std::boyer_moore_searcher - cppreference.com (original) (raw)

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

std::boyer_moore_searcher is CopyConstructible and CopyAssignable.

RandomIt1 must meet the requirements of LegacyRandomAccessIterator.

Contents

• 1 Member functions
• 2 std::boyer_moore_searcher::boyer_moore_searcher
  • 2.1 Parameters
  • 2.2 Exceptions
• 3 std::boyer_moore_searcher::operator()
  • 3.1 Parameters
  • 3.2 Return value
  • 3.3 Notes
  • 3.4 Example
  • 3.5 See also

[edit] 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 std::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

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

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

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.

[edit] Notes

[edit] Example

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

Output:

The string "pisci" found at offset 43

[edit] See also