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match.c
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132 lines (110 loc) · 3.28 KB
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#include "match.h"
#include <ctype.h>
#include <string.h>
static unsigned char tolower_ascii(unsigned char c) {
if (c >= 'A' && c <= 'Z') {
return (unsigned char) (c + ('a' - 'A'));
}
return c;
}
static int contains_case_insensitive(const char *text, const char *pattern, int pat_len) {
if (pat_len == 0) {
return 1;
}
int text_len = (int) strlen(text);
if (pat_len > text_len) {
return 0;
}
for (int i = 0; i <= text_len - pat_len; i++) {
int j = 0;
while (j < pat_len) {
unsigned char tc = tolower_ascii((unsigned char) text[i + j]);
unsigned char pc = tolower_ascii((unsigned char) pattern[j]);
if (tc != pc) {
break;
}
j++;
}
if (j == pat_len) {
return 1;
}
}
return 0;
}
static int subseq_case_insensitive(const char *text, const char *pattern, int pat_len) {
if (pat_len == 0) {
return 1;
}
int pi = 0;
int ti = 0;
int text_len = (int) strlen(text);
while (ti < text_len && pi < pat_len) {
unsigned char tc = tolower_ascii((unsigned char) text[ti]);
unsigned char pc = tolower_ascii((unsigned char) pattern[pi]);
if (tc == pc) {
pi++;
}
ti++;
}
return (pi == pat_len);
}
SEXP match_with_c(SEXP x, SEXP token) {
if (!Rf_isString(x)) {
Rf_error("x must be a character vector");
}
if (!Rf_isString(token) || Rf_length(token) != 1) {
Rf_error("token must be a single character string");
}
SEXP out = PROTECT(Rf_allocVector(LGLSXP, Rf_length(x)));
int *out_ptr = LOGICAL(out);
if (STRING_ELT(token, 0) == NA_STRING) {
for (int i = 0; i < Rf_length(x); i++) {
out_ptr[i] = NA_LOGICAL;
}
UNPROTECT(1);
return out;
}
const char *pat = Rf_translateCharUTF8(STRING_ELT(token, 0));
int pat_len = (int) strlen(pat);
for (int i = 0; i < Rf_length(x); i++) {
SEXP item = STRING_ELT(x, i);
if (item == NA_STRING) {
out_ptr[i] = NA_LOGICAL;
continue;
}
const char *text = Rf_translateCharUTF8(item);
out_ptr[i] = contains_case_insensitive(text, pat, pat_len);
}
UNPROTECT(1);
return out;
}
SEXP fuzzy_find_c(SEXP x, SEXP pattern) {
if (!Rf_isString(x)) {
Rf_error("x must be a character vector");
}
if (!Rf_isString(pattern) || Rf_length(pattern) != 1) {
Rf_error("pattern must be a single character string");
}
SEXP out = PROTECT(Rf_allocVector(LGLSXP, Rf_length(x)));
int *out_ptr = LOGICAL(out);
if (STRING_ELT(pattern, 0) == NA_STRING) {
for (int i = 0; i < Rf_length(x); i++) {
out_ptr[i] = NA_LOGICAL;
}
UNPROTECT(1);
return out;
}
const char *pat = Rf_translateCharUTF8(STRING_ELT(pattern, 0));
int pat_len = (int) strlen(pat);
for (int i = 0; i < Rf_length(x); i++) {
SEXP item = STRING_ELT(x, i);
if (item == NA_STRING) {
out_ptr[i] = NA_LOGICAL;
continue;
}
const char *text = Rf_translateCharUTF8(item);
out_ptr[i] = subseq_case_insensitive(text, pat, pat_len);
}
UNPROTECT(1);
return out;
}