📄 metaphon.c
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/* +++Date last modified: 05-Jul-1997 */
/*
** METAPHON.C - Phonetic string matching
**
** The Metaphone algorithm was developed by Lawrence Phillips. Like the
** Soundex algorithm, it compares words that sound alike but are spelled
** differently. Metaphone was designed to overcome difficulties encountered
** with Soundex.
**
** This implementation was written by Gary A. Parker and originally published
** in the June/July, 1991 (vol. 5 nr. 4) issue of C Gazette. As published,
** this code was explicitly placed in the public domain by the author.
*/
#include <ctype.h>
#include "phonetic.h"
/*
** Character coding array
*/
static char vsvfn[26] = {
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};
/* 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 */
/*
** Macros to access the character coding array
*/
#define vowel(x) (vsvfn[(x) - 'A'] & 1) /* AEIOU */
#define same(x) (vsvfn[(x) - 'A'] & 2) /* FJLMNR */
#define varson(x) (vsvfn[(x) - 'A'] & 4) /* CGPST */
#define frontv(x) (vsvfn[(x) - 'A'] & 8) /* EIY */
#define noghf(x) (vsvfn[(x) - 'A'] & 16) /* BDH */
/*
** metaphone()
**
** Arguments: 1 - The word to be converted to a metaphone code.
** 2 - A MAXMETAPH+1 char field for the result.
** 3 - Function flag:
** If 0: Compute the Metaphone code for the first argument,
** then compare it to the Metaphone code passed in
** the second argument.
** If 1: Compute the Metaphone code for the first argument,
** then store the result in the area pointed to by the
** second argument.
**
** Returns: If function code is 0, returns Success_ for a match, else Error_.
** If function code is 1, returns Success_.
*/
Boolean_T metaphone(const char *Word, char *Metaph, metaphlag Flag)
{
char *n, *n_start, *n_end; /* Pointers to string */
char *metaph, *metaph_end; /* Pointers to metaph */
char ntrans[512]; /* Word with uppercase letters */
char newm[MAXMETAPH + 4]; /* New metaph for comparison */
int KSflag; /* State flag for X translation */
/*
** Copy word to internal buffer, dropping non-alphabetic characters
** and converting to upper case.
*/
for (n = ntrans + 1, n_end = ntrans + sizeof(ntrans) - 2;
*Word && n < n_end; ++Word)
{
if (isalpha(*Word))
*n++ = toupper(*Word);
}
if (n == ntrans + 1)
return Error_; /* Return if zero characters */
else n_end = n; /* Set end of string pointer */
/*
** Pad with NULs, front and rear
*/
*n++ = NUL;
*n = NUL;
n = ntrans;
*n++ = NUL;
/*
** If doing comparison, redirect pointers
*/
if (COMPARE == Flag)
{
metaph = Metaph;
Metaph = newm;
}
/*
** Check for PN, KN, GN, WR, WH, and X at start
*/
switch (*n)
{
case 'P':
case 'K':
case 'G':
if ('N' == *(n + 1))
*n++ = NUL;
break;
case 'A':
if ('E' == *(n + 1))
*n++ = NUL;
break;
case 'W':
if ('R' == *(n + 1))
*n++ = NUL;
else if ('H' == *(n + 1))
{
*(n + 1) = *n;
*n++ = NUL;
}
break;
case 'X':
*n = 'S';
break;
}
/*
** Now loop through the string, stopping at the end of the string
** or when the computed Metaphone code is MAXMETAPH characters long.
*/
KSflag = False_; /* State flag for KStranslation */
for (metaph_end = Metaph + MAXMETAPH, n_start = n;
n <= n_end && Metaph < metaph_end; ++n)
{
if (KSflag)
{
KSflag = False_;
*Metaph++ = *n;
}
else
{
/* Drop duplicates except for CC */
if (*(n - 1) == *n && *n != 'C')
continue;
/* Check for F J L M N R or first letter vowel */
if (same(*n) || (n == n_start && vowel(*n)))
*Metaph++ = *n;
else switch (*n)
{
case 'B':
if (n < n_end || *(n - 1) != 'M')
*Metaph++ = *n;
break;
case 'C':
if (*(n - 1) != 'S' || !frontv(*(n + 1)))
{
if ('I' == *(n + 1) && 'A' == *(n + 2))
*Metaph++ = 'X';
else if (frontv(*(n + 1)))
*Metaph++ = 'S';
else if ('H' == *(n + 1))
*Metaph++ = ((n == n_start &&
!vowel(*(n + 2))) ||
'S' == *(n - 1)) ? 'K' : 'X';
else *Metaph++ = 'K';
}
break;
case 'D':
*Metaph++ = ('G' == *(n + 1) && frontv(*(n + 2))) ?
'J' : 'T';
break;
case 'G':
if ((*(n + 1) != 'H' || vowel(*(n + 2))) &&
(*(n + 1) != 'N' || ((n + 1) < n_end &&
(*(n + 2) != 'E' || *(n + 3) != 'D'))) &&
(*(n - 1) != 'D' || !frontv(*(n + 1))))
{
*Metaph++ = (frontv(*(n + 1)) &&
*(n + 2) != 'G') ? 'J' : 'K';
}
else if ('H' == *(n + 1) && !noghf(*(n - 3)) &&
*(n - 4) != 'H')
{
*Metaph++ = 'F';
}
break;
case 'H':
if (!varson(*(n - 1)) && (!vowel(*(n - 1)) ||
vowel(*(n + 1))))
{
*Metaph++ = 'H';
}
break;
case 'K':
if (*(n - 1) != 'C')
*Metaph++ = 'K';
break;
case 'P':
*Metaph++ = ('H' == *(n + 1)) ? 'F' : 'P';
break;
case 'Q':
*Metaph++ = 'K';
break;
case 'S':
*Metaph++ = ('H' == *(n + 1) || ('I' == *(n + 1) &&
('O' == *(n + 2) || 'A' == *(n + 2)))) ?
'X' : 'S';
break;
case 'T':
if ('I' == *(n + 1) && ('O' == *(n + 2) ||
'A' == *(n + 2)))
{
*Metaph++ = 'X';
}
else if ('H' == *(n + 1))
*Metaph++ = 'O';
else if (*(n + 1) != 'C' || *(n + 2) != 'H')
*Metaph++ = 'T';
break;
case 'V':
*Metaph++ = 'F';
break;
case 'W':
case 'Y':
if (vowel(*(n + 1)))
*Metaph++ = *n;
break;
case 'X':
if (n == n_start)
*Metaph++ = 'S';
else
{
*Metaph++ = 'K';
KSflag = True_;
}
break;
case 'Z':
*Metaph++ = 'S';
break;
}
}
/*
** Compare new Metaphone code with old
*/
if (COMPARE == Flag &&
*(Metaph - 1) != metaph[(Metaph - newm) - 1])
{
return Error_;
}
}
/*
** If comparing, check if Metaphone codes were equal in length
*/
if (COMPARE == Flag && metaph[Metaph - newm])
return Error_;
*Metaph = NUL;
return Success_;
}
#ifdef TEST
/*
** Test demo to search a drive for a filename which sounds similar to
** file names passed on the command line
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "dirent.h" /* metaphone() is portable so use Posix */
#include "filnames.h" /* valid_fname() prototype */
#include "snip_str.h" /* strchcat() prototype */
/*
** Prototypes
*/
void print_find_t(char * dir, DOSFileData *find);
void search(char *dir, char *name);
Boolean_T found = False_;
char meta[MAXMETAPH + 4];
main(int argc, char *argv[])
{
char *ptr;
if (2 > argc)
{
puts("Usage: METAPHON filename [...filename]");
return EXIT_FAILURE;
}
while (--argc)
{
char *fname = *++argv;
if (Success_ != valid_fname(fname, -1))
{
printf("\nIllegal filename: %s\n", fname);
continue;
}
printf("\nSearching for: %s\n", fname);
/* Remove the extension, if any */
if (NULL != (ptr = strchr(fname, '.')))
*ptr = NUL;
/* Store the Metaphone code */
metaphone(fname, meta, GENERATE);
printf("Metaphone for %s is %s\n", fname, meta);
/* Search for matches */
search("", "");
if (!found)
puts("A match was not found");
}
return EXIT_SUCCESS;
}
void search(char *dir, char *newdir)
{
char curdir[FILENAME_MAX];
DIR *dirp;
DOSFileData *dstruct;
char *ptr;
Boolean_T retval;
while (NULL != (ptr = strchr(dir, '\\')))
*ptr = '/';
strcpy(curdir, dir);
if ('/' != LAST_CHAR(curdir))
strchcat(curdir, '/', FILENAME_MAX);
strcat(curdir, newdir);
if (NULL != (dirp = opendir(curdir)))
{
while (NULL != (dstruct = readdir(dirp)))
{
if ('.' == *(ff_name(dstruct)))
continue;
else
{
/* Don't look at file extension */
if (NULL != (ptr = strchr(ff_name(dstruct), '.')))
*ptr = NUL;
else ptr = NULL;
retval = metaphone(ff_name(dstruct), meta, COMPARE);
/* Restore extension, if any */
if (ptr != NULL)
*ptr = '.';
if (Success_ == retval)
print_find_t(curdir, dstruct);
}
if (ff_attr(dstruct) & _A_SUBDIR)
search(curdir, ff_name(dstruct));
}
closedir(dirp);
}
}
void print_find_t(char *dir, DOSFileData *find)
{
printf("%s/%-12s %8ld %2.2d-%02.2d-%02.2d %c%c%c%c%c\n", dir,
ff_name(find), ff_size(find), ff_mo(find),
ff_day(find), (ff_yr(find) + 80) % 100,
(ff_attr(find) & _A_SUBDIR) ? 'D' : '.',
(ff_attr(find) & _A_RDONLY) ? 'R' : '.',
(ff_attr(find) & _A_HIDDEN) ? 'H' : '.',
(ff_attr(find) & _A_SYSTEM) ? 'S' : '.',
(ff_attr(find) & _A_ARCH) ? 'A' : '.');
found = True_;
}
#endif /* TEST */
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