1 files changed, 129 insertions, 0 deletions
diff --git a/ethchain/closure.go b/ethchain/closure.go
new file mode 100644
index 000000000..32b297e90
--- /dev/null
+++ b/ethchain/closure.go
@@ -0,0 +1,129 @@
+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 {
+	caller 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(caller ClosureRef, object *StateObject, script []byte, state *State, gas, price *big.Int) *Closure {
+	c := &Closure{caller: caller, object: object, Script: script, State: state, Args: nil}
+
+	// Gas should be a pointer so it can safely be reduced through the run
+	// This pointer will be off the state transition
+	c.Gas = gas //new(big.Int).Set(gas)
+	// In most cases price and value are pointers to transaction objects
+	// and we don't want the transaction's values to change.
+	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 caller
+	// If no caller is present return it to
+	// the origin (i.e. contract or tx)
+	if c.caller != nil {
+		c.caller.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 caller 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) Caller() ClosureRef {
+	return c.caller
+}
+
+func (c *Closure) N() *big.Int {
+	return c.object.N()
+}