#include "..\commons.h" PfxEntry::PfxEntry(AffixMgr* pmgr, affentry* dp) { // register affix manager pmyMgr = pmgr; // set up its initial 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; // length of the condition opts = dp->opts; // cross product flag // then copy over all of the conditions if (opts & aeLONGCOND) { memcpy(c.conds, dp->c.l.conds1, MAXCONDLEN_1); c.l.conds2 = dp->c.l.conds2; } else memcpy(c.conds, dp->c.conds, MAXCONDLEN); 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 & aeLONGCOND) free(c.l.conds2); 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 == 0 && pmyMgr->get_fullstrip())) && (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 char * PfxEntry::nextchar(char * p) { if (p) { p++; if (opts & aeLONGCOND) { // jump to the 2nd part of the condition if (p == c.conds + MAXCONDLEN_1) return c.l.conds2; // end of the MAXCONDLEN length condition } else if (p == c.conds + MAXCONDLEN) return NULL; return *p ? p : NULL; } return NULL; } inline int PfxEntry::test_condition(const char * st) { const char * pos = NULL; // group with pos input position bool neg = false; // complementer bool ingroup = false; // character in the group if (numconds == 0) return 1; char * p = c.conds; while (1) { switch (*p) { case '\0': return 1; case '[': { neg = false; ingroup = false; p = nextchar(p); pos = st; break; } case '^': { p = nextchar(p); neg = true; break; } case ']': { if ((neg && ingroup) || (!neg && !ingroup)) return 0; pos = NULL; p = nextchar(p); // skip the next character if (!ingroup && *st) for (st++; (opts & aeUTF8) && (*st & 0xc0) == 0x80; st++); if (*st == '\0' && p) return 0; // word <= condition break; } case '.': if (!pos) { // dots are not metacharacters in groups: [.] p = nextchar(p); // skip the next character for (st++; (opts & aeUTF8) && (*st & 0xc0) == 0x80; st++); if (*st == '\0' && p) return 0; // word <= condition break; } default: { if (*st == *p) { st++; p = nextchar(p); if ((opts & aeUTF8) && (*(st - 1) & 0x80)) { // multibyte while (p && (*p & 0xc0) == 0x80) { // character if (*p != *st) { if (!pos) return 0; st = pos; break; } p = nextchar(p); st++; } if (pos && st != pos) { ingroup = true; while (p && *p != ']' && (p = nextchar(p))); } } else if (pos) { ingroup = true; while (p && *p != ']' && (p = nextchar(p))); } } else if (pos) { // group p = nextchar(p); } else return 0; } } if (!p) return 1; } } // check if this prefix entry matches struct hentry * PfxEntry::checkword(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 == 0 && pmyMgr->get_fullstrip())) { // 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 needaffix flag ! TESTAFF(contclass, pmyMgr->get_needaffix(), contclasslen) && // needflag ((!needflag) || TESTAFF(he->astr, needflag, he->alen) || (contclass && TESTAFF(contclass, needflag, contclasslen)))) return he; he = he->next_homonym; // check homonyms } while (he); } // 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, 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 == 0 && pmyMgr->get_fullstrip())) && (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, 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 == 0 && pmyMgr->get_fullstrip())) && (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, 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 == 0 && pmyMgr->get_fullstrip())) && (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 needaffix flag ! TESTAFF(contclass, pmyMgr->get_needaffix(), contclasslen) && // needflag ((!needflag) || TESTAFF(he->astr, needflag, he->alen) || (contclass && TESTAFF(contclass, needflag, contclasslen)))) { if (morphcode) { mystrcat(result, " ", MAXLNLEN); mystrcat(result, morphcode, MAXLNLEN); } else mystrcat(result,getKey(), MAXLNLEN); if (!HENTRY_FIND(he, MORPH_STEM)) { mystrcat(result, " ", MAXLNLEN); mystrcat(result, MORPH_STEM, MAXLNLEN); mystrcat(result, HENTRY_WORD(he), MAXLNLEN); } // store the pointer of the hash entry if (HENTRY_DATA(he)) { mystrcat(result, " ", MAXLNLEN); mystrcat(result, HENTRY_DATA2(he), MAXLNLEN); } else { // return with debug information char * flag = pmyMgr->encode_flag(getFlag()); mystrcat(result, " ", MAXLNLEN); mystrcat(result, MORPH_FLAG, MAXLNLEN); mystrcat(result, flag, MAXLNLEN); free(flag); } mystrcat(result, "\n", MAXLNLEN); } he = he->next_homonym; } while (he); } // 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, this, FLAG_NULL, needflag); if (st) { mystrcat(result, st, MAXLNLEN); free(st); } } } } if (*result) return mystrdup(result); return NULL; } SfxEntry::SfxEntry(AffixMgr * pmgr, affentry* dp) { // register affix manager pmyMgr = pmgr; // set up its initial 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; // length of the condition opts = dp->opts; // cross product flag // then copy over all of the conditions if (opts & aeLONGCOND) { memcpy(c.l.conds1, dp->c.l.conds1, MAXCONDLEN_1); c.l.conds2 = dp->c.l.conds2; } else memcpy(c.conds, dp->c.conds, MAXCONDLEN); 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 & aeLONGCOND) free(c.l.conds2); 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 == 0 && pmyMgr->get_fullstrip())) && (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 char * SfxEntry::nextchar(char * p) { if (p) { p++; if (opts & aeLONGCOND) { // jump to the 2nd part of the condition if (p == c.l.conds1 + MAXCONDLEN_1) return c.l.conds2; // end of the MAXCONDLEN length condition } else if (p == c.conds + MAXCONDLEN) return NULL; return *p ? p : NULL; } return NULL; } inline int SfxEntry::test_condition(const char * st, const char * beg) { const char * pos = NULL; // group with pos input position bool neg = false; // complementer bool ingroup = false; // character in the group if (numconds == 0) return 1; char * p = c.conds; st--; int i = 1; while (1) { switch (*p) { case '\0': return 1; case '[': { p = nextchar(p); pos = st; break; } case '^': { p = nextchar(p); neg = true; break; } case ']': { if (!neg && !ingroup) return 0; i++; // skip the next character if (!ingroup) { for (; (opts & aeUTF8) && (st >= beg) && (*st & 0xc0) == 0x80; st--); st--; } pos = NULL; neg = false; ingroup = false; p = nextchar(p); if (st < beg && p) return 0; // word <= condition break; } case '.': if (!pos) { // dots are not metacharacters in groups: [.] p = nextchar(p); // skip the next character for (st--; (opts & aeUTF8) && (st >= beg) && (*st & 0xc0) == 0x80; st--); if (st < beg) { // word <= condition if (p) return 0; else return 1; } if ((opts & aeUTF8) && (*st & 0x80)) { // head of the UTF-8 character st--; if (st < beg) { // word <= condition if (p) return 0; else return 1; } } break; } default: { if (*st == *p) { p = nextchar(p); if ((opts & aeUTF8) && (*st & 0x80)) { st--; while (p && (st >= beg)) { if (*p != *st) { if (!pos) return 0; st = pos; break; } // first byte of the UTF-8 multibyte character if ((*p & 0xc0) != 0x80) break; p = nextchar(p); st--; } if (pos && st != pos) { if (neg) return 0; else if (i == numconds) return 1; ingroup = true; while (p && *p != ']' && (p = nextchar(p))); st--; } if (p && *p != ']') p = nextchar(p); } else if (pos) { if (neg) return 0; else if (i == numconds) return 1; ingroup = true; while (p && *p != ']' && (p = nextchar(p))); // if (p && *p != ']') p = nextchar(p); st--; } if (!pos) { i++; st--; } if (st < beg && p && *p != ']') return 0; // word <= condition } else if (pos) { // group p = nextchar(p); } else return 0; } } if (!p) return 1; } } // see if this suffix is present in the word struct hentry * SfxEntry::checkword(const char * word, int len, int optflags, PfxEntry* ppfx, char ** wlst, int maxSug, int * ns, const FLAG cclass, const FLAG needflag, const FLAG badflag) { int tmpl; // length of tmpword struct hentry * he; // hash entry pointer unsigned char * cp; char tmpword[MAXWORDUTF8LEN + 4]; PfxEntry* ep = 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 == 0 && pmyMgr->get_fullstrip())) && (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) || (ep && TESTAFF(he->astr, ep->getFlag(), he->alen)) || // enabled by prefix ((contclass) && (ep && TESTAFF(contclass, ep->getFlag(), contclasslen))) ) && // handle cont. class ((!cclass) || ((contclass) && TESTAFF(contclass, cclass, contclasslen)) ) && // check only in compound homonyms (bad flags) (!badflag || !TESTAFF(he->astr, badflag, he->alen) ) && // handle required flag ((!needflag) || (TESTAFF(he->astr, needflag, he->alen) || ((contclass) && TESTAFF(contclass, needflag, contclasslen))) ) ) return he; he = he->next_homonym; // check homonyms } while (he); // 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, PfxEntry* ppfx, const FLAG needflag) { int tmpl; // length of tmpword struct hentry * he; // hash entry pointer unsigned char * cp; char tmpword[MAXWORDUTF8LEN + 4]; PfxEntry* ep = 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 == 0 && pmyMgr->get_fullstrip())) && (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, PfxEntry* ppfx, const FLAG needflag) { int tmpl; // length of tmpword unsigned char * cp; char tmpword[MAXWORDUTF8LEN + 4]; PfxEntry* ep = 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 == 0 && pmyMgr->get_fullstrip())) && (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 (ppfx->getMorph()) { mystrcat(result, ppfx->getMorph(), MAXLNLEN); mystrcat(result, " ", MAXLNLEN); } mystrcat(result,st, MAXLNLEN); free(st); mychomp(result); } } else { st = pmyMgr->suffix_check_morph(tmpword, tmpl, optflags, ppfx, aflag, needflag); if (st) { mystrcat(result, st, MAXLNLEN); free(st); mychomp(result); } } } else { st = pmyMgr->suffix_check_morph(tmpword, tmpl, 0, NULL, aflag, needflag); if (st) { mystrcat(result, st, MAXLNLEN); 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, PfxEntry* ppfx, const FLAG cclass, const FLAG needflag) { PfxEntry* ep = ppfx; FLAG eFlag = ep ? ep->getFlag() : FLAG_NULL; 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, eFlag, he->alen) || // handle conditional suffix ((contclass) && TESTAFF(contclass, eFlag, 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