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content_id.go
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/
content_id.go
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// Copyright © 2017-2018 The IPFN Developers. 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.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License 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 cells
import (
"fmt"
cid "gx/ipfs/QmR8BauakNcBa3RbE4nbQu76PDiJgoQgz8AJdhJuiU4TAw/go-cid"
mh "gx/ipfs/QmerPMzPk1mJVowm8KgmoknWa4yCYvvugMPsgWmDNUvDLW/go-multihash"
)
// CID - Content ID wrapper.
type CID struct {
cid.Cid
}
// UndefCID - Alias to an empty content ID.
var UndefCID = CID{}
// NewCID - Creates new wrapped content ID v1 for codec and hash.
func NewCID(codecType uint64, mhash mh.Multihash) CID {
return CID{Cid: cid.NewCidV1(codecType, mhash)}
}
// NewCIDFromHash - Creates new wrapped content ID v1 for codec and hash.
func NewCIDFromHash(codecType uint64, hash []byte, hashType uint64) CID {
mhash, _ := mh.Encode(hash, mh.SHA2_256)
return NewCID(cid.EthStateTrie, mhash)
}
// SumCID - Sums content id and wraps.
func SumCID(prefix cid.Prefix, body []byte) (_ CID, err error) {
c, err := prefix.Sum(body)
if err != nil {
return
}
return WrapCID(c), nil
}
// WrapCID - Wraps content id.
func WrapCID(c cid.Cid) CID {
return CID{Cid: c}
}
// DecodeCID - Decodes CID.
func DecodeCID(v string) (_ CID, err error) {
c, err := cid.Decode(v)
if err != nil {
return
}
return CID{Cid: c}, nil
}
// ParseCID - Parses CID.
func ParseCID(v interface{}) (_ CID, err error) {
c, err := cid.Parse(v)
if err != nil {
return
}
return CID{Cid: c}, nil
}
// Digest - Returns 32 bytes of hash.
func (c CID) Digest() []byte {
h := c.Hash()
return h[len(h)-32:]
}
// UnmarshalJSON - Parses the JSON string representation of a cid.
func (c *CID) UnmarshalJSON(b []byte) (err error) {
if len(b) < 2 {
return fmt.Errorf("invalid cid json blob")
}
b = b[1 : len(b)-1]
c.Cid, err = cid.Decode(string(b))
return
}
// MarshalJSON - Marshals the cid as string.
func (c CID) MarshalJSON() ([]byte, error) {
return []byte(fmt.Sprintf("%q", c)), nil
}
// Defined - Returns true if CID is not empty.
func (c *CID) Defined() bool {
return c != nil && c.Cid.Defined()
}