diff options
Diffstat (limited to 'string-list.h')
| -rw-r--r-- | string-list.h | 196 |
1 files changed, 165 insertions, 31 deletions
diff --git a/string-list.h b/string-list.h index 29bfb7ae45..ff8f6094a3 100644 --- a/string-list.h +++ b/string-list.h @@ -1,6 +1,69 @@ #ifndef STRING_LIST_H #define STRING_LIST_H +/** + * The string_list API offers a data structure and functions to handle + * sorted and unsorted arrays of strings. A "sorted" list is one whose + * entries are sorted by string value in `strcmp()` order. + * + * 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 `string_list_sort`. + * + * . 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). + */ + +/** + * 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_item { char *string; void *util; @@ -8,6 +71,18 @@ struct string_list_item { typedef int (*compare_strings_fn)(const char *, const char *); +/** + * 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. + * . The `compare_strings_fn` member is used to specify a custom compare + * function, otherwise `strcmp()` is used as the default function. + */ struct string_list { struct string_list_item *items; unsigned int nr, alloc; @@ -18,33 +93,65 @@ struct string_list { #define STRING_LIST_INIT_NODUP { NULL, 0, 0, 0, NULL } #define STRING_LIST_INIT_DUP { NULL, 0, 0, 1, NULL } +/* General functions which work with both sorted and unsorted lists. */ + +/** + * Initialize the members of the string_list, set `strdup_strings` + * member according to the value of the second parameter. + */ void string_list_init(struct string_list *list, int strdup_strings); +/** Callback function type for for_each_string_list */ +typedef int (*string_list_each_func_t)(struct string_list_item *, void *); + +/** + * Apply `want` to each item in `list`, retaining only the ones 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. + */ +void filter_string_list(struct string_list *list, int free_util, + string_list_each_func_t want, void *cb_data); + +/** + * 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. + */ void print_string_list(const struct string_list *p, const char *text); + +/** + * 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. + */ void string_list_clear(struct string_list *list, int free_util); -/* Use this function to call a custom clear function on each util pointer */ -/* The string associated with the util pointer is passed as the second argument */ +/** + * Callback type for `string_list_clear_func`. The string associated + * with the util pointer is passed as the second argument + */ typedef void (*string_list_clear_func_t)(void *p, const char *str); + +/** Call a custom clear function on each util pointer */ void string_list_clear_func(struct string_list *list, string_list_clear_func_t clearfunc); -/* Use this function or the macro below to iterate over each item */ -typedef int (*string_list_each_func_t)(struct string_list_item *, void *); +/** + * Apply `func` to each item. If `func` returns nonzero, the + * iteration aborts and the return value is propagated. + */ int for_each_string_list(struct string_list *list, - string_list_each_func_t, void *cb_data); -#define for_each_string_list_item(item,list) \ - for (item = (list)->items; item < (list)->items + (list)->nr; ++item) + string_list_each_func_t func, void *cb_data); -/* - * Apply want to each item in list, retaining only the ones 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. - */ -void filter_string_list(struct string_list *list, int free_util, - string_list_each_func_t want, void *cb_data); +/** Iterate over each item, as a macro. */ +#define for_each_string_list_item(item,list) \ + for (item = (list)->items; \ + item && item < (list)->items + (list)->nr; \ + ++item) -/* +/** * 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. @@ -52,25 +159,34 @@ void filter_string_list(struct string_list *list, int free_util, void string_list_remove_empty_items(struct string_list *list, int free_util); /* Use these functions only on sorted lists: */ + +/** Determine if the string_list has a given string or not. */ int string_list_has_string(const struct string_list *list, const char *string); int string_list_find_insert_index(const struct string_list *list, const char *string, int negative_existing_index); -/* - * Inserts the given string into the sorted list. - * If the string already exists, the list is not altered. - * Returns the string_list_item, the string is part of. + +/** + * 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 = ...;`. */ struct string_list_item *string_list_insert(struct string_list *list, const char *string); -/* - * Removes the given string from the sorted list. - * If the string doesn't exist, the list is not altered. +/** + * Remove the given string from the sorted list. If the string + * doesn't exist, the list is not altered. */ extern void string_list_remove(struct string_list *list, const char *string, int free_util); -/* - * Checks if the given string is part of a sorted list. If it is part of the list, +/** + * Check if the given string is part of a sorted list. If it is part of the list, * return the coresponding string_list_item, NULL otherwise. */ struct string_list_item *string_list_lookup(struct string_list *list, const char *string); @@ -85,14 +201,14 @@ void string_list_remove_duplicates(struct string_list *sorted_list, int free_uti /* Use these functions only on unsorted lists: */ -/* +/** * Add string to the end of list. If list->strdup_string is set, then * string is copied; otherwise the new string_list_entry refers to the * input string. */ struct string_list_item *string_list_append(struct string_list *list, const char *string); -/* +/** * Like string_list_append(), except string is never copied. When * list->strdup_strings is set, this function can be used to hand * ownership of a malloc()ed string to list without making an extra @@ -100,16 +216,34 @@ struct string_list_item *string_list_append(struct string_list *list, const char */ struct string_list_item *string_list_append_nodup(struct string_list *list, char *string); +/** + * Sort the list's entries by string value in `strcmp()` order. + */ void string_list_sort(struct string_list *list); + +/** + * Like `string_list_has_string()` but for unsorted lists. Linear in + * size of the list. + */ int unsorted_string_list_has_string(struct string_list *list, const char *string); + +/** + * Like `string_list_lookup()` but for unsorted lists. Linear in size + * of the list. + */ struct string_list_item *unsorted_string_list_lookup(struct string_list *list, const char *string); - +/** + * 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. + */ void unsorted_string_list_delete_item(struct string_list *list, int i, int free_util); -/* - * Split string into substrings on character delim and append the - * substrings to list. The input string is not modified. +/** + * Split string into substrings on character `delim` and append the + * substrings to `list`. The input string is not modified. * list->strdup_strings must be set, as new memory needs to be * allocated to hold the substrings. If maxsplit is non-negative, * then split at most maxsplit times. Return the number of substrings |