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package ethchain
// TODO Re write VM to use values instead of big integers?
import (
"github.com/ethereum/eth-go/ethutil"
"math/big"
)
type ClosureRef interface {
ReturnGas(*big.Int, *big.Int, *State)
Address() []byte
GetMem(*big.Int) *ethutil.Value
SetStorage(*big.Int, *ethutil.Value)
N() *big.Int
}
// Basic inline closure object which implement the 'closure' interface
type Closure struct {
callee ClosureRef
object *StateObject
Script []byte
State *State
Gas, UsedGas, Price *big.Int
Args []byte
}
// Create a new closure for the given data items
func NewClosure(callee ClosureRef, object *StateObject, script []byte, state *State, gas, price *big.Int) *Closure {
c := &Closure{callee: callee, object: object, Script: script, State: state, Args: nil}
// In most cases gas, price and value are pointers to transaction objects
// and we don't want the transaction's values to change.
c.Gas = new(big.Int).Set(gas)
c.Price = new(big.Int).Set(price)
c.UsedGas = new(big.Int)
return c
}
// Retuns the x element in data slice
func (c *Closure) GetMem(x *big.Int) *ethutil.Value {
m := c.object.GetMem(x)
if m == nil {
return ethutil.EmptyValue()
}
return m
}
func (c *Closure) Get(x *big.Int) *ethutil.Value {
return c.Gets(x, big.NewInt(1))
}
func (c *Closure) Gets(x, y *big.Int) *ethutil.Value {
if x.Int64() >= int64(len(c.Script)) || y.Int64() >= int64(len(c.Script)) {
return ethutil.NewValue(0)
}
partial := c.Script[x.Int64() : x.Int64()+y.Int64()]
return ethutil.NewValue(partial)
}
func (c *Closure) SetStorage(x *big.Int, val *ethutil.Value) {
c.object.SetStorage(x, val)
}
func (c *Closure) Address() []byte {
return c.object.Address()
}
type DebugHook func(step int, op OpCode, mem *Memory, stack *Stack, stateObject *StateObject) bool
func (c *Closure) Call(vm *Vm, args []byte, hook DebugHook) ([]byte, *big.Int, error) {
c.Args = args
ret, err := vm.RunClosure(c, hook)
return ret, c.UsedGas, err
}
func (c *Closure) Return(ret []byte) []byte {
// Return the remaining gas to the callee
// If no callee is present return it to
// the origin (i.e. contract or tx)
if c.callee != nil {
c.callee.ReturnGas(c.Gas, c.Price, c.State)
} else {
c.object.ReturnGas(c.Gas, c.Price, c.State)
}
return ret
}
func (c *Closure) UseGas(gas *big.Int) bool {
if c.Gas.Cmp(gas) < 0 {
return false
}
// Sub the amount of gas from the remaining
c.Gas.Sub(c.Gas, gas)
c.UsedGas.Add(c.UsedGas, gas)
return true
}
// Implement the Callee interface
func (c *Closure) ReturnGas(gas, price *big.Int, state *State) {
// Return the gas to the closure
c.Gas.Add(c.Gas, gas)
c.UsedGas.Sub(c.UsedGas, gas)
}
func (c *Closure) Object() *StateObject {
return c.object
}
func (c *Closure) Callee() ClosureRef {
return c.callee
}
func (c *Closure) N() *big.Int {
return c.object.N()
}
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