1 // Copyright 2019, 2020 OCI Contributors 2 // Copyright 2017 Docker, Inc. 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // https://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 16 package digest 17 18 import "hash" 19 20 // Digester calculates the digest of written data. Writes should go directly 21 // to the return value of Hash, while calling Digest will return the current 22 // value of the digest. 23 type Digester interface { 24 Hash() hash.Hash // provides direct access to underlying hash instance. 25 Digest() Digest 26 } 27 28 // digester provides a simple digester definition that embeds a hasher. 29 type digester struct { 30 alg Algorithm 31 hash hash.Hash 32 } 33 34 func (d *digester) Hash() hash.Hash { 35 return d.hash 36 } 37 38 func (d *digester) Digest() Digest { 39 return NewDigest(d.alg, d.hash) 40 } 41