(var-TimeZone): Make nil the default value.

(math-calendar-tzinfo): New variable.
(math-get-calendar-tzinfo): New function.
(calcFunc-tzone, calcFunc-dst): Use Emacs's calendar
to get information when zone is nil.

2 files changed, 85 insertions, 59 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index ccf7d130c52..bce24e6d625 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,12 @@
+2007-08-25  Jay Belanger  <jay.p.belanger@gmail.com>
+
+        * calc/calc-forms.el (var-TimeZone): Make nil explicitly
+        the default value.
+        (math-calendar-tzinfo): New variable.
+        (math-get-calendar-tzinfo): New function.
+        (calcFunc-tzone, calcFunc-dst): Use Emacs's calendar
+        to get information when zone is nil.
+
 2007-08-24  Dan Nicolaescu  <dann@ics.uci.edu>
 
         * log-view.el (log-view-toggle-mark-entry): New function.
diff --git a/lisp/calc/calc-forms.el b/lisp/calc/calc-forms.el
index 7ac0a0bb0db..3839fc93666 100644
--- a/lisp/calc/calc-forms.el
+++ b/lisp/calc/calc-forms.el
@@ -1201,7 +1201,29 @@ as measured in the integer number of days before January 1 of the year 1AD.")
     )
   "No doc yet.  See calc manual for now. ")
 
-(defvar var-TimeZone)
+(defvar var-TimeZone nil)
+
+;; From cal-dst
+(defvar calendar-current-time-zone-cache)
+
+(defvar math-calendar-tzinfo 
+  nil
+  "Information about the timezone, retrieved from the calendar.")
+
+(defun math-get-calendar-tzinfo ()
+  "Get information about the timezone from the calendar.
+The result should be a list of two items about the current time zone:
+first, the number of seconds difference from GMT
+second, the number of seconds offset for daylight savings."
+  (if math-calendar-tzinfo
+      math-calendar-tzinfo
+    (require 'cal-dst)
+    (let ((tzinfo (progn
+                    (calendar-current-time-zone)
+                    calendar-current-time-zone-cache)))
+      (setq math-calendar-tzinfo
+            (list (* 60 (abs (nth 0 tzinfo)))
+                  (* 60 (nth 1 tzinfo)))))))
 
 (defun calcFunc-tzone (&optional zone date)
   (if zone
@@ -1233,53 +1255,9 @@ as measured in the integer number of days before January 1 of the year 1AD.")
             (t (math-reject-arg zone "*Expected a time zone")))
     (if (calc-var-value 'var-TimeZone)
         (calcFunc-tzone (calc-var-value 'var-TimeZone) date)
-      (let ((p math-tzone-names)
-            (offset 0)
-            (tz '(var error var-error)))
-        (save-excursion
-          (set-buffer (get-buffer-create " *Calc Temporary*"))
-          (erase-buffer)
-          (call-process "date" nil t)
-          (goto-char 1)
-          (let ((case-fold-search t))
-            (while (and p (not (search-forward (car (car p)) nil t)))
-              (setq p (cdr p))))
-          (if (looking-at "\\([-+][0-9]?[0-9]\\)\\([0-9][0-9]\\)?\\(\\'\\|[^0-9]\\)")
-              (setq offset (math-add
-                            (string-to-number (buffer-substring
-                                            (match-beginning 1)
-                                            (match-end 1)))
-                            (if (match-beginning 2)
-                                (math-div (string-to-number (buffer-substring
-                                                             (match-beginning 2)
-                                                             (match-end 2)))
-                                          60)
-                              0)))))
-        (if p
-            (progn
-              (setq p (car p))
-              ;; Try to convert to a generalized time zone.
-              (if (integerp (nth 2 p))
-                  (let ((gen math-tzone-names))
-                    (while (and gen
-                                (not (equal (nth 2 (car gen)) (car p)))
-                                (not (equal (nth 3 (car gen)) (car p)))
-                                (not (equal (nth 4 (car gen)) (car p)))
-                                (not (equal (nth 5 (car gen)) (car p))))
-                      (setq gen (cdr gen)))
-                    (and gen
-                         (setq gen (car gen))
-                         (equal (math-daylight-savings-adjust nil (car gen))
-                                (nth 2 p))
-                         (setq p gen))))
-              (setq tz (math-add (list 'var
-                                       (intern (car p))
-                                       (intern (concat "var-" (car p))))
-                                 offset))))
-        (kill-buffer " *Calc Temporary*")
-        (setq var-TimeZone tz)
-        (calc-refresh-evaltos 'var-TimeZone)
-        (calcFunc-tzone tz date)))))
+      (let ((tzinfo (math-get-calendar-tzinfo)))
+        (+ (nth 0 tzinfo) 
+           (* (math-cal-daylight-savings-adjust date) (nth 1 tzinfo)))))))
 
 (defvar math-daylight-savings-hook 'math-std-daylight-savings)
 
@@ -1300,21 +1278,60 @@ as measured in the integer number of days before January 1 of the year 1AD.")
     (and math-daylight-savings-hook
          (funcall math-daylight-savings-hook date dt zone bump))))
 
+;;; Based on part of dst-adjust-time in cal-dst.el
+;;; For calcFunc-dst, when zone=nil
+(defun math-cal-daylight-savings-adjust (date)
+  "Return -1 if DATE is using daylight saving, 0 otherwise."
+  (require 'cal-dst)
+  (unless date (setq date (calcFunc-now)))
+  (let* ((dt (math-date-to-dt date))
+         (time (cond
+                ((nth 3 dt)
+                 (nth 3 dt))
+                ((nth 4 dt)
+                 (+ (nth 3 dt) (/ (nth 4 dt) 60.0)))
+                (t
+                 0)))
+         (rounded-abs-date 
+          (+ 
+           (calendar-absolute-from-gregorian 
+            (list (nth 1 dt) (nth 2 dt) (nth 0 dt)))
+           (/ (round (* 60 time)) 60.0 24.0))))
+    (if (dst-in-effect rounded-abs-date)
+        -1
+      0)))
+
 (defun calcFunc-dsadj (date &optional zone)
   (if zone
       (or (eq (car-safe zone) 'var)
           (math-reject-arg zone "*Time zone variable expected"))
-    (setq zone (or (calc-var-value 'var-TimeZone)
-                   (progn
-                     (calcFunc-tzone)
-                     (calc-var-value 'var-TimeZone)))))
-  (setq zone (and (eq (car-safe zone) 'var)
-                  (upcase (symbol-name (nth 1 zone)))))
-  (let ((zadj (assoc zone math-tzone-names)))
-    (or zadj (math-reject-arg zone "*Unrecognized time zone name"))
-    (if (integerp (nth 2 zadj))
-        (nth 2 zadj)
-      (math-daylight-savings-adjust date zone))))
+    (setq zone (calc-var-value 'var-TimeZone)))
+  (if zone
+      (progn
+        (setq zone (and (eq (car-safe zone) 'var)
+                        (upcase (symbol-name (nth 1 zone)))))
+        (let ((zadj (assoc zone math-tzone-names)))
+          (or zadj (math-reject-arg zone "*Unrecognized time zone name"))
+          (if (integerp (nth 2 zadj))
+              (nth 2 zadj)
+            (math-daylight-savings-adjust date zone))))
+    (math-cal-daylight-savings-adjust date)))
+
+;; (defun calcFunc-dsadj (date &optional zone)
+;;   (if zone
+;;       (or (eq (car-safe zone) 'var)
+;;        (math-reject-arg zone "*Time zone variable expected"))
+;;     (setq zone (or (calc-var-value 'var-TimeZone)
+;;                 (progn
+;;                   (calcFunc-tzone)
+;;                   (calc-var-value 'var-TimeZone)))))
+;;   (setq zone (and (eq (car-safe zone) 'var)
+;;                (upcase (symbol-name (nth 1 zone)))))
+;;   (let ((zadj (assoc zone math-tzone-names)))
+;;     (or zadj (math-reject-arg zone "*Unrecognized time zone name"))
+;;     (if (integerp (nth 2 zadj))
+;;      (nth 2 zadj)
+;;       (math-daylight-savings-adjust date zone))))
 
 (defun calcFunc-tzconv (date z1 z2)
   (if (math-realp date)