revwalk: Parse revision ranges

All the hard work is already in revparse.

Signed-off-by: Greg Price <price@mit.edu>

include/git2/revwalk.h

@@ -216,6 +216,21 @@ GIT_EXTERN(int) git_revwalk_next(git_oid *out, git_revwalk *walk);
  */
 GIT_EXTERN(void) git_revwalk_sorting(git_revwalk *walk, unsigned int sort_mode);
 
+/**
+ * Push and hide the respective endpoints of the given range.
+ *
+ * The range should be of the form
+ *   <commit>..<commit>
+ * where each <commit> is in the form accepted by 'git_revparse_single'.
+ * The left-hand commit will be hidden and the right-hand commit pushed.
+ *
+ * @param walk the walker being used for the traversal
+ * @param range the range
+ * @return 0 or an error code
+ *
+ */
+GIT_EXTERN(int) git_revwalk_push_range(git_revwalk *walk, const char *range);
+
 /**
  * Free a revision walker previously allocated.
  *

src/revwalk.c

@@ -11,6 +11,7 @@
 #include "pool.h"
 
 #include "revwalk.h"
+#include "git2/revparse.h"
 #include "merge.h"
 
 #include <regex.h>
@@ -228,6 +229,30 @@ int git_revwalk_push_ref(git_revwalk *walk, const char *refname)
 	return push_ref(walk, refname, 0);
 }
 
+int git_revwalk_push_range(git_revwalk *walk, const char *range)
+{
+	git_object *left, *right;
+	int threedots;
+	int error = 0;
+
+	if ((error = git_revparse_rangelike(&left, &right, &threedots, walk->repo, range)))
+		return error;
+	if (threedots) {
+		/* TODO: support "<commit>...<commit>" */
+		giterr_set(GITERR_INVALID, "Symmetric differences not implemented in revwalk");
+		return GIT_EINVALIDSPEC;
+	}
+
+	if ((error = push_commit(walk, git_object_id(left), 1)))
+		goto out;
+	error = push_commit(walk, git_object_id(right), 0);
+
+  out:
+	git_object_free(left);
+	git_object_free(right);
+	return error;
+}
+
 int git_revwalk_hide_ref(git_revwalk *walk, const char *refname)
 {
 	assert(walk && refname);

tests-clar/revwalk/basic.c

@@ -38,6 +38,10 @@ static const int commit_sorting_time_reverse[][6] = {
 	{4, 5, 2, 1, 3, 0}
 };
 
+static const int commit_sorting_segment[][6] = {
+	{1, 2, -1, -1, -1, -1}
+};
+
 #define commit_count 6
 static const int result_bytes = 24;
 
@@ -192,3 +196,11 @@ void test_revwalk_basic__disallow_non_commit(void)
 	cl_git_pass(git_oid_fromstr(&oid, "521d87c1ec3aef9824daf6d96cc0ae3710766d91"));
 	cl_git_fail(git_revwalk_push(_walk, &oid));
 }
+
+void test_revwalk_basic__push_range(void)
+{
+	git_revwalk_reset(_walk);
+	git_revwalk_sorting(_walk, 0);
+	cl_git_pass(git_revwalk_push_range(_walk, "9fd738e~2..9fd738e"));
+	cl_git_pass(test_walk_only(_walk, commit_sorting_segment, 1));
+}