[PATCH] path-list documentation: document all functions and data structures

@@ -1,9 +1,93 @@
 path-list API
 =============
 
-Talk about <path-list.h>, things like
+The path_list API offers a data structure and functions to handle sorted
+and unsorted string lists.
 
-* it is not just paths but strings in general;
-* the calling sequence.
+The name is a bit misleading, a path_list may store not only paths but
+strings in general.
 
-(Dscho)
+The caller:
+
+. Allocates and clears (`memset(&list, \'\0', sizeof(list));`) a
+  `struct path_list` variable.
+
+. Initializes the members. You can manually set the `items` member, but
+  then you have to set `nr`, accordingly. Also don't forget to set
+  `strdup_paths` if you need it.
+
+. Adds new items to the list, using `path_list_append` or `path_list_insert`.
+
+. Can check if a string is in the list using `path_list_has_path` or
+  `unsorted_path_list_has_path` and get it from the list using
+  `path_list_lookup` for sorted lists.
+
+. Can sort an unsorted list using `sort_path_list`.
+
+. Finally it should free the list using `path_list_clear`.
+
+Functions
+---------
+
+* General ones (works with sorted and unsorted lists as well)
+
+`print_path_list`::
+
+	Dump a path_list to stdout, useful mainly for debugging purposes. It
+	can take an optional header argument and it writes out the
+	string-pointer pairs of the path_list, each one in its own line.
+
+`path_list_clear`::
+
+	Free a path_list. The `path` pointer of the items will be freed in case
+	the `strdup_paths` member of the path_list is set. The second parameter
+	controls if the `util` pointer of the items should be freed or not.
+
+* Functions for sorted lists only
+
+`path_list_has_path`::
+
+	Determine if the path_list has a given string or not.
+
+`path_list_insert`::
+
+	Insert a new element to the path_list. The returned pointer can be handy
+	if you want to write something to the `util` pointer of the
+	path_list_item containing the just added string.
+
+`path_list_lookup`::
+
+	Look up a given string in the path_list, returning the containing
+	path_list_item. If the string is not found, NULL is returned.
+
+* Functions for unsorted lists only
+
+`path_list_append`::
+
+	Append a new string to the end of the path_list.
+
+`sort_path_list`::
+
+	Make an unsorted list sorted.
+
+`unsorted_path_list_has_path`::
+
+	It's like `path_list_has_path()` but for unsorted lists.
+
+Data structures
+---------------
+
+* `struct path_list_item`
+
+Represent an item of the list. The `path` member is a pointer to the
+string, and you may use the `util` member for any purpose, if you want.
+
+* `struct path_list`
+
+Represents the list itself.
+
+. The array of items are available via the `items` member.
+. The `nr` member contains the number of items stored in the list.
+. The `alloc` member is used for `ALLOC_GROW()`.
+. Setting the `strdup_paths` member to 1 means that the added paths are
+  copied to the path list and not just a pointer to them is stored.