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-rw-r--r--vm/closure.go140
1 files changed, 140 insertions, 0 deletions
diff --git a/vm/closure.go b/vm/closure.go
new file mode 100644
index 000000000..5a1e1d4d5
--- /dev/null
+++ b/vm/closure.go
@@ -0,0 +1,140 @@
+package vm
+
+// TODO Re write VM to use values instead of big integers?
+
+import (
+ "math/big"
+
+ "github.com/ethereum/eth-go/ethstate"
+ "github.com/ethereum/eth-go/ethutil"
+)
+
+type ClosureRef interface {
+ ReturnGas(*big.Int, *big.Int)
+ Address() []byte
+ Object() *ethstate.StateObject
+ GetStorage(*big.Int) *ethutil.Value
+ SetStorage(*big.Int, *ethutil.Value)
+}
+
+// Basic inline closure object which implement the 'closure' interface
+type Closure struct {
+ caller ClosureRef
+ object *ethstate.StateObject
+ Code []byte
+ message *ethstate.Message
+ exe *Execution
+
+ Gas, UsedGas, Price *big.Int
+
+ Args []byte
+}
+
+// Create a new closure for the given data items
+func NewClosure(msg *ethstate.Message, caller ClosureRef, object *ethstate.StateObject, code []byte, gas, price *big.Int) *Closure {
+ c := &Closure{message: msg, caller: caller, object: object, Code: code, 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) GetStorage(x *big.Int) *ethutil.Value {
+ m := c.object.GetStorage(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) GetOp(x int) OpCode {
+ return OpCode(c.GetByte(x))
+}
+
+func (c *Closure) GetByte(x int) byte {
+ if x < len(c.Code) {
+ return c.Code[x]
+ }
+
+ return 0
+}
+
+func (c *Closure) GetBytes(x, y int) []byte {
+ if x >= len(c.Code) || y >= len(c.Code) {
+ return nil
+ }
+
+ return c.Code[x : x+y]
+}
+
+func (c *Closure) Gets(x, y *big.Int) *ethutil.Value {
+ if x.Int64() >= int64(len(c.Code)) || y.Int64() >= int64(len(c.Code)) {
+ return ethutil.NewValue(0)
+ }
+
+ partial := c.Code[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()
+}
+
+func (c *Closure) Call(vm VirtualMachine, args []byte) ([]byte, *big.Int, error) {
+ c.Args = args
+
+ ret, err := vm.RunClosure(c)
+
+ return ret, c.UsedGas, err
+}
+
+func (c *Closure) Return(ret []byte) []byte {
+ // Return the remaining gas to the caller
+ c.caller.ReturnGas(c.Gas, c.Price)
+
+ 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) {
+ // Return the gas to the closure
+ c.Gas.Add(c.Gas, gas)
+ c.UsedGas.Sub(c.UsedGas, gas)
+}
+
+func (c *Closure) Object() *ethstate.StateObject {
+ return c.object
+}
+
+func (c *Closure) Caller() ClosureRef {
+ return c.caller
+}