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git/t/helper/test-string-list.c
Taylor Blau 52acddf36c string-list: multi-delimiter `string_list_split_in_place()`
Enhance `string_list_split_in_place()` to accept multiple characters as
delimiters instead of a single character.

Instead of using `strchr(2)` to locate the first occurrence of the given
delimiter character, `string_list_split_in_place_multi()` uses
`strcspn(2)` to move past the initial segment of characters comprised of
any characters in the delimiting set.

When only a single delimiting character is provided, `strpbrk(2)` (which
is implemented with `strcspn(2)`) has equivalent performance to
`strchr(2)`. Modern `strcspn(2)` implementations treat an empty
delimiter or the singleton delimiter as a special case and fall back to
calling strchrnul(). Both glibc[1] and musl[2] implement `strcspn(2)`
this way.

This change is one step to removing `strtok(2)` from the tree. Note that
`string_list_split_in_place()` is not a strict replacement for
`strtok()`, since it will happily turn sequential delimiter characters
into empty entries in the resulting string_list. For example:

    string_list_split_in_place(&xs, "foo:;:bar:;:baz", ":;", -1)

would yield a string list of:

    ["foo", "", "", "bar", "", "", "baz"]

Callers that wish to emulate the behavior of strtok(2) more directly
should call `string_list_remove_empty_items()` after splitting.

To avoid regressions for the new multi-character delimter cases, update
t0063 in this patch as well.

[1]: https://sourceware.org/git/?p=glibc.git;a=blob;f=string/strcspn.c;hb=glibc-2.37#l35
[2]: https://git.musl-libc.org/cgit/musl/tree/src/string/strcspn.c?h=v1.2.3#n11

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-24 16:01:28 -07:00

130 lines
3.1 KiB
C

#include "test-tool.h"
#include "cache.h"
#include "string-list.h"
/*
* Parse an argument into a string list. arg should either be a
* ':'-separated list of strings, or "-" to indicate an empty string
* list (as opposed to "", which indicates a string list containing a
* single empty string). list->strdup_strings must be set.
*/
static void parse_string_list(struct string_list *list, const char *arg)
{
if (!strcmp(arg, "-"))
return;
(void)string_list_split(list, arg, ':', -1);
}
static void write_list(const struct string_list *list)
{
int i;
for (i = 0; i < list->nr; i++)
printf("[%d]: \"%s\"\n", i, list->items[i].string);
}
static void write_list_compact(const struct string_list *list)
{
int i;
if (!list->nr)
printf("-\n");
else {
printf("%s", list->items[0].string);
for (i = 1; i < list->nr; i++)
printf(":%s", list->items[i].string);
printf("\n");
}
}
static int prefix_cb(struct string_list_item *item, void *cb_data)
{
const char *prefix = (const char *)cb_data;
return starts_with(item->string, prefix);
}
int cmd__string_list(int argc, const char **argv)
{
if (argc == 5 && !strcmp(argv[1], "split")) {
struct string_list list = STRING_LIST_INIT_DUP;
int i;
const char *s = argv[2];
int delim = *argv[3];
int maxsplit = atoi(argv[4]);
i = string_list_split(&list, s, delim, maxsplit);
printf("%d\n", i);
write_list(&list);
string_list_clear(&list, 0);
return 0;
}
if (argc == 5 && !strcmp(argv[1], "split_in_place")) {
struct string_list list = STRING_LIST_INIT_NODUP;
int i;
char *s = xstrdup(argv[2]);
const char *delim = argv[3];
int maxsplit = atoi(argv[4]);
i = string_list_split_in_place(&list, s, delim, maxsplit);
printf("%d\n", i);
write_list(&list);
string_list_clear(&list, 0);
free(s);
return 0;
}
if (argc == 4 && !strcmp(argv[1], "filter")) {
/*
* Retain only the items that have the specified prefix.
* Arguments: list|- prefix
*/
struct string_list list = STRING_LIST_INIT_DUP;
const char *prefix = argv[3];
parse_string_list(&list, argv[2]);
filter_string_list(&list, 0, prefix_cb, (void *)prefix);
write_list_compact(&list);
string_list_clear(&list, 0);
return 0;
}
if (argc == 3 && !strcmp(argv[1], "remove_duplicates")) {
struct string_list list = STRING_LIST_INIT_DUP;
parse_string_list(&list, argv[2]);
string_list_remove_duplicates(&list, 0);
write_list_compact(&list);
string_list_clear(&list, 0);
return 0;
}
if (argc == 2 && !strcmp(argv[1], "sort")) {
struct string_list list = STRING_LIST_INIT_NODUP;
struct strbuf sb = STRBUF_INIT;
struct string_list_item *item;
strbuf_read(&sb, 0, 0);
/*
* Split by newline, but don't create a string_list item
* for the empty string after the last separator.
*/
if (sb.len && sb.buf[sb.len - 1] == '\n')
strbuf_setlen(&sb, sb.len - 1);
string_list_split_in_place(&list, sb.buf, "\n", -1);
string_list_sort(&list);
for_each_string_list_item(item, &list)
puts(item->string);
string_list_clear(&list, 0);
strbuf_release(&sb);
return 0;
}
fprintf(stderr, "%s: unknown function name: %s\n", argv[0],
argv[1] ? argv[1] : "(there was none)");
return 1;
}