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array.go
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/
array.go
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package adt
import (
"bytes"
"fmt"
"github.com/filecoin-project/go-amt-ipld/v4"
"github.com/filecoin-project/go-state-types/cbor"
"github.com/ipfs/go-cid"
cbg "github.com/whyrusleeping/cbor-gen"
)
// DefaultAmtOptions default amt option
var DefaultAmtOptions = []amt.Option{}
// Array stores a sparse sequence of values in an AMT.
type Array struct {
root *amt.Root
store Store
}
// AsArray interprets a store as an AMT-based array with root `r`.
func AsArray(s Store, r cid.Cid, bitwidth int) (*Array, error) {
options := append(DefaultAmtOptions, amt.UseTreeBitWidth(uint(bitwidth)))
root, err := amt.LoadAMT(s.Context(), s, r, options...)
if err != nil {
return nil, fmt.Errorf("failed to root: %w", err)
}
return &Array{
root: root,
store: s,
}, nil
}
// MakeEmptyArray creates a new array backed by an empty AMT.
func MakeEmptyArray(s Store, bitwidth int) (*Array, error) {
options := append(DefaultAmtOptions, amt.UseTreeBitWidth(uint(bitwidth)))
root, err := amt.NewAMT(s, options...)
if err != nil {
return nil, err
}
return &Array{
root: root,
store: s,
}, nil
}
// StoreEmptyArray writes a new empty array to the store, returning its CID.
func StoreEmptyArray(s Store, bitwidth int) (cid.Cid, error) {
arr, err := MakeEmptyArray(s, bitwidth)
if err != nil {
return cid.Undef, err
}
return arr.Root()
}
// Root returns the root CID of the underlying AMT.
func (a *Array) Root() (cid.Cid, error) {
return a.root.Flush(a.store.Context())
}
// AppendContinuous appends a value to the end of the array. Assumes continuous array.
// If the array isn't continuous use Set and a separate counter
func (a *Array) AppendContinuous(value cbor.Marshaler) error {
if err := a.root.Set(a.store.Context(), a.root.Len(), value); err != nil {
return fmt.Errorf("append failed to set index %v value %v in root %v: %w", a.root.Len(), value, a.root, err)
}
return nil
}
// Set set marshaler value to array
func (a *Array) Set(i uint64, value cbor.Marshaler) error {
if err := a.root.Set(a.store.Context(), i, value); err != nil {
return fmt.Errorf("failed to set index %v value %v in root %v: %w", i, value, a.root, err)
}
return nil
}
// TryDelete removes the value at index `i` from the AMT, if it exists.
// returns whether the index was previously present.
func (a *Array) TryDelete(i uint64) (bool, error) {
if found, err := a.root.Delete(a.store.Context(), i); err != nil {
return false, fmt.Errorf("array delete failed to delete index %v in root %v: %w", i, a.root, err)
} else { //nolint
return found, nil
}
}
// Delete removes the value at index `i` from the AMT, expecting it to exist.
func (a *Array) Delete(i uint64) error {
if found, err := a.root.Delete(a.store.Context(), i); err != nil {
return fmt.Errorf("failed to delete index %v in root %v: %w", i, a.root, err)
} else if !found {
return fmt.Errorf("no such index %v in root %v to delete: %w", i, a.root, err)
}
return nil
}
// BatchDelete batch delete
func (a *Array) BatchDelete(ix []uint64, strict bool) error {
if _, err := a.root.BatchDelete(a.store.Context(), ix, strict); err != nil {
return fmt.Errorf("failed to batch delete keys %v: %w", ix, err)
}
return nil
}
// ForEach iterates all entries in the array, deserializing each value in turn into `out` and then calling a function.
// Iteration halts if the function returns an error.
// If the output parameter is nil, deserialization is skipped.
func (a *Array) ForEach(out cbor.Unmarshaler, fn func(i int64) error) error {
return a.root.ForEach(a.store.Context(), func(k uint64, val *cbg.Deferred) error {
if out != nil {
if deferred, ok := out.(*cbg.Deferred); ok {
// fast-path deferred -> deferred to avoid re-decoding.
*deferred = *val
} else if err := out.UnmarshalCBOR(bytes.NewReader(val.Raw)); err != nil {
return err
}
}
return fn(int64(k))
})
}
// Length get element number in array
func (a *Array) Length() uint64 {
return a.root.Len()
}
// Get retrieves array element into the 'out' unmarshaler, returning a boolean
//
// indicating whether the element was found in the array
func (a *Array) Get(k uint64, out cbor.Unmarshaler) (bool, error) {
if found, err := a.root.Get(a.store.Context(), k, out); err != nil {
return false, fmt.Errorf("failed to get index %v in root %v: %w", k, a.root, err)
} else { //nolint
return found, nil
}
}
// Pop retrieves an array value into the 'out' unmarshaler (if non-nil), and removes the entry.
// Returns a boolean indicating whether the element was previously in the array.
func (a *Array) Pop(k uint64, out cbor.Unmarshaler) (bool, error) {
if found, err := a.root.Get(a.store.Context(), k, out); err != nil {
return false, fmt.Errorf("failed to get index %v in root %v: %w", k, a.root, err)
} else if !found {
return false, nil
}
if found, err := a.root.Delete(a.store.Context(), k); err != nil {
return false, fmt.Errorf("failed to delete index %v in root %v: %w", k, a.root, err)
} else if !found {
return false, fmt.Errorf("can't find index %v to delete in root %v", k, a.root)
}
return true, nil
}