cpp-mini-stl

A header-only C++20 library reimplementing core Standard Library components from first principles, including a dynamic array (Vector<T>), hash table (HashMap<K,V>), smart pointers (UniquePtr<T>, SharedPtr<T>), and a fixed-block memory pool allocator.

Highlights

• Reimplemented Vector<T> with manual memory management and move-aware reallocation
• Built a separate-chaining HashMap<K,V> with automatic rehashing
• Implemented UniquePtr<T> and reference-counted SharedPtr<T>
• Designed a fixed-block MemoryPool allocator for fast small-object allocation
• Header-only C++20 library
• Unit tested and benchmarked
• AddressSanitizer and UBSan clean

Components

Component	Description
Vector<T>	Dynamic contiguous array with amortized O(1) insertion
HashMap<K,V>	Hash table using separate chaining
UniquePtr<T>	Exclusive ownership smart pointer
SharedPtr<T>	Reference-counted smart pointer
MemoryPool	Fixed-block allocator with free-list management

Project Structure

cpp-mini-stl/
├── CMakeLists.txt
├── README.md
├── include/
│   └── mini/
│       ├── vector.hpp
│       ├── hash_map.hpp
│       ├── unique_ptr.hpp
│       ├── shared_ptr.hpp
│       └── memory_pool.hpp
├── src/
│   └── main.cpp
├── tests/
│   └── test_cases.cpp
├── benchmarks/
│   └── benchmark.cpp
├── docs/
│   └── architecture.md
└── design.md

Build

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j

Run Tests

ctest --test-dir build

Usage

#include <mini/vector.hpp>
#include <mini/hash_map.hpp>
#include <mini/unique_ptr.hpp>
#include <iostream>

int main() {
    mini::Vector<int> numbers;
    numbers.push_back(10);
    numbers.push_back(20);
    numbers.push_back(30);

    mini::HashMap<std::string, int> scores;
    scores["alice"] = 95;
    scores["bob"] = 88;

    mini::UniquePtr<int> value(new int(42));

    std::cout << "Vector size: " << numbers.size() << '\n';
    std::cout << "Alice: " << scores["alice"] << '\n';
    std::cout << "Value: " << *value << '\n';

    return 0;
}

Benchmarks

./build/benchmarks/benchmark

Example results:

Benchmark	Result
MemoryPool Allocation (64B)	8.4× faster than malloc
Vector Push Back	Measured
HashMap Lookup	Measured
SharedPtr Creation	Measured

Documentation

• docs/architecture.md — implementation details and architecture
• design.md — design decisions and tradeoffs

Requirements

• C++20
• CMake 3.20+

License

MIT License