[ffigen] ffigen only regenerates if input mtimes > output mtimes (#874)

pkgs/ffigen/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 12.0.1
+
+- ffigen now only regenerates the dart bindings only if input (the `config.yaml` 
+and header files) mtimes is greater than the output mtimes.
+
 ## 12.0.0-wip
 
 - Global variables are now compatible with the `ffi-native` option.

pkgs/ffigen/lib/src/executables/ffigen.dart

@@ -56,10 +56,19 @@ void main(List<String> args) async {
   final library = parse(config);
 
   // Generate file for the parsed bindings.
-  final gen = File(config.output);
-  library.generateFile(gen);
-  _logger
-      .info(successPen('Finished, Bindings generated in ${gen.absolute.path}'));
+  final fileToBeGenerated = File(config.output);
+
+  // Consider regenif config has been updated
+  final bool inputHasBeenUpdated = _inputHasBeenUpdated(
+      fileToBeGenerated, [config.filename!, ...config.headers.entryPoints]);
+  if (!inputHasBeenUpdated) {
+    _logger.info('Bindings are up-to-date. No changes to headers detected.');
+    return;
+  }
+
+  library.generateFile(fileToBeGenerated);
+  _logger.info(successPen(
+      'Finished, Bindings generated in ${fileToBeGenerated.absolute.path}'));
 
   if (config.symbolFile != null) {
     final symbolFileGen = File(config.symbolFile!.output);
@@ -70,6 +79,25 @@ void main(List<String> args) async {
   }
 }
 
+bool _inputHasBeenUpdated(
+    File fileToBeGenerated, List<String> configAndHeaders) {
+  // if file does not exist, consider it needs to be generated.
+  if (!fileToBeGenerated.existsSync()) {
+    _logger.info('Bindings file does not exist, generating bindings.');
+    return true;
+  }
+
+  for (final configOrHeader in configAndHeaders) {
+    final headerMTime = File(configOrHeader).lastModifiedSync();
+
+    if (fileToBeGenerated.existsSync() &&
+        headerMTime.isAfter(fileToBeGenerated.lastModifiedSync())) {
+      return true; // file needs to be regenerated.
+    }
+  }
+  return false;
+}
+
 Config getConfig(ArgResults result, PackageConfig? packageConfig) {
   _logger.info('Running in ${Directory.current}');
   Config config;

pkgs/ffigen/pubspec.yaml

@@ -3,7 +3,7 @@
 # BSD-style license that can be found in the LICENSE file.
 
 name: ffigen
-version: 12.0.0-wip
+version: 12.0.1
 description: >
   Generator for FFI bindings, using LibClang to parse C, Objective-C, and Swift
   files.

pkgs/ffigen/test/code_generator_tests/ffigen_smart_regen/config.yaml

@@ -0,0 +1,11 @@
+# yaml-language-server: $schema=../../ffigen.schema.json
+
+output: 'generated_bindings.dart'
+name: 'OnlyRegenIfUpdated'
+description: 'Holds bindings to the test header files.'
+headers:
+  entry-points:
+    - 'test/code_generator_tests/ffigen_smart_regen/headers/header1.h'
+  include-directives:
+    - '**header*.h'
+comments: true

pkgs/ffigen/test/code_generator_tests/ffigen_smart_regen/generated_bindings.dart

@@ -0,0 +1,4 @@
+// AUTO GENERATED FILE, DO NOT EDIT.
+//
+// Generated by `package:ffigen`.
+// ignore_for_file: type=lint

pkgs/ffigen/test/code_generator_tests/ffigen_smart_regen/headers/file.c

@@ -0,0 +1,21 @@
+#include "header1.h"
+
+int doNothingToStruct1(Color dumInput) {
+  return 0;
+}
+
+int doNothingToStruct2(Vertex dumInput) {
+  return 0;
+}
+
+int doNothingToStruct3(Vector2 dumInput) {
+  return 0;
+}
+
+int doNothingToStruct4(Vector3 dumInput) {
+  return 0;
+}
+
+int doNothingToStruct5(Vector4 dumInput) {
+  return 0;
+}

pkgs/ffigen/test/code_generator_tests/ffigen_smart_regen/headers/header1.h

@@ -0,0 +1,35 @@
+typedef struct {
+    int m_red;
+    int m_green;
+    int m_blue;
+} Color;
+
+
+typedef struct {
+    float x, y, z;
+    Color color;
+} Vertex;
+
+typedef struct {
+    float x, y;
+} Vector2;
+
+typedef struct {
+    float x, y, z;
+} Vector3;
+
+typedef struct {
+    float x, y, z, w;
+} Vector4;
+
+typedef struct {
+    float m[4][4];
+} Matrix4x4;
+
+int doNothing(double dumInput, unsigned int dumInput2) {
+  return 0;
+}
+
+int doNothingToStruct6(Matrix4x4 dumInput) {
+  return 0;
+}

pkgs/ffigen/test/code_generator_tests/smart_regen_test.dart

@@ -0,0 +1,143 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:ffigen/ffigen.dart';
+import 'package:path/path.dart' as path;
+import 'package:test/test.dart';
+
+import '../test_utils.dart';
+
+final _testDirectoryPath =
+    path.join("test", "code_generator_tests", "ffigen_smart_regen");
+final _configYamlPath = path.join(_testDirectoryPath, "config.yaml");
+final _headerFiles = Directory(path.join(_testDirectoryPath, "headers"))
+    .listSync()
+    .map((e) => e.path)
+    .where((e) => e.endsWith('.h') || e.endsWith('.c'));
+final _configAndHeaders = [
+  _configYamlPath,
+  ..._headerFiles,
+];
+
+void main() {
+  group('_inputHasBeenUpdated', () {
+    test('should return true if file does not exist', () {
+      _cleanUp();
+
+      final fileToBeGenerated =
+          File(path.join(_testDirectoryPath, "generated_bindings.dart"));
+
+      final result = _inputHasBeenUpdated(fileToBeGenerated, _configAndHeaders);
+
+      expect(result, isTrue);
+    });
+
+    test(
+        'should return true if the config or any header file is newer than the generated file',
+        () {
+      _ensureGeneratedBindings();
+      final fileToBeGenerated =
+          File(path.join(_testDirectoryPath, "generated_bindings.dart"));
+
+      // Set the last modified time of the generated file to be older than the header files
+      fileToBeGenerated.setLastModifiedSync(DateTime(2022, 1, 1));
+
+      // Set the last modified time of one of the header files to be newer than the generated file
+      final headerFile =
+          File(path.join(_testDirectoryPath, 'headers', 'header1.h'));
+      headerFile.setLastModifiedSync(DateTime(2023, 1, 1));
+
+      final result = _inputHasBeenUpdated(fileToBeGenerated, _configAndHeaders);
+
+      expect(result, isTrue);
+    });
+
+    test('should return true if the config is newer than the generated file',
+        () {
+      _ensureGeneratedBindings();
+      final fileToBeGenerated =
+          File(path.join(_testDirectoryPath, "generated_bindings.dart"));
+
+      // Set the last modified time of the generated file to be older than the header files
+      fileToBeGenerated.setLastModifiedSync(DateTime(2022, 1, 1));
+
+      // Set the last modified time of the config file to be newer than the generated file
+      final configFile = File(_configYamlPath);
+      configFile.setLastModifiedSync(DateTime(2023, 1, 1));
+
+      final result = _inputHasBeenUpdated(fileToBeGenerated, _configAndHeaders);
+
+      expect(result, isTrue);
+    });
+
+    test(
+        'should return false if the config and header files are all older than the generated file',
+        () {
+      _ensureGeneratedBindings();
+      final fileToBeGenerated =
+          File(path.join(_testDirectoryPath, "generated_bindings.dart"));
+
+      // Set the last modified time of the generated file to be older than the header files
+      fileToBeGenerated.setLastModifiedSync(DateTime.now());
+
+      final configFile = File(_configYamlPath);
+      configFile.setLastModifiedSync(DateTime(2021, 1, 1));
+
+      // Set the last modified time of the header files to be newer than the generated file
+      final headerFile1 =
+          File(path.join(_testDirectoryPath, 'headers', 'header1.h'));
+      headerFile1.setLastModifiedSync(DateTime(2023, 1, 1));
+
+      final headerFile2 =
+          File(path.join(_testDirectoryPath, 'headers', 'file.c'));
+      headerFile2.setLastModifiedSync(DateTime(2023, 1, 1));
+
+      final result = _inputHasBeenUpdated(fileToBeGenerated, _configAndHeaders);
+
+      expect(result, isFalse);
+    });
+
+    _cleanUp();
+  });
+}
+
+/// Returns true if the file needs to be regenerated.
+
+bool _inputHasBeenUpdated(
+    File fileToBeGenerated, List<String> configAndHeaders) {
+  // if file does not exist, consider it needs to be generated.
+  if (!fileToBeGenerated.existsSync()) {
+    return true;
+  }
+
+  for (final configOrHeader in configAndHeaders) {
+    final headerMTime = File(configOrHeader).lastModifiedSync();
+
+    if (fileToBeGenerated.existsSync() &&
+        headerMTime.isAfter(fileToBeGenerated.lastModifiedSync())) {
+      return true; // file needs to be regenerated.
+    }
+  }
+  return false;
+}
+
+void _ensureGeneratedBindings() {
+  final config = testConfigFromPath(path.join(
+      'test', 'code_generator_tests', 'ffigen_smart_regen', 'config.yaml'));
+  final library = parse(config);
+  // Generate file for the parsed bindings.
+  final fileToBeGenerated = File(config.output);
+
+  library.generateFile(fileToBeGenerated);
+}
+
+void _cleanUp() {
+  final genFile =
+      File(path.join(_testDirectoryPath, "generated_bindings.dart"));
+  if (genFile.existsSync()) {
+    genFile.deleteSync();
+  }
+}