#45 lessons/002_upn_calculator/calc_002 doesn't produce a useful example program

[Marja Hölttä]

The problem is the fill() routine; if there are less than 3 characters to fill, it just fails, and doesn't try to do anything with the data.

For example:
$ ./a.out "1"
OOD

$ ./a.out "12"
OOD

$ ./a.out "123"
Num
EOF

$ ./a.out "1+1"
Num
+
OOD

$ ./a.out "1+12"
Num
+
OOD

$ ./a.out "1+123"
Num
+
Num
EOF

[Marja Hölttä]

I don't fully understand the YYFILL stuff (just reading through the lessons), but this seems to produce a more useful example prog:

--- a/re2c/lessons/001_upn_calculator/calc_002.re
+++ b/re2c/lessons/001_upn_calculator/calc_002.re
@@ -33,13 +33,14 @@ int scan(char s)
char p = s;
char l = s;
char q = 0;
+ int cont = 1;
#define YYCTYPE char
#define YYCURSOR p
#define YYLIMIT l
#define YYMARKER q
-#define YYFILL(n) { if (!fill(p, n, &l)) break; }
+#define YYFILL(n) { if (!fill(p, n, &l)) cont=0; }

- for(;;)
+ while(cont)
{
/!re2c
re2c:indent:top = 2;
@@ -52,7 +53,7 @@ int scan(char s)
[^] { printf("ERR\n"); return 1; }
*/
}
- printf("OOD\n"); return 2;
+ printf("EOF\n"); return 0;
}

$ ./a.out "1"
Num
EOF

$ ./a.out "12"
Num
EOF

$ ./a.out "1+1"
Num
+
Num
EOF

$ ./a.out "1+12"
Num
+
Num
EOF

[Marja Hölttä]

More investigation: If we look at the graph for calc_002 (generated by re2c -D calc_002.re), that automaton accepts "0" and "1" and "11" but it doesn't accept "01" -- it only accepts octal numbers which are 3 digits long or longer! So there is another problem there: based on the grammar, "01" should be accepted, but based on the graph, it's not. What's up with that?