| string-list API |
| =============== |
| |
| The string_list API offers a data structure and functions to handle |
| sorted and unsorted string lists. A "sorted" list is one whose |
| entries are sorted by string value in `strcmp()` order. |
| |
| The 'string_list' struct used to be called 'path_list', but was renamed |
| because it is not specific to paths. |
| |
| The caller: |
| |
| . Allocates and clears a `struct string_list` variable. |
| |
| . Initializes the members. You might want to set the flag `strdup_strings` |
| if the strings should be strdup()ed. For example, this is necessary |
| when you add something like git_path("..."), since that function returns |
| a static buffer that will change with the next call to git_path(). |
| + |
| If you need something advanced, you can manually malloc() the `items` |
| member (you need this if you add things later) and you should set the |
| `nr` and `alloc` members in that case, too. |
| |
| . Adds new items to the list, using `string_list_append`, |
| `string_list_append_nodup`, `string_list_insert`, |
| `string_list_split`, and/or `string_list_split_in_place`. |
| |
| . Can check if a string is in the list using `string_list_has_string` or |
| `unsorted_string_list_has_string` and get it from the list using |
| `string_list_lookup` for sorted lists. |
| |
| . Can sort an unsorted list using `sort_string_list`. |
| |
| . Can remove duplicate items from a sorted list using |
| `string_list_remove_duplicates`. |
| |
| . Can remove individual items of an unsorted list using |
| `unsorted_string_list_delete_item`. |
| |
| . Can remove items not matching a criterion from a sorted or unsorted |
| list using `filter_string_list`, or remove empty strings using |
| `string_list_remove_empty_items`. |
| |
| . Finally it should free the list using `string_list_clear`. |
| |
| Example: |
| |
| ---- |
| struct string_list list = STRING_LIST_INIT_NODUP; |
| int i; |
| |
| string_list_append(&list, "foo"); |
| string_list_append(&list, "bar"); |
| for (i = 0; i < list.nr; i++) |
| printf("%s\n", list.items[i].string) |
| ---- |
| |
| NOTE: It is more efficient to build an unsorted list and sort it |
| afterwards, instead of building a sorted list (`O(n log n)` instead of |
| `O(n^2)`). |
| + |
| However, if you use the list to check if a certain string was added |
| already, you should not do that (using unsorted_string_list_has_string()), |
| because the complexity would be quadratic again (but with a worse factor). |
| |
| Functions |
| --------- |
| |
| * General ones (works with sorted and unsorted lists as well) |
| |
| `filter_string_list`:: |
| |
| Apply a function to each item in a list, retaining only the |
| items for which the function returns true. If free_util is |
| true, call free() on the util members of any items that have |
| to be deleted. Preserve the order of the items that are |
| retained. |
| |
| `string_list_remove_empty_items`:: |
| |
| Remove any empty strings from the list. If free_util is true, |
| call free() on the util members of any items that have to be |
| deleted. Preserve the order of the items that are retained. |
| |
| `print_string_list`:: |
| |
| Dump a string_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 string_list, each one in its own line. |
| |
| `string_list_clear`:: |
| |
| Free a string_list. The `string` pointer of the items will be freed in |
| case the `strdup_strings` member of the string_list is set. The second |
| parameter controls if the `util` pointer of the items should be freed |
| or not. |
| |
| * Functions for sorted lists only |
| |
| `string_list_has_string`:: |
| |
| Determine if the string_list has a given string or not. |
| |
| `string_list_insert`:: |
| |
| Insert a new element to the string_list. The returned pointer can be |
| handy if you want to write something to the `util` pointer of the |
| string_list_item containing the just added string. If the given |
| string already exists the insertion will be skipped and the |
| pointer to the existing item returned. |
| + |
| Since this function uses xrealloc() (which die()s if it fails) if the |
| list needs to grow, it is safe not to check the pointer. I.e. you may |
| write `string_list_insert(...)->util = ...;`. |
| |
| `string_list_lookup`:: |
| |
| Look up a given string in the string_list, returning the containing |
| string_list_item. If the string is not found, NULL is returned. |
| |
| `string_list_remove_duplicates`:: |
| |
| Remove all but the first of consecutive entries that have the |
| same string value. If free_util is true, call free() on the |
| util members of any items that have to be deleted. |
| |
| * Functions for unsorted lists only |
| |
| `string_list_append`:: |
| |
| Append a new string to the end of the string_list. If |
| `strdup_string` is set, then the string argument is copied; |
| otherwise the new `string_list_entry` refers to the input |
| string. |
| |
| `string_list_append_nodup`:: |
| |
| Append a new string to the end of the string_list. The new |
| `string_list_entry` always refers to the input string, even if |
| `strdup_string` is set. This function can be used to hand |
| ownership of a malloc()ed string to a `string_list` that has |
| `strdup_string` set. |
| |
| `sort_string_list`:: |
| |
| Sort the list's entries by string value in `strcmp()` order. |
| |
| `unsorted_string_list_has_string`:: |
| |
| It's like `string_list_has_string()` but for unsorted lists. |
| |
| `unsorted_string_list_lookup`:: |
| |
| It's like `string_list_lookup()` but for unsorted lists. |
| + |
| The above two functions need to look through all items, as opposed to their |
| counterpart for sorted lists, which performs a binary search. |
| |
| `unsorted_string_list_delete_item`:: |
| |
| Remove an item from a string_list. The `string` pointer of the items |
| will be freed in case the `strdup_strings` member of the string_list |
| is set. The third parameter controls if the `util` pointer of the |
| items should be freed or not. |
| |
| `string_list_split`:: |
| `string_list_split_in_place`:: |
| |
| Split a string into substrings on a delimiter character and |
| append the substrings to a `string_list`. If `maxsplit` is |
| non-negative, then split at most `maxsplit` times. Return the |
| number of substrings appended to the list. |
| + |
| `string_list_split` requires a `string_list` that has `strdup_strings` |
| set to true; it leaves the input string untouched and makes copies of |
| the substrings in newly-allocated memory. |
| `string_list_split_in_place` requires a `string_list` that has |
| `strdup_strings` set to false; it splits the input string in place, |
| overwriting the delimiter characters with NULs and creating new |
| string_list_items that point into the original string (the original |
| string must therefore not be modified or freed while the `string_list` |
| is in use). |
| |
| |
| Data structures |
| --------------- |
| |
| * `struct string_list_item` |
| |
| Represents an item of the list. The `string` member is a pointer to the |
| string, and you may use the `util` member for any purpose, if you want. |
| |
| * `struct string_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 to avoid reallocating at every insertion. |
| You should not tamper with it. |
| . Setting the `strdup_strings` member to 1 will strdup() the strings |
| before adding them, see above. |