1 files changed, 60 insertions, 0 deletions
diff --git a/cmd/evm/json_logger.go b/cmd/evm/json_logger.go
new file mode 100644
index 000000000..a84d5daeb
--- /dev/null
+++ b/cmd/evm/json_logger.go
@@ -0,0 +1,60 @@
+// Copyright 2017 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 main
+
+import (
+	"encoding/json"
+	"io"
+	"time"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
+	"github.com/ethereum/go-ethereum/core/vm"
+)
+
+type JSONLogger struct {
+	encoder *json.Encoder
+}
+
+func NewJSONLogger(writer io.Writer) *JSONLogger {
+	return &JSONLogger{json.NewEncoder(writer)}
+}
+
+// CaptureState outputs state information on the logger.
+func (l *JSONLogger) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, memory *vm.Memory, stack *vm.Stack, contract *vm.Contract, depth int, err error) error {
+	return l.encoder.Encode(vm.StructLog{
+		Pc:      pc,
+		Op:      op,
+		Gas:     gas + cost,
+		GasCost: cost,
+		Memory:  memory.Data(),
+		Stack:   stack.Data(),
+		Storage: nil,
+		Depth:   depth,
+		Err:     err,
+	})
+}
+
+// CaptureEnd is triggered at end of execution.
+func (l *JSONLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration) error {
+	type endLog struct {
+		Output  string              `json:"output"`
+		GasUsed math.HexOrDecimal64 `json:"gasUsed"`
+		Time    time.Duration       `json:"time"`
+	}
+	return l.encoder.Encode(endLog{common.Bytes2Hex(output), math.HexOrDecimal64(gasUsed), t})
+}