default_hasher.go

/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package ionhash

// defaultHasher computes the hash of the given algorithm and appends the hash to the provider's hash logs.
// Used for testing purposes only.
type defaultHasher struct {
	cryptoHasher IonHasher
	provider     *testIonHasherProvider
}

// newDefaultHasher returns a new defaultHasher. Returns an error if the algorithm argument is invalid.
func newDefaultHasher(algorithm Algorithm, provider *testIonHasherProvider) (IonHasher, error) {
	cryptoHasher, err := newCryptoHasher(algorithm)
	if err != nil {
		return nil, &InvalidArgumentError{"algorithm", algorithm}
	}
	return &defaultHasher{cryptoHasher: cryptoHasher, provider: provider}, nil
}

// Write adds more data to the running hash and appends to provider's updateHashlog.
func (dh *defaultHasher) Write(b []byte) (n int, err error) {
	dh.provider.updateHashLog = append(dh.provider.updateHashLog, b)
	return dh.cryptoHasher.Write(b)
}

// Sum appends the current hash to b and provider's digestHashlog, and returns the resulting slice.
// It does not change the underlying hash provider's state.
func (dh *defaultHasher) Sum(b []byte) []byte {
	hash := dh.cryptoHasher.Sum(b)
	dh.provider.digestHashLog = append(dh.provider.digestHashLog, hash)
	return hash
}

// Reset resets the hash value to nil.
func (dh *defaultHasher) Reset() {
	dh.cryptoHasher.Reset()
}