1 files changed, 77 insertions, 0 deletions
diff --git a/rpc/types.go b/rpc/types.go
new file mode 100644
index 0000000..7312397
--- /dev/null
+++ b/rpc/types.go
@@ -0,0 +1,77 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package rpc
+
+import (
+	"fmt"
+	"math"
+	"strings"
+
+	"github.com/ava-labs/go-ethereum/common/hexutil"
+)
+
+type BlockNumber int64
+
+const (
+	AcceptedBlockNumber = BlockNumber(-3)
+	PendingBlockNumber  = BlockNumber(-2)
+	LatestBlockNumber   = BlockNumber(-1)
+	EarliestBlockNumber = BlockNumber(0)
+)
+
+// UnmarshalJSON parses the given JSON fragment into a BlockNumber. It supports:
+// - "latest", "earliest" or "pending" as string arguments
+// - the block number
+// Returned errors:
+// - an invalid block number error when the given argument isn't a known strings
+// - an out of range error when the given block number is either too little or too large
+func (bn *BlockNumber) UnmarshalJSON(data []byte) error {
+	input := strings.TrimSpace(string(data))
+	if len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"' {
+		input = input[1 : len(input)-1]
+	}
+
+	switch input {
+	case "earliest":
+		*bn = EarliestBlockNumber
+		return nil
+	case "latest":
+		*bn = LatestBlockNumber
+		return nil
+	case "pending":
+		*bn = PendingBlockNumber
+		return nil
+	case "accepted":
+		*bn = AcceptedBlockNumber
+		return nil
+	}
+
+	blckNum, err := hexutil.DecodeUint64(input)
+	if err != nil {
+		return err
+	}
+	if blckNum > math.MaxInt64 {
+		return fmt.Errorf("Blocknumber too high")
+	}
+
+	*bn = BlockNumber(blckNum)
+	return nil
+}
+
+func (bn BlockNumber) Int64() int64 {
+	return (int64)(bn)
+}