frostfs-node/pkg/morph/event/opcodes.go
Leonard Lyubich 3173bf345e [#907] morph/event: Implement Op to string converter
Implement `StringFromOpcode` function that tries to retrieve `string` to
`Op`. Add a comment about neo-go source code that is used for implementation
of converters.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
2021-10-18 11:54:34 +03:00

59 lines
1.4 KiB
Go

package event
import (
"fmt"
"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
)
// Op is wrapper over Neo VM's opcode
// and its parameter.
type Op struct {
code opcode.Opcode
param []byte
}
// Code returns Neo VM opcode.
func (o Op) Code() opcode.Opcode {
return o.code
}
// Param returns parameter of wrapped
// Neo VM opcode.
func (o Op) Param() []byte {
return o.param
}
// Below are the functions which reverse the results of github.com/nspcc-dev/neo-go/pkg/vm/emit.Array function.
// BytesFromOpcode tries to retrieve bytes from Op.
func BytesFromOpcode(op Op) ([]byte, error) {
switch code := op.Code(); code {
case opcode.PUSHDATA1, opcode.PUSHDATA2, opcode.PUSHDATA4:
return op.Param(), nil
default:
return nil, fmt.Errorf("unexpected ByteArray opcode %s", code)
}
}
// IntFromOpcode tries to retrieve int from Op.
func IntFromOpcode(op Op) (int64, error) {
switch code := op.Code(); {
case code == opcode.PUSHM1:
return -1, nil
case code >= opcode.PUSH0 && code <= opcode.PUSH16:
return int64(code - opcode.PUSH0), nil
case code <= opcode.PUSHINT256:
return bigint.FromBytes(op.Param()).Int64(), nil
default:
return 0, fmt.Errorf("unexpected INT opcode %s", code)
}
}
// StringFromOpcode tries to retrieve string from Op.
func StringFromOpcode(op Op) (string, error) {
// strings are emitted like bytes
data, err := BytesFromOpcode(op)
return string(data), err
}