circular_buffer.h

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#pragma once
 
#include "fl/math_macros.h"
#include "fl/namespace.h"
#include "fl/ptr.h" // Assuming this provides `scoped_array` or similar
#include <stddef.h> // For size_t
#include <stdint.h> // For standard integer types
 
namespace fl {
 
template <typename T> class CircularBuffer {
  public:
    CircularBuffer(size_t capacity)
        : mCapacity(capacity + 1), mHead(0),
          mTail(0) { // Extra space for distinguishing full/empty
        mBuffer.reset(new T[mCapacity]);
    }
 
    CircularBuffer(const CircularBuffer &) = delete;
    CircularBuffer &operator=(const CircularBuffer &) = delete;
 
    bool push_back(const T &value) {
        if (full()) {
            mTail = increment(mTail); // Overwrite the oldest element
        }
        mBuffer[mHead] = value;
        mHead = increment(mHead);
        return true;
    }
 
    bool pop_front(T *dst = nullptr) {
        if (empty()) {
            return false;
        }
        if (dst) {
            *dst = mBuffer[mTail];
        }
        mTail = increment(mTail);
        return true;
    }
 
    bool push_front(const T &value) {
        if (full()) {
            mHead = decrement(mHead); // Overwrite the oldest element
        }
        mTail = decrement(mTail);
        mBuffer[mTail] = value;
        return true;
    }
 
    bool pop_back(T *dst = nullptr) {
        if (empty()) {
            return false;
        }
        mHead = decrement(mHead);
        if (dst) {
            *dst = mBuffer[mHead];
        }
        return true;
    }
 
    T &front() { return mBuffer[mTail]; }
 
    const T &front() const { return mBuffer[mTail]; }
 
    T &back() { return mBuffer[(mHead + mCapacity - 1) % mCapacity]; }
 
    const T &back() const {
        return mBuffer[(mHead + mCapacity - 1) % mCapacity];
    }
 
    T &operator[](size_t index) { return mBuffer[(mTail + index) % mCapacity]; }
 
    const T &operator[](size_t index) const {
        return mBuffer[(mTail + index) % mCapacity];
    }
 
    size_t size() const { return (mHead + mCapacity - mTail) % mCapacity; }
 
    size_t capacity() const { return mCapacity - 1; }
 
    bool empty() const { return mHead == mTail; }
 
    bool full() const { return increment(mHead) == mTail; }
 
    void clear() { mHead = mTail = 0; }
 
  private:
    size_t increment(size_t index) const { return (index + 1) % mCapacity; }
 
    size_t decrement(size_t index) const {
        return (index + mCapacity - 1) % mCapacity;
    }
 
    fl::scoped_array<T> mBuffer;
    size_t mCapacity;
    size_t mHead;
    size_t mTail;
};
 
} // namespace fl