1string-list API 2=============== 3 4The string_list API offers a data structure and functions to handle 5sorted and unsorted string lists. A "sorted" list is one whose 6entries are sorted by string value in `strcmp()` order. 7 8The 'string_list' struct used to be called 'path_list', but was renamed 9because it is not specific to paths. 10 11The caller: 12 13. Allocates and clears a `struct string_list` variable. 14 15. Initializes the members. You might want to set the flag `strdup_strings` 16 if the strings should be strdup()ed. For example, this is necessary 17 when you add something like git_path("..."), since that function returns 18 a static buffer that will change with the next call to git_path(). 19+ 20If you need something advanced, you can manually malloc() the `items` 21member (you need this if you add things later) and you should set the 22`nr` and `alloc` members in that case, too. 23 24. Adds new items to the list, using `string_list_append`, 25 `string_list_append_nodup`, `string_list_insert`, 26 `string_list_split`, and/or `string_list_split_in_place`. 27 28. Can check if a string is in the list using `string_list_has_string` or 29 `unsorted_string_list_has_string` and get it from the list using 30 `string_list_lookup` for sorted lists. 31 32. Can sort an unsorted list using `string_list_sort`. 33 34. Can remove duplicate items from a sorted list using 35 `string_list_remove_duplicates`. 36 37. Can remove individual items of an unsorted list using 38 `unsorted_string_list_delete_item`. 39 40. Can remove items not matching a criterion from a sorted or unsorted 41 list using `filter_string_list`, or remove empty strings using 42 `string_list_remove_empty_items`. 43 44. Finally it should free the list using `string_list_clear`. 45 46Example: 47 48---- 49struct string_list list = STRING_LIST_INIT_NODUP; 50int i; 51 52string_list_append(&list, "foo"); 53string_list_append(&list, "bar"); 54for (i = 0; i < list.nr; i++) 55 printf("%s\n", list.items[i].string) 56---- 57 58NOTE: It is more efficient to build an unsorted list and sort it 59afterwards, instead of building a sorted list (`O(n log n)` instead of 60`O(n^2)`). 61+ 62However, if you use the list to check if a certain string was added 63already, you should not do that (using unsorted_string_list_has_string()), 64because the complexity would be quadratic again (but with a worse factor). 65 66Functions 67--------- 68 69* General ones (works with sorted and unsorted lists as well) 70 71`string_list_init`:: 72 73 Initialize the members of the string_list, set `strdup_strings` 74 member according to the value of the second parameter. 75 76`filter_string_list`:: 77 78 Apply a function to each item in a list, retaining only the 79 items for which the function returns true. If free_util is 80 true, call free() on the util members of any items that have 81 to be deleted. Preserve the order of the items that are 82 retained. 83 84`string_list_remove_empty_items`:: 85 86 Remove any empty strings from the list. If free_util is true, 87 call free() on the util members of any items that have to be 88 deleted. Preserve the order of the items that are retained. 89 90`print_string_list`:: 91 92 Dump a string_list to stdout, useful mainly for debugging purposes. It 93 can take an optional header argument and it writes out the 94 string-pointer pairs of the string_list, each one in its own line. 95 96`string_list_clear`:: 97 98 Free a string_list. The `string` pointer of the items will be freed in 99 case the `strdup_strings` member of the string_list is set. The second 100 parameter controls if the `util` pointer of the items should be freed 101 or not. 102 103* Functions for sorted lists only 104 105`string_list_has_string`:: 106 107 Determine if the string_list has a given string or not. 108 109`string_list_insert`:: 110 111 Insert a new element to the string_list. The returned pointer can be 112 handy if you want to write something to the `util` pointer of the 113 string_list_item containing the just added string. If the given 114 string already exists the insertion will be skipped and the 115 pointer to the existing item returned. 116+ 117Since this function uses xrealloc() (which die()s if it fails) if the 118list needs to grow, it is safe not to check the pointer. I.e. you may 119write `string_list_insert(...)->util = ...;`. 120 121`string_list_lookup`:: 122 123 Look up a given string in the string_list, returning the containing 124 string_list_item. If the string is not found, NULL is returned. 125 126`string_list_remove_duplicates`:: 127 128 Remove all but the first of consecutive entries that have the 129 same string value. If free_util is true, call free() on the 130 util members of any items that have to be deleted. 131 132* Functions for unsorted lists only 133 134`string_list_append`:: 135 136 Append a new string to the end of the string_list. If 137 `strdup_string` is set, then the string argument is copied; 138 otherwise the new `string_list_entry` refers to the input 139 string. 140 141`string_list_append_nodup`:: 142 143 Append a new string to the end of the string_list. The new 144 `string_list_entry` always refers to the input string, even if 145 `strdup_string` is set. This function can be used to hand 146 ownership of a malloc()ed string to a `string_list` that has 147 `strdup_string` set. 148 149`string_list_sort`:: 150 151 Sort the list's entries by string value in `strcmp()` order. 152 153`unsorted_string_list_has_string`:: 154 155 It's like `string_list_has_string()` but for unsorted lists. 156 157`unsorted_string_list_lookup`:: 158 159 It's like `string_list_lookup()` but for unsorted lists. 160+ 161The above two functions need to look through all items, as opposed to their 162counterpart for sorted lists, which performs a binary search. 163 164`unsorted_string_list_delete_item`:: 165 166 Remove an item from a string_list. The `string` pointer of the items 167 will be freed in case the `strdup_strings` member of the string_list 168 is set. The third parameter controls if the `util` pointer of the 169 items should be freed or not. 170 171`string_list_split`:: 172`string_list_split_in_place`:: 173 174 Split a string into substrings on a delimiter character and 175 append the substrings to a `string_list`. If `maxsplit` is 176 non-negative, then split at most `maxsplit` times. Return the 177 number of substrings appended to the list. 178+ 179`string_list_split` requires a `string_list` that has `strdup_strings` 180set to true; it leaves the input string untouched and makes copies of 181the substrings in newly-allocated memory. 182`string_list_split_in_place` requires a `string_list` that has 183`strdup_strings` set to false; it splits the input string in place, 184overwriting the delimiter characters with NULs and creating new 185string_list_items that point into the original string (the original 186string must therefore not be modified or freed while the `string_list` 187is in use). 188 189 190Data structures 191--------------- 192 193* `struct string_list_item` 194 195Represents an item of the list. The `string` member is a pointer to the 196string, and you may use the `util` member for any purpose, if you want. 197 198* `struct string_list` 199 200Represents the list itself. 201 202. The array of items are available via the `items` member. 203. The `nr` member contains the number of items stored in the list. 204. The `alloc` member is used to avoid reallocating at every insertion. 205 You should not tamper with it. 206. Setting the `strdup_strings` member to 1 will strdup() the strings 207 before adding them, see above. 208. The `compare_strings_fn` member is used to specify a custom compare 209 function, otherwise `strcmp()` is used as the default function.