[PATCH(RFC) 2/2] xdl_merge(): introduce XDL_MERGE_ZEALOUS_ALNUM
When a merge conflicts, there are often common lines that are not really common, such as empty lines or lines containing a single curly bracket.
With XDL_MERGE_ZEALOUS_ALNUM, we use the following heuristics: when a hunk does not contain any letters or digits, it is treated as conflicting.
In other words, a conflict which used to look like this:
<<<<<<<
a = 1;
=======
output();
>>>>>>>
}
}
}
<<<<<<<
output();
=======
b = 1;
>>>>>>>
will look like this with ZEALOUS_ALNUM:
<<<<<<<
a = 1;
}
}
}
output();
=======
output();
}
}
}
b = 1;
>>>>>>>
To demonstrate this, git-merge-file has been switched from XDL_MERGE_ZEALOUS to XDL_MERGE_ZEALOUS_ALNUM.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Conflicts:
t/t6023-merge-file.sh
---
builtin-merge-file.c | 2 +-
t/t6023-merge-file.sh | 10 ++++++++++
xdiff/xdiff.h | 1 +
xdiff/xmerge.c | 31 ++++++++++++++++++++++++++++---
4 files changed, 40 insertions(+), 4 deletions(-)
diff --git a/builtin-merge-file.c b/builtin-merge-file.c
index 58deb62..adce6d4 100644
--- a/builtin-merge-file.c
+++ b/builtin-merge-file.c
@@ -46,7 +46,7 @@ int cmd_merge_file(int argc, const char **argv, const char *prefix)
}
ret = xdl_merge(mmfs + 1, mmfs + 0, names[0], mmfs + 2, names[2],
- &xpp, XDL_MERGE_ZEALOUS, &result);
+ &xpp, XDL_MERGE_ZEALOUS_ALNUM, &result);
for (i = 0; i < 3; i++)
free(mmfs[i].ptr);
diff --git a/t/t6023-merge-file.sh b/t/t6023-merge-file.sh
index 869e8d5..79dc58b 100755
--- a/t/t6023-merge-file.sh
+++ b/t/t6023-merge-file.sh
@@ -149,4 +149,14 @@ test_expect_success 'MERGE_ZEALOUS simplifies non-conflicts' '
'
+sed -e 's/deerit./&\n\n\n\n/' -e "s/locavit,/locavit;/" < new6.txt > new8.txt
+sed -e 's/deerit./&\n\n\n\n/' -e "s/locavit,/locavit --/" < new7.txt > new9.txt
+
+test_expect_success 'ZEALOUS_ALNUM' '
+
+ ! git merge-file -p new8.txt new5.txt new9.txt > merge.out &&
+ test 1 = $(grep ======= < merge.out | wc -l)
+
+'
+
test_done
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index c00ddaa..413082e 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -53,6 +53,7 @@ extern "C" {
#define XDL_MERGE_MINIMAL 0
#define XDL_MERGE_EAGER 1
#define XDL_MERGE_ZEALOUS 2
+#define XDL_MERGE_ZEALOUS_ALNUM 3
typedef struct s_mmfile {
char *ptr;
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 9cd448c..2128eaf 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -248,6 +248,23 @@ static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
return 0;
}
+static int line_contains_alnum(const char *ptr, long size)
+{
+ while (size--)
+ if (isalnum(*(ptr++)))
+ return 1;
+ return 0;
+}
+
+static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
+{
+ for (; chg; chg--, i++)
+ if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
+ xe->xdf2.recs[i]->size))
+ return 1;
+ return 0;
+}
+
/*
* This function merges m and m->next, marking everything between those hunks
* as conflicting, too.
@@ -266,7 +283,8 @@ static void xdl_merge_two_conflicts(xdmerge_t *m)
* it appears simpler -- because it takes up less (or as many) lines --
* if the lines are moved into the conflicts.
*/
-static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m)
+static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
+ int simplify_if_no_alnum)
{
int result = 0;
@@ -282,7 +300,11 @@ static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m)
begin = m->i1 + m->chg1;
end = next_m->i1;
- if (m->mode != 0 || next_m->mode != 0 || end - begin > 3)
+ if (m->mode != 0 || next_m->mode != 0 ||
+ (end - begin > 3 &&
+ (!simplify_if_no_alnum ||
+ lines_contain_alnum(xe1, begin,
+ end - begin))))
m = next_m;
else {
result++;
@@ -295,6 +317,8 @@ static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m)
* level == 0: mark all overlapping changes as conflict
* level == 1: mark overlapping changes as conflict only if not identical
* level == 2: analyze non-identical changes for minimal conflict set
+ * level == 3: analyze non-identical changes for minimal conflict set, but
+ * treat hunks not containing any letter or number as conflicting
*
* returns < 0 on error, == 0 for no conflicts, else number of conflicts
*/
@@ -400,7 +424,8 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
/* refine conflicts */
if (level > 1 &&
(xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
- xdl_simplify_non_conflicts(xe1, changes) < 0)) {
+ xdl_simplify_non_conflicts(xe1, changes,
+ level > 2) < 0)) {
xdl_cleanup_merge(changes);
return -1;
}
--
1.5.4.1.1396.g177d-dirty
