feat(checkout): add bindings and api

lib/src/bindings/checkout.dart

@@ -0,0 +1,127 @@
+import 'dart:ffi';
+import 'package:ffi/ffi.dart';
+import '../error.dart';
+import 'libgit2_bindings.dart';
+import '../util.dart';
+
+/// Updates files in the index and the working tree to match the content of the commit
+/// pointed at by HEAD.
+///
+/// Note that this is not the correct mechanism used to switch branches; do not change
+/// your HEAD and then call this method, that would leave you with checkout conflicts
+/// since your working directory would then appear to be dirty. Instead, checkout the
+/// target of the branch and then update HEAD using `setHead` to point to the branch you checked out.
+///
+/// Throws a [LibGit2Error] if error occured.
+void head(
+  Pointer<git_repository> repo,
+  int strategy,
+  String? directory,
+  List<String>? paths,
+) {
+  final initOptions = _initOptions(strategy, directory, paths);
+  final optsC = initOptions[0];
+  final pathPointers = initOptions[1];
+  final strArray = initOptions[2];
+
+  final error = libgit2.git_checkout_head(repo, optsC);
+
+  for (var p in pathPointers) {
+    calloc.free(p);
+  }
+
+  calloc.free(strArray);
+  calloc.free(optsC);
+
+  if (error < 0) {
+    throw LibGit2Error(libgit2.git_error_last());
+  }
+}
+
+/// Updates files in the working tree to match the content of the index.
+///
+/// Throws a [LibGit2Error] if error occured.
+void index(
+  Pointer<git_repository> repo,
+  int strategy,
+  String? directory,
+  List<String>? paths,
+) {
+  final initOptions = _initOptions(strategy, directory, paths);
+  final optsC = initOptions[0];
+  final pathPointers = initOptions[1];
+  final strArray = initOptions[2];
+
+  final error = libgit2.git_checkout_index(repo, nullptr, optsC);
+
+  for (var p in pathPointers) {
+    calloc.free(p);
+  }
+
+  calloc.free(strArray);
+  calloc.free(optsC);
+
+  if (error < 0) {
+    throw LibGit2Error(libgit2.git_error_last());
+  }
+}
+
+/// Updates files in the index and working tree to match the content of the tree
+/// pointed at by the treeish.
+///
+/// Throws a [LibGit2Error] if error occured.
+void tree(
+  Pointer<git_repository> repo,
+  Pointer<git_object> treeish,
+  int strategy,
+  String? directory,
+  List<String>? paths,
+) {
+  final initOptions = _initOptions(strategy, directory, paths);
+  final optsC = initOptions[0];
+  final pathPointers = initOptions[1];
+  final strArray = initOptions[2];
+
+  final error = libgit2.git_checkout_tree(repo, treeish, optsC);
+
+  for (var p in pathPointers) {
+    calloc.free(p);
+  }
+
+  calloc.free(strArray);
+  calloc.free(optsC);
+
+  if (error < 0) {
+    throw LibGit2Error(libgit2.git_error_last());
+  }
+}
+
+List<dynamic> _initOptions(
+  int strategy,
+  String? directory,
+  List<String>? paths,
+) {
+  final optsC = calloc<git_checkout_options>(sizeOf<git_checkout_options>());
+  libgit2.git_checkout_options_init(optsC, GIT_CHECKOUT_OPTIONS_VERSION);
+  optsC.ref.checkout_strategy = strategy;
+  if (directory != null) {
+    optsC.ref.target_directory = directory.toNativeUtf8().cast<Int8>();
+  }
+  List<Pointer<Int8>> pathPointers = [];
+  Pointer<Pointer<Int8>> strArray = nullptr;
+  if (paths != null) {
+    pathPointers = paths.map((e) => e.toNativeUtf8().cast<Int8>()).toList();
+    strArray = calloc(paths.length);
+    for (var i = 0; i < paths.length; i++) {
+      strArray[i] = pathPointers[i];
+    }
+    optsC.ref.paths.strings = strArray;
+    optsC.ref.paths.count = paths.length;
+  }
+
+  var result = <dynamic>[];
+  result.add(optsC);
+  result.add(pathPointers);
+  result.add(strArray);
+  return result;
+}