To decide whether letters are upper or lower case, and convert between the two.
§1. Char Is Of Case. The following decides whether a character c belongs to case case, where
0 means lower case and 1 means upper. c is interpreted according to the
character casing chart in "UnicodeData.i6t", which means, it will be
ZSCII for the Z-machine and Unicode for Glulx.
[ CharIsOfCase c case
i tab min max len par;
if (c<'A') rfalse;
if (case == 0) {
if ((c >= 'a') && (c <= 'z')) rtrue;
tab = CharCasingChart0;
} else {
if ((c >= 'A') && (c <= 'Z')) rtrue;
tab = CharCasingChart1;
}
if (c<128) rfalse;
while (tab-->i) {
min = tab-->i; i++;
len = tab-->i; i++;
i++;
par = 0;
if (len<0) { par = 1; len = -len; }
if (c < min) rfalse;
if (c < min+len) {
if (par) { if ((c-min) % 2 == 0) rtrue; }
else { rtrue; }
}
}
rfalse;
];
§2. Char To Case. And the following converts character c to the desired case, or returns
it unchanged if it is not a letter with variant casings.
[ CharToCase c case
i tab min max len par del f;
if (c<'A') return c;
if (case == 1) {
if ((c >= 'a') && (c <= 'z')) return c-32;
tab = CharCasingChart0;
} else {
if ((c >= 'A') && (c <= 'Z')) return c+32;
tab = CharCasingChart1;
}
if (c<128) return c;
while (tab-->i) {
min = tab-->i; i++;
len = tab-->i; i++;
del = tab-->i; i++;
par = 0;
if (len<0) { par = 1; len = -len; }
if (c < min) return c;
if (c < min+len) {
f = false;
if (par) { if ((c-min) % 2 == 0) f = true; }
else { f = true; }
if (f) {
if (del == UNIC_NCT) return c;
return c+del;
}
}
}
return c;
];
§3. Reversing Case. It's convenient to provide this relatively fast routine to reverse the case of a letter since this is an operation used frequently in regular expression matching (see "RegExp.i6t").
#IFDEF TARGET_ZCODE;
[ TEXT_TY_RevCase ch;
if (ch<'A') return ch;
if ((ch >= 'a') && (ch <= 'z')) return ch-'a'+'A';
if ((ch >= 'A') && (ch <= 'Z')) return ch-'A'+'a';
if (ch<128) return ch;
if ((ch >= 155) && (ch <= 157)) return ch+3; ! a, o, u umlaut in ZSCII
if ((ch >= 158) && (ch <= 160)) return ch-3; ! A, O, U umlaut
if ((ch >= 164) && (ch <= 165)) return ch+3; ! e, i umlaut
if ((ch >= 167) && (ch <= 168)) return ch-3; ! E, I umlaut
if ((ch >= 169) && (ch <= 174)) return ch+6; ! a, e, i, o, u, y acute
if ((ch >= 175) && (ch <= 180)) return ch-6; ! A, E, I, O, U, Y acute
if ((ch >= 181) && (ch <= 185)) return ch+5; ! a, e, i, o, u grave
if ((ch >= 186) && (ch <= 190)) return ch-5; ! A, E, I, O, U grave
if ((ch >= 191) && (ch <= 195)) return ch+5; ! a, e, i, o, u circumflex
if ((ch >= 196) && (ch <= 200)) return ch-5; ! A, E, I, O, U circumflex
if (ch == 201) return 202; ! a circle
if (ch == 202) return 201; ! A circle
if (ch == 203) return 204; ! o slash
if (ch == 204) return 203; ! O slash
if ((ch >= 205) && (ch <= 207)) return ch+3; ! a, n, o tilde
if ((ch >= 208) && (ch <= 210)) return ch-3; ! A, N, O tilde
if (ch == 211) return 212; ! ae ligature
if (ch == 212) return 211; ! AE ligature
if (ch == 213) return 214; ! c cedilla
if (ch == 214) return 213; ! C cedilla
if (ch == 215 or 216) return ch+2; ! thorn, eth
if (ch == 217 or 218) return ch-2; ! Thorn, Eth
if (ch == 220) return 221; ! oe ligature
if (ch == 221) return 220; ! OE ligature
return ch;
];
#IFNOT;
[ TEXT_TY_RevCase ch;
if (ch<'A') return ch;
if ((ch >= 'a') && (ch <= 'z')) return ch-'a'+'A';
if ((ch >= 'A') && (ch <= 'Z')) return ch-'A'+'a';
if (ch<128) return ch;
if (CharIsOfCase(ch, 0)) return CharToCase(ch, 1);
if (CharIsOfCase(ch, 1)) return CharToCase(ch, 0);
return ch;
];
#ENDIF;
§4. DigitToValue. This takes a ZSCII or Unicode character code and returns its value as a digit, or returns -1 if it isn't a digit.
[ DigitToValue c n;
n = c-'0';
if ((n<0) || (n>9)) return -1;
return n;
];
§5. Testing. Not actually used: simply for testing the tables.
[ CharTestCases case i j;
for (i=32: i<$E0: i++) {
if ((i>=127) && (i<155)) continue;
print i, " - ", (char) i, " -";
if (CharIsOfCase(i, 0)) print " lower";
if (CharIsOfCase(i, 1)) print " upper";
j = CharToCase(i, 0); if (j ~= i) print " tolower: ", (char) j;
j = CharToCase(i, 1); if (j ~= i) print " toupper: ", (char) j;
print "^";
}
];