vendor/github.com/opencontainers/go-digest/digester.go

package digest

import "hash"

// Digester calculates the digest of written data. Writes should go directly
// to the return value of Hash, while calling Digest will return the current
// value of the digest.
type Digester interface {
	Hash() hash.Hash // provides direct access to underlying hash instance.
	Digest() Digest
}

// digester provides a simple digester definition that embeds a hasher.
type digester struct {
	alg  Algorithm
	hash hash.Hash
}

func (d *digester) Hash() hash.Hash {
	return d.hash
}

func (d *digester) Digest() Digest {
	return NewDigest(d.alg, d.hash)
}