path: root/ethchain/closure.go

package ethchain

// TODO Re write VM to use values instead of big integers?

import (
    "github.com/ethereum/eth-go/ethutil"
    "math/big"
)

type Callee interface {
    ReturnGas(*big.Int, *State)
    Address() []byte
}

type Reference interface {
    Callee
    ethutil.RlpEncodable
    GetMem(*big.Int) *ethutil.Value
    SetMem(*big.Int, *ethutil.Value)
}

// Basic inline closure object which implement the 'closure' interface
type Closure struct {
    callee Callee
    object Reference
    Script []byte
    State  *State

    Gas   *big.Int
    Value *big.Int

    Args []byte
}

// Create a new closure for the given data items
func NewClosure(callee Callee, object Reference, script []byte, state *State, gas, val *big.Int) *Closure {
    return &Closure{callee, object, script, state, gas, val, nil}
}

// 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 {
    partial := c.Script[x.Int64() : x.Int64()+y.Int64()]

    return ethutil.NewValue(partial)
}

func (c *Closure) SetMem(x *big.Int, val *ethutil.Value) {
    c.object.SetMem(x, val)
}

func (c *Closure) Address() []byte {
    return c.object.Address()
}

func (c *Closure) Call(vm *Vm, args []byte) []byte {
    c.Args = args

    return vm.RunClosure(c)
}

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.State)
    } else {
        c.object.ReturnGas(c.Gas, c.State)
        // TODO incase it's a POST contract we gotta serialise the contract again.
        // But it's not yet defined
    }

    return ret
}

// Implement the Callee interface
func (c *Closure) ReturnGas(gas *big.Int, state *State) {
    // Return the gas to the closure
    c.Gas.Add(c.Gas, gas)
}

func (c *Closure) Object() Reference {
    return c.object
}

func (c *Closure) Callee() Callee {
    return c.callee
}