Udpate calendar to remove some circular dependencies

extra/calendar/backend/backend.factor

@@ -0,0 +1,5 @@
+USING: kernel ;
+IN: calendar.backend
+
+SYMBOL: calendar-backend
+HOOK: gmt-offset calendar-backend

extra/calendar/calendar.factor

@@ -3,13 +3,10 @@
 
 USING: arrays hashtables io io.streams.string kernel math
 math.vectors math.functions math.parser namespaces sequences
-strings tuples system debugger combinators vocabs.loader ;
+strings tuples system debugger combinators vocabs.loader
+calendar.backend structs alien.c-types unix ;
 IN: calendar
 
-SYMBOL: calendar-impl
-
-HOOK: gmt-offset calendar-impl ( -- n )
-
 TUPLE: timestamp year month day hour minute second gmt-offset ;
 
 C: <timestamp> timestamp
@@ -225,6 +222,24 @@ M: timestamp <=> ( ts1 ts2 -- n )
 : timestamp>unix-time ( timestamp -- n )
     unix-1970 timestamp- >bignum ;
 
+: timestamp>timeval ( timestamp -- timeval ) 
+    timestamp>unix-time 1000 * make-timeval ; 
+
+: timeval>timestamp ( timeval -- timestamp ) 
+    [ timeval-sec ] keep
+    timeval-usec 1000000 / + unix-time>timestamp ; 
+
+: timestamp>timespec ( timestamp -- timespec ) 
+    timestamp>unix-time "timespec" <c-object>
+    [ set-timespec-sec ] keep ; 
+
+: timespec>timestamp ( timespec -- timestamp ) 
+    [ timespec-sec ] keep
+    timespec-nsec 1000000000 / + 
+    unix-time>timestamp ; 
+
+
+
 : gmt ( -- timestamp )
     #! GMT time, right now
     unix-1970 millis 1000 /f seconds +dt ; 
@@ -353,6 +368,37 @@ M: timestamp <=> ( ts1 ts2 -- n )
         ] if
     ] string-out ;
 
+: day-offset ( timestamp m -- timestamp n )
+    over day-of-week - ; inline
+    
+: day-this-week ( timestamp n -- timestamp )
+    day-offset days +dt ;
+    
+: sunday ( timestamp -- timestamp ) 0 day-this-week ;
+: monday ( timestamp -- timestamp ) 1 day-this-week ;
+: tuesday ( timestamp -- timestamp ) 2 day-this-week ;
+: wednesday ( timestamp -- timestamp ) 3 day-this-week ;
+: thursday ( timestamp -- timestamp ) 4 day-this-week ;
+: friday ( timestamp -- timestamp ) 5 day-this-week ; 
+: saturday ( timestamp -- timestamp ) 6 day-this-week ;
+
+: beginning-of-day ( timestamp -- new-timestamp )
+    clone dup >r 0 0 0 r>
+    { set-timestamp-hour set-timestamp-minute set-timestamp-second }
+    set-slots ; inline
+
+: beginning-of-month ( timestamp -- new-timestamp )
+    clone dup beginning-of-day dup >r 1 r> { set-timestamp-day } set-slots ;
+
+: beginning-of-week ( timestamp -- new-timestamp )
+    clone dup sunday beginning-of-day ;
+
+: beginning-of-year ( timestamp -- new-timestamp )
+    clone dup beginning-of-month dup >r 1 r> { set-timestamp-month } set-slots ;
+
+: seconds-since-midnight ( timestamp -- x )
+    dup beginning-of-day timestamp- ;
+
 {
     { [ unix? ] [ "calendar.unix" ] }
     { [ windows? ] [ "calendar.windows" ] }

extra/calendar/unix/unix.factor

@@ -1,10 +1,10 @@
-USING: alien alien.c-types arrays kernel structs
-math unix calendar namespaces ;
+USING: alien alien.c-types arrays calendar.backend
+kernel structs math unix namespaces ;
 IN: calendar.unix
 
 TUPLE: unix-calendar ;
 
-T{ unix-calendar } calendar-impl set-global
+T{ unix-calendar } calendar-backend set-global
 
 : get-time
     f time <uint> localtime ;
@@ -14,19 +14,3 @@ T{ unix-calendar } calendar-impl set-global
 
 M: unix-calendar gmt-offset
     get-time tm-gmtoff 3600 / ;
-
-: timestamp>timeval ( timestamp -- timeval )
-    timestamp>unix-time 1000 * make-timeval ;
-
-: timeval>timestamp ( timeval -- timestamp )
-    [ timeval-sec ] keep
-    timeval-usec 1000000 / + unix-time>timestamp ;
-
-: timestamp>timespec ( timestamp -- timespec )
-    timestamp>unix-time "timespec" <c-object>
-    [ set-timespec-sec ] keep ;
-
-: timespec>timestamp ( timespec -- timestamp )
-    [ timespec-sec ] keep
-    timespec-nsec 1000000000 / +
-    unix-time>timestamp ;

extra/calendar/windows/windows.factor

@@ -1,10 +1,10 @@
 USING: alien alien.c-types kernel math
-windows windows.kernel32 calendar namespaces ;
+windows windows.kernel32 namespaces ;
 IN: calendar.windows
 
 TUPLE: windows-calendar ;
 
-T{ windows-calendar } calendar-impl set-global
+T{ windows-calendar } calendar-backend set-global
 
 M: windows-calendar gmt-offset ( -- float )
     "TIME_ZONE_INFORMATION" <c-object>
@@ -45,4 +45,3 @@ M: windows-calendar gmt-offset ( -- float )
 
 : FILETIME>timestamp ( FILETIME -- timestamp/f )
     FILETIME>windows-time windows-time>timestamp ;
-