std::boyer_moore_searcher (3) - Linux Manuals

std::boyer_moore_searcher: std::boyer_moore_searcher

NAME

std::boyer_moore_searcher - std::boyer_moore_searcher

Synopsis

Defined in header <functional>
template< class RandomIt1,
class Hash = std::hash<typename std::iterator_traits<RandomIt1>::value_type>, (since C++17)
class BinaryPredicate = std::equal_to<> >
class boyer_moore_searcher;

A searcher suitable for use with the Searcher overload of std::search that implements the Boyer-Moore_string_searching_algorithm.
boyer_moore_searcher is CopyConstructible and CopyAssignable.
RandomIt1 must meet the requirements of LegacyRandomAccessIterator.

Member functions

 std::boyer_moore_searcher::boyer_moore_searcher

boyer_moore_searcher( RandomIt1 pat_first,
RandomIt1 pat_last,
Hash hf = Hash(),
BinaryPredicate pred = BinaryPredicate());

Constructs a boyer_moore_searcher by storing copies of pat_first, pat_last, hf, and pred, setting up any necessary internal data structures.
The value type of RandomIt1 must be DefaultConstructible, CopyConstructible and CopyAssignable.
For any two values A and B of the type std::iterator_traits<RandomIt1>::value_type, if pred(A, B) == true, then hf(A) == hf(B) shall be true.

Parameters

pat_first, pat_last - a pair of iterators designating the string to be searched for
hf - a callable object used to hash the elements of the string
pred - a callable object used to determine equality

Exceptions

Any exceptions thrown by

* the copy constructor of RandomIt1;
* the default constructor, copy constructor, and copy assignment operator of the value type of RandomIt1; or
* the copy constructor and function call operator of BinaryPredicate or Hash.

May also throw std::bad_alloc if additional memory required for internal data structures cannot be allocated.

 std::boyer_moore_searcher::operator()

template< class RandomIt2 > (since C++17)
std::pair<RandomIt2,RandomIt2> operator()( RandomIt2 first, RandomIt2 last ) const;

The member function called by the Searcher overload of std::search to perform a search with this searcher. RandomIt2 must meet the requirements of LegacyRandomAccessIterator.
RandomIt1 and RandomIt2 must have the same value type.

Parameters

first, last - a pair of iterators designating the string to be examined

Return value

If the pattern ([pat_first, pat_last)) is empty, returns make_pair(first, first).
Otherwise, returns a pair of iterators to the first and one past last positions in [first, last) where a subsequence that compares equal to [pat_first, pat_last) as defined by pred is located, or make_pair(last, last) otherwise.

Example

// Run this code

  #include <iostream>
  #include <string>
  #include <algorithm>
  #include <functional>

  int main()
  {
      std::string in = "Lorem ipsum dolor sit amet, consectetur adipiscing elit,"
                       " sed do eiusmod tempor incididunt ut labore et dolore magna aliqua";
      std::string needle = "pisci";
      auto it = std::search(in.begin(), in.end(),
                     std::boyer_moore_searcher(
                         needle.begin(), needle.end()));
      if(it != in.end())
          std::cout << "The string " << needle << " found at offset "
                    << it - in.begin() << '\n';
      else
          std::cout << "The string " << needle << " not found\n";
  }

Output:

  The string pisci found at offset 43