std::boyer_moore_searcher(3)

💖 NAME 💖

Okay so welcome to the std::boyer_moore_searcher page from the C++ Standard Libary manual, bestie 💅 The name is std::boyer_moore_searcher - std::boyer_moore_searcher, and yes that's the whole NAME section, no cap ✨

🌈 Synopsis 🌈

Defined in header <functional>.

The template signature is literally this, so copy it exactly:

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_searcher;

So this class is a searcher suitable for use with the Searcher overload of std::search, and it implements the Boyer-Moore string searching algorithm. Iconic. 🎀

std::boyer_moore_searcher is CopyConstructible and CopyAssignable.

RandomIt1 must meet the requirements of LegacyRandomAccessIterator, fr fr 🦋

🧚 Member functions 🧚

💖 std::boyer_moore_searcher::boyer_moore_searcher 💖

boyer_moore_searcher( RandomIt1 pat_first,

                      RandomIt1 pat_last,
                      Hash hf = Hash(),

                      BinaryPredicate pred = BinaryPredicate() );

This constructor constructs a std::boyer_moore_searcher by storing copies of pat_first, pat_last, hf, and pred, and 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. That's the vibe check 🌸

💕 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 yeah, memory said no, careful 😭

🌟 std::boyer_moore_searcher::operator() 🌟

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

This is 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. That's the whole return-value tea. 🍵

📝 Notes 📝

Feature-test macro vibe check:

• Feature-test macro: __cpp_lib_boyer_moore_searcher
• Value: 201603L
• Std: (C++17)
• Feature: searchers

That's the whole table, bestie ✨

🍓 Example 🍓

// Run this code

        #include <algorithm>
        #include <functional>
        #include <iomanip>
        #include <iostream>
        #include <string_view>

        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

👀 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_horspool_searcher — Boyer-Moore-Horspool search algorithm implementation (C++17) (class template) 🦋

xoxo, your Unix bestie 💖 — source/version: http://cppreference.com; date: 2024.06.10; page: std::boyer_moore_searcher(3). Bye bestie 🫶✨