Reorganize diff and add basic diff driver

This is a significant reorganization of the diff code to break it
into a set of more clearly distinct files and to document the new
organization.  Hopefully this will make the diff code easier to
understand and to extend.

This adds a new `git_diff_driver` object that looks of diff driver
information from the attributes and the config so that things like
function content in diff headers can be provided.  The full driver
spec is not implemented in the commit - this is focused on the
reorganization of the code and putting the driver hooks in place.

This also removes a few #includes from src/repository.h that were
overbroad, but as a result required extra #includes in a variety
of places since including src/repository.h no longer results in
pulling in the whole world.

1 files changed, 54 insertions, 0 deletions

diff --git a/src/diff_file.h b/src/diff_file.h
new file mode 100644
index 000000000..51c6878a9
--- /dev/null
+++ b/src/diff_file.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_diff_file_h__
+#define INCLUDE_diff_file_h__
+
+#include "common.h"
+#include "diff.h"
+#include "diff_driver.h"
+#include "map.h"
+
+/* expanded information for one side of a delta */
+typedef struct {
+	git_repository *repo;
+	const git_diff_options *opts;
+	git_diff_file file;
+	git_diff_driver *driver;
+	git_iterator_type_t src;
+	const git_blob *blob;
+	git_map map;
+} git_diff_file_content;
+
+extern int diff_file_content_init_from_diff(
+	git_diff_file_content *fc,
+	git_diff_list *diff,
+	size_t delta_index,
+	bool use_old);
+
+extern int diff_file_content_init_from_blob(
+	git_diff_file_content *fc,
+	git_repository *repo,
+	const git_diff_options *opts,
+	const git_blob *blob);
+
+extern int diff_file_content_init_from_raw(
+	git_diff_file_content *fc,
+	git_repository *repo,
+	const git_diff_options *opts,
+	const char *buf,
+	size_t buflen);
+
+/* this loads the blob/file-on-disk as needed */
+extern int diff_file_content_load(git_diff_file_content *fc);
+
+/* this releases the blob/file-in-memory */
+extern void diff_file_content_unload(git_diff_file_content *fc);
+
+/* this unloads and also releases any other resources */
+extern void diff_file_content_clear(git_diff_file_content *fc);
+
+#endif