Project 5: Custom Ring Buffer Iterator

A simple, fixed-size ring buffer (a circular queue) from scratch. The main goal of the project is not the container itself, but implementing a fully compliant STL-style iterator for it. This iterator should correctly handle wrapping around the end of the buffer’s underlying array. You will then demonstrate that standard STL algorithms like std::for_each and std::find work perfectly with your custom container.

Quick Reference

Attribute Value
Primary Language C++
Alternative Languages N/A
Difficulty Level 4: Expert
Time Estimate 2-3 weeks
Knowledge Area Iterators / API Design / Custom Data Structures
Tooling N/A
Prerequisites Strong C++ skills, including templates and operator overloading.

What You Will Build

A simple, fixed-size ring buffer (a circular queue) from scratch. The main goal of the project is not the container itself, but implementing a fully compliant STL-style iterator for it. This iterator should correctly handle wrapping around the end of the buffer’s underlying array. You will then demonstrate that standard STL algorithms like std::for_each and std::find work perfectly with your custom container.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • Implementing the ring buffer logic → maps to using modulo arithmetic for indexing
  • Designing the iterator class → maps to storing a pointer to the container and an index
  • Overloading iterator operators → maps to implementing operator*, operator->, operator++, operator--, operator==, operator!=
  • Providing begin() and end() methods → maps to connecting your container to the STL

Key Concepts

  • Iterator Categories: Understanding the difference between Input, Forward, Bidirectional, and Random Access iterators. (Your ring buffer can have a Random Access Iterator).
  • std::iterator_traits: A helper for writing generic algorithms that work with custom iterators.
  • Operator Overloading: The C++ mechanism that makes iterators feel like pointers.

Real-World Outcome

#include "ring_buffer.h"
#include <algorithm>
#include <iostream>

int main() {
    RingBuffer<int, 5> rb;
    rb.push(10);
    rb.push(20);
    rb.push(30);

    // Using a range-based for loop (requires begin()/end())
    std::cout << "Contents: ";
    for (int val : rb) {
        std::cout << val << " ";
    } // Output: 10 20 30

    // Using an STL algorithm with our custom iterators
    auto it = std::find(rb.begin(), rb.end(), 20);
    if (it != rb.end()) {
        std::cout << "\nFound " << *it << "!\n";
    }
}

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References

  • Main guide: LEARN_CPP_STL_DEEP_DIVE.md
  • “The C++ Standard Library: A Tutorial and Reference” by Nicolai M. Josuttis