parse-datetime.y & ISO8601 timestamps

[J.T. Conklin]

First some background.  

The continuous integration build framework I maintain at work uses
timestamp files for "last_build", "last_success", etc.  The contents
of each file is the timestamp in ISO 8601 format (the inode mtime is
set to the same value, but thats besides the point).

I used this format thinking that the 'T' separator between date and
time would be more resistant to errors (shell quoting, etc.) than a
format that used spaces.

But someone reported that coreutils' date's -d option could not parse
this format.  Fortunately, date -r could be used; but this challenges
my idea that the ISO format is more useful.

I've done some tweaks to parse-datetime.y as shown.  Since 'T' now can
be either a millitary-style single character timezone and a separator,
I've special cased it as a token in the lexer.  With the changes, the
function can parse the ISO 8601 / RFC 3339 YYYY-MM-DDTHH:MM:DD+MMSS 
format (but not other valid ISO 8601 formats that omit -'s and :'s).
This adds another grammar conflict, but the parse-getdate test suite 
still executes correctly.

I'm interested in comments on both the idea of supporting such time
formats, and whether there is a better implementation.

    --jtc


diff --git a/lib/parse-datetime.y b/lib/parse-datetime.y
index d77955f..0046d8d 100644
--- a/lib/parse-datetime.y
+++ b/lib/parse-datetime.y
@@ -285,8 +285,8 @@ set_hhmmss (parser_control *pc, long int hour, long int 
minutes,
 %parse-param { parser_control *pc }
 %lex-param { parser_control *pc }
 
-/* This grammar has 20 shift/reduce conflicts. */
-%expect 20
+/* This grammar has 21 shift/reduce conflicts. */
+%expect 21
 
 %union
 {
@@ -333,7 +333,9 @@ items:
   ;
 
 item:
-    time
+    datetime
+      { pc->times_seen++; pc->dates_seen++; }
+  | time
       { pc->times_seen++; }
   | local_zone
       { pc->local_zones_seen++; }
@@ -348,6 +350,11 @@ item:
   | hybrid
   ;
 
+datetime: 
+    date 'T' time
+  ;
+  
+
 time:
     tUNUMBER tMERIDIAN
       {
@@ -405,6 +412,8 @@ zone:
       { pc->time_zone = $1 + 60; }
   | tZONE tDST
       { pc->time_zone = $1 + 60; }
+  | 'T' 
+      { pc->time_zone = HOUR(7); }
   ;
 
 day:
@@ -794,7 +803,7 @@ static table const military_table[] =
   { "Q", tZONE,  HOUR ( 4) },
   { "R", tZONE,  HOUR ( 5) },
   { "S", tZONE,  HOUR ( 6) },
-  { "T", tZONE,  HOUR ( 7) },
+  { "T", 'T',    0         },
   { "U", tZONE,  HOUR ( 8) },
   { "V", tZONE,  HOUR ( 9) },
   { "W", tZONE,  HOUR (10) },


-- 
J.T. Conklin