From 84015d3ac4d585e48a7c4275cf55b2c2ffaef2d5 Mon Sep 17 00:00:00 2001
From: Andrew Lane <contact@lungers.com>
Date: Fri, 1 Oct 2021 12:34:36 +0300
Subject: [PATCH] Handle errors when replacing

---
 babi/screen.py                 |  8 +++++++-
 tests/features/replace_test.py | 10 ++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/babi/screen.py b/babi/screen.py
index 9d725d4..c86bc71 100644
--- a/babi/screen.py
+++ b/babi/screen.py
@@ -7,6 +7,7 @@ import hashlib
 import os
 import re
 import signal
+import sre_parse
 import sys
 from typing import Generator
 from typing import NamedTuple
@@ -419,7 +420,12 @@ class Screen:
                 'replace with', history='replace', allow_empty=True,
             )
             if response is not PromptResult.CANCELLED:
-                self.file.replace(self, search_response, response)
+                try:
+                    sre_parse.parse_template(response, search_response)
+                except re.error:
+                    self.status.update('invalid replacement string')
+                else:
+                    self.file.replace(self, search_response, response)
 
     def command(self) -> EditResult | None:
         response = self.prompt('', history='command')
diff --git a/tests/features/replace_test.py b/tests/features/replace_test.py
index f42cf10..83e489c 100644
--- a/tests/features/replace_test.py
+++ b/tests/features/replace_test.py
@@ -22,6 +22,16 @@ def test_replace_invalid_regex(run):
         h.await_text("invalid regex: '('")
 
 
+def test_replace_invalid_replacement(run, ten_lines):
+    with run(str(ten_lines)) as h, and_exit(h):
+        h.press('^\\')
+        h.await_text('search (to replace):')
+        h.press_and_enter('line_0')
+        h.await_text('replace with:')
+        h.press_and_enter('\\')
+        h.await_text('invalid replacement string')
+
+
 def test_replace_cancel_at_replace_string(run):
     with run() as h, and_exit(h):
         h.press('^\\')