129 lines
3.9 KiB
Plaintext
129 lines
3.9 KiB
Plaintext
string-list API
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===============
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The string_list API offers a data structure and functions to handle sorted
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and unsorted string lists.
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The 'string_list' struct used to be called 'path_list', but was renamed
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because it is not specific to paths.
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The caller:
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. Allocates and clears a `struct string_list` variable.
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. Initializes the members. You might want to set the flag `strdup_strings`
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if the strings should be strdup()ed. For example, this is necessary
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when you add something like git_path("..."), since that function returns
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a static buffer that will change with the next call to git_path().
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+
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If you need something advanced, you can manually malloc() the `items`
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member (you need this if you add things later) and you should set the
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`nr` and `alloc` members in that case, too.
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. Adds new items to the list, using `string_list_append` or
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`string_list_insert`.
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. Can check if a string is in the list using `string_list_has_string` or
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`unsorted_string_list_has_string` and get it from the list using
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`string_list_lookup` for sorted lists.
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. Can sort an unsorted list using `sort_string_list`.
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. Finally it should free the list using `string_list_clear`.
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Example:
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----
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struct string_list list;
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int i;
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memset(&list, 0, sizeof(struct string_list));
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string_list_append("foo", &list);
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string_list_append("bar", &list);
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for (i = 0; i < list.nr; i++)
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printf("%s\n", list.items[i].string)
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----
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NOTE: It is more efficient to build an unsorted list and sort it
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afterwards, instead of building a sorted list (`O(n log n)` instead of
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`O(n^2)`).
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+
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However, if you use the list to check if a certain string was added
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already, you should not do that (using unsorted_string_list_has_string()),
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because the complexity would be quadratic again (but with a worse factor).
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Functions
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---------
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* General ones (works with sorted and unsorted lists as well)
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`print_string_list`::
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Dump a string_list to stdout, useful mainly for debugging purposes. It
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can take an optional header argument and it writes out the
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string-pointer pairs of the string_list, each one in its own line.
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`string_list_clear`::
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Free a string_list. The `string` pointer of the items will be freed in
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case the `strdup_strings` member of the string_list is set. The second
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parameter controls if the `util` pointer of the items should be freed
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or not.
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* Functions for sorted lists only
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`string_list_has_string`::
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Determine if the string_list has a given string or not.
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`string_list_insert`::
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Insert a new element to the string_list. The returned pointer can be
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handy if you want to write something to the `util` pointer of the
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string_list_item containing the just added string.
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+
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Since this function uses xrealloc() (which die()s if it fails) if the
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list needs to grow, it is safe not to check the pointer. I.e. you may
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write `string_list_insert(...)->util = ...;`.
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`string_list_lookup`::
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Look up a given string in the string_list, returning the containing
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string_list_item. If the string is not found, NULL is returned.
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* Functions for unsorted lists only
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`string_list_append`::
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Append a new string to the end of the string_list.
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`sort_string_list`::
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Make an unsorted list sorted.
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`unsorted_string_list_has_string`::
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It's like `string_list_has_string()` but for unsorted lists.
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+
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This function needs to look through all items, as opposed to its
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counterpart for sorted lists, which performs a binary search.
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Data structures
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---------------
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* `struct string_list_item`
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Represents an item of the list. The `string` member is a pointer to the
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string, and you may use the `util` member for any purpose, if you want.
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* `struct string_list`
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Represents the list itself.
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. The array of items are available via the `items` member.
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. The `nr` member contains the number of items stored in the list.
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. The `alloc` member is used to avoid reallocating at every insertion.
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You should not tamper with it.
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. Setting the `strdup_strings` member to 1 will strdup() the strings
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before adding them, see above.
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