parameter scopes

[Zefram <zefram@xxxxxxxxxxxxxxxxx>]

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This patch removes locallist, replacing it with a scan over the parameter
table when the scope ends.  This makes little difference to timing[1]
or memory usage[2], but it is a big simplicity win, as locallist doesn't
have to be maintained in multiple places.  This patch depends on the
ZLE parameters patch (3014).

 -zefram

[1] It saves on some dynamic memory allocation, at the expense of
walking through the hash table more when there are few local parameters.
It scales better: O(N) rather than O(Nn), where N is the number of
parameters and n the number of declarations in the scope.

[2] Fewer strings copied.

 *** Src/builtin.c	1997/03/29 19:09:39	1.71
 --- Src/builtin.c	1997/03/29 19:17:44
 ***************
 *** 1446,1455 ****
   		if (!asg->value)
   		    asg->value = dupstring(getsparam(asg->name));
   		unsetparam(asg->name);
 - 	    } else if (locallist && func != BIN_EXPORT) {
 - 		PERMALLOC {
 - 		    addlinknode(locallist, ztrdup(asg->name));
 - 		} LASTALLOC;
   	    }
   	    /* create a new node for a parameter with the *
   	     * flags in `on' minus the readonly flag      */
 --- 1446,1451 ----
 *** Src/exec.c	1997/03/26 04:48:46	1.55
 --- Src/exec.c	1997/03/29 19:19:47
 ***************
 *** 2504,2510 ****
   {
       char **tab, **x, *oargv0 = NULL;
       int xexittr, newexittr, oldzoptind, oldlastval;
 -     LinkList olist;
       char *ou;
       void *xexitfn, *newexitfn;
       char saveopts[OPT_SIZE];
 --- 2504,2509 ----
 ***************
 *** 2553,2565 ****
   		argzero = ztrdup(argzero);
   	    }
   	}
 ! 	olist = startparamscope();
   	ou = underscore;
   	underscore = ztrdup(underscore);
   	execlist(dupstruct(list), 1, 0);
   	zsfree(underscore);
   	underscore = ou;
 ! 	endparamscope(olist);
   
   	if (retflag) {
   	    retflag = 0;
 --- 2552,2564 ----
   		argzero = ztrdup(argzero);
   	    }
   	}
 ! 	startparamscope();
   	ou = underscore;
   	underscore = ztrdup(underscore);
   	execlist(dupstruct(list), 1, 0);
   	zsfree(underscore);
   	underscore = ou;
 ! 	endparamscope();
   
   	if (retflag) {
   	    retflag = 0;
 *** Src/globals.h	1997/03/27 01:57:48	1.41
 --- Src/globals.h	1997/03/29 19:17:44
 ***************
 *** 373,382 ****
   EXTERN char *nullcmd;
   EXTERN char *readnullcmd;
    
 - /* the List of local variables we have to destroy */
 -  
 - EXTERN LinkList locallist;
 - 
   /* what level of localness we are at */
    
   EXTERN int locallevel;
 --- 373,378 ----
 *** Src/init.c	1997/03/27 01:57:49	1.47
 --- Src/init.c	1997/03/29 19:17:44
 ***************
 *** 535,541 ****
   
       breaks = loops = 0;
       lastmailcheck = time(NULL);
 -     locallist = NULL;
       locallevel = sourcelevel = 0;
       trapreturn = 0;
       noerrexit = -1;
 --- 535,540 ----
 *** Src/params.c	1997/03/29 19:09:42	1.39
 --- Src/params.c	1997/03/29 19:23:09
 ***************
 *** 1954,1996 ****
       }
   }
   
 ! /* Start a parameter scope: create a lew list for the recording of parameters *
 !  * local to this new scope.  Returns the list for the enclosing scope, which  *
 !  * should be stored and then passed to endparamscope().  (Neater, I think,    *
 !  * than having everyone deal with locallist explicitly.)                      */
   
   /**/
 ! LinkList
   startparamscope(void)
   {
 -     LinkList olist = locallist;
 - 
 -     PERMALLOC {
 - 	locallist = newlinklist();
 -     } LASTALLOC;
       locallevel++;
 -     return olist;
   }
   
   /* End a parameter scope: delete the parameters local to the scope. */
   
   /**/
   void
 ! endparamscope(LinkList olist)
   {
 -     char *s;
 -     Param pm;
 - 
       locallevel--;
   
       /* destroy the local variables we have created in the scope just left */
 !     while ((s = (char *) getlinknode(locallist))) {
 ! 	if((pm = (Param) paramtab->getnode(paramtab, s)) &&
 ! 	    (pm->level > locallevel))
 ! 	    unsetparam_pm(pm, 0, 0);
 ! 	zsfree(s);
 !     }
 !     zfree(locallist, sizeof(struct linklist));
   
 !     locallist = olist;	/* restore the old list of local variables */
   }
 --- 1954,1998 ----
       }
   }
   
 ! /* Start a parameter scope */
   
   /**/
 ! void
   startparamscope(void)
   {
       locallevel++;
   }
   
   /* End a parameter scope: delete the parameters local to the scope. */
   
 + static LinkList locallist;
 + 
   /**/
   void
 ! endparamscope(void)
   {
       locallevel--;
   
       /* destroy the local variables we have created in the scope just left */
 !     PERMALLOC {
 ! 	locallist = newlinklist();
 ! 	scanhashtable(paramtab, 0, 0, 0, scanendscope, 0);
 ! 	freelinklist(locallist, freeendscope);
 !     } LASTALLOC;
 ! }
   
 ! /**/
 ! void
 ! scanendscope(HashNode hn, int flags)
 ! {
 !     Param pm = (Param)hn;
 !     if(pm->level > locallevel)
 ! 	addlinknode(locallist, pm);
 ! }
 ! 
 ! /**/
 ! void
 ! freeendscope(void *dat)
 ! {
 !     unsetparam_pm((Param)dat, 0, 0);
   }
 *** Src/Zle/zle_main.c	1997/03/26 09:09:35	1.34
 --- Src/Zle/zle_main.c	1997/03/29 19:19:56
 ***************
 *** 518,527 ****
   	    zsfree(msg);
   	    feep();
   	} else {
 ! 	  LinkList olist = startparamscope();
   	  makezleparams();
   	  doshfunc(l, NULL, 0, 1);
 ! 	  endparamscope(olist);
   	  lastcmd = 0;
   	}
       }
 --- 518,527 ----
   	    zsfree(msg);
   	    feep();
   	} else {
 ! 	  startparamscope();
   	  makezleparams();
   	  doshfunc(l, NULL, 0, 1);
 ! 	  endparamscope();
   	  lastcmd = 0;
   	}
       }
 *** Src/Zle/zle_params.c	1997/03/23 20:20:44	1.4
 --- Src/Zle/zle_params.c	1997/03/29 19:17:44
 ***************
 *** 88,96 ****
   	Param pm = createparam(zp->name, zp->type | PM_SPECIAL);
   
   	pm->level = locallevel;
 - 	PERMALLOC {
 - 	    addlinknode(locallist, ztrdup(zp->name));
 - 	} LASTALLOC;
   	pm->u.data = zp->data;
   	switch(PM_TYPE(zp->type)) {
   	    case PM_SCALAR:
 --- 88,93 ----

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