std::boyer_moore_searcher (3) Linux Manual Page

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

See also

       searches for a range of elements
search (function template)