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reimplement find_bm() using std::search #33

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Jan 19, 2024
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reimplement find_bm() using std::search #33

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37 changes: 2 additions & 35 deletions mimetic/utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
***************************************************************************/
#ifndef _MIMETIC_UTILS_H_
#define _MIMETIC_UTILS_H_
#include <algorithm>
#include <iostream>
#include <string>
#include <ctype.h>
Expand Down Expand Up @@ -43,37 +44,6 @@ int str2int(const std::string& s);
/// returns a string hexadecimal representation of \p n
std::string int2hex(unsigned int n);

// find_bm specialization for random access iterators
template<typename Iterator>
Iterator find_bm(Iterator bit, Iterator eit, const std::string& word, const std::random_access_iterator_tag&)
{
int bLen = word.length();
const char* pWord = word.c_str();
int i, t, shift[256];
unsigned char c;

for(i = 0; i < 256; ++i)
shift[i] = bLen;

for(i = 0; i < bLen; ++i)
shift[ (unsigned char) pWord[i] ] = bLen -i - 1;

for(i = t = bLen-1; t >= 0; --i, --t)
{
if((bit + i) >= eit)
return eit;

while((c = *(bit + i)) != pWord[t])
{
i += std::max(bLen-t, shift[c]);
if((bit + i) >= eit) return eit;
t = bLen-1;
}
}

return bit + i + 1;
}

// boyer-moore find
/**
* find the first occurrence of \p word in (\p bit, \p eit]
Expand All @@ -84,12 +54,9 @@ Iterator find_bm(Iterator bit, Iterator eit, const std::string& word, const std:
template<typename Iterator>
Iterator find_bm(Iterator bit, Iterator eit, const std::string& word)
{
return find_bm(bit, eit, word,
typename std::iterator_traits<Iterator>::iterator_category());
return std::search(bit, eit, word.begin(), word.end());
}



} // ns utils

}
Expand Down