feat(index): add ability to change attributes of index entry

lib/libgit2dart.dart

@@ -2,3 +2,4 @@ export 'src/repository.dart';
 export 'src/config.dart';
 export 'src/error.dart';
 export 'src/reference.dart';
+export 'src/types.dart';

lib/src/index.dart

@@ -2,6 +2,7 @@ import 'dart:ffi';
 import 'package:ffi/ffi.dart';
 import 'bindings/libgit2_bindings.dart';
 import 'bindings/index.dart' as bindings;
+import 'oid.dart';
 import 'util.dart';
 
 class Index {
@@ -116,18 +117,30 @@ class IndexEntry {
   /// Pointer to memory address for allocated index entry object.
   late final Pointer<git_index_entry> _indexEntryPointer;
 
-  /// Returns path to file.
+  /// Unique identity of the index entry.
+  Oid get id => Oid.fromSHA(sha);
+
+  set id(Oid oid) => _indexEntryPointer.ref.id = oid.pointer.ref;
+
+  /// Path of the index entry.
   String get path => _indexEntryPointer.ref.path.cast<Utf8>().toDartString();
 
-  /// Returns sha-1 of file.
+  set path(String path) =>
-  String get sha {
+      _indexEntryPointer.ref.path = path.toNativeUtf8().cast<Int8>();
+
+  /// Returns id of the index entry as sha-1 hex.
+  String get sha => _oidToHex(_indexEntryPointer.ref.id);
+
+  /// Mode of the index entry.
+  int get mode => _indexEntryPointer.ref.mode;
+
+  set mode(int mode) => _indexEntryPointer.ref.mode = mode;
+
+  String _oidToHex(git_oid oid) {
     var hex = StringBuffer();
     for (var i = 0; i < 20; i++) {
-      hex.write(_indexEntryPointer.ref.id.id[i].toRadixString(16));
+      hex.write(oid.id[i].toRadixString(16));
     }
     return hex.toString();
   }
-
-  /// Returns mode of file.
-  int get mode => _indexEntryPointer.ref.mode;
 }

lib/src/types.dart

@@ -0,0 +1,9 @@
+/// Valid modes for index and tree entries.
+abstract class GitFilemode {
+  static const int unreadable = 0;
+  static const int tree = 16384;
+  static const int blob = 33188;
+  static const int blobExecutable = 33261;
+  static const int link = 40960;
+  static const int commit = 57344;
+}

test/index_test.dart

@@ -1,8 +1,10 @@
 import 'dart:io';
 
+import 'package:libgit2dart/libgit2dart.dart';
 import 'package:test/test.dart';
 import 'package:libgit2dart/src/index.dart';
 import 'package:libgit2dart/src/repository.dart';
+import 'package:libgit2dart/src/types.dart';
 import 'package:libgit2dart/src/error.dart';
 
 import 'helpers/util.dart';
@@ -60,6 +62,22 @@ void main() {
       expect(() => index[10], throwsA(isA<ArgumentError>()));
     });
 
+    test('successfully changes attributes', () {
+      final entry = index['file'];
+      final otherEntry = index['feature_file'];
+
+      expect(entry.id == otherEntry.id, false);
+      expect(entry.mode, isNot(GitFilemode.blobExecutable));
+
+      entry.path = 'some.txt';
+      entry.id = otherEntry.id;
+      entry.mode = GitFilemode.blobExecutable;
+
+      expect(entry.path, 'some.txt');
+      expect(entry.id == otherEntry.id, true);
+      expect(entry.mode, GitFilemode.blobExecutable);
+    });
+
     test('clears the contents', () {
       expect(index.count, 3);
       index.clear();