More work on merging with git-read-tree..

[git.git] / read-tree.c

diff --git a/read-tree.c b/read-tree.c
index 3746984..1a575eb 100644 (file)
--- a/read-tree.c
+++ b/read-tree.c
@@ -6,6 +6,7 @@
 #include "cache.h"
 
 static int stage = 0;
+static int update = 0;
 
 static int unpack_tree(unsigned char *sha1)
 {
@@ -130,27 +131,29 @@ static void trivially_merge_cache(struct cache_entry **src, int nr)
        struct cache_entry **dst = src;
        struct cache_entry *old = NULL;
 
-       while (nr) {
+       while (nr--) {
                struct cache_entry *ce, *result;
 
-               ce = src[0];
+               ce = *src++;
 
                /* We throw away original cache entries except for the stat information */
                if (!ce_stage(ce)) {
                        if (old)
                                reject_merge(old);
                        old = ce;
-                       src++;
-                       nr--;
                        active_nr--;
                        continue;
                }
                if (old && !path_matches(old, ce))
                        reject_merge(old);
                if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
+                       result->ce_flags |= htons(CE_UPDATE);
                        /*
                         * See if we can re-use the old CE directly?
                         * That way we get the uptodate stat info.
+                        *
+                        * This also removes the UPDATE flag on
+                        * a match.
                         */
                        if (old && same(old, result)) {
                                *result = *old;
@@ -172,42 +175,113 @@ static void trivially_merge_cache(struct cache_entry **src, int nr)
                 */
                CHECK_OLD(ce);
                *dst++ = ce;
-               src++;
-               nr--;
        }
        if (old)
                reject_merge(old);
 }
 
-static void merge_stat_info(struct cache_entry **src, int nr)
+/*
+ * Two-way merge.
+ *
+ * The rule is: 
+ *  - every current entry has to match the old tree
+ *  - if the current entry matches the new tree, we leave it
+ *    as-is. Otherwise we require that it be up-to-date.
+ */
+static void twoway_merge(struct cache_entry **src, int nr)
 {
        static struct cache_entry null_entry;
+       struct cache_entry *old = NULL, *stat = &null_entry;
        struct cache_entry **dst = src;
-       struct cache_entry *old = &null_entry;
 
-       while (nr) {
-               struct cache_entry *ce;
+       while (nr--) {
+               struct cache_entry *ce = *src++;
+               int stage = ce_stage(ce);
+
+               switch (stage) {
+               case 0:
+                       if (old)
+                               reject_merge(old);
+                       old = ce;
+                       stat = ce;
+                       active_nr--;
+                       continue;
+
+               case 1:
+                       active_nr--;
+                       if (!old)
+                               continue;
+                       if (!path_matches(old, ce) || !same(old, ce))
+                               reject_merge(old);
+                       continue;
+
+               case 2:
+                       ce->ce_flags |= htons(CE_UPDATE);
+                       if (old) {
+                               if (!path_matches(old, ce))
+                                       reject_merge(old);
+                               /*
+                                * This also removes the UPDATE flag on
+                                * a match
+                                */
+                               if (same(old, ce))
+                                       *ce = *old;
+                               else
+                                       verify_uptodate(old);
+                               old = NULL;
+                       }
+                       ce->ce_flags &= ~htons(CE_STAGEMASK);
+                       *dst++ = ce;
+                       continue;
+               }
+               die("impossible two-way stage");
+       }
+       if (old)
+               reject_merge(old);
+}
+
+static void merge_stat_info(struct cache_entry **src, int nr)
+{
+       static struct cache_entry null_entry;
+       struct cache_entry **dst = src;
+       struct cache_entry *stat = &null_entry;
 
-               ce = src[0];
+       while (nr--) {
+               struct cache_entry *ce = *src++;
 
                /* We throw away original cache entries except for the stat information */
                if (!ce_stage(ce)) {
-                       old = ce;
-                       src++;
-                       nr--;
+                       stat = ce;
                        active_nr--;
                        continue;
                }
-               if (path_matches(ce, old) && same(ce, old))
-                       *ce = *old;
+               if (path_matches(ce, stat) && same(ce, stat))
+                       *ce = *stat;
                ce->ce_flags &= ~htons(CE_STAGEMASK);
                *dst++ = ce;
-               src++;
-               nr--;
        }
 }
 
-static char *read_tree_usage = "git-read-tree (<sha> | -m <sha1> [<sha2> <sha3>])";
+static void check_updates(struct cache_entry **src, int nr)
+{
+       static struct checkout state = {
+               .base_dir = "",
+               .force = 1,
+               .quiet = 1,
+               .refresh_cache = 1,
+       };
+       unsigned short mask = htons(CE_UPDATE);
+       while (nr--) {
+               struct cache_entry *ce = *src++;
+               if (ce->ce_flags & mask) {
+                       ce->ce_flags &= ~mask;
+                       if (update)
+                               checkout_entry(ce, &state);
+               }
+       }
+}
+
+static char *read_tree_usage = "git-read-tree (<sha> | -m <sha1> [<sha2> [<sha3>]])";
 
 int main(int argc, char **argv)
 {
@@ -228,6 +302,12 @@ int main(int argc, char **argv)
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
 
+               /* "-u" means "update", meaning that a merge will update the working directory */
+               if (!strcmp(arg, "-u")) {
+                       update = 1;
+                       continue;
+               }
+
                /* "-m" stands for "merge", meaning we start in stage 1 */
                if (!strcmp(arg, "-m")) {
                        int i;
@@ -254,6 +334,11 @@ int main(int argc, char **argv)
                switch (stage) {
                case 4: /* Three-way merge */
                        trivially_merge_cache(active_cache, active_nr);
+                       check_updates(active_cache, active_nr);
+                       break;
+               case 3: /* Update from one tree to another */
+                       twoway_merge(active_cache, active_nr);
+                       check_updates(active_cache, active_nr);
                        break;
                case 2: /* Just read a tree, merge with old cache contents */
                        merge_stat_info(active_cache, active_nr);