/* STUFF TO DO
* - Make max_phonemes useful
*/
#include "metaphone.h"
#include "metachar.h"
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
/* I suppose I could have been using a character pointer instead of
* accesssing the array directly... */
/* Look at the next letter in the word */
#define Next_Letter (toupper(word[w_idx+1]))
/* Look at the current letter in the word */
#define Curr_Letter (toupper(word[w_idx]))
/* Go N letters back. */
#define Look_Back_Letter(n) (w_idx >= n ? toupper(word[w_idx-n]) : '\0')
/* Previous letter. I dunno, should this return null on failure? */
#define Prev_Letter (Look_Back_Letter(1))
/* Look two letters down. It makes sure you don't walk off the string. */
#define After_Next_Letter (Next_Letter != '\0' ? toupper(word[w_idx+2]) \
: '\0')
#define Look_Ahead_Letter(n) (toupper(Lookahead(word+w_idx, n)))
/* Allows us to safely look ahead an arbitrary # of letters */
/* I probably could have just used strlen... */
char Lookahead(char * word, int how_far) {
char letter_ahead = '\0'; /* null by default */
int idx;
for(idx = 0; word[idx] != '\0' && idx < how_far; idx++);
/* Edge forward in the string... */
letter_ahead = word[idx]; /* idx will be either == to how_far or
* at the end of the string
*/
return letter_ahead;
}
/* phonize one letter */
#define Phonize(c) {phoned_word[p_idx++] = c;}
/* How long is the phoned word? */
#define Phone_Len (p_idx)
/* Note is a letter is a 'break' in the word */
#define Isbreak(c) (!isalpha(c))
char *metaphone ( char *word, size_t max_phonemes ) {
int w_idx = 0; /* point in the phonization we're at. */
int p_idx = 0; /* end of the phoned phrase */
char *phoned_word;
/* Assume largest possible if we're given no limit */
if( max_phonemes == 0 )
max_phonemes = strlen(word);
/* It's +2 because X -> KS can result in the phoned word being
one larger than the original word.
*/
phoned_word = calloc( max_phonemes + 2, sizeof(char) );
/*-- The first phoneme has to be processed specially. --*/
/* Find our first letter */
for( ; !isalpha(Curr_Letter); w_idx++ ) {
/* On the off chance we were given nothing but crap... */
if( Curr_Letter == '\0' ) {
return phoned_word;
}
}
switch (Curr_Letter) {
/* AE becomes E */
case 'A':
if( Next_Letter == 'E' ) {
Phonize('E');
w_idx+=2;
}
/* Remember, preserve vowels at the beginning */
else {
Phonize('A');
w_idx++;
}
break;
/* [GKP]N becomes N */
case 'G':
case 'K':
case 'P':
if( Next_Letter == 'N' ) {
Phonize('N');
w_idx+=2;
}
break;
/* WH becomes H,
WR becomes R
W if followed by a vowel */
case 'W':
if( Next_Letter == 'H' ||
Next_Letter == 'R' )
{
Phonize(Next_Letter);
w_idx+=2;
}
else if ( isvowel(Next_Letter) ) {
Phonize('W');
w_idx+=2;
}
/* else ignore */
break;
/* X becomes S */
case 'X':
Phonize('S');
w_idx++;
break;
/* Vowels are kept */
/* We did A already
case 'A':
case 'a':
*/
case 'E':
case 'I':
case 'O':
case 'U':
Phonize(Curr_Letter);
w_idx++;
break;
default:
/* do nothing */
break;
}
/* On to the metaphoning */
for(;
Curr_Letter != '\0' &&
(max_phonemes == 0 || Phone_Len < max_phonemes);
w_idx++
) {
/* How many letters to skip because an eariler encoding handled
* multiple letters */
unsigned short int skip_letter = 0;
/* THOUGHT: It would be nice if, rather than having things like...
* well, SCI. For SCI you encode the S, then have to remember
* to skip the C. So the phonome SCI invades both S and C. It would
* be better, IMHO, to skip the C from the S part of the encoding.
* Hell, I'm trying it.
*/
/* Ignore non-alphas */
if( !isalpha(Curr_Letter) )
continue;
/* Drop duplicates, except CC */
if( Curr_Letter == Prev_Letter &&
Curr_Letter != 'C' )
continue;
switch (Curr_Letter) {
/* B -> B unless in MB */
case 'B':
if( Prev_Letter != 'M' )
Phonize('B');
break;
/* 'sh' if -CIA- or -CH, but not SCH, except SCHW.
* (SCHW is handled in S)
* S if -CI-, -CE- or -CY-
* dropped if -SCI-, SCE-, -SCY- (handed in S)
* else K
*/
case 'C':
if( MAKESOFT(Next_Letter) ) { /* C[IEY] */
if( After_Next_Letter == 'A' &&
Next_Letter == 'I' ) { /* CIA */
Phonize(SH);
}
/* SC[IEY] */
else if ( Prev_Letter == 'S' ) {
/* Dropped */
}
else {
Phonize('S');
}
}
else if ( Next_Letter == 'H' ) {
#ifndef USE_TRADITIONAL_METAPHONE
if( After_Next_Letter == 'R' ||
Prev_Letter == 'S' ) { /* Christ, School */
Phonize('K');
}
else {
Phonize(SH);
}
#else
Phonize(SH);
#endif
skip_letter++;
}
else {
Phonize('K');
}
break;
/* J if in -DGE-, -DGI- or -DGY-
* else T
*/
case 'D':
if( Next_Letter == 'G' &&
MAKESOFT(After_Next_Letter) ) {
Phonize('J');
skip_letter++;
}
else
Phonize('T');
break;
/* F if in -GH and not B--GH, D--GH, -H--GH, -H---GH
* else dropped if -GNED, -GN,
* else dropped if -DGE-, -DGI- or -DGY- (handled in D)
* else J if in -GE-, -GI, -GY and not GG
* else K
*/
case 'G':
if( Next_Letter == 'H' ) {
if( !( NOGHTOF(Look_Back_Letter(3)) ||
Look_Back_Letter(4) == 'H' ) ) {
Phonize('F');
skip_letter++;
}
else {
/* silent */
}
}
else if( Next_Letter == 'N' ) {
if( Isbreak(After_Next_Letter) ||
( After_Next_Letter == 'E' &&
Look_Ahead_Letter(3) == 'D' ) ) {
/* dropped */
}
else
Phonize('K');
}
else if( MAKESOFT(Next_Letter) &&
Prev_Letter != 'G' ) {
Phonize('J');
}
else {
Phonize('K');
}
break;
/* H if before a vowel and not after C,G,P,S,T */
case 'H':
if( isvowel(Next_Letter) &&
!AFFECTH(Prev_Letter) )
Phonize('H');
break;
/* dropped if after C
* else K
*/
case 'K':
if( Prev_Letter != 'C' )
Phonize('K');
break;
/* F if before H
* else P
*/
case 'P':
if( Next_Letter == 'H' ) {
Phonize('F');
}
else {
Phonize('P');
}
break;
/* K
*/
case 'Q':
Phonize('K');
break;
/* 'sh' in -SH-, -SIO- or -SIA- or -SCHW-
* else S
*/
case 'S':
if( Next_Letter == 'I' &&
( After_Next_Letter == 'O' ||
After_Next_Letter == 'A' ) ) {
Phonize(SH);
}
else if ( Next_Letter == 'H' ) {
Phonize(SH);
skip_letter++;
}
#ifndef USE_TRADITIONAL_METAPHONE
else if ( Next_Letter == 'C' &&
Look_Ahead_Letter(2) == 'H' &&
Look_Ahead_Letter(3) == 'W' ) {
Phonize(SH);
skip_letter += 2;
}
#endif
else {
Phonize('S');
}
break;
/* 'sh' in -TIA- or -TIO-
* else 'th' before H
* else T
*/
case 'T':
if( Next_Letter == 'I' &&
( After_Next_Letter == 'O' ||
After_Next_Letter == 'A' ) ) {
Phonize(SH);
}
else if ( Next_Letter == 'H' ) {
Phonize(TH);
skip_letter++;
}
else {
Phonize('T');
}
break;
/* F */
case 'V':
Phonize('F');
break;
/* W before a vowel, else dropped */
case 'W':
if( isvowel(Next_Letter) )
Phonize('W');
break;
/* KS */
case 'X':
Phonize('K');
Phonize('S');
break;
/* Y if followed by a vowel */
case 'Y':
if( isvowel(Next_Letter) )
Phonize('Y');
break;
/* S */
case 'Z':
Phonize('S');
break;
/* No transformation */
case 'F':
case 'J':
case 'L':
case 'M':
case 'N':
case 'R':
Phonize(Curr_Letter);
break;
default:
/* nothing */
break;
}
w_idx += skip_letter;
}
return phoned_word;
}