xdl_merge(): move file1 and file2 labels to xmparam structure

The labels for the three participants in a potential conflict are all
optional arguments for the xdiff merge routine; if they are NULL, then
xdl_merge() can cope by omitting the labels from its output.  Move
them to the xmparam structure to allow new callers to save some
keystrokes where they are not needed.

This also has the virtue of making the xdiff merge interface more
similar to merge_trees, which might make it easier to learn.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/merge-file.c

@@ -77,8 +77,9 @@ int cmd_merge_file(int argc, const char **argv, const char *prefix)
 					argv[i]);
 	}
 
-	ret = xdl_merge(mmfs + 1, mmfs + 0, names[0], mmfs + 2, names[2],
-			&xmp, &result);
+	xmp.file1 = names[0];
+	xmp.file2 = names[2];
+	ret = xdl_merge(mmfs + 1, mmfs + 0, mmfs + 2, &xmp, &result);
 
 	for (i = 0; i < 3; i++)
 		free(mmfs[i].ptr);

ll-merge.c

@@ -83,7 +83,9 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 		xmp.style = git_xmerge_style;
 	if (marker_size > 0)
 		xmp.marker_size = marker_size;
-	return xdl_merge(orig, src1, name1, src2, name2, &xmp, result);
+	xmp.file1 = name1;
+	xmp.file2 = name2;
+	return xdl_merge(orig, src1, src2, &xmp, result);
 }
 
 static int ll_union_merge(const struct ll_merge_driver *drv_unused,

xdiff/xdiff.h

@@ -118,12 +118,13 @@ typedef struct s_xmparam {
 	int favor;
 	int style;
 	const char *ancestor;	/* label for orig */
+	const char *file1;	/* label for mf1 */
+	const char *file2;	/* label for mf2 */
 } xmparam_t;
 
 #define DEFAULT_CONFLICT_MARKER_SIZE 7
 
-int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
-		mmfile_t *mf2, const char *name2,
+int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 		xmparam_t const *xmp, mmbuffer_t *result);
 
 #ifdef __cplusplus

xdiff/xmerge.c

@@ -407,12 +407,15 @@ static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
  *
  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
  */
-static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
-		xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
-		xmparam_t const *xmp, mmbuffer_t *result) {
+static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1,
+		xdfenv_t *xe2, xdchange_t *xscr2,
+		xmparam_t const *xmp, mmbuffer_t *result)
+{
 	xdmerge_t *changes, *c;
 	xpparam_t const *xpp = &xmp->xpp;
 	const char *const ancestor_name = xmp->ancestor;
+	const char *const name1 = xmp->file1;
+	const char *const name2 = xmp->file2;
 	int i0, i1, i2, chg0, chg1, chg2;
 	int level = xmp->level;
 	int style = xmp->style;
@@ -566,9 +569,9 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 	return xdl_cleanup_merge(changes);
 }
 
-int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
-		mmfile_t *mf2, const char *name2,
-		xmparam_t const *xmp, mmbuffer_t *result) {
+int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
+		xmparam_t const *xmp, mmbuffer_t *result)
+{
 	xdchange_t *xscr1, *xscr2;
 	xdfenv_t xe1, xe2;
 	int status;
@@ -603,8 +606,8 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 		memcpy(result->ptr, mf1->ptr, mf1->size);
 		result->size = mf1->size;
 	} else {
-		status = xdl_do_merge(&xe1, xscr1, name1,
-				      &xe2, xscr2, name2,
+		status = xdl_do_merge(&xe1, xscr1,
+				      &xe2, xscr2,
 				      xmp, result);
 	}
 	xdl_free_script(xscr1);