Fix in {m,n} syntax. Improved driver code.

The issue is that the parser partially consumes broken {m,n}
syntax. The eat_rep_notation function must backtrack fully,
and its caller must detect it has done so.

1 files changed, 36 insertions, 11 deletions

diff --git a/awkreg.awk b/awkreg.awk
index a0ea898..f966168 100644
--- a/awkreg.awk
+++ b/awkreg.awk
@@ -1,3 +1,9 @@
+function dbg(x)
+{
+  printf("dbg: <%s>\n", x)
+  return x
+}
+
 function empty(s)
 {
   return s == ""
@@ -25,6 +31,13 @@ function match_and_eat(s, pfx)
   return s
 }
 
+function match_and_eat_else(s, pfx, e)
+{
+  if (matches(s, pfx))
+    return eat_chars(s, length(pfx))
+  return e
+}
+
 function eat_rchar(c)
 {
   if (c ~ /^\\./)
@@ -102,12 +115,15 @@ function eat_bracket_exp(e,
   }
 }
 
-function eat_rep_notation(n)
+function eat_rep_notation(n,
+                          # local
+                          o)
 {
+  o = n
   n = eat_char(n)
 
   if (n !~ /^[0-9]/)
-    return n
+    return o
 
   while (n ~ /^[0-9]/)
     n = eat_char(n)
@@ -116,7 +132,7 @@ function eat_rep_notation(n)
     return eat_char(n)
 
   if (!matches(n, ","))
-    return n
+    return o
 
   n = eat_char(n)
 
@@ -124,18 +140,18 @@ function eat_rep_notation(n)
     return eat_char(n)
 
   if (n !~ /^[0-9]/)
-    return n
+    return o
 
   while (n ~ /^[0-9]/)
     n = eat_char(n)
 
-  return match_and_eat(n, "}")
+  return match_and_eat_else(n, "}", o)
 }
 
 function eat_factor(f)
 {
   if (matches(f, "("))
-    return match_and_eat(eat_regex(eat_char(f)), ")")
+    return match_and_eat_else(eat_regex(eat_char(f)), ")", f)
 
   if (matches(f, "["))
     return eat_bracket_exp(f)
@@ -183,23 +199,32 @@ function eat_regex(r,
   return eat_regex(r)
 }
 
-
-function is_regex(r)
+function regex_check(r)
 {
   if (matches(r, "^"))
     r = eat_char(r)
 
   if (empty(r))
-    return 1
+    return r
 
   r = eat_regex(r)
 
   if (r == "$")
     r = ""
 
-  return empty(r);
+  return r
+}
+
+function is_regex(r)
+{
+  return empty(regex_check(r))
 }
 
 {
-   printf("is_regex(%s)\n", is_regex($0) ? "yes" : "no")
+  ok = is_regex($0)
+
+  printf("is_regex(\"%s\") = %d", $0, ir)
+  if (!ok)
+    printf(", junk = \"%s\"", regex_check($0))
+  printf("\n")
 }