tree_entry_interesting(): give meaningful names to return values

It is a basic code hygiene to avoid magic constants that are unnamed.
Besides, this helps extending the value later on for "interesting, but
cannot decide if the entry truely matches yet" (ie. prefix matches)

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/tree-walk.c b/tree-walk.c
index cc2f14a..4a03e9b 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -577,27 +577,23 @@
  *
  * Pre-condition: either baselen == base_offset (i.e. empty path)
  * or base[baselen-1] == '/' (i.e. with trailing slash).
- *
- * Return:
- *  - 2 for "yes, and all subsequent entries will be"
- *  - 1 for yes
- *  - zero for no
- *  - negative for "no, and no subsequent entries will be either"
  */
-int tree_entry_interesting(const struct name_entry *entry,
-			   struct strbuf *base, int base_offset,
-			   const struct pathspec *ps)
+enum interesting tree_entry_interesting(const struct name_entry *entry,
+					struct strbuf *base, int base_offset,
+					const struct pathspec *ps)
 {
 	int i;
 	int pathlen, baselen = base->len - base_offset;
-	int never_interesting = ps->has_wildcard ? 0 : -1;
+	int never_interesting = ps->has_wildcard ?
+		entry_not_interesting : all_entries_not_interesting;
 
 	if (!ps->nr) {
 		if (!ps->recursive || ps->max_depth == -1)
-			return 2;
-		return !!within_depth(base->buf + base_offset, baselen,
-				      !!S_ISDIR(entry->mode),
-				      ps->max_depth);
+			return all_entries_interesting;
+		return within_depth(base->buf + base_offset, baselen,
+				    !!S_ISDIR(entry->mode),
+				    ps->max_depth) ?
+			entry_interesting : entry_not_interesting;
 	}
 
 	pathlen = tree_entry_len(entry);
@@ -614,12 +610,13 @@
 				goto match_wildcards;
 
 			if (!ps->recursive || ps->max_depth == -1)
-				return 2;
+				return all_entries_interesting;
 
-			return !!within_depth(base_str + matchlen + 1,
-					      baselen - matchlen - 1,
-					      !!S_ISDIR(entry->mode),
-					      ps->max_depth);
+			return within_depth(base_str + matchlen + 1,
+					    baselen - matchlen - 1,
+					    !!S_ISDIR(entry->mode),
+					    ps->max_depth) ?
+				entry_interesting : entry_not_interesting;
 		}
 
 		/* Either there must be no base, or the base must match. */
@@ -627,18 +624,18 @@
 			if (match_entry(entry, pathlen,
 					match + baselen, matchlen - baselen,
 					&never_interesting))
-				return 1;
+				return entry_interesting;
 
 			if (ps->items[i].use_wildcard) {
 				if (!fnmatch(match + baselen, entry->path, 0))
-					return 1;
+					return entry_interesting;
 
 				/*
 				 * Match all directories. We'll try to
 				 * match files later on.
 				 */
 				if (ps->recursive && S_ISDIR(entry->mode))
-					return 1;
+					return entry_interesting;
 			}
 
 			continue;
@@ -657,7 +654,7 @@
 
 		if (!fnmatch(match, base->buf + base_offset, 0)) {
 			strbuf_setlen(base, base_offset + baselen);
-			return 1;
+			return entry_interesting;
 		}
 		strbuf_setlen(base, base_offset + baselen);
 
@@ -666,7 +663,7 @@
 		 * later on.
 		 */
 		if (ps->recursive && S_ISDIR(entry->mode))
-			return 1;
+			return entry_interesting;
 	}
 	return never_interesting; /* No matches */
 }