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#include <ctype.h>
#include <string.h>
#include <strings.h>
#include <stdio.h>
#include <float.h>
#include <math.h>
#include "match.h"
int has_match(const char *needle, const char *haystack){
while(*needle){
char nch = tolower(*needle++);
for(;;){
char ch = *haystack++;
if(!ch)
return 0;
else if(nch == tolower(ch))
break;
}
}
return 1;
}
#define max(a, b) (((a) > (b)) ? (a) : (b))
typedef double score_t;
#define SCORE_MAX INFINITY
#define SCORE_MIN -INFINITY
/* print one of the internal matrices */
void mat_print(score_t *mat, const char *needle, const char *haystack){
int n = strlen(needle);
int m = strlen(haystack);
int i, j;
fprintf(stderr, " ");
for(j = 0; j < m; j++){
fprintf(stderr, " %c", haystack[j]);
}
fprintf(stderr, "\n");
for(i = 0; i < n; i++){
fprintf(stderr, " %c |", needle[i]);
for(j = 0; j < m; j++){
score_t val = mat[i*m + j];
if(val == SCORE_MIN){
fprintf(stderr, " -inf");
}else{
fprintf(stderr, " % .2f", val);
}
}
fprintf(stderr, "\n");
}
fprintf(stderr, "\n\n");
}
double calculate_score(const char *needle, const char *haystack, size_t *positions){
if(!*haystack || !*needle)
return SCORE_MIN;
int n = strlen(needle);
int m = strlen(haystack);
if(m > 1024){
/*
* Unreasonably large candidate: return no score
* If it is a valid match it will still be returned, it will
* just be ranked below any reasonably sized candidates
*/
return SCORE_MIN;
}
score_t match_bonus[m];
score_t D[n][m], M[n][m];
/*
* D[][] Stores the best score for this position ending with a match.
* M[][] Stores the best possible score at this position.
*/
#define SCORE_GAP_LEADING -0.005
#define SCORE_GAP_TRAILING -0.005
#define SCORE_GAP_INNER -0.01
#define SCORE_MATCH_CONSECUTIVE 1.0
#define SCORE_MATCH_SLASH 0.9
#define SCORE_MATCH_WORD 0.8
#define SCORE_MATCH_CAPITAL 0.7
#define SCORE_MATCH_DOT 0.6
/* Which positions are beginning of words */
char last_ch = '\0';
for(int i = 0; i < m; i++){
char ch = haystack[i];
score_t score = 0;
if(isalnum(ch)){
if(!last_ch || last_ch == '/'){
score = SCORE_MATCH_SLASH;
}else if(last_ch == '-' ||
last_ch == '_' ||
last_ch == ' ' ||
(last_ch >= '0' && last_ch <= '9')){
score = SCORE_MATCH_WORD;
}else if(last_ch >= 'a' && last_ch <= 'z' &&
ch >= 'A' && ch <= 'Z'){
/* CamelCase */
score = SCORE_MATCH_CAPITAL;
}else if(last_ch == '.'){
score = SCORE_MATCH_DOT;
}
}
match_bonus[i] = score;
last_ch = ch;
}
for(int i = 0; i < n; i++){
double prev_score = SCORE_MIN;
double gap_score = i == n-1 ? SCORE_GAP_TRAILING : SCORE_GAP_INNER;
for(int j = 0; j < m; j++){
score_t score = SCORE_MIN;
if(tolower(needle[i]) == tolower(haystack[j])){
if(!i){
score = (j * SCORE_GAP_LEADING) + match_bonus[j];
}else if(j){
score = max(
M[i-1][j-1] + match_bonus[j],
/* consecutive match, doesn't stack with match_bonus */
D[i-1][j-1] + SCORE_MATCH_CONSECUTIVE
);
}
}
D[i][j] = score;
M[i][j] = prev_score = max(score, prev_score + gap_score);
}
}
#if 0
fprintf(stderr, "\"%s\" =~ \"%s\"\n", needle, haystack);
mat_print(&D[0][0], needle, haystack);
mat_print(&M[0][0], needle, haystack);
fprintf(stderr, "\n");
#endif
/* backtrace to find the positions of optimal matching */
if(positions){
int match_required = 0;
for(int i = n-1, j = m-1; i >= 0; i--){
for(; j >= 0; j--){
/*
* There may be multiple paths which result in
* the optimal weight.
*
* For simplicity, we will pick the first one
* we encounter, the latest in the candidate
* string.
*/
if(D[i][j] != SCORE_MIN && (match_required || D[i][j] == M[i][j])){
/* If this score was determined using
* SCORE_MATCH_CONSECUTIVE, the
* previous character MUST be a match
*/
match_required = i && j && M[i][j] == D[i-1][j-1] + SCORE_MATCH_CONSECUTIVE;
positions[i] = j--;
break;
}
}
}
}
return M[n-1][m-1];
}
double match_positions(const char *needle, const char *haystack, size_t *positions){
if(!*needle){
return SCORE_MAX;
}else if(!strcasecmp(needle, haystack)){
if(positions){
int n = strlen(needle);
for(int i = 0; i < n; i++)
positions[i] = i;
}
return SCORE_MAX;
}else{
return calculate_score(needle, haystack, positions);
}
}
double match(const char *needle, const char *haystack){
return match_positions(needle, haystack, NULL);
}
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