core, core/state, core/vm: remove exported account getters (#3618)

Removed exported statedb object accessors, reducing the chance for nasty
bugs to creep in. It's also ugly and unnecessary to have these methods.

core/vm/contract.go

@@ -25,11 +25,20 @@ import (
 // ContractRef is a reference to the contract's backing object
 type ContractRef interface {
 	Address() common.Address
-	Value() *big.Int
-	SetCode(common.Hash, []byte)
-	ForEachStorage(callback func(key, value common.Hash) bool)
 }
 
+// AccountRef implements ContractRef.
+//
+// Account references are used during EVM initialisation and
+// it's primary use is to fetch addresses. Removing this object
+// proves difficult because of the cached jump destinations which
+// are fetched from the parent contract (i.e. the caller), which
+// is a ContractRef.
+type AccountRef common.Address
+
+// Address casts AccountRef to a Address
+func (ar AccountRef) Address() common.Address { return (common.Address)(ar) }
+
 // Contract represents an ethereum contract in the state database. It contains
 // the the contract code, calling arguments. Contract implements ContractRef
 type Contract struct {
@@ -69,7 +78,8 @@ func NewContract(caller ContractRef, object ContractRef, value *big.Int, gas uin
 	// 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
-	c.value = new(big.Int).Set(value)
+	// ensures a value is set
+	c.value = value
 
 	return c
 }
@@ -80,7 +90,10 @@ func (c *Contract) AsDelegate() *Contract {
 	c.DelegateCall = true
 	// NOTE: caller must, at all times be a contract. It should never happen
 	// that caller is something other than a Contract.
-	c.CallerAddress = c.caller.(*Contract).CallerAddress
+	parent := c.caller.(*Contract)
+	c.CallerAddress = parent.CallerAddress
+	c.value = parent.value
+
 	return c
 }
 
@@ -138,9 +151,3 @@ func (self *Contract) SetCallCode(addr *common.Address, hash common.Hash, code [
 	self.CodeHash = hash
 	self.CodeAddr = addr
 }
-
-// EachStorage iterates the contract's storage and calls a method for every key
-// value pair.
-func (self *Contract) ForEachStorage(cb func(key, value common.Hash) bool) {
-	self.caller.ForEachStorage(cb)
-}