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string-list.h: move documentation from Documentation/api/ into header 

This mirrors commit 'bdfdaa497 ("strbuf.h: integrate api-strbuf.txt
documentation, 2015-01-16") which did the same for strbuf.h:

* API documentation uses /** */ to set it apart from other comments.

* Function names were stripped from the comments.

* Ordering of the header was adjusted to follow the one from the text
  file.

* Edited some existing comments from string-list.h for consistency.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
maint
Han-Wen Nienhuys 2017-09-26 13:21:50 +02:00 committed by Junio C Hamano
parent 28996cec80
commit 4f665f2cf3
2 changed files with 166 additions and 243 deletions
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209
Documentation/technical/api-string-list.txt
View File

@ -1,209 +0,0 @@
string-list API
===============

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:

. 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).

Functions
---------

* General ones (works with sorted and unsorted lists as well)

`string_list_init`::

Initialize the members of the string_list, set `strdup_strings`
member 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.

`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.

`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.

`string_list_clear`::

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.

* Functions for sorted lists only

`string_list_has_string`::

Determine if the string_list has a given string or not.

`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 `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 = ...;`.

`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.

`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.

* Functions for unsorted lists only

`string_list_append`::

Append a new string to the end of the string_list. If
`strdup_string` is set, then the string argument is copied;
otherwise the new `string_list_entry` refers to the input
string.

`string_list_append_nodup`::

Append a new string to the end of the string_list. The new
`string_list_entry` always refers to the input string, even if
`strdup_string` is set. This function can be used to hand
ownership of a malloc()ed string to a `string_list` that has
`strdup_string` set.

`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.

`unsorted_string_list_delete_item`::

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.

`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`. If `maxsplit` is
non-negative, then split at most `maxsplit` times. Return the
number of substrings appended to the list.
+
`string_list_split` requires a `string_list` that has `strdup_strings`
set to true; it leaves the input string untouched and makes copies of
the substrings in newly-allocated memory.
`string_list_split_in_place` requires a `string_list` that has
`strdup_strings` set 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 the `string_list`
is in use).


Data structures
---------------

* `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.

* `struct string_list`

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.

200
string-list.h
View File

@ -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;
@ -18,35 +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);

void print_string_list(const struct string_list *p, const char *text);
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 */
typedef void (*string_list_clear_func_t)(void *p, const char *str);
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 */
/** Callback function type for for_each_string_list */
typedef int (*string_list_each_func_t)(struct string_list_item *, void *);
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 && item < (list)->items + (list)->nr; \
++item)

/*
* 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
/**
* 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);

/**
* 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);

/**
* 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 func, 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.
@ -54,25 +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);
@ -87,14 +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
@ -102,16 +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