From 3bd28dc3cad6b8f6f238f9a017464ec5641d718a Mon Sep 17 00:00:00 2001
From: Andrew Lapp <andrew@github.rew.la>
Date: Thu, 16 May 2024 20:49:30 -0500
Subject: [PATCH] use simpler xor pattern without negative lookahead for OneOf

---
 outlines/fsm/json_schema.py | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/outlines/fsm/json_schema.py b/outlines/fsm/json_schema.py
index d96597d4c..2c53fd240 100644
--- a/outlines/fsm/json_schema.py
+++ b/outlines/fsm/json_schema.py
@@ -195,13 +195,7 @@ def to_regex(
             to_regex(resolver, t, whitespace_pattern) for t in instance["oneOf"]
         ]
 
-        xor_patterns = []
-        # json schema validation ensured there is no overlapping schemas in oneOf
-        for subregex in subregexes:
-            other_subregexes = filter(lambda r: r != subregex, subregexes)
-            other_subregexes_str = "|".join([f"{s}" for s in other_subregexes])
-            negative_lookahead = f"(?!.*({other_subregexes_str}))"
-            xor_patterns.append(f"({subregex}){negative_lookahead}")
+        xor_patterns = [f"(?:{subregex})" for subregex in subregexes]
 
         return rf"({'|'.join(xor_patterns)})"