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std::boyer_moore_horspool_searcher, std::make_boyer_moore_horspool_searcher

From cppreference.com
< cpp‎ | utility‎ | functional
 
 
 
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Searchers
boyer_moore_horspool_searcher
(C++17)
make_boyer_moore_horspool_searcher
(C++17)
Old binders and adaptors
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Defined in header <functional>
template< class RandomIt1,

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

class boyer_moore_horspool_searcher;
(since C++17)

A searcher suitable for use with the Searcher overload of std::search that implements the Boyer-Moore-Horspool string searching algorithm.

boyer_moore_horspool_searcher is CopyConstructible and CopyAssignable.

RandomIt1 must meet the requirements of RandomAccessIterator.

Contents

[edit] Member functions

std::boyer_moore_horspool_searcher::boyer_moore_horspool_searcher

boyer_moore_horspool_searcher( RandomIt1 pat_first,

                               RandomIt1 pat_last,
                               Hash hf = Hash(),

                               BinaryPredicate pred = BinaryPredicate());

Constructs a boyer_moore_horspool_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, or copy assignment operator of the value type of RandomIt1; or
  • the copy constructor or 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_horspool_searcher::operator()

template< class RandomIt2 >
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 RandomAccessIterator.

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.

[edit] Helper Functions

template< class RandomIt,

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

                                        BinaryPredicate pred = BinaryPredicate());
(since C++17)

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

[edit] 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

[edit] Return value

A boyer_moore_horspool_searcher constructed with the arguments pat_first, pat_last, hf, and pred.

[edit] Example

#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::make_boyer_moore_horspool_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

[edit] See also

searches for a range of elements
(function template) [edit]