std::experimental::boyer_moore_searcher, std::experimental::make_boyer_moore_searcher

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Defined in header <experimental/functional>
template < class RandomIt1,

class Hash = std::hash < typename std::iterator_traits <RandomIt1> :: value_type >,
class BinaryPredicate = std::equal_to <> >

class boyer_moore_searcher;
(library fundamentals TS)

A searcher suitable for use with std::experimental::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::experimental::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

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::experimental::boyer_moore_searcher::operator()

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

The member function called by std::experimental::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 first

Otherwise, an iterator to the first position in [ first ,  last ) where a subsequence that compares equal to [ pat_first ,  pat_last ) as defined by pred is located, or a copy of last

(until C++17)

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)

(since C++17)

Helper Functions

template < class RandomIt,

class Hash = std::hash < typename std::iterator_traits <RandomIt> :: value_type >,
class BinaryPredicate = std::equal_to <> >
boyer_moore_searcher<RandomIt, Hash, BinaryPredicate> make_boyer_moore_searcher(
    RandomIt pat_first,
    RandomIt pat_last,
    Hash hf = Hash( ),

    BinaryPredicate pred = BinaryPredicate( ) ) ;
(library fundamentals TS)

Helper function that constructs a std::experimental::boyer_moore_searcher using template argument deduction. Equivalent to return boyer_moore_searcher<RandomIt, Hash, BinaryPredicate> (pat_first, pat_last, hf, pred) ;

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

Return value

A boyer_moore_searcher constructed with the arguments pat_first, pat_last, hf, and pred

Example

Run this code
#include <experimental/algorithm>
#include <experimental/functional>
#include <iostream>
#include <string>
 
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::experimental::search(in.begin(), in.end(),
                  std::experimental::make_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 the first occurrence of a range of elements
(function template)
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