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, 72 insertions, 0 deletions

diff --git a/src/diff.c b/src/diff.c
index 05ef4f16b..97ccb3cbd 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -11,6 +11,8 @@
 #include "attr_file.h"
 #include "filter.h"
 #include "pathspec.h"
+#include "index.h"
+#include "odb.h"
 
 #define DIFF_FLAG_IS_SET(DIFF,FLAG) (((DIFF)->opts.flags & (FLAG)) != 0)
 #define DIFF_FLAG_ISNT_SET(DIFF,FLAG) (((DIFF)->opts.flags & (FLAG)) == 0)
@@ -1170,3 +1172,73 @@ int git_diff_tree_to_workdir(
 
 	return error;
 }
+
+size_t git_diff_num_deltas(git_diff_list *diff)
+{
+	assert(diff);
+	return (size_t)diff->deltas.length;
+}
+
+size_t git_diff_num_deltas_of_type(git_diff_list *diff, git_delta_t type)
+{
+	size_t i, count = 0;
+	git_diff_delta *delta;
+
+	assert(diff);
+
+	git_vector_foreach(&diff->deltas, i, delta) {
+		count += (delta->status == type);
+	}
+
+	return count;
+}
+
+int git_diff__paired_foreach(
+	git_diff_list *idx2head,
+	git_diff_list *wd2idx,
+	int (*cb)(git_diff_delta *i2h, git_diff_delta *w2i, void *payload),
+	void *payload)
+{
+	int cmp;
+	git_diff_delta *i2h, *w2i;
+	size_t i, j, i_max, j_max;
+	int (*strcomp)(const char *, const char *);
+
+	i_max = idx2head ? idx2head->deltas.length : 0;
+	j_max = wd2idx   ? wd2idx->deltas.length   : 0;
+
+	/* Get appropriate strcmp function */
+	strcomp = idx2head ? idx2head->strcomp : wd2idx ? wd2idx->strcomp : NULL;
+
+	/* Assert both iterators use matching ignore-case. If this function ever
+	* supports merging diffs that are not sorted by the same function, then
+	* it will need to spool and sort on one of the results before merging
+	*/
+	if (idx2head && wd2idx) {
+		assert(idx2head->strcomp == wd2idx->strcomp);
+	}
+
+	for (i = 0, j = 0; i < i_max || j < j_max; ) {
+		i2h = idx2head ? GIT_VECTOR_GET(&idx2head->deltas,i) : NULL;
+		w2i = wd2idx   ? GIT_VECTOR_GET(&wd2idx->deltas,j)   : NULL;
+
+		cmp = !w2i ? -1 : !i2h ? 1 :
+			strcomp(i2h->old_file.path, w2i->old_file.path);
+
+		if (cmp < 0) {
+			if (cb(i2h, NULL, payload))
+				return GIT_EUSER;
+			i++;
+		} else if (cmp > 0) {
+			if (cb(NULL, w2i, payload))
+				return GIT_EUSER;
+			j++;
+		} else {
+			if (cb(i2h, w2i, payload))
+				return GIT_EUSER;
+			i++; j++;
+		}
+	}
+
+	return 0;
+}