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// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package vm
import (
"fmt"
"math/big"
)
// Stack is an object for basic stack operations. Items popped to the stack are
// expected to be changed and modified. stack does not take care of adding newly
// initialised objects.
type Stack struct {
Data []*big.Int
}
func (st *Stack) Push(d *big.Int) {
// NOTE push limit (1024) is checked in baseCheck
//stackItem := new(big.Int).Set(d)
//st.Data = append(st.Data, stackItem)
st.Data = append(st.Data, d)
}
func (st *Stack) PushN(ds ...*big.Int) {
st.Data = append(st.Data, ds...)
}
func (st *Stack) Pop() (ret *big.Int) {
ret = st.Data[len(st.Data)-1]
st.Data = st.Data[:len(st.Data)-1]
return
}
func (st *Stack) Len() int {
return len(st.Data)
}
func (st *Stack) Swap(n int) {
st.Data[st.Len()-n], st.Data[st.Len()-1] = st.Data[st.Len()-1], st.Data[st.Len()-n]
}
func (st *Stack) Dup(pool *IntPool, n int) {
st.Push(pool.Get().Set(st.Data[st.Len()-n]))
}
func (st *Stack) Peek() *big.Int {
return st.Data[st.Len()-1]
}
// Back returns the n'th item in stack
func (st *Stack) Back(n int) *big.Int {
return st.Data[st.Len()-n-1]
}
func (st *Stack) Require(n int) error {
if st.Len() < n {
return fmt.Errorf("stack underflow (%d <=> %d)", len(st.Data), n)
}
return nil
}
// Print dumps the content of the stack
func (st *Stack) Print() {
fmt.Println("### stack ###")
if len(st.Data) > 0 {
for i, val := range st.Data {
fmt.Printf("%-3d %v\n", i, val)
}
} else {
fmt.Println("-- empty --")
}
fmt.Println("#############")
}
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