NAME¶

std::boyer_moore_horspool_searcher - std::boyer_moore_horspool_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_horspool_searcher;

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 LegacyRandomAccessIterator.

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
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 std::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 std::make_pair(last, last) otherwise.

Notes¶

Feature-test macro: __cpp_lib_boyer_moore_searcher

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_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

See also¶

search searches for a range of elements
(function template)
default_searcher standard C++ library search algorithm implementation
(C++17) (class template)
boyer_moore_searcher Boyer-Moore search algorithm implementation
(C++17) (class template)