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 `sort_string_list`. 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`. 42 43. Finally it should free the list using `string_list_clear`. 44 45Example: 46 47---- 48struct string_list list = STRING_LIST_INIT_NODUP; 49int i; 50 51string_list_append(&list, "foo"); 52string_list_append(&list, "bar"); 53for (i = 0; i < list.nr; i++) 54 printf("%s\n", list.items[i].string) 55---- 56 57NOTE: It is more efficient to build an unsorted list and sort it 58afterwards, instead of building a sorted list (`O(n log n)` instead of 59`O(n^2)`). 60+ 61However, if you use the list to check if a certain string was added 62already, you should not do that (using unsorted_string_list_has_string()), 63because the complexity would be quadratic again (but with a worse factor). 64 65Functions 66--------- 67 68* General ones (works with sorted and unsorted lists as well) 69 70`filter_string_list`:: 71 72 Apply a function to each item in a list, retaining only the 73 items for which the function returns true. If free_util is 74 true, call free() on the util members of any items that have 75 to be deleted. Preserve the order of the items that are 76 retained. 77 78`string_list_longest_prefix`:: 79 80 Return the longest string within a string_list that is a 81 prefix (in the sense of prefixcmp()) of the specified string, 82 or NULL if no such prefix exists. This function does not 83 require the string_list to be sorted (it does a linear 84 search). 85 86`print_string_list`:: 87 88 Dump a string_list to stdout, useful mainly for debugging purposes. It 89 can take an optional header argument and it writes out the 90 string-pointer pairs of the string_list, each one in its own line. 91 92`string_list_clear`:: 93 94 Free a string_list. The `string` pointer of the items will be freed in 95 case the `strdup_strings` member of the string_list is set. The second 96 parameter controls if the `util` pointer of the items should be freed 97 or not. 98 99* Functions for sorted lists only 100 101`string_list_has_string`:: 102 103 Determine if the string_list has a given string or not. 104 105`string_list_insert`:: 106 107 Insert a new element to the string_list. The returned pointer can be 108 handy if you want to write something to the `util` pointer of the 109 string_list_item containing the just added string. If the given 110 string already exists the insertion will be skipped and the 111 pointer to the existing item returned. 112+ 113Since this function uses xrealloc() (which die()s if it fails) if the 114list needs to grow, it is safe not to check the pointer. I.e. you may 115write `string_list_insert(...)->util = ...;`. 116 117`string_list_lookup`:: 118 119 Look up a given string in the string_list, returning the containing 120 string_list_item. If the string is not found, NULL is returned. 121 122`string_list_remove_duplicates`:: 123 124 Remove all but the first of consecutive entries that have the 125 same string value. If free_util is true, call free() on the 126 util members of any items that have to be deleted. 127 128* Functions for unsorted lists only 129 130`string_list_append`:: 131 132 Append a new string to the end of the string_list. If 133 `strdup_string` is set, then the string argument is copied; 134 otherwise the new `string_list_entry` refers to the input 135 string. 136 137`string_list_append_nodup`:: 138 139 Append a new string to the end of the string_list. The new 140 `string_list_entry` always refers to the input string, even if 141 `strdup_string` is set. This function can be used to hand 142 ownership of a malloc()ed string to a `string_list` that has 143 `strdup_string` set. 144 145`sort_string_list`:: 146 147 Sort the list's entries by string value in `strcmp()` order. 148 149`unsorted_string_list_has_string`:: 150 151 It's like `string_list_has_string()` but for unsorted lists. 152 153`unsorted_string_list_lookup`:: 154 155 It's like `string_list_lookup()` but for unsorted lists. 156+ 157The above two functions need to look through all items, as opposed to their 158counterpart for sorted lists, which performs a binary search. 159 160`unsorted_string_list_delete_item`:: 161 162 Remove an item from a string_list. The `string` pointer of the items 163 will be freed in case the `strdup_strings` member of the string_list 164 is set. The third parameter controls if the `util` pointer of the 165 items should be freed or not. 166 167`string_list_split`:: 168`string_list_split_in_place`:: 169 170 Split a string into substrings on a delimiter character and 171 append the substrings to a `string_list`. If `maxsplit` is 172 non-negative, then split at most `maxsplit` times. Return the 173 number of substrings appended to the list. 174+ 175`string_list_split` requires a `string_list` that has `strdup_strings` 176set to true; it leaves the input string untouched and makes copies of 177the substrings in newly-allocated memory. 178`string_list_split_in_place` requires a `string_list` that has 179`strdup_strings` set to false; it splits the input string in place, 180overwriting the delimiter characters with NULs and creating new 181string_list_items that point into the original string (the original 182string must therefore not be modified or freed while the `string_list` 183is in use). 184 185 186Data structures 187--------------- 188 189* `struct string_list_item` 190 191Represents an item of the list. The `string` member is a pointer to the 192string, and you may use the `util` member for any purpose, if you want. 193 194* `struct string_list` 195 196Represents the list itself. 197 198. The array of items are available via the `items` member. 199. The `nr` member contains the number of items stored in the list. 200. The `alloc` member is used to avoid reallocating at every insertion. 201 You should not tamper with it. 202. Setting the `strdup_strings` member to 1 will strdup() the strings 203 before adding them, see above.