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It's indeed a ridiculous data structure, but I did actually need it.

It's a dynamically sized ring buffer with an optimization analogous to that of C++ strings; if the required capacity is small enough, the buffer is stored inline in the object rather than in a separate heap-allocated object. So something in the spirit of (but not exactly like):

  struct rb {
      union {
          Value* array;
          // Set N such that this array uses the same amount of space as the pointer.
          Value inline_array[N];
      uint16_t read;
      uint16_t write;
      uint16_t capacity;
You'd dynamically switch between the two internal representations, and choose whether to read from array or inline_array based on whether capacity is larger than N. In this setup it'd be pretty common for N to be 1. Having to add a special case to every single method would kind of suck, generic code that could handle any size seemed like a nice property to have.

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