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deb-goldedplus/goldlib/hunspell/affentry.cxx

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Added HunSpell library to project
2006-04-05 17:20:12 +00:00
#include "license.hun"
#include "license.mys"
#include <cctype>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include "affentry.hxx"
#include "csutil.hxx"
#if !defined(_MSC_VER)
using namespace std;
#endif
PfxEntry::PfxEntry(AffixMgr* pmgr, affentry* dp)
{
// register affix manager
pmyMgr = pmgr;
// set up its intial values
aflag = dp->aflag; // flag
strip = dp->strip; // string to strip
appnd = dp->appnd; // string to append
stripl = dp->stripl; // length of strip string
appndl = dp->appndl; // length of append string
numconds = dp->numconds; // number of conditions to match
opts = dp->opts; // cross product flag
// then copy over all of the conditions
memcpy(&conds.base[0],&dp->conds.base[0],SETSIZE*sizeof(conds.base[0]));
next = NULL;
nextne = NULL;
nexteq = NULL;
morphcode = dp->morphcode;
contclass = dp->contclass;
contclasslen = dp->contclasslen;
}
PfxEntry::~PfxEntry()
{
aflag = 0;
if (appnd) free(appnd);
if (strip) free(strip);
pmyMgr = NULL;
appnd = NULL;
strip = NULL;
if (opts & aeUTF8) {
for (int i = 0; i < 8; i++) {
if (conds.utf8.wchars[i]) free(conds.utf8.wchars[i]);
}
}
if (morphcode && !(opts & aeALIASM)) free(morphcode);
if (contclass && !(opts & aeALIASF)) free(contclass);
}
// add prefix to this word assuming conditions hold
char * PfxEntry::add(const char * word, int len)
{
char tword[MAXWORDUTF8LEN + 4];
if ((len > stripl) && (len >= numconds) && test_condition(word) &&
(!stripl || (strncmp(word, strip, stripl) == 0)) &&
((MAXWORDUTF8LEN + 4) > (len + appndl - stripl))) {
/* we have a match so add prefix */
char * pp = tword;
if (appndl) {
strcpy(tword,appnd);
pp += appndl;
}
strcpy(pp, (word + stripl));
return mystrdup(tword);
}
return NULL;
}
inline int PfxEntry::test_condition(const char * st)
{
int cond;
unsigned char * cp = (unsigned char *)st;
if (!(opts & aeUTF8)) { // 256-character codepage
for (cond = 0; cond < numconds; cond++) {
if ((conds.base[*cp++] & (1 << cond)) == 0) return 0;
}
} else { // UTF-8 encoding
unsigned short wc;
for (cond = 0; cond < numconds; cond++) {
// a simple 7-bit ASCII character in UTF-8
if ((*cp >> 7) == 0) {
// also check limit (end of word)
if ((!*cp) || ((conds.utf8.ascii[*cp++] & (1 << cond)) == 0)) return 0;
// UTF-8 multibyte character
} else {
// not dot wildcard in rule
if (!conds.utf8.all[cond]) {
if (conds.utf8.neg[cond]) {
u8_u16((w_char *) &wc, 1, (char *) cp);
if (conds.utf8.wchars[cond] &&
flag_bsearch((unsigned short *)conds.utf8.wchars[cond],
wc, (short) conds.utf8.wlen[cond])) return 0;
} else {
if (!conds.utf8.wchars[cond]) return 0;
u8_u16((w_char *) &wc, 1, (char *) cp);
if (!flag_bsearch((unsigned short *)conds.utf8.wchars[cond],
wc, (short)conds.utf8.wlen[cond])) return 0;
}
}
// jump to next UTF-8 character
for(cp++; (*cp & 0xc0) == 0x80; cp++);
}
}
}
return 1;
}
// check if this prefix entry matches
struct hentry * PfxEntry::check(const char * word, int len, char in_compound, const FLAG needflag)
{
int tmpl; // length of tmpword
struct hentry * he; // hash entry of root word or NULL
char tmpword[MAXWORDUTF8LEN + 4];
// on entry prefix is 0 length or already matches the beginning of the word.
// So if the remaining root word has positive length
// and if there are enough chars in root word and added back strip chars
// to meet the number of characters conditions, then test it
tmpl = len - appndl;
if ((tmpl > 0) && (tmpl + stripl >= numconds)) {
// generate new root word by removing prefix and adding
// back any characters that would have been stripped
if (stripl) strcpy (tmpword, strip);
strcpy ((tmpword + stripl), (word + appndl));
// now make sure all of the conditions on characters
// are met. Please see the appendix at the end of
// this file for more info on exactly what is being
// tested
// if all conditions are met then check if resulting
// root word in the dictionary
if (test_condition(tmpword)) {
tmpl += stripl;
if ((he = pmyMgr->lookup(tmpword)) != NULL) {
do {
if (TESTAFF(he->astr, aflag, he->alen) &&
// forbid single prefixes with pseudoroot flag
! TESTAFF(contclass, pmyMgr->get_pseudoroot(), contclasslen) &&
// needflag
((!needflag) || TESTAFF(he->astr, needflag, he->alen) ||
(contclass && TESTAFF(contclass, needflag, contclasslen))))
return he;
} while ((he = he->next_homonym)); // check homonyms
}
// prefix matched but no root word was found
// if aeXPRODUCT is allowed, try again but now
// ross checked combined with a suffix
//if ((opts & aeXPRODUCT) && in_compound) {
if ((opts & aeXPRODUCT)) {
he = pmyMgr->suffix_check(tmpword, tmpl, aeXPRODUCT, (AffEntry *)this, NULL,
0, NULL, FLAG_NULL, needflag, in_compound);
if (he) return he;
}
}
}
return NULL;
}
// check if this prefix entry matches
struct hentry * PfxEntry::check_twosfx(const char * word, int len,
char in_compound, const FLAG needflag)
{
int tmpl; // length of tmpword
struct hentry * he; // hash entry of root word or NULL
char tmpword[MAXWORDUTF8LEN + 4];
// on entry prefix is 0 length or already matches the beginning of the word.
// So if the remaining root word has positive length
// and if there are enough chars in root word and added back strip chars
// to meet the number of characters conditions, then test it
tmpl = len - appndl;
if ((tmpl > 0) && (tmpl + stripl >= numconds)) {
// generate new root word by removing prefix and adding
// back any characters that would have been stripped
if (stripl) strcpy (tmpword, strip);
strcpy ((tmpword + stripl), (word + appndl));
// now make sure all of the conditions on characters
// are met. Please see the appendix at the end of
// this file for more info on exactly what is being
// tested
// if all conditions are met then check if resulting
// root word in the dictionary
if (test_condition(tmpword)) {
tmpl += stripl;
// prefix matched but no root word was found
// if aeXPRODUCT is allowed, try again but now
// cross checked combined with a suffix
if ((opts & aeXPRODUCT) && (in_compound != IN_CPD_BEGIN)) {
he = pmyMgr->suffix_check_twosfx(tmpword, tmpl, aeXPRODUCT, (AffEntry *)this, needflag);
if (he) return he;
}
}
}
return NULL;
}
// check if this prefix entry matches
char * PfxEntry::check_twosfx_morph(const char * word, int len,
char in_compound, const FLAG needflag)
{
int tmpl; // length of tmpword
char tmpword[MAXWORDUTF8LEN + 4];
// on entry prefix is 0 length or already matches the beginning of the word.
// So if the remaining root word has positive length
// and if there are enough chars in root word and added back strip chars
// to meet the number of characters conditions, then test it
tmpl = len - appndl;
if ((tmpl > 0) && (tmpl + stripl >= numconds)) {
// generate new root word by removing prefix and adding
// back any characters that would have been stripped
if (stripl) strcpy (tmpword, strip);
strcpy ((tmpword + stripl), (word + appndl));
// now make sure all of the conditions on characters
// are met. Please see the appendix at the end of
// this file for more info on exactly what is being
// tested
// if all conditions are met then check if resulting
// root word in the dictionary
if (test_condition(tmpword)) {
tmpl += stripl;
// prefix matched but no root word was found
// if aeXPRODUCT is allowed, try again but now
// ross checked combined with a suffix
if ((opts & aeXPRODUCT) && (in_compound != IN_CPD_BEGIN)) {
return pmyMgr->suffix_check_twosfx_morph(tmpword, tmpl,
aeXPRODUCT, (AffEntry *)this, needflag);
}
}
}
return NULL;
}
// check if this prefix entry matches
char * PfxEntry::check_morph(const char * word, int len, char in_compound, const FLAG needflag)
{
int tmpl; // length of tmpword
struct hentry * he; // hash entry of root word or NULL
char tmpword[MAXWORDUTF8LEN + 4];
char result[MAXLNLEN];
char * st;
*result = '\0';
// on entry prefix is 0 length or already matches the beginning of the word.
// So if the remaining root word has positive length
// and if there are enough chars in root word and added back strip chars
// to meet the number of characters conditions, then test it
tmpl = len - appndl;
if ((tmpl > 0) && (tmpl + stripl >= numconds)) {
// generate new root word by removing prefix and adding
// back any characters that would have been stripped
if (stripl) strcpy (tmpword, strip);
strcpy ((tmpword + stripl), (word + appndl));
// now make sure all of the conditions on characters
// are met. Please see the appendix at the end of
// this file for more info on exactly what is being
// tested
// if all conditions are met then check if resulting
// root word in the dictionary
if (test_condition(tmpword)) {
tmpl += stripl;
if ((he = pmyMgr->lookup(tmpword)) != NULL) {
do {
if (TESTAFF(he->astr, aflag, he->alen) &&
// forbid single prefixes with pseudoroot flag
! TESTAFF(contclass, pmyMgr->get_pseudoroot(), contclasslen) &&
// needflag
((!needflag) || TESTAFF(he->astr, needflag, he->alen) ||
(contclass && TESTAFF(contclass, needflag, contclasslen)))) {
if (morphcode) strcat(result, morphcode); else strcat(result,getKey());
if (he->description) {
if ((*(he->description)=='[')||(*(he->description)=='<')) strcat(result,he->word);
strcat(result,he->description);
}
strcat(result, "\n");
}
} while ((he = he->next_homonym));
}
// prefix matched but no root word was found
// if aeXPRODUCT is allowed, try again but now
// ross checked combined with a suffix
if ((opts & aeXPRODUCT) && (in_compound != IN_CPD_BEGIN)) {
st = pmyMgr->suffix_check_morph(tmpword, tmpl, aeXPRODUCT, (AffEntry *)this,
FLAG_NULL, needflag);
if (st) {
strcat(result, st);
free(st);
}
}
}
}
if (*result) return mystrdup(result);
return NULL;
}
SfxEntry::SfxEntry(AffixMgr * pmgr, affentry* dp)
{
// register affix manager
pmyMgr = pmgr;
// set up its intial values
aflag = dp->aflag; // char flag
strip = dp->strip; // string to strip
appnd = dp->appnd; // string to append
stripl = dp->stripl; // length of strip string
appndl = dp->appndl; // length of append string
numconds = dp->numconds; // number of conditions to match
opts = dp->opts; // cross product flag
// then copy over all of the conditions
memcpy(&conds.base[0],&dp->conds.base[0],SETSIZE*sizeof(conds.base[0]));
rappnd = myrevstrdup(appnd);
morphcode = dp->morphcode;
contclass = dp->contclass;
contclasslen = dp->contclasslen;
}
SfxEntry::~SfxEntry()
{
aflag = 0;
if (appnd) free(appnd);
if (rappnd) free(rappnd);
if (strip) free(strip);
pmyMgr = NULL;
appnd = NULL;
strip = NULL;
if (opts & aeUTF8) {
for (int i = 0; i < 8; i++) {
if (conds.utf8.wchars[i]) free(conds.utf8.wchars[i]);
}
}
if (morphcode && !(opts & aeALIASM)) free(morphcode);
if (contclass && !(opts & aeALIASF)) free(contclass);
}
// add suffix to this word assuming conditions hold
char * SfxEntry::add(const char * word, int len)
{
char tword[MAXWORDUTF8LEN + 4];
/* make sure all conditions match */
if ((len > stripl) && (len >= numconds) && test_condition(word + len, word) &&
(!stripl || (strcmp(word + len - stripl, strip) == 0)) &&
((MAXWORDUTF8LEN + 4) > (len + appndl - stripl))) {
/* we have a match so add suffix */
strcpy(tword,word);
if (appndl) {
strcpy(tword + len - stripl, appnd);
} else {
*(tword + len - stripl) = '\0';
}
return mystrdup(tword);
}
return NULL;
}
inline int SfxEntry::test_condition(const char * st, const char * beg)
{
int cond;
unsigned char * cp = (unsigned char *) st;
if (!(opts & aeUTF8)) { // 256-character codepage
// D<>m<EFBFBD>lki affix algorithm
for (cond = numconds; --cond >= 0; ) {
if ((conds.base[*--cp] & (1 << cond)) == 0) return 0;
}
} else { // UTF-8 encoding
unsigned short wc;
for (cond = numconds; --cond >= 0; ) {
// go to next character position and check limit
if ((char *) --cp < beg) return 0;
// a simple 7-bit ASCII character in UTF-8
if ((*cp >> 7) == 0) {
if ((conds.utf8.ascii[*cp] & (1 << cond)) == 0) return 0;
// UTF-8 multibyte character
} else {
// go to first character of UTF-8 multibyte character
for (; (*cp & 0xc0) == 0x80; cp--);
// not dot wildcard in rule
if (!conds.utf8.all[cond]) {
if (conds.utf8.neg[cond]) {
u8_u16((w_char *) &wc, 1, (char *) cp);
if (conds.utf8.wchars[cond] &&
flag_bsearch((unsigned short *)conds.utf8.wchars[cond],
wc, (short) conds.utf8.wlen[cond])) return 0;
} else {
if (!conds.utf8.wchars[cond]) return 0;
u8_u16((w_char *) &wc, 1, (char *) cp);
if (!flag_bsearch((unsigned short *)conds.utf8.wchars[cond],
wc, (short)conds.utf8.wlen[cond])) return 0;
}
}
}
}
}
return 1;
}
// see if this suffix is present in the word
struct hentry * SfxEntry::check(const char * word, int len, int optflags,
AffEntry* ppfx, char ** wlst, int maxSug, int * ns, const FLAG cclass, const FLAG needflag)
{
int tmpl; // length of tmpword
struct hentry * he; // hash entry pointer
unsigned char * cp;
char tmpword[MAXWORDUTF8LEN + 4];
PfxEntry* ep = (PfxEntry *) ppfx;
// if this suffix is being cross checked with a prefix
// but it does not support cross products skip it
if (((optflags & aeXPRODUCT) != 0) && ((opts & aeXPRODUCT) == 0))
return NULL;
// upon entry suffix is 0 length or already matches the end of the word.
// So if the remaining root word has positive length
// and if there are enough chars in root word and added back strip chars
// to meet the number of characters conditions, then test it
tmpl = len - appndl;
// the second condition is not enough for UTF-8 strings
// it checked in test_condition()
if ((tmpl > 0) && (tmpl + stripl >= numconds)) {
// generate new root word by removing suffix and adding
// back any characters that would have been stripped or
// or null terminating the shorter string
strcpy (tmpword, word);
cp = (unsigned char *)(tmpword + tmpl);
if (stripl) {
strcpy ((char *)cp, strip);
tmpl += stripl;
cp = (unsigned char *)(tmpword + tmpl);
} else *cp = '\0';
// now make sure all of the conditions on characters
// are met. Please see the appendix at the end of
// this file for more info on exactly what is being // tested
// if all conditions are met then check if resulting
// root word in the dictionary
if (test_condition((char *) cp, (char *) tmpword)) {
#ifdef SZOSZABLYA_POSSIBLE_ROOTS
fprintf(stdout,"%s %s %c\n", word, tmpword, aflag);
#endif
if ((he = pmyMgr->lookup(tmpword)) != NULL) {
do {
// check conditional suffix (enabled by prefix)
if ((TESTAFF(he->astr, aflag, he->alen) || (ep && ep->getCont() &&
TESTAFF(ep->getCont(), aflag, ep->getContLen()))) &&
(((optflags & aeXPRODUCT) == 0) ||
TESTAFF(he->astr, ep->getFlag(), he->alen) ||
// enabled by prefix
((contclass) && TESTAFF(contclass, ep->getFlag(), contclasslen))
) &&
// handle cont. class
((!cclass) ||
((contclass) && TESTAFF(contclass, cclass, contclasslen))
) &&
// handle required flag
((!needflag) ||
(TESTAFF(he->astr, needflag, he->alen) ||
((contclass) && TESTAFF(contclass, needflag, contclasslen)))
)
) return he;
} while ((he = he->next_homonym)); // check homonyms
// obsolote stemming code (used only by the
// experimental SuffixMgr:suggest_pos_stems)
// store resulting root in wlst
} else if (wlst && (*ns < maxSug)) {
int cwrd = 1;
for (int k=0; k < *ns; k++)
if (strcmp(tmpword, wlst[k]) == 0) cwrd = 0;
if (cwrd) {
wlst[*ns] = mystrdup(tmpword);
if (wlst[*ns] == NULL) {
for (int j=0; j<*ns; j++) free(wlst[j]);
*ns = -1;
return NULL;
}
(*ns)++;
}
}
}
}
return NULL;
}
// see if two-level suffix is present in the word
struct hentry * SfxEntry::check_twosfx(const char * word, int len, int optflags,
AffEntry* ppfx, const FLAG needflag)
{
int tmpl; // length of tmpword
struct hentry * he; // hash entry pointer
unsigned char * cp;
char tmpword[MAXWORDUTF8LEN + 4];
PfxEntry* ep = (PfxEntry *) ppfx;
// if this suffix is being cross checked with a prefix
// but it does not support cross products skip it
if ((optflags & aeXPRODUCT) != 0 && (opts & aeXPRODUCT) == 0)
return NULL;
// upon entry suffix is 0 length or already matches the end of the word.
// So if the remaining root word has positive length
// and if there are enough chars in root word and added back strip chars
// to meet the number of characters conditions, then test it
tmpl = len - appndl;
if ((tmpl > 0) && (tmpl + stripl >= numconds)) {
// generate new root word by removing suffix and adding
// back any characters that would have been stripped or
// or null terminating the shorter string
strcpy (tmpword, word);
cp = (unsigned char *)(tmpword + tmpl);
if (stripl) {
strcpy ((char *)cp, strip);
tmpl += stripl;
cp = (unsigned char *)(tmpword + tmpl);
} else *cp = '\0';
// now make sure all of the conditions on characters
// are met. Please see the appendix at the end of
// this file for more info on exactly what is being
// tested
// if all conditions are met then recall suffix_check
if (test_condition((char *) cp, (char *) tmpword)) {
if (ppfx) {
// handle conditional suffix
if ((contclass) && TESTAFF(contclass, ep->getFlag(), contclasslen))
he = pmyMgr->suffix_check(tmpword, tmpl, 0, NULL, NULL, 0, NULL, (FLAG) aflag, needflag);
else
he = pmyMgr->suffix_check(tmpword, tmpl, optflags, ppfx, NULL, 0, NULL, (FLAG) aflag, needflag);
} else {
he = pmyMgr->suffix_check(tmpword, tmpl, 0, NULL, NULL, 0, NULL, (FLAG) aflag, needflag);
}
if (he) return he;
}
}
return NULL;
}
// see if two-level suffix is present in the word
char * SfxEntry::check_twosfx_morph(const char * word, int len, int optflags,
AffEntry* ppfx, const FLAG needflag)
{
int tmpl; // length of tmpword
unsigned char * cp;
char tmpword[MAXWORDUTF8LEN + 4];
PfxEntry* ep = (PfxEntry *) ppfx;
char * st;
char result[MAXLNLEN];
*result = '\0';
// if this suffix is being cross checked with a prefix
// but it does not support cross products skip it
if ((optflags & aeXPRODUCT) != 0 && (opts & aeXPRODUCT) == 0)
return NULL;
// upon entry suffix is 0 length or already matches the end of the word.
// So if the remaining root word has positive length
// and if there are enough chars in root word and added back strip chars
// to meet the number of characters conditions, then test it
tmpl = len - appndl;
if ((tmpl > 0) && (tmpl + stripl >= numconds)) {
// generate new root word by removing suffix and adding
// back any characters that would have been stripped or
// or null terminating the shorter string
strcpy (tmpword, word);
cp = (unsigned char *)(tmpword + tmpl);
if (stripl) {
strcpy ((char *)cp, strip);
tmpl += stripl;
cp = (unsigned char *)(tmpword + tmpl);
} else *cp = '\0';
// now make sure all of the conditions on characters
// are met. Please see the appendix at the end of
// this file for more info on exactly what is being
// tested
// if all conditions are met then recall suffix_check
if (test_condition((char *) cp, (char *) tmpword)) {
if (ppfx) {
// handle conditional suffix
if ((contclass) && TESTAFF(contclass, ep->getFlag(), contclasslen)) {
st = pmyMgr->suffix_check_morph(tmpword, tmpl, 0, NULL, aflag, needflag);
if (st) {
if (((PfxEntry *) ppfx)->getMorph()) {
strcat(result, ((PfxEntry *) ppfx)->getMorph());
}
strcat(result,st);
free(st);
mychomp(result);
}
} else {
st = pmyMgr->suffix_check_morph(tmpword, tmpl, optflags, ppfx, aflag, needflag);
if (st) {
strcat(result, st);
free(st);
mychomp(result);
}
}
} else {
st = pmyMgr->suffix_check_morph(tmpword, tmpl, 0, NULL, aflag, needflag);
if (st) {
strcat(result, st);
free(st);
mychomp(result);
}
}
if (*result) return mystrdup(result);
}
}
return NULL;
}
// get next homonym with same affix
struct hentry * SfxEntry::get_next_homonym(struct hentry * he, int optflags, AffEntry* ppfx,
const FLAG cclass, const FLAG needflag)
{
PfxEntry* ep = (PfxEntry *) ppfx;
while (he->next_homonym) {
he = he->next_homonym;
if ((TESTAFF(he->astr, aflag, he->alen) || (ep && ep->getCont() && TESTAFF(ep->getCont(), aflag, ep->getContLen()))) &&
((optflags & aeXPRODUCT) == 0 ||
TESTAFF(he->astr, ep->getFlag(), he->alen) ||
// handle conditional suffix
((contclass) && TESTAFF(contclass, ep->getFlag(), contclasslen))
) &&
// handle cont. class
((!cclass) ||
((contclass) && TESTAFF(contclass, cclass, contclasslen))
) &&
// handle required flag
((!needflag) ||
(TESTAFF(he->astr, needflag, he->alen) ||
((contclass) && TESTAFF(contclass, needflag, contclasslen)))
)
) return he;
}
return NULL;
}
#if 0
Appendix: Understanding Affix Code
An affix is either a prefix or a suffix attached to root words to make
other words.
Basically a Prefix or a Suffix is set of AffEntry objects
which store information about the prefix or suffix along
with supporting routines to check if a word has a particular
prefix or suffix or a combination.
The structure affentry is defined as follows:
struct affentry
{
unsigned short aflag; // ID used to represent the affix
char * strip; // string to strip before adding affix
char * appnd; // the affix string to add
unsigned char stripl; // length of the strip string
unsigned char appndl; // length of the affix string
char numconds; // the number of conditions that must be met
char opts; // flag: aeXPRODUCT- combine both prefix and suffix
char conds[SETSIZE]; // array which encodes the conditions to be met
};
Here is a suffix borrowed from the en_US.aff file. This file
is whitespace delimited.
SFX D Y 4
SFX D 0 e d
SFX D y ied [^aeiou]y
SFX D 0 ed [^ey]
SFX D 0 ed [aeiou]y
This information can be interpreted as follows:
In the first line has 4 fields
Field
-----
1 SFX - indicates this is a suffix
2 D - is the name of the character flag which represents this suffix
3 Y - indicates it can be combined with prefixes (cross product)
4 4 - indicates that sequence of 4 affentry structures are needed to
properly store the affix information
The remaining lines describe the unique information for the 4 SfxEntry
objects that make up this affix. Each line can be interpreted
as follows: (note fields 1 and 2 are as a check against line 1 info)
Field
-----
1 SFX - indicates this is a suffix
2 D - is the name of the character flag for this affix
3 y - the string of chars to strip off before adding affix
(a 0 here indicates the NULL string)
4 ied - the string of affix characters to add
5 [^aeiou]y - the conditions which must be met before the affix
can be applied
Field 5 is interesting. Since this is a suffix, field 5 tells us that
there are 2 conditions that must be met. The first condition is that
the next to the last character in the word must *NOT* be any of the
following "a", "e", "i", "o" or "u". The second condition is that
the last character of the word must end in "y".
So how can we encode this information concisely and be able to
test for both conditions in a fast manner? The answer is found
but studying the wonderful ispell code of Geoff Kuenning, et.al.
(now available under a normal BSD license).
If we set up a conds array of 256 bytes indexed (0 to 255) and access it
using a character (cast to an unsigned char) of a string, we have 8 bits
of information we can store about that character. Specifically we
could use each bit to say if that character is allowed in any of the
last (or first for prefixes) 8 characters of the word.
Basically, each character at one end of the word (up to the number
of conditions) is used to index into the conds array and the resulting
value found there says whether the that character is valid for a
specific character position in the word.
For prefixes, it does this by setting bit 0 if that char is valid
in the first position, bit 1 if valid in the second position, and so on.
If a bit is not set, then that char is not valid for that postion in the
word.
If working with suffixes bit 0 is used for the character closest
to the front, bit 1 for the next character towards the end, ...,
with bit numconds-1 representing the last char at the end of the string.
Note: since entries in the conds[] are 8 bits, only 8 conditions
(read that only 8 character positions) can be examined at one
end of a word (the beginning for prefixes and the end for suffixes.
So to make this clearer, lets encode the conds array values for the
first two affentries for the suffix D described earlier.
For the first affentry:
numconds = 1 (only examine the last character)
conds['e'] = (1 << 0) (the word must end in an E)
all others are all 0
For the second affentry:
numconds = 2 (only examine the last two characters)
conds[X] = conds[X] | (1 << 0) (aeiou are not allowed)
where X is all characters *but* a, e, i, o, or u
conds['y'] = (1 << 1) (the last char must be a y)
all other bits for all other entries in the conds array are zero
#endif
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