diff options
Diffstat (limited to 'handy.h')
| -rw-r--r-- | handy.h | 18 |
1 files changed, 18 insertions, 0 deletions
@@ -1706,6 +1706,24 @@ typedef U32 line_t; * both ASCII and EBCDIC the last 3 bits of the octal digits range from 0-7. */ #define OCTAL_VALUE(c) (__ASSERT_(isOCTAL(c)) (7 & (c))) +/* Efficiently returns a boolean as to if two native characters are equivalent + * case-insenstively. At least one of the characters must be one of [A-Za-z]; + * the ALPHA in the name is to remind you of that. This is asserted() in + * DEBUGGING builds. Because [A-Za-z] are invariant under UTF-8, this macro + * works (on valid input) for both non- and UTF-8-encoded bytes. + * + * When one of the inputs is a compile-time constant and gets folded by the + * compiler, this reduces to an AND and a TEST. On both EBCDIC and ASCII + * machines, 'A' and 'a' differ by a single bit; the same with the upper and + * lower case of all other ASCII-range alphabetics. On ASCII platforms, they + * are 32 apart; on EBCDIC, they are 64. This uses an exclusive 'or' to find + * that bit and then inverts it to form a mask, with just a single 0, in the + * bit position where the upper- and lowercase differ. */ +#define isALPHA_FOLD_EQ(c1, c2) \ + (__ASSERT_(isALPHA_A(c1) || isALPHA_A(c2)) \ + ((c1) & ~('A' ^ 'a')) == ((c2) & ~('A' ^ 'a'))) +#define isALPHA_FOLD_NE(c1, c2) (! isALPHA_FOLD_EQ((c1), (c2))) + /* =head1 Memory Management |