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storage.md

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Summary

storage

The storage module, it's a type constructor where you pass a type T and a non-zero positive integer size value.

The result is a storage type capable of storing size entries of type T, always re-using free slots as possible.

For example, if you use a storage capable of storing 3 entries and you push 3 entries on it, and then removes the second entry, then a fourth entry can be pushed and it will use the second slot, thus the generational index of this fourth entry will be a second generation of the second slot.

storage

local storage = @record{
    entries: [SIZE]T,
    unavailables: [SIZE]boolean,
    generations: [SIZE]usize,
    next_idx: usize,
  }

the storage type

storage:push

function storage:push(value: facultative(T)): (boolean, GenIdx, *T)

Push a new entry on the storage on the next free slot, if no free slots are available, then a warning will be printed and this function will return false, a zeroed generational index and nilptr.

Otherwise, the entry will be inserted on the found free slot and this function will return true, the generational index of the used slot and a reference to the inserted entry.

You can optionally pass a value to initialize this entry.

storage:remove

function storage:remove(idx: GenIdx, destroyer: facultative(function(*T))): boolean

Removes an entry associated with the generational index.

If the entry is found, then the slot it's zeroed and the function returns true. Othewise it does nothing and returns false.

You can optionally pass a destroyer function, which will be called passing a pointer to the entry, this is useful if you need to free resources on this entry.

storage:mget

function storage:mget(idx: GenIdx): (boolean, *T)

Try to find the entry of the generational index.

If found, then it returns true and a reference to the entry on the storage. Otherwise, it returns false and a nilptr.

To void undefined behavior, always check or assert the returned boolean value.

storage:__mnext

function storage:__mnext(ctrl_var: isize): (boolean, isize, *T)

mnext method, used by __mpairs method, it finds the next entry to iterate.

storage:__mpairs

function storage:__mpairs(): (auto, *storage, isize)

Iterator for mpairs, this allows using for in using the mpairs iterator on the storage, it iterates only on the entries and skips unused slots.

storage:clear

function storage:clear(on_clear: facultative(function(*T)))

resets storage to a zeroed state

storage

local storage: type

Storage generic used to instantiate an storage type in the form of component(T, size), where size is the maximum number of entries.