Expansion: Added documentation for wildcard checking

src/subst/wildcard_exp_utils.c

@@ -6,7 +6,7 @@
 /*   By: khais <marvin@42.fr>                       +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2025/03/21 13:46/14 by khais             #+#    #+#             */
-/*   Updated: 2025/03/21 13:46:14 by khais            ###   ########.fr       */
+/*   Updated: 2025/03/24 13:51:30 by jguelen          ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -90,8 +90,41 @@ static void	init_pattern_checker(t_worddesc *pattern, char **checker)
 ** This construction is only done for the current diectory so no special
 ** treatment is to be considered for '/' characters which otherwise have
 ** to be matched explicitely. We do however consider the case where the '.'
-** character cannot be matched unless explicitely when in first position
+** character cannot be matched except explicitely when in first position
 ** in str.
+** This function has the goal of building an array of prefix recognition
+** where each and every cell i,j in the array corresponds to the matching of the
+** prefix str[0 .. i - 1] with pattern[0 .. j - 1].
+** the array has the form:
+** empty string will be noted ε.
+** pattern  |                   | p[0]     | . . . | p[pattern_len - 1]
+** _s_\_(p)_|___________________|__________|_______|____________________
+**   i \ j  |         0         |   1      | . . . |     pattern_len
+** _____\___|___________________|__________|_______|____________________
+**       0  |      ε == ε       |          |       |    pattern == ε
+** _________|___________________|__________|_______|____________________
+**       1  |   str[0..0] == ε  |str[0..0] |       |
+**          |                   |== p[0..0]|       | pattern == p[0..0]
+** _________|___________________|__________|_______|____________________
+**       .  |                   |          |       |
+**       .  |                   |          |       |
+**       .  |                   |          |       |
+** _________|___________________|__________|_______|____________________
+** str  len||      str == ε     | str ==   |       |
+** [len - 1]|                   | p[0..0]  |       |  pattern == str
+**
+** There are several ways to preserve a match while going forward either in str,
+** in pattern or both: either you are matching corresponding characters or a '?'
+** wildcard in pattern with str or you are considering a '*' wildcard in
+** pattern. In those cases you can inherit from a match previously reached.
+** Otherwise, no match can be found.
+** When considering two characters that are identical (or '?' in pattern) you
+** will match exactly if amd only if you matched one character before in both
+** strings.
+** In the case of the consideration of the '*' wildcard in pattern, since it
+** matches both ε and any arbitrary string, you will match if before seeing the
+** '*' in pattern you already matched (case ε i.e. checker[i-1][j]) or if you
+** englobe the character currently considered in str (checker[i][j - 1]).
 */
 void	build_pattern_checks(char *str, t_worddesc *pattern,
 		char **checker)