LANG-1680 Add support for standalone month formats (#892)

3 files changed, 49 insertions, 0 deletions

diff --git a/src/main/java/org/apache/commons/lang3/time/DateUtils.java b/src/main/java/org/apache/commons/lang3/time/DateUtils.java
index 33c61dcad..493136e51 100644
--- a/src/main/java/org/apache/commons/lang3/time/DateUtils.java
+++ b/src/main/java/org/apache/commons/lang3/time/DateUtils.java
@@ -22,6 +22,7 @@ import java.util.Calendar;
 import java.util.Date;
 import java.util.Iterator;
 import java.util.Locale;
+import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.TimeZone;
 import java.util.concurrent.TimeUnit;
@@ -1831,4 +1832,40 @@ public class DateUtils {
         }
     }
 
+    /**
+     * Gets full standalone month names as used in "LLLL" date formatting.
+     * @param locale Locale
+     * @return Long names of months
+     */
+    static String[] getStandaloneLongMonths(final Locale locale) {
+        return getMonthNames(locale, Calendar.LONG_STANDALONE);
+    }
+
+    /**
+     * Gets short standalone month names as used in "LLLL" date formatting.
+     * @param locale Locale
+     * @return Short names of months
+     */
+    static String[] getStandaloneShortMonths(final Locale locale) {
+        return getMonthNames(locale, Calendar.SHORT_STANDALONE);
+    }
+
+    /**
+     * Gets month names in the requested style.
+     * @param locale Locale
+     * @param style Must be a valid {@link Calendar#getDisplayNames(int, int, Locale)} month style.
+     * @return Styled names of months
+     */
+    private static String[] getMonthNames(final Locale locale, final int style) {
+        // Unfortunately standalone month names are not available in DateFormatSymbols,
+        // so we have to extract them.
+        final Calendar calendar = Calendar.getInstance(locale);
+        Map<String, Integer> displayNames = calendar.getDisplayNames(Calendar.MONTH, style, locale);
+        final String[] monthNames = new String[displayNames.size()];
+        for (Map.Entry<String, Integer> entry: displayNames.entrySet()) {
+          monthNames[entry.getValue()] = entry.getKey();
+        }
+        return monthNames;
+    }
+
 }
diff --git a/src/main/java/org/apache/commons/lang3/time/FastDateParser.java b/src/main/java/org/apache/commons/lang3/time/FastDateParser.java
index 19b882456..98b48d261 100644
--- a/src/main/java/org/apache/commons/lang3/time/FastDateParser.java
+++ b/src/main/java/org/apache/commons/lang3/time/FastDateParser.java
@@ -606,6 +606,7 @@ public class FastDateParser implements DateParser, Serializable {
         case 'K': // Hour in am/pm (0-11)
             return HOUR_STRATEGY;
         case 'M':
+        case 'L':
             return width >= 3 ? getLocaleSpecificStrategy(Calendar.MONTH, definingCalendar) : NUMBER_MONTH_STRATEGY;
         case 'S':
             return MILLISECOND_STRATEGY;
diff --git a/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java b/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java
index 00651587d..df5f1b72d 100644
--- a/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java
+++ b/src/main/java/org/apache/commons/lang3/time/FastDatePrinter.java
@@ -233,6 +233,17 @@ public class FastDatePrinter implements DatePrinter, Serializable {
                     rule = UnpaddedMonthField.INSTANCE;
                 }
                 break;
+            case 'L': // month in year (text and number)
+                if (tokenLen >= 4) {
+                    rule = new TextField(Calendar.MONTH, DateUtils.getStandaloneLongMonths(mLocale));
+                } else if (tokenLen == 3) {
+                    rule = new TextField(Calendar.MONTH, DateUtils.getStandaloneShortMonths(mLocale));
+                } else if (tokenLen == 2) {
+                    rule = TwoDigitMonthField.INSTANCE;
+                } else {
+                    rule = UnpaddedMonthField.INSTANCE;
+                }
+                break;
             case 'd': // day in month (number)
                 rule = selectNumberRule(Calendar.DAY_OF_MONTH, tokenLen);
                 break;