1/*
2   +----------------------------------------------------------------------+
3   | PHP Version 5                                                        |
4   +----------------------------------------------------------------------+
5   | Copyright (c) 1997-2013 The PHP Group                                |
6   +----------------------------------------------------------------------+
7   | This source file is subject to version 3.01 of the PHP license,      |
8   | that is bundled with this package in the file LICENSE, and is        |
9   | available through the world-wide-web at the following url:           |
10   | http://www.php.net/license/3_01.txt                                  |
11   | If you did not receive a copy of the PHP license and are unable to   |
12   | obtain it through the world-wide-web, please send a note to          |
13   | license@php.net so we can mail you a copy immediately.               |
14   +----------------------------------------------------------------------+
15   | Author: Thies C. Arntzen <thies@thieso.net>                          |
16   +----------------------------------------------------------------------+
17*/
18
19/* $Id$ */
20
21/*
22    Based on CPANs "Text-Metaphone-1.96" by Michael G Schwern <schwern@pobox.com>
23*/
24
25#include "php.h"
26#include "php_metaphone.h"
27
28static int metaphone(unsigned char *word, int word_len, long max_phonemes, char **phoned_word, int traditional);
29
30/* {{{ proto string metaphone(string text[, int phones])
31   Break english phrases down into their phonemes */
32PHP_FUNCTION(metaphone)
33{
34    char *str;
35    char *result = 0;
36    int str_len;
37    long phones = 0;
38
39    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &str, &str_len,
40                              &phones) == FAILURE) {
41        return;
42    }
43
44    if (metaphone((unsigned char *)str, str_len, phones, &result, 1) == 0) {
45        RETVAL_STRING(result, 0);
46    } else {
47        if (result) {
48            efree(result);
49        }
50        RETURN_FALSE;
51    }
52}
53/* }}} */
54
55/*
56   this is now the original code by Michael G Schwern:
57   i've changed it just a slightly bit (use emalloc,
58   get rid of includes etc)
59    - thies - 13.09.1999
60*/
61
62/*-----------------------------  */
63/* this used to be "metaphone.h" */
64/*-----------------------------  */
65
66/* Special encodings */
67#define  SH     'X'
68#define  TH     '0'
69
70/*-----------------------------  */
71/* end of "metaphone.h"          */
72/*-----------------------------  */
73
74/*----------------------------- */
75/* this used to be "metachar.h" */
76/*----------------------------- */
77
78/* Metachar.h ... little bits about characters for metaphone */
79/*-- Character encoding array & accessing macros --*/
80/* Stolen directly out of the book... */
81char _codes[26] =
82{
83    1, 16, 4, 16, 9, 2, 4, 16, 9, 2, 0, 2, 2, 2, 1, 4, 0, 2, 4, 4, 1, 0, 0, 0, 8, 0
84/*  a  b c  d e f g  h i j k l m n o p q r s t u v w x y z */
85};
86
87
88#define ENCODE(c) (isalpha(c) ? _codes[((toupper(c)) - 'A')] : 0)
89
90#define isvowel(c)  (ENCODE(c) & 1)     /* AEIOU */
91
92/* These letters are passed through unchanged */
93#define NOCHANGE(c) (ENCODE(c) & 2)     /* FJMNR */
94
95/* These form dipthongs when preceding H */
96#define AFFECTH(c)  (ENCODE(c) & 4)     /* CGPST */
97
98/* These make C and G soft */
99#define MAKESOFT(c) (ENCODE(c) & 8)     /* EIY */
100
101/* These prevent GH from becoming F */
102#define NOGHTOF(c)  (ENCODE(c) & 16)    /* BDH */
103
104/*----------------------------- */
105/* end of "metachar.h"          */
106/*----------------------------- */
107
108/* I suppose I could have been using a character pointer instead of
109 * accesssing the array directly... */
110
111/* Look at the next letter in the word */
112#define Next_Letter (toupper(word[w_idx+1]))
113/* Look at the current letter in the word */
114#define Curr_Letter (toupper(word[w_idx]))
115/* Go N letters back. */
116#define Look_Back_Letter(n) (w_idx >= n ? toupper(word[w_idx-n]) : '\0')
117/* Previous letter.  I dunno, should this return null on failure? */
118#define Prev_Letter (Look_Back_Letter(1))
119/* Look two letters down.  It makes sure you don't walk off the string. */
120#define After_Next_Letter   (Next_Letter != '\0' ? toupper(word[w_idx+2]) \
121                                                 : '\0')
122#define Look_Ahead_Letter(n) (toupper(Lookahead(word+w_idx, n)))
123
124
125/* Allows us to safely look ahead an arbitrary # of letters */
126/* I probably could have just used strlen... */
127static char Lookahead(char *word, int how_far)
128{
129    char letter_ahead = '\0';   /* null by default */
130    int idx;
131    for (idx = 0; word[idx] != '\0' && idx < how_far; idx++);
132    /* Edge forward in the string... */
133
134    letter_ahead = word[idx];   /* idx will be either == to how_far or
135                                 * at the end of the string
136                                 */
137    return letter_ahead;
138}
139
140
141/* phonize one letter
142 * We don't know the buffers size in advance. On way to solve this is to just
143 * re-allocate the buffer size. We're using an extra of 2 characters (this
144 * could be one though; or more too). */
145#define Phonize(c)  { \
146                        if (p_idx >= max_buffer_len) { \
147                            *phoned_word = safe_erealloc(*phoned_word, 2, sizeof(char), max_buffer_len); \
148                            max_buffer_len += 2; \
149                        } \
150                        (*phoned_word)[p_idx++] = c; \
151                    }
152/* Slap a null character on the end of the phoned word */
153#define End_Phoned_Word { \
154                            if (p_idx == max_buffer_len) { \
155                                *phoned_word = safe_erealloc(*phoned_word, 1, sizeof(char), max_buffer_len); \
156                            } \
157                            (*phoned_word)[p_idx] = '\0'; \
158                        }
159/* How long is the phoned word? */
160#define Phone_Len   (p_idx)
161
162/* Note is a letter is a 'break' in the word */
163#define Isbreak(c)  (!isalpha(c))
164
165/* {{{ metaphone
166 */
167static int metaphone(unsigned char *word, int word_len, long max_phonemes, char **phoned_word, int traditional)
168{
169    int w_idx = 0;              /* point in the phonization we're at. */
170    int p_idx = 0;              /* end of the phoned phrase */
171    int max_buffer_len = 0;     /* maximum length of the destination buffer */
172
173/*-- Parameter checks --*/
174    /* Negative phoneme length is meaningless */
175
176    if (max_phonemes < 0)
177        return -1;
178
179    /* Empty/null string is meaningless */
180    /* Overly paranoid */
181    /* assert(word != NULL && word[0] != '\0'); */
182
183    if (word == NULL)
184        return -1;
185
186/*-- Allocate memory for our phoned_phrase --*/
187    if (max_phonemes == 0) {    /* Assume largest possible */
188        max_buffer_len = word_len;
189        *phoned_word = safe_emalloc(sizeof(char), word_len, 1);
190    } else {
191        max_buffer_len = max_phonemes;
192        *phoned_word = safe_emalloc(sizeof(char), max_phonemes, 1);
193    }
194
195
196/*-- The first phoneme has to be processed specially. --*/
197    /* Find our first letter */
198    for (; !isalpha(Curr_Letter); w_idx++) {
199        /* On the off chance we were given nothing but crap... */
200        if (Curr_Letter == '\0') {
201            End_Phoned_Word
202                return SUCCESS; /* For testing */
203        }
204    }
205
206    switch (Curr_Letter) {
207        /* AE becomes E */
208    case 'A':
209        if (Next_Letter == 'E') {
210            Phonize('E');
211            w_idx += 2;
212        }
213        /* Remember, preserve vowels at the beginning */
214        else {
215            Phonize('A');
216            w_idx++;
217        }
218        break;
219        /* [GKP]N becomes N */
220    case 'G':
221    case 'K':
222    case 'P':
223        if (Next_Letter == 'N') {
224            Phonize('N');
225            w_idx += 2;
226        }
227        break;
228        /* WH becomes W,
229           WR becomes R
230           W if followed by a vowel */
231    case 'W':
232        if (Next_Letter == 'R') {
233            Phonize(Next_Letter);
234            w_idx += 2;
235        } else if (Next_Letter == 'H' || isvowel(Next_Letter)) {
236            Phonize('W');
237            w_idx += 2;
238        }
239        /* else ignore */
240        break;
241        /* X becomes S */
242    case 'X':
243        Phonize('S');
244        w_idx++;
245        break;
246        /* Vowels are kept */
247        /* We did A already
248           case 'A':
249           case 'a':
250         */
251    case 'E':
252    case 'I':
253    case 'O':
254    case 'U':
255        Phonize(Curr_Letter);
256        w_idx++;
257        break;
258    default:
259        /* do nothing */
260        break;
261    }
262
263
264
265    /* On to the metaphoning */
266    for (; Curr_Letter != '\0' &&
267         (max_phonemes == 0 || Phone_Len < max_phonemes);
268         w_idx++) {
269        /* How many letters to skip because an eariler encoding handled
270         * multiple letters */
271        unsigned short int skip_letter = 0;
272
273
274        /* THOUGHT:  It would be nice if, rather than having things like...
275         * well, SCI.  For SCI you encode the S, then have to remember
276         * to skip the C.  So the phonome SCI invades both S and C.  It would
277         * be better, IMHO, to skip the C from the S part of the encoding.
278         * Hell, I'm trying it.
279         */
280
281        /* Ignore non-alphas */
282        if (!isalpha(Curr_Letter))
283            continue;
284
285        /* Drop duplicates, except CC */
286        if (Curr_Letter == Prev_Letter &&
287            Curr_Letter != 'C')
288            continue;
289
290        switch (Curr_Letter) {
291            /* B -> B unless in MB */
292        case 'B':
293            if (Prev_Letter != 'M')
294                Phonize('B');
295            break;
296            /* 'sh' if -CIA- or -CH, but not SCH, except SCHW.
297             * (SCHW is handled in S)
298             *  S if -CI-, -CE- or -CY-
299             *  dropped if -SCI-, SCE-, -SCY- (handed in S)
300             *  else K
301             */
302        case 'C':
303            if (MAKESOFT(Next_Letter)) {    /* C[IEY] */
304                if (After_Next_Letter == 'A' &&
305                    Next_Letter == 'I') {   /* CIA */
306                    Phonize(SH);
307                }
308                /* SC[IEY] */
309                else if (Prev_Letter == 'S') {
310                    /* Dropped */
311                } else {
312                    Phonize('S');
313                }
314            } else if (Next_Letter == 'H') {
315                if ((!traditional) && (After_Next_Letter == 'R' || Prev_Letter == 'S')) {   /* Christ, School */
316                    Phonize('K');
317                } else {
318                    Phonize(SH);
319                }
320                skip_letter++;
321            } else {
322                Phonize('K');
323            }
324            break;
325            /* J if in -DGE-, -DGI- or -DGY-
326             * else T
327             */
328        case 'D':
329            if (Next_Letter == 'G' &&
330                MAKESOFT(After_Next_Letter)) {
331                Phonize('J');
332                skip_letter++;
333            } else
334                Phonize('T');
335            break;
336            /* F if in -GH and not B--GH, D--GH, -H--GH, -H---GH
337             * else dropped if -GNED, -GN,
338             * else dropped if -DGE-, -DGI- or -DGY- (handled in D)
339             * else J if in -GE-, -GI, -GY and not GG
340             * else K
341             */
342        case 'G':
343            if (Next_Letter == 'H') {
344                if (!(NOGHTOF(Look_Back_Letter(3)) ||
345                      Look_Back_Letter(4) == 'H')) {
346                    Phonize('F');
347                    skip_letter++;
348                } else {
349                    /* silent */
350                }
351            } else if (Next_Letter == 'N') {
352                if (Isbreak(After_Next_Letter) ||
353                    (After_Next_Letter == 'E' &&
354                     Look_Ahead_Letter(3) == 'D')) {
355                    /* dropped */
356                } else
357                    Phonize('K');
358            } else if (MAKESOFT(Next_Letter) &&
359                       Prev_Letter != 'G') {
360                Phonize('J');
361            } else {
362                Phonize('K');
363            }
364            break;
365            /* H if before a vowel and not after C,G,P,S,T */
366        case 'H':
367            if (isvowel(Next_Letter) &&
368                !AFFECTH(Prev_Letter))
369                Phonize('H');
370            break;
371            /* dropped if after C
372             * else K
373             */
374        case 'K':
375            if (Prev_Letter != 'C')
376                Phonize('K');
377            break;
378            /* F if before H
379             * else P
380             */
381        case 'P':
382            if (Next_Letter == 'H') {
383                Phonize('F');
384            } else {
385                Phonize('P');
386            }
387            break;
388            /* K
389             */
390        case 'Q':
391            Phonize('K');
392            break;
393            /* 'sh' in -SH-, -SIO- or -SIA- or -SCHW-
394             * else S
395             */
396        case 'S':
397            if (Next_Letter == 'I' &&
398                (After_Next_Letter == 'O' ||
399                 After_Next_Letter == 'A')) {
400                Phonize(SH);
401            } else if (Next_Letter == 'H') {
402                Phonize(SH);
403                skip_letter++;
404            } else if ((!traditional) && (Next_Letter == 'C' && Look_Ahead_Letter(2) == 'H' && Look_Ahead_Letter(3) == 'W')) {
405                Phonize(SH);
406                skip_letter += 2;
407            } else {
408                Phonize('S');
409            }
410            break;
411            /* 'sh' in -TIA- or -TIO-
412             * else 'th' before H
413             * else T
414             */
415        case 'T':
416            if (Next_Letter == 'I' &&
417                (After_Next_Letter == 'O' ||
418                 After_Next_Letter == 'A')) {
419                Phonize(SH);
420            } else if (Next_Letter == 'H') {
421                Phonize(TH);
422                skip_letter++;
423            } else if (!(Next_Letter == 'C' && After_Next_Letter == 'H')) {
424                Phonize('T');
425            }
426            break;
427            /* F */
428        case 'V':
429            Phonize('F');
430            break;
431            /* W before a vowel, else dropped */
432        case 'W':
433            if (isvowel(Next_Letter))
434                Phonize('W');
435            break;
436            /* KS */
437        case 'X':
438            Phonize('K');
439            Phonize('S');
440            break;
441            /* Y if followed by a vowel */
442        case 'Y':
443            if (isvowel(Next_Letter))
444                Phonize('Y');
445            break;
446            /* S */
447        case 'Z':
448            Phonize('S');
449            break;
450            /* No transformation */
451        case 'F':
452        case 'J':
453        case 'L':
454        case 'M':
455        case 'N':
456        case 'R':
457            Phonize(Curr_Letter);
458            break;
459        default:
460            /* nothing */
461            break;
462        }                       /* END SWITCH */
463
464        w_idx += skip_letter;
465    }                           /* END FOR */
466
467    End_Phoned_Word;
468
469    return 0;
470}                               /* END metaphone */
471/* }}} */
472
473/*
474 * Local variables:
475 * tab-width: 4
476 * c-basic-offset: 4
477 * End:
478 * vim600: sw=4 ts=4 fdm=marker
479 * vim<600: sw=4 ts=4
480 */
481