Tessil/array-hash

#include <city.h>

struct str_hash {
    std::size_t operator()(const char* key, std::size_t key_size) const {
        return CityHash64(key, key_size);
    }
};

tsl::array_map<char, int, str_hash> map;

struct custom_policy {
    // Called on hash table construction and rehash, min_bucket_count_in_out is the minimum buckets
    // that the hash table needs. The policy can change it to a higher number of buckets if needed 
    // and the hash table will use this value as bucket count. If 0 bucket is asked, then the value
    // must stay at 0.
    explicit custom_policy(std::size_t& min_bucket_count_in_out);
    
    // Return the bucket [0, bucket_count()) to which the hash belongs. 
    // If bucket_count() is 0, it must always return 0.
    std::size_t bucket_for_hash(std::size_t hash) const noexcept;
    
    // Return the number of buckets that should be used on next growth
    std::size_t next_bucket_count() const;
    
    // Maximum number of buckets supported by the policy
    std::size_t max_bucket_count() const;
    
    // Reset the growth policy as if the policy was created with a bucket count of 0.
    // After a clear, the policy must always return 0 when bucket_for_hash() is called.
    void clear() noexcept;
}

#include <iostream>
#include <tsl/array_map.h>
#include <tsl/array_set.h>


int main() {
    // Map of const char* to int
    tsl::array_map<char, int> map = {{"one", 1}, {"two", 2}};
    map["three"] = 3;
    map["four"] = 4;
    
    map.insert("five", 5);
    map.insert_ks("six_with_extra_chars_we_ignore", 3, 6);
    
    map.erase("two");
    
    // When template parameter StoreNullTerminator is true (default) and there is no
    // null character in the strings.
    for(auto it = map.begin(); it != map.end(); ++it) {
        std::cout << "{" << it.key() << ", " << it.value() << "}" << std::endl;
    }
    
    // If StoreNullTerminator is false for space efficiency or you are storing null characters, 
    // you can access to the size of the key.
    for(auto it = map.begin(); it != map.end(); ++it) {
        (std::cout << "{").write(it.key(), it.key_size()) << ", " << it.value() << "}" << std::endl;
    }
    
    // Better, use key_sv() if you compiler provides access to std::string_view.
    for(auto it = map.begin(); it != map.end(); ++it) {
        std::cout << "{" << it.key_sv() << ", " << it.value() << "}" << std::endl;
    }
    
    // Or if you just want the values.
    for(int value: map) {
        std::cout << "{" << value << "}" << std::endl;
    }


    // Map of const char32_t* to int
    tsl::array_map<char32_t, int> map_char32 = {{U"one", 1}, {U"two", 2}};
    map_char32[U"three"] = 3;
    
    
    // Set of const char*
    tsl::array_set<char> set = {"one", "two", "three"};
    set.insert({"four", "five"});
    
    for(auto it = set.begin(); it != set.end(); ++it) {
        std::cout << "{" << it.key() << "}" << std::endl;
    }
}

struct serializer {
    // Must support the following types for U: std::uint64_t, float and T if a map is used.
    template<typename U>
    void operator()(const U& value);
    void operator()(const CharT* value, std::size_t value_size);
};

struct deserializer {
    // Must support the following types for U: std::uint64_t, float and T if a map is used.
    template<typename U>
    U operator()();
    void operator()(CharT* value_out, std::size_t value_size);
};

#include <cassert>
#include <cstdint>
#include <fstream>
#include <type_traits>
#include <tsl/array_map.h>


class serializer {
public:
    serializer(const char* file_name) {
        m_ostream.exceptions(m_ostream.badbit | m_ostream.failbit);
        m_ostream.open(file_name);
    }
    
    template<class T,
             typename std::enable_if<std::is_arithmetic<T>::value>::type* = nullptr>
    void operator()(const T& value) {
        m_ostream.write(reinterpret_cast<const char*>(&value), sizeof(T));
    }
    
    void operator()(const char32_t* value, std::size_t value_size) {
        m_ostream.write(reinterpret_cast<const char*>(value), value_size*sizeof(char32_t));
    }

private:
    std::ofstream m_ostream;
};

class deserializer {
public:
    deserializer(const char* file_name) {
        m_istream.exceptions(m_istream.badbit | m_istream.failbit | m_istream.eofbit);
        m_istream.open(file_name);
    }
    
    template<class T,
             typename std::enable_if<std::is_arithmetic<T>::value>::type* = nullptr>
    T operator()() {
        T value;
        m_istream.read(reinterpret_cast<char*>(&value), sizeof(T));
        
        return value;
    }
    
    void operator()(char32_t* value_out, std::size_t value_size) {
        m_istream.read(reinterpret_cast<char*>(value_out), value_size*sizeof(char32_t));
    }

private:
    std::ifstream m_istream;
};


int main() {
    const tsl::array_map<char32_t, std::int64_t> map = {{U"one", 1}, {U"two", 2}, 
                                                        {U"three", 3}, {U"four", 4}};
    
    
    const char* file_name = "array_map.data";
    {
        serializer serial(file_name);
        map.serialize(serial);
    }
    
    {
        deserializer dserial(file_name);
        auto map_deserialized = tsl::array_map<char32_t, std::int64_t>::deserialize(dserial);
        
        assert(map == map_deserialized);
    }
    
    {
        deserializer dserial(file_name);
        
        /**
         * If the serialized and deserialized map are hash compatibles (see conditions in API), 
         * setting the argument to true speed-up the deserialization process as we don't have 
         * to recalculate the hash of each key. We also know how much space each bucket needs.
         */
        const bool hash_compatible = true;
        auto map_deserialized = 
            tsl::array_map<char32_t, std::int64_t>::deserialize(dserial, hash_compatible);
        
        assert(map == map_deserialized);
    }
}

#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/iostreams/filter/zlib.hpp>
#include <boost/iostreams/filtering_stream.hpp>
#include <boost/serialization/split_free.hpp>
#include <boost/serialization/utility.hpp>
#include <cassert>
#include <cstdint>
#include <fstream>
#include <tsl/array_map.h>


template<typename Archive>
struct serializer {
    Archive& ar;
    
    template<typename T>
    void operator()(const T& val) { ar & val; }
    
    template<typename CharT>
    void operator()(const CharT* val, std::size_t val_size) {
        ar.save_binary(reinterpret_cast<const void*>(val), val_size*sizeof(CharT));
    }   
};

template<typename Archive>
struct deserializer {
    Archive& ar;
    
    template<typename T>
    T operator()() { T val; ar & val; return val; }
    
    template<typename CharT>
    void operator()(CharT* val_out, std::size_t val_size) {
        ar.load_binary(reinterpret_cast<void*>(val_out), val_size*sizeof(CharT));
    }  
};

namespace boost { namespace serialization {
template<class Archive, class CharT, class T>
void serialize(Archive & ar, tsl::array_map<CharT, T>& map, const unsigned int version) {
    split_free(ar, map, version); 
}

template<class Archive, class CharT, class T>
void save(Archive & ar, const tsl::array_map<CharT, T>& map, const unsigned int version) {
    serializer<Archive> serial{ar};
    map.serialize(serial);
}


template<class Archive, class CharT, class T>
void load(Archive & ar, tsl::array_map<CharT, T>& map, const unsigned int version) {
    deserializer<Archive> deserial{ar};
    map = tsl::array_map<CharT, T>::deserialize(deserial);
}
}}


int main() {
    const tsl::array_map<char32_t, std::int64_t> map = {{U"one", 1}, {U"two", 2}, 
                                                        {U"three", 3}, {U"four", 4}};
    
    
    const char* file_name = "array_map.data";
    {
        std::ofstream ofs;
        ofs.exceptions(ofs.badbit | ofs.failbit);
        ofs.open(file_name, std::ios::binary);
        
        boost::iostreams::filtering_ostream fo;
        fo.push(boost::iostreams::zlib_compressor());
        fo.push(ofs);
        
        boost::archive::binary_oarchive oa(fo);
        
        oa << map;
    }
    
    {
        std::ifstream ifs;
        ifs.exceptions(ifs.badbit | ifs.failbit | ifs.eofbit);
        ifs.open(file_name, std::ios::binary);
        
        boost::iostreams::filtering_istream fi;
        fi.push(boost::iostreams::zlib_decompressor());
        fi.push(ifs);
        
        boost::archive::binary_iarchive ia(fi);
     
        tsl::array_map<char32_t, std::int64_t> map_deserialized;   
        ia >> map_deserialized;
        
        assert(map == map_deserialized);
    }
}