From 5335bdbe34528ef92997a752280457133255a55c Mon Sep 17 00:00:00 2001
From: George Potoshin <george.potoshin@gmail.com>
Date: Wed, 25 Feb 2026 14:33:09 +0100
Subject: [PATCH] [core:text/regex] Follow up to fix #6323 and add test case.
 As was said in the issue discussion I had suspicion that there may be a
 sibling bug in .Assert_Non_Word_Boundary implementation and I was able to
 confirm that with `re.findall(rB", ")` python code. Odin implementation
 outputed an empty string wherase python gave "'". That is the same bug
 related to incorrect logic on string ends. This commit makes implementation
 of those 2 instructions cleaner and adds a test case.

---
 .../virtual_machine/virtual_machine.odin      | 24 +++++++------------
 .../core/text/regex/test_core_text_regex.odin |  4 ++++
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/core/text/regex/virtual_machine/virtual_machine.odin b/core/text/regex/virtual_machine/virtual_machine.odin
index e90a27e63..ab2e9515c 100644
--- a/core/text/regex/virtual_machine/virtual_machine.odin
+++ b/core/text/regex/virtual_machine/virtual_machine.odin
@@ -204,15 +204,8 @@ add_thread :: proc(vm: ^Machine, saved: ^[2 * common.MAX_CAPTURE_GROUPS]int, pc:
 		case .Assert_Word_Boundary:
 			sp := vm.string_pointer+vm.current_rune_size
 
-			left_is_wc := false
-			if sp > 0 {
-				left_is_wc = is_word_class(vm.current_rune)
-			}
-
-			right_is_wc := false
-			if sp < len(vm.memory) {
-				right_is_wc = is_word_class(vm.next_rune)
-			}
+			left_is_wc := sp > 0 && is_word_class(vm.current_rune)
+			right_is_wc := sp < len(vm.memory) && is_word_class(vm.next_rune)
 
 			if left_is_wc != right_is_wc {
 				pc += size_of(Opcode)
@@ -221,14 +214,13 @@ add_thread :: proc(vm: ^Machine, saved: ^[2 * common.MAX_CAPTURE_GROUPS]int, pc:
 
 		case .Assert_Non_Word_Boundary:
 			sp := vm.string_pointer+vm.current_rune_size
-			if sp != 0 && sp != len(vm.memory) {
-				last_rune_is_wc := is_word_class(vm.current_rune)
-				this_rune_is_wc := is_word_class(vm.next_rune)
 
-				if last_rune_is_wc && this_rune_is_wc || !last_rune_is_wc && !this_rune_is_wc {
-					pc += size_of(Opcode)
-					continue
-				}
+			left_is_wc := sp > 0 && is_word_class(vm.current_rune)
+			right_is_wc := sp < len(vm.memory) && is_word_class(vm.next_rune)
+
+			if left_is_wc == right_is_wc {
+				pc += size_of(Opcode)
+				continue
 			}
 
 		case .Wait_For_Byte:
diff --git a/tests/core/text/regex/test_core_text_regex.odin b/tests/core/text/regex/test_core_text_regex.odin
index 578ebc242..732a3d321 100644
--- a/tests/core/text/regex/test_core_text_regex.odin
+++ b/tests/core/text/regex/test_core_text_regex.odin
@@ -564,6 +564,10 @@ test_non_word_boundaries :: proc(t: ^testing.T) {
 		EXPR :: `.+\B`
 		check_expression(t, EXPR, "abc", "ab")
 	}
+	{
+		EXPR :: `\B'`
+		check_expression(t, EXPR, "'", "'")
+	}
 }
 
 @test