From bb6c20f9fa5c6c13e088c205fffbe94900e36588 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 26 Oct 2016 21:14:37 -0700
Subject: Same fix in tok-where as tok-str.

lib.c (tok_where) Implement new loop which suppresses
empty tokens immediately matching after non-empty
tokens. Old loop available under compatibility.
No documentation update needed since tok-where
is already documented as working like tok-str.
---
 lib.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/lib.c b/lib.c
index ab07ed10..5b304237 100644
--- a/lib.c
+++ b/lib.c
@@ -4049,8 +4049,9 @@ val tok_where(val str, val tok_regex)
 {
   list_collect_decl (out, iter);
   val pos = zero;
+  int prev_empty = 1;
 
-  for (;;) {
+  if (opt_compat && opt_compat <= 155) for (;;) {
     val range = range_regex(str, tok_regex, pos, nil);
 
     if (range) {
@@ -4065,6 +4066,27 @@ val tok_where(val str, val tok_regex)
       continue;
     }
 
+    break;
+  } else for (;;) {
+    val range = range_regex(str, tok_regex, pos, nil);
+
+    if (range) {
+      range_bind (match_start, match_end, range);
+
+      if (match_end != match_start || prev_empty) {
+        iter = list_collect(iter, range);
+        prev_empty = (match_end == match_start);
+      } else {
+        prev_empty = 1;
+      }
+
+      pos = match_end;
+
+      if (match_end == match_start)
+        pos = plus(pos, one);
+      continue;
+    }
+
     break;
   }
 
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