std::experi...re_searcher(3)

💖 std::experimental::boyer_moore_searcher & std::experimental::make_boyer_moore_searcher 💖

okay bestie, this is the std::experi...re_searcher(3) manual page from the C++ Standard Libary (yes, that's the spelling in the header, we're keeping it 💀). it's all about std::experimental::boyer_moore_searcher and std::experimental::make_boyer_moore_searcher — a whole duo, and they're here to make Boyer-Moore string searching happen with std::experimental::search. periodt ✨

🌸 NAME 🌸

std::experimental::boyer_moore_searcher, std::experimental::make_boyer_moore_searcher — that's the pair, no cap 💅. (The class and the helper function, both in the library fundamentals TS.)

🦋 Synopsis 🦋

Defined in header <experimental/functional> — and yes, it's in the library fundamentals TS.

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

so boyer_moore_searcher is a searcher suitable for use with std::experimental::search that implements the Boyer-Moore string searching algorithm. it's giving algorithm royalty 👑.

boyer_moore_searcher is CopyConstructible and CopyAssignable — love that for it 🫶.

RandomIt1 must meet the requirements of LegacyRandomAccessIterator. no skipping that vibe check, bestie.

💅 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, setting up any necessary internal data structures. it's literally collecting its little ingredients and getting ready to search 🧚.

The value type of RandomIt1 must be DefaultConstructible, CopyConstructible and CopyAssignable. periodt.

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. this is a hard requirement, bestie — don't let your hash and equality be in a situationship where they disagree 😭.

💜 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. so dramatic, but fair 💀.

💖 std::experimental::boyer_moore_searcher::operator() 💖

until C++17

template< class RandomIt2 >
RandomIt2 operator()( RandomIt2 first, RandomIt2 last ) const;

since C++17

template< class RandomIt2 >
std::pair<RandomIt2,RandomIt2> operator()( RandomIt2 first, RandomIt2 last ) const;

The member function called by std::experimental::search to perform a search with this searcher. RandomIt2 must meet the requirements of LegacyRandomAccessIterator. also, RandomIt1 and RandomIt2 must have the same value type — no mismatched bestie energy 🙈.

💜 Parameters 💜

• first, last — a pair of iterators designating the string to be examined.

🌟 Return value 🌟

until C++17: 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 otherwise.

since 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) otherwise.

🧚 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());

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); — cute, convenient, iconic ✨.

(this one is also in the library fundamentals TS.)

💜 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. slay 🫶.

🍓 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 👀

• search — searches for a range of elements (function template).

🏷️ Category 🏷️

• Noindexed pages

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okay that's the whole page, bestie 💖 source/version/date sign-off vibes: http://cppreference.com, 2024.06.10, and the manual page tag std::experi...re_searcher(3) — that's the footer, and we're done. mwah 🎀