Merge pull request #135 from jtraglia/epoch-json-marshal-funcs

Add Marshaling functions for Epoch

spec/phase0/types.go

@@ -13,9 +13,47 @@
 
 package phase0
 
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+
+	"github.com/pkg/errors"
+)
+
 // Epoch is an epoch number.
 type Epoch uint64
 
+// UnmarshalJSON implements json.Unmarshaler.
+func (e *Epoch) UnmarshalJSON(input []byte) error {
+	if len(input) == 0 {
+		return errors.New("input missing")
+	}
+	if len(input) < 3 {
+		return errors.New("input malformed")
+	}
+
+	if !bytes.HasPrefix(input, []byte{'"'}) {
+		return errors.New("invalid prefix")
+	}
+	if !bytes.HasSuffix(input, []byte{'"'}) {
+		return errors.New("invalid suffix")
+	}
+
+	val, err := strconv.ParseUint(string(input[1:len(input)-1]), 10, 64)
+	if err != nil {
+		return errors.Wrapf(err, "invalid value %s", string(input[1:len(input)-1]))
+	}
+	*e = Epoch(val)
+
+	return nil
+}
+
+// MarshalJSON implements json.Marshaler.
+func (e Epoch) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf(`"%d"`, e)), nil
+}
+
 // CommitteeIndex is a committee index at a slot.
 type CommitteeIndex uint64