Re: gnuplot-4.4.0-rc1 breaks gnuplot script (patch)

[Teo S B. <teo...@gm...>]

On Fri, Feb 12, 2010 at 7:07 PM, Ethan Merritt <merritt@u.washington.edu> wrote:
>
> On Friday 12 February 2010 09:58:45 Teo S Bernhard wrote:
> > Problem:
> > Gnuplot script that set parameter repeatedly in plot command to address the
> > data index (within a data file) does not work when using gnuplot version
> > 4.4.0-rc1.
> > It works in 4.2 version and, from memory, did also work in version 4.3. See
> > the below shortened example reproducing the error message:
> >
> >
> > # file: trial.gpl
> > f(x)=x
> > plot a=1, \
> >      f(x)*a   title "data from index a=1" w l lw 2 lt a ,  a=a+1,       \
> >      f(x)*a   title "data from index a=2" w l lw 2 lt a ,  a=a+1,       \
> >      a=0
>
> Please see Bug #2907028
>  https://sourceforge.net/tracker/?func=detail&aid=2907028&group_id=2055&atid=102055
>
> So far as I can tell from running old versions of gnuplot (back to 3.7),
> it never did work correctly to increment a variable multiple times inside
> a plot command.

I have looked into the code, plot2d.c, regarding this issue. I have a
suggestion for a patch that seems to:
1)  solve referred Bug #2907028
2)  also allow trailing assignments to the plot command.

There are spurious print-outs in the patch, I have assumed the
intuitive meaning of END_OF_COMMAND.
The purpose of the 'was_definition' flag is not clear to me, I set it
to TRUE always since I belive that the
result of is_definition(...)  would guarantee this.

I have tested it on small examples similar to those presented in this thread.
Review and comments on the conceptual idea as presented below in a
diff-form are appreciated.

Teo
--------------------------------
Diff agains gnuplot-4.4.0-rc1, 'hg diff' was run in ./src-directory:

diff -r 9c57e57e6e92 plot2d.c
--- a/plot2d.c	Fri Feb 12 22:35:43 2010 +0100
+++ b/plot2d.c	Sat Feb 13 14:23:04 2010 +0100
@@ -1457,12 +1457,29 @@
 	    newhist_pattern = fs.fillpattern;
 	} else

-	if (is_definition(c_token)) {
-	    define();
-	    if (!equals(c_token,",")) {
-		was_definition = TRUE;
-		continue;
-	    }
+        if (is_definition(c_token)) {   /*skip over definitions in first pass*/
+          if (1==0){ /*original version that evaluate definitions
also in first pass*/
+            printf("fp: original: definition for c_token: %i\n", c_token);
+            define();
+            printf("fp: original:         done,  c_token: %i\n", c_token);
+            if (!equals(c_token,",")) {
+                 was_definition = TRUE;
+                 continue;
+            }
+          }
+          else { /*modified version that skips definitions in first pass*/
+            was_definition = TRUE;
+            printf("fp: modified: definition for c_token: %i\n", c_token);
+            while(!END_OF_COMMAND && !equals(c_token,",")){
+              c_token++;
+            }
+            printf("fp: modified:         done,  c_token: %i\n", c_token);
+            if (END_OF_COMMAND){
+              printf("fp: END_OF_COMMAND: %i\n", END_OF_COMMAND);
+              break;
+            }
+          }
+

 	} else {
 	    int specs = 0;
@@ -2172,12 +2189,28 @@
 	    if (!in_parametric && !was_definition)
 		start_token = c_token;

-	    if (is_definition(c_token)) {
+	    if (is_definition(c_token)) { /*do definitions on second pass */
+	      if (1==0){ /*original version*/
+		printf("sp: original: definition for c_token: %i\n", c_token);
 		define();
+		printf("sp: original:         done,  c_token: %i\n", c_token);
 		if (!equals(c_token,",")) {
 		    was_definition = TRUE;
 		    continue;
 		}
+	      }
+	      else { /*modified version does definitions and allows a trailing one*/
+		printf("sp: modified: definition for c_token: %i\n", c_token);
+		define();
+		was_definition = TRUE;
+		printf("sp: modified:         done,  c_token: %i\n", c_token);
+		if (END_OF_COMMAND){
+		  printf("sp: END_OF_COMMAND: %i\n", END_OF_COMMAND);
+		  break;
+		}
+	      }
+
+

 	    } else {
 		struct at_type *at_ptr;