From 8496112a18c887449d37e5aadbb6daec34ae54c0 Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Thu, 3 Sep 2020 09:52:43 -0300 Subject: [PATCH] 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 ('.'). --- lctype.h | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/lctype.h b/lctype.h index cbff4d7e..864e1901 100644 --- a/lctype.h +++ b/lctype.h @@ -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];)