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utils: add ascii ctype helpers

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Add some constexpr ctype helpers that avoid any possible UB (i.e.,
handling casting to unsigned), and explicitly avoid any
locale-specifics.
This commit is contained in:
Dirk-Jan C. Binnema
2026-07-21 13:21:09 +03:00
committed by Seth Ladygo
parent 39b7cf2e9d
commit f2960a197e
3 changed files with 169 additions and 1 deletions
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41
lib/utils/tests/test-utils.cc
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@ -335,6 +335,46 @@ test_summarize()
"fortification by the Bais raja Sathna. ");
}
static void
test_ascii_ctype()
{
/* the ascii ctype functions are constexpr and work for any
* integral character type... */
static_assert(is_ascii('m'));
static_assert(!is_ascii(static_cast<char>(0x80)));
static_assert(is_ascii_cntrl('\n'));
static_assert(!is_ascii_cntrl(' '));
static_assert(is_ascii_blank('\t'));
static_assert(!is_ascii_blank('\n'));
static_assert(to_ascii_lower('Q') == 'q');
static_assert(to_ascii_lower(U'Q') == U'q');
static_assert(to_ascii_lower('8') == '8');
static_assert(to_ascii_lower('\xc4'/* Ä */) == '\xc4');
/* ... and, unlike their libc cousins, are well-defined for
* negative chars; check the full range against glib's
* (locale-independent) g_ascii_* versions. */
for (int i = -128; i != 128; ++i) {
const auto c{static_cast<char>(i)};
g_assert_cmpint(is_ascii_cntrl(c), ==, !!g_ascii_iscntrl(c));
g_assert_cmpint(is_ascii_alpha(c), ==, !!g_ascii_isalpha(c));
g_assert_cmpint(is_ascii_digit(c), ==, !!g_ascii_isdigit(c));
g_assert_cmpint(is_ascii_alnum(c), ==, !!g_ascii_isalnum(c));
/* NB: unlike isspace(3), g_ascii_isspace excludes VT */
g_assert_cmpint(is_ascii_space(c), ==,
!!g_ascii_isspace(c) || c == '\v');
g_assert_cmpint(is_ascii_punct(c), ==, !!g_ascii_ispunct(c));
g_assert_cmpint(to_ascii_lower(c), ==, g_ascii_tolower(c));
}
/* values beyond the char range must not get truncated */
const gunichar uc{0x2028/* line separator */};
g_assert_false(is_ascii(uc));
g_assert_false(is_ascii_cntrl(uc));
g_assert_false(is_ascii_punct(uc));
g_assert_true(to_ascii_lower(uc) == uc);
}
int
main(int argc, char* argv[])
{
@ -355,6 +395,7 @@ main(int argc, char* argv[])
g_test_add_func("/utils/define-bitmap", test_define_bitmap);
g_test_add_func("/utils/to-from-lexnum", test_to_from_lexnum);
g_test_add_func("/utils/locale-workaround", test_locale_workaround);
g_test_add_func("/utils/ascii-ctype", test_ascii_ctype);
return g_test_run();
}