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-rw-r--r--xdiff/xdiff.h2
-rw-r--r--xdiff/xdiffi.c40
2 files changed, 38 insertions, 4 deletions
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index 4fb7e7941..7423f77fc 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -41,6 +41,8 @@ extern "C" {
#define XDF_IGNORE_BLANK_LINES (1 << 7)
+#define XDF_COMPACTION_HEURISTIC (1 << 8)
+
#define XDL_EMIT_FUNCNAMES (1 << 0)
#define XDL_EMIT_FUNCCONTEXT (1 << 2)
diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
index 2358a2d63..b3c684887 100644
--- a/xdiff/xdiffi.c
+++ b/xdiff/xdiffi.c
@@ -400,9 +400,23 @@ static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1,
}
+static int is_blank_line(xrecord_t **recs, long ix, long flags)
+{
+ return xdl_blankline(recs[ix]->ptr, recs[ix]->size, flags);
+}
+
+static int recs_match(xrecord_t **recs, long ixs, long ix, long flags)
+{
+ return (recs[ixs]->ha == recs[ix]->ha &&
+ xdl_recmatch(recs[ixs]->ptr, recs[ixs]->size,
+ recs[ix]->ptr, recs[ix]->size,
+ flags));
+}
+
int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
long ix, ixo, ixs, ixref, grpsiz, nrec = xdf->nrec;
char *rchg = xdf->rchg, *rchgo = xdfo->rchg;
+ unsigned int blank_lines;
xrecord_t **recs = xdf->recs;
/*
@@ -436,14 +450,14 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
do {
grpsiz = ix - ixs;
+ blank_lines = 0;
/*
* If the line before the current change group, is equal to
* the last line of the current change group, shift backward
* the group.
*/
- while (ixs > 0 && recs[ixs - 1]->ha == recs[ix - 1]->ha &&
- xdl_recmatch(recs[ixs - 1]->ptr, recs[ixs - 1]->size, recs[ix - 1]->ptr, recs[ix - 1]->size, flags)) {
+ while (ixs > 0 && recs_match(recs, ixs - 1, ix - 1, flags)) {
rchg[--ixs] = 1;
rchg[--ix] = 0;
@@ -470,8 +484,9 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
* the line next of the current change group, shift forward
* the group.
*/
- while (ix < nrec && recs[ixs]->ha == recs[ix]->ha &&
- xdl_recmatch(recs[ixs]->ptr, recs[ixs]->size, recs[ix]->ptr, recs[ix]->size, flags)) {
+ while (ix < nrec && recs_match(recs, ixs, ix, flags)) {
+ blank_lines += is_blank_line(recs, ix, flags);
+
rchg[ixs++] = 0;
rchg[ix++] = 1;
@@ -498,6 +513,23 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
rchg[--ix] = 0;
while (rchgo[--ixo]);
}
+
+ /*
+ * If a group can be moved back and forth, see if there is a
+ * blank line in the moving space. If there is a blank line,
+ * make sure the last blank line is the end of the group.
+ *
+ * As we already shifted the group forward as far as possible
+ * in the earlier loop, we need to shift it back only if at all.
+ */
+ if ((flags & XDF_COMPACTION_HEURISTIC) && blank_lines) {
+ while (ixs > 0 &&
+ !is_blank_line(recs, ix - 1, flags) &&
+ recs_match(recs, ixs - 1, ix - 1, flags)) {
+ rchg[--ixs] = 1;
+ rchg[--ix] = 0;
+ }
+ }
}
return 0;