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:
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Allocates and clears a
struct string_listvariable. -
Initializes the members. You might want to set the flag
strdup_stringsif 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
itemsmember (you need this if you add things later) and you should set thenrandallocmembers 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/orstring_list_split_in_place. -
Can check if a string is in the list using
string_list_has_stringorunsorted_string_list_has_stringand get it from the list usingstring_list_lookupfor 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 usingstring_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)
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Note
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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
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General ones (works with sorted and unsorted lists as well)
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string_list_init -
Initialize the members of the string_list, set
strdup_stringsmember according to the value of the second parameter. -
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.
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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.
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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.
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string_list_clear -
Free a string_list. The
stringpointer of the items will be freed in case thestrdup_stringsmember of the string_list is set. The second parameter controls if theutilpointer of the items should be freed or not.
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-
Functions for sorted lists only
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string_list_has_string -
Determine if the string_list has a given string or not.
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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
utilpointer 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.
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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.
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Functions for unsorted lists only
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string_list_append -
Append a new string to the end of the string_list. If
strdup_stringis set, then the string argument is copied; otherwise the newstring_list_entryrefers to the input string. -
string_list_append_nodup -
Append a new string to the end of the string_list. The new
string_list_entryalways refers to the input string, even ifstrdup_stringis set. This function can be used to hand ownership of a malloc()ed string to astring_listthat hasstrdup_stringset. -
string_list_sort -
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.
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unsorted_string_list_delete_item -
Remove an item from a string_list. The
stringpointer of the items will be freed in case thestrdup_stringsmember of the string_list is set. The third parameter controls if theutilpointer 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. Ifmaxsplitis non-negative, then split at mostmaxsplittimes. Return the number of substrings appended to the list.string_list_splitrequires astring_listthat hasstrdup_stringsset to true; it leaves the input string untouched and makes copies of the substrings in newly-allocated memory.string_list_split_in_placerequires astring_listthat hasstrdup_stringsset 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 thestring_listis in use).
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Data structures
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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.
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struct string_list
Represents the list itself.
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The array of items are available via the
itemsmember. -
The
nrmember contains the number of items stored in the list. -
The
allocmember is used to avoid reallocating at every insertion. You should not tamper with it. -
Setting the
strdup_stringsmember to 1 will strdup() the strings before adding them, see above. -
The
compare_strings_fnmember is used to specify a custom compare function, otherwisestrcmp()is used as the default function.