/
stack.go
81 lines (67 loc) · 1.74 KB
/
stack.go
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// Copyright (c) 2018 The MATRIX Authors
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php
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 newstack() *Stack {
return &Stack{data: make([]*big.Int, 0, 1024)}
}
func (st *Stack) Data() []*big.Int {
return st.data
}
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
}
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("#############")
}