gno.land/p/gnoland/boards/v0⧉

1package boards23import (4	"errors"56	"gno.land/p/nt/bptree/v0"7)89type (10	// PostIterFn defines a function type to iterate posts.11	PostIterFn func(*Post) bool1213	// PostStorage defines an interface for posts storage.14	PostStorage interface {15		// Get retruns a post that matches an ID.16		Get(ID) (_ *Post, found bool)1718		// Remove removes a post from the storage.19		Remove(ID) (_ *Post, removed bool)2021		// Add adds a post in the storage.22		Add(*Post) error2324		// Size returns the number of posts in the storage.25		Size() int2627		// Iterate iterates posts.28		// To reverse iterate posts use a negative count.29		// If the callback returns true, the iteration is stopped.30		Iterate(start, count int, fn PostIterFn) bool31	}32)3334// NewPostStorage creates a new storage for posts.35// The new storage uses an AVL tree to store posts.36func NewPostStorage() PostStorage {37	return &postStorage{bptree.NewBPTree32()}38}3940type postStorage struct {41	posts *bptree.BPTree // string(Post.ID) -> *Post42}4344// Get retruns a post that matches an ID.45func (s postStorage) Get(id ID) (*Post, bool) {46	k := makePostKey(id)47	v := s.posts.Get(k)48	if v == nil {49		return nil, false50	}51	return v.(*Post), true52}5354// Remove removes a post from the storage.55func (s *postStorage) Remove(id ID) (*Post, bool) {56	k := makePostKey(id)57	v, removed := s.posts.Remove(k)58	if !removed {59		return nil, false60	}61	return v.(*Post), true62}6364// Add adds a post in the storage.65// It updates existing posts when storage contains one with the same ID.66func (s *postStorage) Add(p *Post) error {67	if p == nil {68		return errors.New("saving nil posts is not allowed")69	}7071	s.posts.Set(makePostKey(p.ID), p)72	return nil73}7475// Size returns the number of posts in the storage.76func (s postStorage) Size() int {77	return s.posts.Size()78}7980// Iterate iterates posts.81// To reverse iterate posts use a negative count.82// If the callback returns true, the iteration is stopped.83func (s postStorage) Iterate(start, count int, fn PostIterFn) bool {84	if count < 0 {85		return s.posts.ReverseIterateByOffset(start, -count, func(_ string, v any) bool {86			return fn(v.(*Post))87		})88	}8990	return s.posts.IterateByOffset(start, count, func(_ string, v any) bool {91		return fn(v.(*Post))92	})93}9495func makePostKey(postID ID) string {96	return postID.PaddedString()97}98