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)
}

type ClosureBody interface {
    Callee
    ethutil.RlpEncodable
    GetMem(int64) *ethutil.Value
}

// Basic inline closure object which implement the 'closure' interface
type Closure struct {
    callee Callee
    object ClosureBody
    state  *State

    gas *big.Int
    val *big.Int
}

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

// Retuns the x element in data slice
func (c *Closure) GetMem(x int64) *ethutil.Value {
    m := c.object.GetMem(x)
    if m == nil {
        return ethutil.EmptyValue()
    }

    return m
}

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) GetGas() *big.Int {
    return c.gas
}