xdiff: add recs_match helper function

It is a common pattern in xdl_change_compact to check that hashes and
strings match. The resulting code to perform this change causes very
long lines and makes it hard to follow the intention. Introduce a helper
function recs_match which performs both checks to increase
code readability.

Original Git commit: 92e5b62fec0e9b647429e8d3736c571c434dd375

Author: jacob-keller

src/xdiff/xdiffi.c

@@ -404,6 +404,14 @@ static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1,
 }
 
 
+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;
@@ -446,8 +454,7 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
 			 * 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;
 
@@ -474,8 +481,7 @@ 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)) {
 				rchg[ixs++] = 0;
 				rchg[ix++] = 1;