Better documentation for 'lctype.h'

The old documentation said that 'ltolower' only works for alphabetic
characters. However, 'l_str2d' uses it (correctly) also on dots ('.').
This commit is contained in:
Roberto Ierusalimschy 2020-09-03 09:52:43 -03:00
parent 6bc0f13505
commit 8496112a18
1 changed files with 10 additions and 4 deletions

View File

@ -13,7 +13,7 @@
/*
** WARNING: the functions defined here do not necessarily correspond
** to the similar functions in the standard C ctype.h. They are
** optimized for the specific needs of Lua
** optimized for the specific needs of Lua.
*/
#if !defined(LUA_USE_CTYPE)
@ -61,13 +61,19 @@
#define lisprint(c) testprop(c, MASK(PRINTBIT))
#define lisxdigit(c) testprop(c, MASK(XDIGITBIT))
/*
** this 'ltolower' only works for alphabetic characters
** In ASCII, this 'ltolower' is correct for alphabetic characters and
** for '.'. That is enough for Lua needs. ('check_exp' ensures that
** the character either is an upper-case letter or is unchanged by
** the transformation, which holds for lower-case letters and '.'.)
*/
#define ltolower(c) ((c) | ('A' ^ 'a'))
#define ltolower(c) \
check_exp(('A' <= (c) && (c) <= 'Z') || (c) == ((c) | ('A' ^ 'a')), \
(c) | ('A' ^ 'a'))
/* two more entries for 0 and -1 (EOZ) */
/* one entry for each character and for -1 (EOZ) */
LUAI_DDEC(const lu_byte luai_ctype_[UCHAR_MAX + 2];)