ICU-4732 Default century support in Persian calendar.

X-SVN-Rev: 24130

icu4c/source/i18n/persncal.cpp

@@ -12,10 +12,14 @@
  *   9/23/2003 mehran        posted to icu-design
  *****************************************************************************
  */
+
 #include "persncal.h"
 
 #if !UCONFIG_NO_FORMATTING
 
+#include "umutex.h"
+#include <float.h>
+
 static const int8_t monthDays[] = { 31, 31, 31, 31, 31, 31, 30, 30, 30, 30, 30, 29 };
 
 static int32_t
@@ -371,19 +375,89 @@ PersianCalendar::inDaylightTime(UErrorCode& status) const
     return (UBool)(U_SUCCESS(status) ? (internalGet(UCAL_DST_OFFSET) != 0) : FALSE);
 }
 
+// default century
+const UDate     PersianCalendar::fgSystemDefaultCentury        = DBL_MIN;
+const int32_t   PersianCalendar::fgSystemDefaultCenturyYear    = -1;
+
+UDate           PersianCalendar::fgSystemDefaultCenturyStart       = DBL_MIN;
+int32_t         PersianCalendar::fgSystemDefaultCenturyStartYear   = -1;
+
 UBool PersianCalendar::haveDefaultCentury() const
 {
-    return FALSE;
+    return TRUE;
 }
 
 UDate PersianCalendar::defaultCenturyStart() const
 {
-    return -1;
+    return internalGetDefaultCenturyStart();
 }
 
 int32_t PersianCalendar::defaultCenturyStartYear() const
 {
-    return -1;
+    return internalGetDefaultCenturyStartYear();
+}
+
+UDate
+PersianCalendar::internalGetDefaultCenturyStart() const
+{
+    // lazy-evaluate systemDefaultCenturyStart
+    UBool needsUpdate;
+    UMTX_CHECK(NULL, (fgSystemDefaultCenturyStart == fgSystemDefaultCentury), needsUpdate);
+
+    if (needsUpdate) {
+        initializeSystemDefaultCentury();
+    }
+
+    // use defaultCenturyStart unless it's the flag value;
+    // then use systemDefaultCenturyStart
+
+    return fgSystemDefaultCenturyStart;
+}
+
+int32_t
+PersianCalendar::internalGetDefaultCenturyStartYear() const
+{
+    // lazy-evaluate systemDefaultCenturyStartYear
+    UBool needsUpdate;
+    UMTX_CHECK(NULL, (fgSystemDefaultCenturyStart == fgSystemDefaultCentury), needsUpdate);
+
+    if (needsUpdate) {
+        initializeSystemDefaultCentury();
+    }
+
+    // use defaultCenturyStart unless it's the flag value;
+    // then use systemDefaultCenturyStartYear
+
+    return    fgSystemDefaultCenturyStartYear;
+}
+
+void
+PersianCalendar::initializeSystemDefaultCentury()
+{
+    // initialize systemDefaultCentury and systemDefaultCenturyYear based
+    // on the current time.  They'll be set to 80 years before
+    // the current time.
+    // No point in locking as it should be idempotent.
+    if (fgSystemDefaultCenturyStart == fgSystemDefaultCentury)
+    {
+        UErrorCode status = U_ZERO_ERROR;
+        PersianCalendar calendar(Locale("@calendar=persian"),status);
+        if (U_SUCCESS(status))
+        {
+            calendar.setTime(Calendar::getNow(), status);
+            calendar.add(UCAL_YEAR, -80, status);
+            UDate    newStart =  calendar.getTime(status);
+            int32_t  newYear  =  calendar.get(UCAL_YEAR, status);
+            {
+                umtx_lock(NULL);
+                fgSystemDefaultCenturyStart = newStart;
+                fgSystemDefaultCenturyStartYear = newYear;
+                umtx_unlock(NULL);
+            }
+        }
+        // We have no recourse upon failure unless we want to propagate the failure
+        // out.
+    }
 }
 
 UOBJECT_DEFINE_RTTI_IMPLEMENTATION(PersianCalendar)

icu4c/source/i18n/persncal.h

@@ -1,6 +1,6 @@
 /*
  ******************************************************************************
- * Copyright (C) 2003-2007, International Business Machines Corporation
+ * Copyright (C) 2003-2008, International Business Machines Corporation
  * and others. All Rights Reserved.
  ******************************************************************************
  *
@@ -279,7 +279,6 @@ class PersianCalendar : public Calendar {
  private:
   PersianCalendar(); // default constructor not implemented
 
-  // Default century.
  protected:
 
   /**
@@ -293,27 +292,67 @@ class PersianCalendar : public Calendar {
    */
   virtual UBool inDaylightTime(UErrorCode& status) const;
 
-
-
   /**
-   * Returns FALSE because the Persian Calendar does not have a default century
+   * Returns TRUE because the Persian Calendar does have a default century
    * @internal
    */
   virtual UBool haveDefaultCentury() const;
 
   /**
-   * Returns -1 
-   * @return -1 
+   * Returns the date of the start of the default century
+   * @return start of century - in milliseconds since epoch, 1970
    * @internal
    */
   virtual UDate defaultCenturyStart() const;
 
   /**
-   * Returns -1
+   * Returns the year in which the default century begins
    * @internal
    */
   virtual int32_t defaultCenturyStartYear() const;
 
+ private: // default century stuff.
+  /**
+   * The system maintains a static default century start date.  This is initialized
+   * the first time it is used.  Before then, it is set to SYSTEM_DEFAULT_CENTURY to
+   * indicate an uninitialized state.  Once the system default century date and year
+   * are set, they do not change.
+   */
+  static UDate         fgSystemDefaultCenturyStart;
+
+  /**
+   * See documentation for systemDefaultCenturyStart.
+   */
+  static int32_t          fgSystemDefaultCenturyStartYear;
+
+  /**
+   * Default value that indicates the defaultCenturyStartYear is unitialized
+   */
+  static const int32_t    fgSystemDefaultCenturyYear;
+
+  /**
+   * start of default century, as a date
+   */
+  static const UDate        fgSystemDefaultCentury;
+
+  /**
+   * Returns the beginning date of the 100-year window that dates 
+   * with 2-digit years are considered to fall within.
+   */
+  UDate         internalGetDefaultCenturyStart(void) const;
+
+  /**
+   * Returns the first year of the 100-year window that dates with 
+   * 2-digit years are considered to fall within.
+   */
+  int32_t          internalGetDefaultCenturyStartYear(void) const;
+
+  /**
+   * Initializes the 100-year window that dates with 2-digit years
+   * are considered to fall within so that its start date is 80 years
+   * before the current time.
+   */
+  static void  initializeSystemDefaultCentury(void);
 };
 
 U_NAMESPACE_END