109 lines
2.4 KiB
Go
109 lines
2.4 KiB
Go
package platform
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import (
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"bytes"
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"encoding/binary"
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"encoding/hex"
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"encoding/json"
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"fmt"
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)
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// IDLength is the exact length a byte slice must have in order to be decoded into an ID
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const IDLength = 16
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// ID is a unique identifier.
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//
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// Its zero value is not a valid ID.
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type ID uint64
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// IDGenerator represents a generator for IDs.
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type IDGenerator interface {
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// ID creates unique byte slice ID.
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ID() ID
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}
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// IDFromString creates an ID from a given string.
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//
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// It errors if the input string does not match a valid ID.
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func IDFromString(str string) (*ID, error) {
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var id ID
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err := id.DecodeFromString(str)
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if err != nil {
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return nil, err
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}
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return &id, nil
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}
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// Decode parses b as a hex-encoded byte-slice-string.
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//
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// It errors if the input byte slice does not have the correct length
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// or if it contains all zeros.
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func (i *ID) Decode(b []byte) error {
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if len(b) != IDLength {
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return fmt.Errorf("input must be an array of %d bytes", IDLength)
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}
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if bytes.Equal(b, make([]byte, IDLength)) {
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return fmt.Errorf("all 0s is not a valid ID")
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}
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dst := make([]byte, hex.DecodedLen(IDLength))
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_, err := hex.Decode(dst, b)
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if err != nil {
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return err
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}
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*i = ID(binary.BigEndian.Uint64(dst))
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return nil
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}
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// DecodeFromString parses s as a hex-encoded string.
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func (i *ID) DecodeFromString(s string) error {
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return i.Decode([]byte(s))
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}
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// Encode converts ID to a hex-encoded byte-slice-string.
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//
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// It errors if the receiving ID holds its zero value.
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func (i ID) Encode() ([]byte, error) {
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if i == 0 {
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return nil, fmt.Errorf("all 0s is not a valid ID")
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}
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b := make([]byte, hex.DecodedLen(IDLength))
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binary.BigEndian.PutUint64(b, uint64(i))
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dst := make([]byte, hex.EncodedLen(len(b)))
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hex.Encode(dst, b)
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return dst, nil
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}
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// Valid checks whether the receiving ID is a valid one or not.
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func (i ID) Valid() bool {
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if _, err := i.Encode(); err != nil {
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return false
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}
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return true
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}
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// String returns the ID as a hex encoded string.
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//
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// Returns an empty string in the case the ID is invalid.
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func (i ID) String() string {
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enc, _ := i.Encode()
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return string(enc)
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}
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// UnmarshalJSON implements JSON unmarshaller for IDs.
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func (i *ID) UnmarshalJSON(b []byte) error {
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b = b[1 : len(b)-1]
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return i.Decode(b)
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}
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// MarshalJSON implements JSON marshaller for IDs.
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func (i ID) MarshalJSON() ([]byte, error) {
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enc, err := i.Encode()
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if err != nil {
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return nil, err
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}
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return json.Marshal(string(enc))
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}
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