From 566407dd94804f02e84c049121cbb7c9dbf192c8 Mon Sep 17 00:00:00 2001
From: danny crasto <danwald79@gmail.com>
Date: Wed, 10 Sep 2025 21:20:47 +0400
Subject: [PATCH] Support extended git PatchFile Prefix

Extend support of traditional source/target Patch File prefix'
to include git's
 [mnemonicPrefix](https://git-scm.com/docs/diff-config#Documentation/diff-config.txt-diffmnemonicPrefix).

- uses regex for prefix match
- adds tests for old and new behavior
---
 tests/test_patchedfile.py | 12 ++++++++++++
 unidiff/constants.py      |  2 ++
 unidiff/patch.py          |  3 ++-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/tests/test_patchedfile.py b/tests/test_patchedfile.py
index cd1342a..962fad2 100644
--- a/tests/test_patchedfile.py
+++ b/tests/test_patchedfile.py
@@ -52,3 +52,15 @@ def test_is_modified_file(self):
         hunk = Hunk(src_start=1, src_len=10, tgt_start=1, tgt_len=8)
         self.patched_file.append(hunk)
         self.assertTrue(self.patched_file.is_modified_file)
+
+    def test_default_file_prefix(self):
+        default_prefix = PatchedFile(source="a/foo/", target="b/foo/")
+        self.assertTrue(default_prefix.path == "foo/")
+
+    def test_git_mnemonic_file_prefix(self):
+        default_prefix = PatchedFile(source="i/foo/", target="c/foo/")
+        self.assertTrue(default_prefix.path == "foo/")
+
+    def test_no_file_prefix(self):
+        default_prefix = PatchedFile(source="/foo/", target="/foo/")
+        self.assertTrue(default_prefix.path == "/foo/")
diff --git a/unidiff/constants.py b/unidiff/constants.py
index 266d59c..be63883 100644
--- a/unidiff/constants.py
+++ b/unidiff/constants.py
@@ -71,6 +71,8 @@
     r'(?P<source_filename>[^\t]+?)(?:\t(?P<source_timestamp>[\s0-9:\+-]+))?'
     r'(?: and (?P<target_filename>[^\t]+?)(?:\t(?P<target_timestamp>[\s0-9:\+-]+))?)? (differ|has changed)')
 
+RE_PATCH_FILE_PREFIX = re.compile(r"^[abciow12]/.*$")
+
 DEFAULT_ENCODING = 'UTF-8'
 
 DEV_NULL = '/dev/null'
diff --git a/unidiff/patch.py b/unidiff/patch.py
index bee28fc..86db378 100644
--- a/unidiff/patch.py
+++ b/unidiff/patch.py
@@ -50,6 +50,7 @@
     RE_TARGET_FILENAME,
     RE_NO_NEWLINE_MARKER,
     RE_BINARY_DIFF,
+    RE_PATCH_FILE_PREFIX,
 )
 from unidiff.errors import UnidiffParseError
 
@@ -397,7 +398,7 @@ def path(self):
         if quoted:
             filepath = filepath[1:-1]
 
-        if filepath.startswith('a/') or filepath.startswith('b/'):
+        if RE_PATCH_FILE_PREFIX.match(filepath):
             filepath = filepath[2:]
 
         if quoted: