move get_merge_bases() to core lib.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/commit.c b/commit.c
index e51ffa1c6cf5948c0e6c6d0b905fc868f4464ccf..0431027ef2398a8fc48b5d4fff251d87efcd62c0 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -846,3 +846,243 @@ void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
        }
        free(nodes);
 }
+
+/* merge-rebase stuff */
+
+#define PARENT1 1
+#define PARENT2 2
+#define UNINTERESTING 4
+
+static struct commit *interesting(struct commit_list *list)
+{
+       while (list) {
+               struct commit *commit = list->item;
+               list = list->next;
+               if (commit->object.flags & UNINTERESTING)
+                       continue;
+               return commit;
+       }
+       return NULL;
+}
+
+/*
+ * A pathological example of how this thing works.
+ *
+ * Suppose we had this commit graph, where chronologically
+ * the timestamp on the commit are A <= B <= C <= D <= E <= F
+ * and we are trying to figure out the merge base for E and F
+ * commits.
+ *
+ *                  F
+ *                 / \
+ *            E   A   D
+ *             \ /   /
+ *              B   /
+ *               \ /
+ *                C
+ *
+ * First we push E and F to list to be processed.  E gets bit 1
+ * and F gets bit 2.  The list becomes:
+ *
+ *     list=F(2) E(1), result=empty
+ *
+ * Then we pop F, the newest commit, from the list.  Its flag is 2.
+ * We scan its parents, mark them reachable from the side that F is
+ * reachable from, and push them to the list:
+ *
+ *     list=E(1) D(2) A(2), result=empty
+ *
+ * Next pop E and do the same.
+ *
+ *     list=D(2) B(1) A(2), result=empty
+ *
+ * Next pop D and do the same.
+ *
+ *     list=C(2) B(1) A(2), result=empty
+ *
+ * Next pop C and do the same.
+ *
+ *     list=B(1) A(2), result=empty
+ *
+ * Now it is B's turn.  We mark its parent, C, reachable from B's side,
+ * and push it to the list:
+ *
+ *     list=C(3) A(2), result=empty
+ *
+ * Now pop C and notice it has flags==3.  It is placed on the result list,
+ * and the list now contains:
+ *
+ *     list=A(2), result=C(3)
+ *
+ * We pop A and do the same.
+ *
+ *     list=B(3), result=C(3)
+ *
+ * Next, we pop B and something very interesting happens.  It has flags==3
+ * so it is also placed on the result list, and its parents are marked
+ * uninteresting, retroactively, and placed back on the list:
+ *
+ *    list=C(7), result=C(7) B(3)
+ *
+ * Now, list does not have any interesting commit.  So we find the newest
+ * commit from the result list that is not marked uninteresting.  Which is
+ * commit B.
+ *
+ *
+ * Another pathological example how this thing used to fail to mark an
+ * ancestor of a merge base as UNINTERESTING before we introduced the
+ * postprocessing phase (mark_reachable_commits).
+ *
+ *               2
+ *               H
+ *         1    / \
+ *         G   A   \
+ *         |\ /     \
+ *         | B       \
+ *         |  \       \
+ *          \  C       F
+ *           \  \     /
+ *            \  D   /
+ *             \ |  /
+ *              \| /
+ *               E
+ *
+ *      list                   A B C D E F G H
+ *      G1 H2                  - - - - - - 1 2
+ *      H2 E1 B1               - 1 - - 1 - 1 2
+ *      F2 E1 B1 A2            2 1 - - 1 2 1 2
+ *      E3 B1 A2               2 1 - - 3 2 1 2
+ *      B1 A2                  2 1 - - 3 2 1 2
+ *      C1 A2                  2 1 1 - 3 2 1 2
+ *      D1 A2                  2 1 1 1 3 2 1 2
+ *      A2                     2 1 1 1 3 2 1 2
+ *      B3                     2 3 1 1 3 2 1 2
+ *      C7                     2 3 7 1 3 2 1 2
+ *
+ * At this point, unfortunately, everybody in the list is
+ * uninteresting, so we fail to complete the following two
+ * steps to fully marking uninteresting commits.
+ *
+ *      D7                     2 3 7 7 3 2 1 2
+ *      E7                     2 3 7 7 7 2 1 2
+ *
+ * and we ended up showing E as an interesting merge base.
+ * The postprocessing phase re-injects C and continues traversal
+ * to contaminate D and E.
+ */
+
+static void mark_reachable_commits(struct commit_list *result,
+                                  struct commit_list *list)
+{
+       struct commit_list *tmp;
+
+       /*
+        * Postprocess to fully contaminate the well.
+        */
+       for (tmp = result; tmp; tmp = tmp->next) {
+               struct commit *c = tmp->item;
+               /* Reinject uninteresting ones to list,
+                * so we can scan their parents.
+                */
+               if (c->object.flags & UNINTERESTING)
+                       commit_list_insert(c, &list);
+       }
+       while (list) {
+               struct commit *c = list->item;
+               struct commit_list *parents;
+
+               tmp = list;
+               list = list->next;
+               free(tmp);
+
+               /* Anything taken out of the list is uninteresting, so
+                * mark all its parents uninteresting.  We do not
+                * parse new ones (we already parsed all the relevant
+                * ones).
+                */
+               parents = c->parents;
+               while (parents) {
+                       struct commit *p = parents->item;
+                       parents = parents->next;
+                       if (!(p->object.flags & UNINTERESTING)) {
+                               p->object.flags |= UNINTERESTING;
+                               commit_list_insert(p, &list);
+                       }
+               }
+       }
+}
+
+struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2)
+{
+       struct commit_list *list = NULL;
+       struct commit_list *result = NULL;
+       struct commit_list *tmp = NULL;
+
+       if (rev1 == rev2)
+               return commit_list_insert(rev1, &result);
+
+       parse_commit(rev1);
+       parse_commit(rev2);
+
+       rev1->object.flags |= PARENT1;
+       rev2->object.flags |= PARENT2;
+       insert_by_date(rev1, &list);
+       insert_by_date(rev2, &list);
+
+       while (interesting(list)) {
+               struct commit *commit = list->item;
+               struct commit_list *parents;
+               int flags = commit->object.flags
+                       & (PARENT1 | PARENT2 | UNINTERESTING);
+
+               tmp = list;
+               list = list->next;
+               free(tmp);
+               if (flags == (PARENT1 | PARENT2)) {
+                       insert_by_date(commit, &result);
+
+                       /* Mark parents of a found merge uninteresting */
+                       flags |= UNINTERESTING;
+               }
+               parents = commit->parents;
+               while (parents) {
+                       struct commit *p = parents->item;
+                       parents = parents->next;
+                       if ((p->object.flags & flags) == flags)
+                               continue;
+                       parse_commit(p);
+                       p->object.flags |= flags;
+                       insert_by_date(p, &list);
+               }
+       }
+
+       if (!result)
+               return NULL;
+
+       if (result->next && list)
+               mark_reachable_commits(result, list);
+
+       /* cull duplicates */
+       for (tmp = result, list = NULL; tmp; ) {
+               struct commit *commit = tmp->item;
+               struct commit_list *next = tmp->next;
+               if (commit->object.flags & UNINTERESTING) {
+                       if (list != NULL)
+                               list->next = next;
+                       free(tmp);
+               } else {
+                       if (list == NULL)
+                               result = tmp;
+                       list = tmp;
+                       commit->object.flags |= UNINTERESTING;
+               }
+
+               tmp = next;
+       }
+
+       /* reset flags */
+       clear_commit_marks(rev1, PARENT1 | PARENT2 | UNINTERESTING);
+       clear_commit_marks(rev2, PARENT1 | PARENT2 | UNINTERESTING);
+
+       return result;
+}

diff --git a/commit.h b/commit.h
index 7c9ca3fbed728d946e48c787720b3ab5ad575a85..89b9dad7ccfc8ed50bbce3989d4a573eea4c1a99 100644 (file)
--- a/commit.h
+++ b/commit.h
@@ -105,4 +105,6 @@ struct commit_graft *read_graft_line(char *buf, int len);
 int register_commit_graft(struct commit_graft *, int);
 int read_graft_file(const char *graft_file);
 
+extern struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2);
+
 #endif /* COMMIT_H */

diff --git a/merge-base.c b/merge-base.c
index 7d87c20b7520fbf2af6071e3965f350edf77ee49..b41f76cb72d02ba77ec04693ec1023d5707571a1 100644 (file)
--- a/merge-base.c
+++ b/merge-base.c
@@ -2,244 +2,6 @@
 #include "cache.h"
 #include "commit.h"
 
-#define PARENT1 1
-#define PARENT2 2
-#define UNINTERESTING 4
-
-static struct commit *interesting(struct commit_list *list)
-{
-       while (list) {
-               struct commit *commit = list->item;
-               list = list->next;
-               if (commit->object.flags & UNINTERESTING)
-                       continue;
-               return commit;
-       }
-       return NULL;
-}
-
-/*
- * A pathological example of how this thing works.
- *
- * Suppose we had this commit graph, where chronologically
- * the timestamp on the commit are A <= B <= C <= D <= E <= F
- * and we are trying to figure out the merge base for E and F
- * commits.
- *
- *                  F
- *                 / \
- *            E   A   D
- *             \ /   /  
- *              B   /
- *               \ /
- *                C
- *
- * First we push E and F to list to be processed.  E gets bit 1
- * and F gets bit 2.  The list becomes:
- *
- *     list=F(2) E(1), result=empty
- *
- * Then we pop F, the newest commit, from the list.  Its flag is 2.
- * We scan its parents, mark them reachable from the side that F is
- * reachable from, and push them to the list:
- *
- *     list=E(1) D(2) A(2), result=empty
- *
- * Next pop E and do the same.
- *
- *     list=D(2) B(1) A(2), result=empty
- *
- * Next pop D and do the same.
- *
- *     list=C(2) B(1) A(2), result=empty
- *
- * Next pop C and do the same.
- *
- *     list=B(1) A(2), result=empty
- *
- * Now it is B's turn.  We mark its parent, C, reachable from B's side,
- * and push it to the list:
- *
- *     list=C(3) A(2), result=empty
- *
- * Now pop C and notice it has flags==3.  It is placed on the result list,
- * and the list now contains:
- *
- *     list=A(2), result=C(3)
- *
- * We pop A and do the same.
- * 
- *     list=B(3), result=C(3)
- *
- * Next, we pop B and something very interesting happens.  It has flags==3
- * so it is also placed on the result list, and its parents are marked
- * uninteresting, retroactively, and placed back on the list:
- *
- *    list=C(7), result=C(7) B(3)
- * 
- * Now, list does not have any interesting commit.  So we find the newest
- * commit from the result list that is not marked uninteresting.  Which is
- * commit B.
- *
- *
- * Another pathological example how this thing used to fail to mark an
- * ancestor of a merge base as UNINTERESTING before we introduced the
- * postprocessing phase (mark_reachable_commits).
- *
- *               2
- *               H
- *         1    / \
- *         G   A   \
- *         |\ /     \ 
- *         | B       \
- *         |  \       \
- *          \  C       F
- *           \  \     / 
- *            \  D   /   
- *             \ |  /
- *              \| /
- *               E
- *
- *      list                   A B C D E F G H
- *      G1 H2                  - - - - - - 1 2
- *      H2 E1 B1               - 1 - - 1 - 1 2
- *      F2 E1 B1 A2            2 1 - - 1 2 1 2
- *      E3 B1 A2               2 1 - - 3 2 1 2
- *      B1 A2                  2 1 - - 3 2 1 2
- *      C1 A2                  2 1 1 - 3 2 1 2
- *      D1 A2                  2 1 1 1 3 2 1 2
- *      A2                     2 1 1 1 3 2 1 2
- *      B3                     2 3 1 1 3 2 1 2
- *      C7                     2 3 7 1 3 2 1 2
- *
- * At this point, unfortunately, everybody in the list is
- * uninteresting, so we fail to complete the following two
- * steps to fully marking uninteresting commits.
- *
- *      D7                     2 3 7 7 3 2 1 2
- *      E7                     2 3 7 7 7 2 1 2
- *
- * and we ended up showing E as an interesting merge base.
- * The postprocessing phase re-injects C and continues traversal
- * to contaminate D and E.
- */
-
-static void mark_reachable_commits(struct commit_list *result,
-                                  struct commit_list *list)
-{
-       struct commit_list *tmp;
-
-       /*
-        * Postprocess to fully contaminate the well.
-        */
-       for (tmp = result; tmp; tmp = tmp->next) {
-               struct commit *c = tmp->item;
-               /* Reinject uninteresting ones to list,
-                * so we can scan their parents.
-                */
-               if (c->object.flags & UNINTERESTING)
-                       commit_list_insert(c, &list);
-       }
-       while (list) {
-               struct commit *c = list->item;
-               struct commit_list *parents;
-
-               tmp = list;
-               list = list->next;
-               free(tmp);
-
-               /* Anything taken out of the list is uninteresting, so
-                * mark all its parents uninteresting.  We do not
-                * parse new ones (we already parsed all the relevant
-                * ones).
-                */
-               parents = c->parents;
-               while (parents) {
-                       struct commit *p = parents->item;
-                       parents = parents->next;
-                       if (!(p->object.flags & UNINTERESTING)) {
-                               p->object.flags |= UNINTERESTING;
-                               commit_list_insert(p, &list);
-                       }
-               }
-       }
-}
-
-struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2)
-{
-       struct commit_list *list = NULL;
-       struct commit_list *result = NULL;
-       struct commit_list *tmp = NULL;
-
-       if (rev1 == rev2)
-               return commit_list_insert(rev1, &result);
-
-       parse_commit(rev1);
-       parse_commit(rev2);
-
-       rev1->object.flags |= PARENT1;
-       rev2->object.flags |= PARENT2;
-       insert_by_date(rev1, &list);
-       insert_by_date(rev2, &list);
-
-       while (interesting(list)) {
-               struct commit *commit = list->item;
-               struct commit_list *parents;
-               int flags = commit->object.flags
-                       & (PARENT1 | PARENT2 | UNINTERESTING);
-
-               tmp = list;
-               list = list->next;
-               free(tmp);
-               if (flags == (PARENT1 | PARENT2)) {
-                       insert_by_date(commit, &result);
-
-                       /* Mark parents of a found merge uninteresting */
-                       flags |= UNINTERESTING;
-               }
-               parents = commit->parents;
-               while (parents) {
-                       struct commit *p = parents->item;
-                       parents = parents->next;
-                       if ((p->object.flags & flags) == flags)
-                               continue;
-                       parse_commit(p);
-                       p->object.flags |= flags;
-                       insert_by_date(p, &list);
-               }
-       }
-
-       if (!result)
-               return NULL;
-
-       if (result->next && list)
-               mark_reachable_commits(result, list);
-
-       /* cull duplicates */
-       for (tmp = result, list = NULL; tmp; ) {
-               struct commit *commit = tmp->item;
-               struct commit_list *next = tmp->next;
-               if (commit->object.flags & UNINTERESTING) {
-                       if (list != NULL)
-                               list->next = next;
-                       free(tmp);
-               } else {
-                       if (list == NULL)
-                               result = tmp;
-                       list = tmp;
-                       commit->object.flags |= UNINTERESTING;
-               }
-
-               tmp = next;
-       }
-
-       /* reset flags */
-       clear_commit_marks(rev1, PARENT1 | PARENT2 | UNINTERESTING);
-       clear_commit_marks(rev2, PARENT1 | PARENT2 | UNINTERESTING);
-
-       return result;
-}
-
 static int show_all = 0;
 
 static int merge_base(struct commit *rev1, struct commit *rev2)