PATCH: SECONDS can be floating point

[Peter Stephenson <pws@xxxxxxx>]

This allows typeset to switch the SECONDS special parameter between
integer and floating point, with evident increase of precision (which is
not the same as accuracy!)  This method preserves backward compatability
and doesn't require any additions to the interface.  The downside is
that as usual the logic in `typeset' is rather hairy --- I've already
had a battle with things like
  fn() { local -F SECONDS; }

It's also possible that you may be using functions which assume SECONDS
is an integer, hence it might be safest not to change the type globally.
Looks like the functions we already have with SECONDS in are robust
about this (though I haven't tested explicitly).

Index: Doc/Zsh/params.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/params.yo,v
retrieving revision 1.16
diff -u -r1.16 params.yo
--- Doc/Zsh/params.yo	5 Aug 2002 12:33:28 -0000	1.16
+++ Doc/Zsh/params.yo	28 Oct 2002 18:51:35 -0000
@@ -589,6 +589,12 @@
 is assigned a value, then the value returned upon reference
 will be the value that was assigned plus the number of seconds
 since the assignment.
+
+Unlike other special parameters, the type of the tt(SECONDS) parameter can
+be changed using the tt(typeset) command.  Only integer and one of the
+floating point types are allowed.  For example, `tt(typeset -F SECONDS)'
+causes the value to be reported as a floating point number.  The precision
+is six decimal places, although not all places may be useful.
 )
 vindex(SHLVL)
 item(tt(SHLVL) <S>)(
Index: Src/builtin.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/builtin.c,v
retrieving revision 1.86
diff -u -r1.86 builtin.c
--- Src/builtin.c	19 Sep 2002 17:57:57 -0000	1.86
+++ Src/builtin.c	28 Oct 2002 18:51:35 -0000
@@ -1653,6 +1653,13 @@
     return &asg;
 }
 
+/* for new special parameters */
+enum {
+    NS_NONE,
+    NS_NORMAL,
+    NS_SECONDS
+};
+
 /* function to set a single parameter */
 
 /**/
@@ -1661,7 +1668,7 @@
 	       int on, int off, int roff, char *value, Param altpm,
 	       Options ops, int auxlen)
 {
-    int usepm, tc, keeplocal = 0, newspecial = 0;
+    int usepm, tc, keeplocal = 0, newspecial = NS_NONE, readonly;
     char *subscript;
 
     /*
@@ -1694,14 +1701,15 @@
 	 * local.  It can be applied either to the special or in the
 	 * typeset/local statement for the local variable.
 	 */
-	newspecial = (pm->flags & PM_SPECIAL)
-	    && !(on & PM_HIDE) && !(pm->flags & PM_HIDE & ~off);
+	if ((pm->flags & PM_SPECIAL)
+	    && !(on & PM_HIDE) && !(pm->flags & PM_HIDE & ~off))
+	    newspecial = NS_NORMAL;
 	usepm = 0;
     }
 
     /* attempting a type conversion, or making a tied colonarray? */
     tc = 0;
-    if (usepm || newspecial) {
+    if (usepm || newspecial != NS_NONE) {
 	int chflags = ((off & pm->flags) | (on & ~pm->flags)) &
 	    (PM_INTEGER|PM_EFLOAT|PM_FFLOAT|PM_HASHED|
 	     PM_ARRAY|PM_TIED|PM_AUTOLOAD);
@@ -1716,11 +1724,31 @@
      * with a special or a parameter which isn't loaded yet (which
      * may be special when it is loaded; we can't tell yet).
      */
-    if (tc || ((usepm || newspecial) && (off & pm->flags & PM_READONLY))) {
+    if ((readonly =
+	 ((usepm || newspecial != NS_NONE) && 
+	  (off & pm->flags & PM_READONLY))) ||
+	tc) {
 	if (pm->flags & PM_SPECIAL) {
-	    zerrnam(cname, "%s: can't change type of a special parameter",
-		    pname, 0);
-	    return NULL;
+	    int err = 1;
+	    if (!readonly && !strcmp(pname, "SECONDS"))
+	    {
+		if (newspecial != NS_NONE)
+		{
+		    newspecial = NS_SECONDS;
+		    err = 0;	/* and continue */
+		    tc = 0;	/* but don't do a normal conversion */
+		} else if (!setsecondstype(pm, on, off)) {
+		    if (value && !setsparam(pname, ztrdup(value)))
+			return NULL;
+		    return pm;
+		}
+	    }
+	    if (err)
+	    {
+		zerrnam(cname, "%s: can't change type of a special parameter",
+			pname, 0);
+		return NULL;
+	    }
 	} else if (pm->flags & PM_AUTOLOAD) {
 	    zerrnam(cname, "%s: can't change type of autoloaded parameter",
 		    pname, 0);
@@ -1820,7 +1848,7 @@
 	unsetparam_pm(pm, 0, 1);
     }
 
-    if (newspecial) {
+    if (newspecial != NS_NONE) {
 	Param tpm, pm2;
 	if ((pm->flags & PM_RESTRICTED) && isset(RESTRICTED)) {
 	    zerrnam(cname, "%s: restricted", pname, 0);
@@ -1866,6 +1894,8 @@
 	 * because we've checked for unpleasant surprises above.
 	 */
 	pm->flags = (PM_TYPE(pm->flags) | on | PM_SPECIAL) & ~off;
+	if (newspecial == NS_SECONDS)
+	    setsecondstype(pm, on, off);
 	/*
 	 * Final tweak: if we've turned on one of the flags with
 	 * numbers, we should use the appropriate integer.
Index: Src/params.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/params.c,v
retrieving revision 1.65
diff -u -r1.65 params.c
--- Src/params.c	5 Aug 2002 12:36:00 -0000	1.65
+++ Src/params.c	28 Oct 2002 18:51:35 -0000
@@ -141,7 +141,7 @@
 IPDEF1("HISTSIZE", histsizegetfn, histsizesetfn, PM_RESTRICTED),
 IPDEF1("RANDOM", randomgetfn, randomsetfn, 0),
 IPDEF1("SAVEHIST", savehistsizegetfn, savehistsizesetfn, PM_RESTRICTED),
-IPDEF1("SECONDS", secondsgetfn, secondssetfn, 0),
+IPDEF1("SECONDS", intsecondsgetfn, intsecondssetfn, 0),
 IPDEF1("UID", uidgetfn, uidsetfn, PM_DONTIMPORT | PM_RESTRICTED),
 IPDEF1("EUID", euidgetfn, euidsetfn, PM_DONTIMPORT | PM_RESTRICTED),
 IPDEF1("TTYIDLE", ttyidlegetfn, nullintsetfn, PM_READONLY),
@@ -2657,7 +2657,7 @@
 
 /**/
 zlong
-secondsgetfn(Param pm)
+intsecondsgetfn(Param pm)
 {
     return time(NULL) - shtimer.tv_sec;
 }
@@ -2666,12 +2666,60 @@
 
 /**/
 void
-secondssetfn(Param pm, zlong x)
+intsecondssetfn(Param pm, zlong x)
 {
     shtimer.tv_sec = time(NULL) - x;
     shtimer.tv_usec = 0;
 }
 
+/**/
+double
+floatsecondsgetfn(Param pm)
+{
+    struct timeval now;
+    struct timezone dummy_tz;
+
+    gettimeofday(&now, &dummy_tz);
+
+    return (double)(now.tv_sec - shtimer.tv_sec) +
+	(double)(now.tv_usec - shtimer.tv_usec) / 1000000.0;
+}
+
+/**/
+void
+floatsecondssetfn(Param pm, double x)
+{
+    struct timeval now;
+    struct timezone dummy_tz;
+
+    gettimeofday(&now, &dummy_tz);
+    shtimer.tv_sec = now.tv_sec - (int)x;
+    shtimer.tv_usec = now.tv_usec - (int)((x - (double)(int)x) * 1000000.0);
+}
+
+/**/
+int
+setsecondstype(Param pm, int on, int off)
+{
+    int newflags = (pm->flags | on) & ~off;
+    int tp = PM_TYPE(newflags);
+    /* Only one of the numeric types is allowed. */
+    if (tp == PM_EFLOAT || tp == PM_FFLOAT)
+    {
+	pm->gets.ffn = floatsecondsgetfn;
+	pm->sets.ffn = floatsecondssetfn;
+    }
+    else if (tp == PM_INTEGER)
+    {
+	pm->gets.ifn = intsecondsgetfn;
+	pm->sets.ifn = intsecondssetfn;
+    }
+    else
+	return 1;
+    pm->flags = newflags;
+    return 0;
+}
+
 /* Function to get value for special parameter `USERNAME' */
 
 /**/
@@ -3422,6 +3470,8 @@
 	     */
 	    Param tpm = pm->old;
 
+	    if (!strcmp(pm->nam, "SECONDS"))
+		setsecondstype(pm, PM_TYPE(tpm->flags), PM_TYPE(pm->flags));
 	    DPUTS(!tpm || PM_TYPE(pm->flags) != PM_TYPE(tpm->flags) ||
 		  !(tpm->flags & PM_SPECIAL),
 		  "BUG: in restoring scope of special parameter");


-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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