feat(blob): add more bindings and API methods (#21)

lib/src/bindings/blob.dart

@@ -123,5 +123,51 @@ Pointer<git_oid> createFromDisk({
   }
 }
 
+/// Create an in-memory copy of a blob. The copy must be explicitly free'd or
+/// it will leak.
+Pointer<git_blob> duplicate(Pointer<git_blob> source) {
+  final out = calloc<Pointer<git_blob>>();
+  libgit2.git_blob_dup(out, source);
+  return out.value;
+}
+
+/// Get a buffer with the filtered content of a blob.
+///
+/// This applies filters as if the blob was being checked out to the working
+/// directory under the specified filename. This may apply CRLF filtering or
+/// other types of changes depending on the file attributes set for the blob
+/// and the content detected in it.
+///
+/// Throws a [LibGit2Error] if error occured.
+String filterContent({
+  required Pointer<git_blob> blobPointer,
+  required String asPath,
+  required int flags,
+  git_oid? attributesCommit,
+}) {
+  final out = calloc<git_buf>();
+  final asPathC = asPath.toNativeUtf8().cast<Int8>();
+  final opts = calloc<git_blob_filter_options>();
+  libgit2.git_blob_filter_options_init(opts, GIT_BLOB_FILTER_OPTIONS_VERSION);
+  opts.ref.flags = flags;
+  if (attributesCommit != null) {
+    opts.ref.attr_commit_id = attributesCommit;
+  }
+
+  final error = libgit2.git_blob_filter(out, blobPointer, asPathC, opts);
+
+  calloc.free(asPathC);
+  calloc.free(opts);
+
+  if (error < 0) {
+    calloc.free(out);
+    throw LibGit2Error(libgit2.git_error_last());
+  } else {
+    final result = out.ref.ptr.cast<Utf8>().toDartString(length: out.ref.size);
+    calloc.free(out);
+    return result;
+  }
+}
+
 /// Close an open blob to release memory.
 void free(Pointer<git_blob> blob) => libgit2.git_blob_free(blob);

lib/src/blob.dart

@@ -80,6 +80,11 @@ class Blob {
   /// Size in bytes of the contents of a blob.
   int get size => bindings.size(_blobPointer);
 
+  /// Creates an in-memory copy of a blob.
+  ///
+  /// **IMPORTANT**: Should be freed to release allocated memory.
+  Blob duplicate() => Blob(bindings.duplicate(_blobPointer));
+
   /// Directly generates a [Patch] from the difference between two blobs.
   ///
   /// [newBlob] is the blob for new side of diff, or null for empty blob.
@@ -161,6 +166,35 @@ class Blob {
     );
   }
 
+  /// Returns filtered content of a blob.
+  ///
+  /// This applies filters as if the blob was being checked out to the working
+  /// directory under the specified filename. This may apply CRLF filtering or
+  /// other types of changes depending on the file attributes set for the blob
+  /// and the content detected in it.
+  ///
+  /// [asPath] is path used for file attribute lookups, etc.
+  ///
+  /// [flags] is a combination of [GitBlobFilter] flags to use for filtering
+  /// the blob. Defaults to none.
+  ///
+  /// [attributesCommit] is the commit to load attributes from, when
+  /// [GitBlobFilter.attributesFromCommit] is provided in [flags].
+  ///
+  /// Throws a [LibGit2Error] if error occured.
+  String filterContent({
+    required String asPath,
+    Set<GitBlobFilter> flags = const {},
+    Commit? attributesCommit,
+  }) {
+    return bindings.filterContent(
+      blobPointer: _blobPointer,
+      asPath: asPath,
+      flags: flags.fold(0, (acc, e) => acc | e.value),
+      attributesCommit: attributesCommit?.oid.pointer.ref,
+    );
+  }
+
   /// Releases memory allocated for blob object.
   void free() => bindings.free(_blobPointer);
 

lib/src/git_types.dart

@@ -1728,3 +1728,40 @@ class GitIndexCapability {
   @override
   String toString() => 'GitIndexCapability.$_name';
 }
+
+/// Flags to control the functionality of blob content filtering.
+class GitBlobFilter {
+  const GitBlobFilter._(this._value, this._name);
+  final int _value;
+  final String _name;
+
+  /// When set, filters will not be applied to binary files.
+  static const checkForBinary = GitBlobFilter._(1, 'checkForBinary');
+
+  /// When set, filters will not load configuration from the
+  /// system-wide `gitattributes` in `/etc` (or system equivalent).
+  static const noSystemAttributes = GitBlobFilter._(2, 'noSystemAttributes');
+
+  /// When set, filters will be loaded from a `.gitattributes` file
+  /// in the HEAD commit.
+  static const attributesFromHead = GitBlobFilter._(4, 'attributesFromHead');
+
+  /// When set, filters will be loaded from a `.gitattributes` file
+  /// in the specified commit.
+  static const attributesFromCommit = GitBlobFilter._(
+    8,
+    'attributesFromCommit',
+  );
+
+  static const List<GitBlobFilter> values = [
+    checkForBinary,
+    noSystemAttributes,
+    attributesFromHead,
+    attributesFromCommit,
+  ];
+
+  int get value => _value;
+
+  @override
+  String toString() => 'GitBlobFilter.$_name';
+}

lib/src/repository.dart

@@ -1142,7 +1142,7 @@ class Repository {
   }
 
   /// Checkouts the provided reference [refName] using the given strategy, and
-  /// update the HEAD.
+  /// updates the HEAD.
   ///
   /// If no reference [refName] is given, checkouts from the index.
   ///