feat(revwalk): add bindings and api

lib/src/revwalk.dart

@@ -0,0 +1,89 @@
+import 'dart:ffi';
+import 'bindings/libgit2_bindings.dart';
+import 'bindings/revwalk.dart' as bindings;
+import 'commit.dart';
+import 'oid.dart';
+import 'repository.dart';
+import 'enums.dart';
+import 'util.dart';
+
+class RevWalk {
+  /// Initializes a new instance of the [RevWalk] class.
+  /// Should be freed with `free()` to release allocated memory.
+  RevWalk(Repository repo) {
+    libgit2.git_libgit2_init();
+    _revWalkPointer = bindings.create(repo.pointer);
+  }
+
+  /// Pointer to memory address for allocated [RevWalk] object.
+  late final Pointer<git_revwalk> _revWalkPointer;
+
+  /// Returns the list of commits from the revision walk.
+  ///
+  /// Default sorting is reverse chronological order (default in git).
+  List<Commit> walk() {
+    final repoPointer = bindings.repository(_revWalkPointer);
+    var result = <Commit>[];
+
+    final commits = bindings.walk(repoPointer, _revWalkPointer);
+    for (var commit in commits) {
+      result.add(Commit(commit));
+    }
+
+    return result;
+  }
+
+  /// Changes the sorting mode when iterating through the repository's contents.
+  ///
+  /// Changing the sorting mode resets the walker.
+  ///
+  /// Throws a [LibGit2Error] if error occured.
+  void sorting(GitSort sorting) {
+    bindings.sorting(
+      _revWalkPointer,
+      // in libgit2 GIT_SORT_REVERSE flag is integer 4 so we are adding 1 to our enum index
+      sorting == GitSort.reverse ? sorting.index + 1 : sorting.index,
+    );
+  }
+
+  /// Adds a new root for the traversal.
+  ///
+  /// The pushed commit will be marked as one of the roots from which to start the walk.
+  /// This commit may not be walked if it or a child is hidden.
+  ///
+  /// At least one commit must be pushed onto the walker before a walk can be started.
+  ///
+  /// The given id must belong to a committish on the walked repository.
+  ///
+  /// Throws a [LibGit2Error] if error occured.
+  void push(Oid oid) => bindings.push(_revWalkPointer, oid.pointer);
+
+  /// Marks a commit (and its ancestors) uninteresting for the output.
+  ///
+  /// The given id must belong to a committish on the walked repository.
+  ///
+  /// The resolved commit and all its parents will be hidden from the output on the revision walk.
+  ///
+  /// Throws a [LibGit2Error] if error occured.
+  void hide(Oid oid) => bindings.hide(_revWalkPointer, oid.pointer);
+
+  /// Resets the revision walker for reuse.
+  ///
+  /// This will clear all the pushed and hidden commits, and leave the walker in a blank state
+  /// (just like at creation) ready to receive new commit pushes and start a new walk.
+  ///
+  /// The revision walk is automatically reset when a walk is over.
+  void reset() => bindings.reset(_revWalkPointer);
+
+  /// Simplify the history by first-parent.
+  ///
+  /// No parents other than the first for each commit will be enqueued.
+  ///
+  /// Throws a [LibGit2Error] if error occured.
+  void simplifyFirstParent() => bindings.simplifyFirstParent(_revWalkPointer);
+
+  /// Releases memory allocated for [RevWalk] object.
+  void free() {
+    bindings.free(_revWalkPointer);
+  }
+}