From 6da44bdb6a9504950caa2fc0a0d15d5edae33e6b Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Mon, 3 Feb 2025 07:36:00 -0600
Subject: [PATCH] Get rid of early termination rule in all finite loops.

---
 src/core/peg.c       |  4 ++--
 test/suite-peg.janet | 11 +++++++----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/core/peg.c b/src/core/peg.c
index 59de5bca..bb30dd0e 100644
--- a/src/core/peg.c
+++ b/src/core/peg.c
@@ -342,8 +342,8 @@ tail:
             while (captured < hi) {
                 CapState cs2 = cap_save(s);
                 next_text = peg_rule(s, rule_a, text);
-                if (!next_text || next_text == text) {
-                    if (!next_text || captured > 0) cap_load(s, cs2);
+                if (!next_text || ((next_text == text) && (hi == UINT32_MAX))) {
+                    cap_load(s, cs2);
                     break;
                 }
                 captured++;
diff --git a/test/suite-peg.janet b/test/suite-peg.janet
index faf8a533..6ef67b19 100644
--- a/test/suite-peg.janet
+++ b/test/suite-peg.janet
@@ -789,13 +789,16 @@
       "abc123"
       @["abc123"])
 
-# Issue 1554
-(test "issue 1554 case 1" '(any (> '1)) "abc" @["a"])
-(test "issue 1554 case 2" '(any (? (> '1))) "abc" @["a"])
-(test "issue 1554 case 3" '(any (> (? '1))) "abc" @["a"])
+# Issue 1554 - 0-width match termination behavior
+(test "issue 1554 case 1" '(any (> '1)) "abc" @[])
+(test "issue 1554 case 2" '(any (? (> '1))) "abc" @[])
+(test "issue 1554 case 3" '(any (> (? '1))) "abc" @[])
 (test "issue 1554 case 4" '(* "a" (> '1)) "abc" @["b"])
 (test "issue 1554 case 5" '(* "a" (? (> '1))) "abc" @["b"])
 (test "issue 1554 case 6" '(* "a" (> (? '1))) "abc" @["b"])
+(test "issue 1554 case 7" '(between 0 2 (> '1)) "abc" @["a" "a"])
+(test "issue 1554 case 8" '(between 2 3 (? (> '1))) "abc" @["a" "a" "a"])
+(test "issue 1554 case 9" '(between 0 0 (> (? '1))) "abc" @[])
 
 (end-suite)