1 files changed, 87 insertions, 0 deletions
diff --git a/core/vm/logger_json.go b/core/vm/logger_json.go
new file mode 100644
index 0000000..5068343
--- /dev/null
+++ b/core/vm/logger_json.go
@@ -0,0 +1,87 @@
+// 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 vm
+
+import (
+	"encoding/json"
+	"io"
+	"math/big"
+	"time"
+
+	"github.com/ava-labs/go-ethereum/common"
+	"github.com/ava-labs/go-ethereum/common/math"
+)
+
+type JSONLogger struct {
+	encoder *json.Encoder
+	cfg     *LogConfig
+}
+
+// NewJSONLogger creates a new EVM tracer that prints execution steps as JSON objects
+// into the provided stream.
+func NewJSONLogger(cfg *LogConfig, writer io.Writer) *JSONLogger {
+	l := &JSONLogger{json.NewEncoder(writer), cfg}
+	if l.cfg == nil {
+		l.cfg = &LogConfig{}
+	}
+	return l
+}
+
+func (l *JSONLogger) CaptureStart(from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) error {
+	return nil
+}
+
+// CaptureState outputs state information on the logger.
+func (l *JSONLogger) CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error {
+	log := StructLog{
+		Pc:            pc,
+		Op:            op,
+		Gas:           gas,
+		GasCost:       cost,
+		MemorySize:    memory.Len(),
+		Storage:       nil,
+		Depth:         depth,
+		RefundCounter: env.StateDB.GetRefund(),
+		Err:           err,
+	}
+	if !l.cfg.DisableMemory {
+		log.Memory = memory.Data()
+	}
+	if !l.cfg.DisableStack {
+		log.Stack = stack.Data()
+	}
+	return l.encoder.Encode(log)
+}
+
+// CaptureFault outputs state information on the logger.
+func (l *JSONLogger) CaptureFault(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error {
+	return nil
+}
+
+// CaptureEnd is triggered at end of execution.
+func (l *JSONLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error {
+	type endLog struct {
+		Output  string              `json:"output"`
+		GasUsed math.HexOrDecimal64 `json:"gasUsed"`
+		Time    time.Duration       `json:"time"`
+		Err     string              `json:"error,omitempty"`
+	}
+	if err != nil {
+		return l.encoder.Encode(endLog{common.Bytes2Hex(output), math.HexOrDecimal64(gasUsed), t, err.Error()})
+	}
+	return l.encoder.Encode(endLog{common.Bytes2Hex(output), math.HexOrDecimal64(gasUsed), t, ""})
+}