Allow to ignore paths using a .clang-format-hook-exclude file

Author: barisione

apply-format

@@ -109,6 +109,7 @@ declare apply_to_staged=false
 declare staged=false
 declare in_place=false
 declare style=file
+declare ignored=()
 while [ $# -gt 0 ]; do
     declare arg="$1"
     shift # Past option.
@@ -138,6 +139,16 @@ while [ $# -gt 0 ]; do
             style="$1"
             shift
             ;;
+        --internal-opt-ignore-regex=* )
+            ignored+=("${arg//--internal-opt-ignore-regex=/}")
+            ;;
+        --internal-opt-ignore-regex )
+            ignored+=("${arg//--internal-opt-ignore-regex=/}")
+            [ $# -gt 0 ] || \
+                error_exit "No argument for --internal-opt-ignore-regex option."
+            ignored+=("$1")
+            shift
+            ;;
         -- )
             # Stop processing further arguments.
             if [ $# -gt 0 ]; then
@@ -299,11 +310,21 @@ else # Diff-only.
     read -r -a format_diff_args <<< "$format_diff"
     [ "$in_place" = true ] && format_diff_args+=("-i")
 
+    # Build the regex for paths to consider or ignore.
+    # We use negative lookahead assertions which preceed the list of allowed patterns
+    # (that is, the extensions we want).
+    exclusions_regex=
+    if [ "${#ignored[@]}" -gt 0 ]; then
+        for pattern in "${ignored[@]}"; do
+            exclusions_regex="$exclusions_regex(?!$pattern)"
+        done
+    fi
+
     "${git_args[@]}" "$@" \
         | "${format_diff_args[@]}" \
             -p1 \
             -style="$style" \
-            -iregex='.*\.(c|cpp|cxx|cc|h|m|mm|js|java)' \
+            -iregex="$exclusions_regex"'.*\.(c|cpp|cxx|cc|h|m|mm|js|java)' \
             > "$patch_dest" \
         || exit 1
 

git-pre-commit-format

@@ -260,9 +260,23 @@ fi
 
 readonly style=$(cd "$top_dir" && git config hooks.clangFormatDiffStyle || echo file)
 
+apply_format_opts=(
+    "--style=$style"
+    --cached
+    )
+
+readonly exclusions_file="$top_dir/.clang-format-hook-exclude"
+if [ -e "$exclusions_file" ]; then
+    while IFS= read -r line; do
+        if [[ "$line" && "$line" != "#"* ]]; then
+            apply_format_opts+=("--internal-opt-ignore-regex=$line")
+        fi
+    done < "$exclusions_file"
+fi
+
 readonly patch=$(mktemp)
 trap '{ rm -f "$patch"; }' EXIT
-"$apply_format" --style="$style" --cached > "$patch" || \
+"$apply_format" --style="$style" --cached "${apply_format_opts[@]}" > "$patch" || \
     error_exit $'\nThe apply-format script failed.'
 
 if [ "$(wc -l < "$patch")" -eq 0 ]; then

tests/test_hook.py

@@ -48,6 +48,12 @@ def install(self, allow_errors=False):
                 raise
             return False, exc.output
 
+    def write_ignore_list(self, *args):
+        with WorkDir(os.path.join(self.repo.git_dir, '..')):
+            with open('.clang-format-hook-exclude', 'w') as exclude_file:
+                exclude_file.write('\n'.join(args))
+                exclude_file.write('\n')
+
     def test_install(self):
         res, output = self.install()
         self.assertTrue(res)
@@ -205,6 +211,57 @@ def test_install_from_scripts_dir(self):
             # The file on disk is updated.
             self.assertEqual(self.repo.read_file(data.FILENAME), data.FIXED)
 
+    def test_commit_ignorefile_empty(self):
+        self.install()
+
+        self.repo.write_file(data.FILENAME, data.CODE)
+        self.repo.add(data.FILENAME)
+
+        # Don't ignore anything.
+        self.write_ignore_list()
+
+        self.repo.commit(input_text='a\n')
+        # The file on disk is updated as it's not ignored.
+        self.assertEqual(self.repo.read_file(data.FILENAME), data.FIXED)
+
+    def test_commit_ignorefile_comments_only(self):
+        self.install()
+
+        self.repo.write_file(data.FILENAME, data.CODE)
+        self.repo.add(data.FILENAME)
+
+        # Don't ignore anything, but add comments and empty lines.
+        self.write_ignore_list('# Hello world', '', '# Bar baz')
+
+        self.repo.commit(input_text='a\n')
+        # The file on disk is updated as it's not ignored.
+        self.assertEqual(self.repo.read_file(data.FILENAME), data.FIXED)
+
+    def test_commit_ignorefile_ignore_foo(self):
+        self.install()
+
+        self.repo.write_file(data.FILENAME, data.CODE)
+        self.repo.add(data.FILENAME)
+
+        # Ignore the C file we modify.
+        self.write_ignore_list(data.FILENAME)
+
+        self.repo.commit()
+        # The file on disk is updated but its formatting was not fixed.
+        self.assertEqual(self.repo.read_file(data.FILENAME), data.CODE)
+
+    def test_commit_ignorefile_ignore_pattern(self):
+        self.install()
+
+        self.repo.write_file(data.FILENAME, data.CODE)
+        self.repo.add(data.FILENAME)
+
+        # Ignore the C file we modify through a pattern.
+        self.write_ignore_list(r'f.o\.c')
+
+        self.repo.commit()
+        # The file on disk is updated but its formatting was not fixed.
+        self.assertEqual(self.repo.read_file(data.FILENAME), data.CODE)
 
 
 class HookClonedTestCase(CloneRepoMixin,