+
+/*
+ * Is a tree entry interesting given the pathspec we have?
+ *
+ * Pre-condition: either baselen == base_offset (i.e. empty path)
+ * or base[baselen-1] == '/' (i.e. with trailing slash).
+ */
+enum interesting tree_entry_interesting(const struct name_entry *entry,
+ struct strbuf *base, int base_offset,
+ const struct pathspec *ps)
+{
+ enum interesting positive, negative;
+ positive = do_match(entry, base, base_offset, ps, 0);
+
+ /*
+ * case | entry | positive | negative | result
+ * -----+-------+----------+----------+-------
+ * 1 | file | -1 | -1..2 | -1
+ * 2 | file | 0 | -1..2 | 0
+ * 3 | file | 1 | -1 | 1
+ * 4 | file | 1 | 0 | 1
+ * 5 | file | 1 | 1 | 0
+ * 6 | file | 1 | 2 | 0
+ * 7 | file | 2 | -1 | 2
+ * 8 | file | 2 | 0 | 2
+ * 9 | file | 2 | 1 | 0
+ * 10 | file | 2 | 2 | -1
+ * -----+-------+----------+----------+-------
+ * 11 | dir | -1 | -1..2 | -1
+ * 12 | dir | 0 | -1..2 | 0
+ * 13 | dir | 1 | -1 | 1
+ * 14 | dir | 1 | 0 | 1
+ * 15 | dir | 1 | 1 | 1 (*)
+ * 16 | dir | 1 | 2 | 0
+ * 17 | dir | 2 | -1 | 2
+ * 18 | dir | 2 | 0 | 2
+ * 19 | dir | 2 | 1 | 1 (*)
+ * 20 | dir | 2 | 2 | -1
+ *
+ * (*) An exclude pattern interested in a directory does not
+ * necessarily mean it will exclude all of the directory. In
+ * wildcard case, it can't decide until looking at individual
+ * files inside. So don't write such directories off yet.
+ */
+
+ if (!(ps->magic & PATHSPEC_EXCLUDE) ||
+ positive <= entry_not_interesting) /* #1, #2, #11, #12 */
+ return positive;
+
+ negative = do_match(entry, base, base_offset, ps, 1);
+
+ /* #3, #4, #7, #8, #13, #14, #17, #18 */
+ if (negative <= entry_not_interesting)
+ return positive;
+
+ /* #15, #19 */
+ if (S_ISDIR(entry->mode) &&
+ positive >= entry_interesting &&
+ negative == entry_interesting)
+ return entry_interesting;
+
+ if ((positive == entry_interesting &&
+ negative >= entry_interesting) || /* #5, #6, #16 */
+ (positive == all_entries_interesting &&
+ negative == entry_interesting)) /* #9 */
+ return entry_not_interesting;
+
+ return all_entries_not_interesting; /* #10, #20 */
+}