fdid_allocator.hpp

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#pragma once

 
#include <cstdint>
#include <format>
 
#include <wowlib/core/error.hpp>
#include <wowlib/core/file_key.hpp>
 
namespace wowlib::fs::detail {
  class FdidAllocator {
  public:
    explicit FdidAllocator(FileDataID start = FileDataID{1'000'000'000}, FileDataID max = FileDataID{0xFFFFFFFE})
      : _next(start.value), _max(max.value) {}

    Result<FileDataID> next() {
      if (_next > _max)
        return makeError(ErrorCode::FdidSpaceExhausted, std::format("custom FileDataID space exhausted at {}", _max));
      return FileDataID{static_cast<std::uint32_t>(_next++)};
    }

    void noteExisting(FileDataID id) {
      if (id.value >= _next && id.value <= _max) _next = id.value + 1;
    }

    FileDataID peek() const {
      return FileDataID{static_cast<std::uint32_t>(_next)};
    }
 
  private:
    std::uint64_t _next;
    // u64 internally so _next can pass _max without wrapping
    std::uint64_t _max;
  };
}