add clang-format.sh

This allows to call clang-format in either the in-place editing mode
(default), or the diff mode (`--diff`, will only print the unified diff
between the formatted and the original files.

2 files changed, 187 insertions, 0 deletions

diff --git a/tools/clang-format/.gitattributes b/tools/clang-format/.gitattributes
new file mode 100644
index 0000000..dfdb8b7
--- /dev/null
+++ b/tools/clang-format/.gitattributes
@@ -0,0 +1 @@
+*.sh text eol=lf
diff --git a/tools/clang-format/clang-format.sh b/tools/clang-format/clang-format.sh
new file mode 100755
index 0000000..00fe712
--- /dev/null
+++ b/tools/clang-format/clang-format.sh
@@ -0,0 +1,186 @@
+#!/usr/bin/env bash
+
+# Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "cmake-common" project.
+# For details, see https://github.com/egor-tensin/cmake-common.
+# Distributed under the MIT License.
+
+set -o errexit -o nounset -o pipefail
+
+# Utility
+
+script_name="$( basename -- "${BASH_SOURCE[0]}" )"
+readonly script_name
+
+dump() {
+    local prefix="${FUNCNAME[0]}"
+    [ "${#FUNCNAME[@]}" -gt 1 ] && prefix="${FUNCNAME[1]}"
+
+    local msg
+    for msg; do
+        echo "$script_name: $prefix: $msg"
+    done
+}
+
+# Settings
+
+clang_format='clang-format'
+clang_format_style='file'
+clang_format_diff=
+
+update_clang_format() {
+    if [ "$#" -ne 1 ]; then
+        echo "usage: ${FUNCNAME[0]} CLANG_FORMAT_PATH" >&2
+        return 1
+    fi
+
+    local new_clang_format="$1"
+
+    if ! command -v "$new_clang_format" > /dev/null 2>&1; then
+        dump "couldn't find clang-format at: $new_clang_format" >&2
+        return 1
+    fi
+
+    clang_format="$new_clang_format"
+}
+
+# Command line parsing
+
+script_usage() {
+    local msg
+    for msg; do
+        echo "$script_name: $msg"
+    done
+
+    echo "usage: $script_name [-h|--help] [-b|--clang-format PATH] [-s|--style STYLE] [--diff]
+  -h,--help            show this message and exit
+  -b,--clang-format    set path to clang-format executable
+  -s,--style           clang-format -style parameter argument
+  --diff               don't edit the files, just show the diff"
+}
+
+parse_script_options() {
+    while [ "$#" -gt 0 ]; do
+        local key="$1"
+        shift
+
+        case "$key" in
+            -h|--help)
+                script_usage
+                exit 0
+                ;;
+            --diff)
+                clang_format_diff=1
+                continue
+                ;;
+            -b|--clang-format|-s|--style)
+                ;;
+            *)
+                script_usage "unrecognized parameter: $key" >&2
+                exit 1
+                ;;
+        esac
+
+        if [ "$#" -eq 0 ]; then
+            script_usage "missing argument for parameter: $key" >&2
+            exit 1
+        fi
+
+        local value="$1"
+        shift
+
+        case "$key" in
+            -b|--clang-format)
+                update_clang_format "$value"
+                ;;
+            -s|--style)
+                clang_format_style="$value"
+                ;;
+            *)
+                script_usage "unrecognized parameter: $key" >&2
+                exit 1
+                ;;
+        esac
+    done
+}
+
+# Routines for running clang-format
+
+run_clang_format_diff() {
+    local exit_code=0
+    local file
+
+    for file; do
+        if "$clang_format" "-style=$clang_format_style" -- "$file" | diff --unified --label="$file (original)" --label="$file (clang-format)" -- "$file" -; then
+            continue
+        else
+            exit_code="$?"
+            [ "$exit_code" -eq 1 ] && continue
+            break
+        fi
+    done
+
+    return "$exit_code"
+}
+
+run_clang_format_edit() {
+    "$clang_format" -i "-style=$clang_format_style" -- "$@"
+}
+
+run_clang_format() {
+    if [ -z "$clang_format_diff" ]; then
+        run_clang_format_edit "$@"
+    else
+        run_clang_format_diff "$@"
+    fi
+}
+
+# File traversal
+
+list_all_files() {
+    git ls-tree -r -z --name-only HEAD
+}
+
+declare -a cpp_extensions=(c h cc hh cpp hpp cxx hxx cp c++)
+
+list_cpp_files() {
+    local -A cpp_extension_set
+    local ext
+
+    for ext in ${cpp_extensions[@]+"${cpp_extensions[@]}"}; do
+        cpp_extension_set[$ext]=1
+    done
+
+    local -a files=()
+    local file
+
+    while IFS= read -d '' -r file; do
+        basename="$( basename -- "$file" )"
+        ext="${basename##*.}"
+        [ "$ext" = "$basename" ] && continue # No .EXTension
+
+        [ -n "${cpp_extension_set[$ext]+x}" ] && files+=("$file")
+    done < <( list_all_files )
+
+    printf -- '%s\0' ${files[@]+"${files[@]}"}
+}
+
+# Main routines
+
+process_cpp_files() {
+    local -a files=()
+    local file
+
+    while IFS= read -d '' -r file; do
+        files+=("$file")
+    done < <( list_cpp_files )
+
+    run_clang_format ${files[@]+"${files[@]}"}
+}
+
+main() {
+    parse_script_options "$@"
+    process_cpp_files
+}
+
+main "$@"