From 958fdaa0731b22ac051caae2c9730b1d660149c7 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Mon, 17 Mar 2014 13:50:16 -0700
Subject: Reject reversed {m,n} repeats where m > n.

---
 awkreg.awk | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/awkreg.awk b/awkreg.awk
index 088b53f..52c8353 100644
--- a/awkreg.awk
+++ b/awkreg.awk
@@ -38,6 +38,22 @@ function match_and_eat_else(s, pfx, e)
   return e
 }
 
+function eat_digits(s)
+{
+  match(s, /^[0-9]+/)
+  if (RLENGTH > 0)
+    return eat_chars(s, RLENGTH)
+  return s
+}
+
+function extract_digits(s)
+{
+  match(s, /^[0-9]+/)
+  if (RLENGTH > 0)
+    return substr(s, 1, RLENGTH)
+  return ""
+}
+
 function eat_rchar(c)
 {
   if (c ~ /^\\./)
@@ -117,16 +133,17 @@ function eat_bracket_exp(e,
 
 function eat_rep_notation(n,
                           # local
-                          o)
+                          o, x, y)
 {
   o = n
   n = eat_char(n)
 
-  if (n !~ /^[0-9]/)
+  x = extract_digits(n)
+
+  if (empty(x))
     return o
 
-  while (n ~ /^[0-9]/)
-    n = eat_char(n)
+  n = eat_digits(n)
 
   if (matches(n, "}"))
     return eat_char(n)
@@ -139,11 +156,15 @@ function eat_rep_notation(n,
   if (matches(n, "}"))
     return eat_char(n)
 
-  if (n !~ /^[0-9]/)
+  y = extract_digits(n)
+
+  if (empty(y))
+    return o
+
+  if (x + 0 > y)
     return o
 
-  while (n ~ /^[0-9]/)
-    n = eat_char(n)
+  n = eat_digits(n)
 
   return match_and_eat_else(n, "}", o)
 }
-- 
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