by MessageFormat.
+ * Note that localizers may need to use single quotes in translated
+ * strings where the original version doesn't have them.
+ * <br>Note also that the simplest way to avoid the problem is to
+ * use the real apostrophe (single quote) character \u2019 (') for
+ * human-readable text, and to use the ASCII apostrophe (\u0027 ' )
+ * only in program syntax, like quoting in MessageFormat.
+ * See the annotations for U+0027 Apostrophe in The Unicode Standard.</p>
+ * </dl>
  * <P>
  * The argumentIndex is a non-negative integer, which corresponds to the
  * index of the arguments presented in an array to be formatted.  The

icu4c/source/test/intltest/tmsgfmt.cpp

@@ -1225,6 +1225,9 @@ void TestMessageFormat::testAutoQuoteApostrophe(void) {
         "{'", "{'",
         "{'a", "{'a",
         "{'a{}'a}'a", "{'a{}'a}''a",
+        "'}'", "'}'",
+        "'} '{'}'", "'} '{'}''",
+        "'} {{{''", "'} {{{'''",
     };
     int32_t pattern_count = sizeof(patterns)/sizeof(patterns[0]);