lua

commit 8496112a18c887449d37e5aadbb6daec34ae54c0
parent 6bc0f13505bf5d4f613d725fe008c79e72f83ddf
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date:   Thu,  3 Sep 2020 09:52:16 -0300

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 ('.').

Diffstat:
M
lctype.h
 | 
14
++++++++++----

1 file changed, 10 insertions(+), 4 deletions(-)
diff --git 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];)