Add swift-format configuration options

Author: ahoppen

.swift-format

@@ -0,0 +1,18 @@
+{
+    "version": 1,
+    "lineLength": 1000,
+    "indentation": {
+        "spaces": 2
+    },
+    "lineBreakBeforeEachArgument": true,
+    "indentConditionalCompilationBlocks": false,
+    "rules": {
+        "AlwaysUseLowerCamelCase": false,
+        "AmbiguousTrailingClosureOverload": false,
+        "DontRepeatTypeInStaticProperties": false,
+        "NoBlockComments": false,
+        "Spacing": false,
+        "UseLetInEveryBoundCaseVariable": false,
+        "UseSynthesizedInitializer": false
+    }
+}

format.py

@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+
+import argparse
+import subprocess
+from pathlib import Path
+from textwrap import dedent
+from typing import List
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(description='''
+    Format files in SwiftSyntax using swift-format. If swift-format is installed in your
+    PATH or passed using --swift-format that executable is used to format the files.
+    Otherwise swift-format is cloned and built by this script into /tmp
+    ''')
+    parser.add_argument(
+        '--swift-format', default='swift-format',
+        help='''
+        The path to the swift-format executable.
+        Looks for swift-format in PATH by default.
+        ''')
+    parser.add_argument(
+        '--lint', action='store_true',
+        help='''
+        Instead of formatting in-place verify that the files are correctly formatted.
+        Exit with 1 if files are not correctly formatted.
+        '''
+    )
+
+    return parser.parse_args()
+
+
+def clone_and_build_swiftformat() -> Path:
+    """
+    Clone the swift-format repository into /tmp, build it and return the path to the
+    swift-format executable. This allows format.py to be fully standalone and run even
+    if swift-format is not installed on your system yet.
+    """
+    print(dedent('''\
+        swift-format was not found on your system. Cloning and building swift-format in /tmp/swift-format.
+
+        To skip this step in the future build swift-format (https://github.com/apple/swift-format) yourself and
+        - put it in your PATH or
+        - pass the path to it to this script via --swift-format
+        '''))  # noqa: E501
+    try:
+        swift_format_dir = Path('/tmp/swift-format')
+        if swift_format_dir.exists():
+            subprocess.check_call(['git', 'pull'], cwd=swift_format_dir)
+        else:
+            subprocess.check_call([
+                'git', 'clone',
+                'https://github.com/apple/swift-format.git'
+            ], cwd=swift_format_dir.parent)
+        subprocess.check_call([
+            'swift', 'build',
+            '--product', 'swift-format'
+            ], cwd=swift_format_dir)
+        bin_dir = subprocess.check_output([
+            'swift', 'build',
+            '--show-bin-path'
+        ], encoding='utf-8', cwd=swift_format_dir)
+        return Path(bin_dir.rstrip()) / 'swift-format'
+    except subprocess.CalledProcessError:
+        print(dedent('''
+            format.py failed to build swift-format.
+
+            Please build it yourself and pass the swift-format executable to format.py
+            using the --swift-format parameter.
+            '''))
+        raise SystemExit(1)
+
+
+def find_swiftformat(swift_format: str) -> Path:
+    """
+    Return a fully resolved path to the swift-format executable named or located at
+    `swift_format`.
+    If swift-format couldn't be found, this clones and builds swift-format.
+    """
+    try:
+        output = subprocess.check_output(['which', swift_format], encoding='utf-8')
+        return Path(output.rstrip())
+    except subprocess.CalledProcessError:
+        return clone_and_build_swiftformat()
+
+
+def get_files_to_format() -> List[Path]:
+    package_dir = Path(__file__).parent
+    files_to_format: List[Path] = []
+    for swift_file_path in (package_dir / "Sources").glob('**/*.swift'):
+        if swift_file_path.match('**/generated/**') or \
+           swift_file_path.match('**/gyb_generated/syntax_nodes/**') or \
+           swift_file_path.match('**/gyb_generated/**'):
+            # Don't format generated files
+            continue
+        files_to_format.append(swift_file_path)
+
+    for swift_file_path in (package_dir / "Tests").glob('**/*.swift'):
+        if swift_file_path.match('**/Inputs/**'):
+            # Don't format test input files
+            continue
+        files_to_format.append(swift_file_path)
+
+    return files_to_format
+
+
+def main() -> None:
+    args = parse_args()
+    swift_format = find_swiftformat(args.swift_format)
+    files_to_format = get_files_to_format()
+
+    if args.lint:
+        try:
+            subprocess.check_call([swift_format, 'lint', '--parallel', '--strict'] +
+                                  files_to_format)
+        except subprocess.CalledProcessError:
+            print(dedent('''\
+                The swift-syntax repo is not formatted according to the style guides.
+                Run the following command to format swift-syntax
+
+                swift-syntax/format.py --swift-format /path/to/executable/swift-format
+
+                If the issue persists, fix any remaining issues manually and verify they
+                match the swift-format style using
+
+                swift-syntax/format.py --swift-format /path/to/executable/swift-format --lint
+                '''))  # noqa: E501
+            raise SystemExit(1)
+    else:
+        subprocess.check_call([swift_format, 'format', '--in-place', '--parallel'] +
+                              files_to_format)
+
+
+if __name__ == '__main__':
+    main()