diff-tree --cc: denser combined diff output for a merge commit.

Building on the previous '-c' (combined) option, '--cc' option
squelches the output further by omitting hunks that consist of
difference with solely one parent.

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

diff --git a/combine-diff.c b/combine-diff.c
index 6690023..062ed8a 100644 (file)
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -278,7 +278,25 @@ static int interesting(struct sline *sline, unsigned long all_mask)
        return ((sline->flag & all_mask) != all_mask || sline->lost_head);
 }
 
-static void make_hunks(struct sline *sline, unsigned long cnt, int num_parent)
+static unsigned long line_diff_parents(struct sline *sline, unsigned long all_mask)
+{
+       /*
+        * Look at the line and see from which parents we have difference.
+        * Lower bits of sline->flag records if the parent had this line,
+        * so XOR with all_mask gives us on-bits for parents we have
+        * differences with.
+        */
+       unsigned long parents = (sline->flag ^ all_mask);
+       if (sline->lost_head) {
+               struct lline *ll;
+               for (ll = sline->lost_head; ll; ll = ll->next)
+                       parents |= ll->parent_map;
+       }
+       return parents & all_mask;
+}
+
+static void make_hunks(struct sline *sline, unsigned long cnt,
+                      int num_parent, int dense)
 {
        unsigned long all_mask = (1UL<<num_parent) - 1;
        unsigned long mark = (1UL<<num_parent);
@@ -302,6 +320,45 @@ static void make_hunks(struct sline *sline, unsigned long cnt, int num_parent)
                }
                i++;
        }
+       if (!dense)
+               return;
+
+       /* Look at each hunk, and if it contains changes from only
+        * one parent, mark that uninteresting.
+        */
+       i = 0;
+       while (i < cnt) {
+               int j, hunk_end, diffs;
+               unsigned long parents;
+               while (i < cnt && !(sline[i].flag & mark))
+                       i++;
+               if (cnt <= i)
+                       break; /* No more interesting hunks */
+               for (hunk_end = i + 1; hunk_end < cnt; hunk_end++)
+                       if (!(sline[hunk_end].flag & mark))
+                               break;
+               /* [i..hunk_end) are interesting.  Now is it from
+                * only one parent?
+                * If lost lines are only from one parent and
+                * remaining lines existed in parents other than
+                * that parent, then the hunk is not that interesting.
+                */
+               parents = 0;
+               diffs = 0;
+               for (j = i; j < hunk_end; j++)
+                       parents |= line_diff_parents(sline + j, all_mask);
+               /* Now, how many bits from [0..num_parent) are on? */
+               for (j = 0; j < num_parent; j++) {
+                       if (parents & (1UL<<j))
+                               diffs++;
+               }
+               if (diffs < 2) {
+                       /* This hunk is not that interesting after all */
+                       for (j = i; j < hunk_end; j++)
+                               sline[j].flag &= ~mark;
+               }
+               i = hunk_end;
+       }
 }
 
 static void dump_sline(struct sline *sline, int cnt, int num_parent)
@@ -351,7 +408,8 @@ static void dump_sline(struct sline *sline, int cnt, int num_parent)
        }
 }
 
-static void show_combined_diff(struct path_list *elem, int num_parent)
+static void show_combined_diff(struct path_list *elem, int num_parent,
+                              int dense)
 {
        unsigned long size, cnt, lno;
        char *result, *cp, *ep;
@@ -390,7 +448,7 @@ static void show_combined_diff(struct path_list *elem, int num_parent)
        for (i = 0; i < num_parent; i++)
                combine_diff(elem->parent_sha1[i], ourtmp, sline, cnt, i);
 
-       make_hunks(sline, cnt, num_parent);
+       make_hunks(sline, cnt, num_parent, dense);
 
        dump_sline(sline, cnt, num_parent);
        unlink(ourtmp);
@@ -410,7 +468,8 @@ static void show_combined_diff(struct path_list *elem, int num_parent)
 }
 
 int diff_tree_combined_merge(const unsigned char *sha1,
-                            const char *header, int show_empty_merge)
+                            const char *header,
+                            int show_empty_merge, int dense)
 {
        struct commit *commit = lookup_commit(sha1);
        struct diff_options diffopts;
@@ -455,7 +514,7 @@ int diff_tree_combined_merge(const unsigned char *sha1,
                        else
                                printf("%s", p->path);
                        putchar('\n');
-                       show_combined_diff(p, num_parent);
+                       show_combined_diff(p, num_parent, dense);
                }
        }
 

diff --git a/diff-tree.c b/diff-tree.c
index 0c68936..99c580c 100644 (file)
--- a/diff-tree.c
+++ b/diff-tree.c
@@ -8,6 +8,7 @@ static int verbose_header = 0;
 static int ignore_merges = 1;
 static int show_empty_combined = 0;
 static int combine_merges = 0;
+static int dense_combined_merges = 0;
 static int read_stdin = 0;
 
 static const char *header = NULL;
@@ -121,7 +122,8 @@ static int diff_tree_commit(const unsigned char *commit_sha1)
                        header = generate_header(sha1, sha1,
                                                 commit->buffer);
                        return diff_tree_combined_merge(sha1, header,
-                                                       show_empty_combined);
+                                                       show_empty_combined,
+                                                       dense_combined_merges);
                }
        }
 
@@ -168,7 +170,7 @@ static int diff_tree_stdin(char *line)
 }
 
 static const char diff_tree_usage[] =
-"git-diff-tree [--stdin] [-m] [-c] [-s] [-v] [--pretty] [-t] [-r] [--root] "
+"git-diff-tree [--stdin] [-m] [-c] [--cc] [-s] [-v] [--pretty] [-t] [-r] [--root] "
 "[<common diff options>] <tree-ish> [<tree-ish>] [<path>...]\n"
 "  -r            diff recursively\n"
 "  --root        include the initial commit as diff against /dev/null\n"
@@ -235,6 +237,10 @@ int main(int argc, const char **argv)
                        combine_merges = 1;
                        continue;
                }
+               if (!strcmp(arg, "--cc")) {
+                       dense_combined_merges = combine_merges = 1;
+                       continue;
+               }
                if (!strcmp(arg, "-v")) {
                        verbose_header = 1;
                        header_prefix = "diff-tree ";

diff --git a/diff.h b/diff.h
index 081234c..ab0d47b 100644 (file)
--- a/diff.h
+++ b/diff.h
@@ -56,7 +56,7 @@ extern int diff_tree(struct tree_desc *t1, struct tree_desc *t2,
 extern int diff_tree_sha1(const unsigned char *old, const unsigned char *new,
                          const char *base, struct diff_options *opt);
 
-extern int diff_tree_combined_merge(const unsigned char *sha1, const char *, int);
+extern int diff_tree_combined_merge(const unsigned char *sha1, const char *, int, int);
 
 extern void diff_addremove(struct diff_options *,
                           int addremove,