github.com/aquanetwork/aquachain@v1.7.8/core/vm/stack.go (about)

     1  // Copyright 2014 The aquachain Authors
     2  // This file is part of the aquachain library.
     3  //
     4  // The aquachain library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The aquachain library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the aquachain library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package vm
    18  
    19  import (
    20  	"fmt"
    21  	"math/big"
    22  )
    23  
    24  // stack is an object for basic stack operations. Items popped to the stack are
    25  // expected to be changed and modified. stack does not take care of adding newly
    26  // initialised objects.
    27  type Stack struct {
    28  	data []*big.Int
    29  }
    30  
    31  func newstack() *Stack {
    32  	return &Stack{data: make([]*big.Int, 0, 1024)}
    33  }
    34  
    35  func (st *Stack) Data() []*big.Int {
    36  	return st.data
    37  }
    38  
    39  func (st *Stack) push(d *big.Int) {
    40  	// NOTE push limit (1024) is checked in baseCheck
    41  	//stackItem := new(big.Int).Set(d)
    42  	//st.data = append(st.data, stackItem)
    43  	st.data = append(st.data, d)
    44  }
    45  
    46  //func (st *Stack) pushN(ds ...*big.Int) {
    47  //	st.data = append(st.data, ds...)
    48  //}
    49  
    50  func (st *Stack) pop() (ret *big.Int) {
    51  	ret = st.data[len(st.data)-1]
    52  	st.data = st.data[:len(st.data)-1]
    53  	return
    54  }
    55  
    56  func (st *Stack) len() int {
    57  	return len(st.data)
    58  }
    59  
    60  func (st *Stack) swap(n int) {
    61  	st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
    62  }
    63  
    64  func (st *Stack) dup(pool *intPool, n int) {
    65  	st.push(pool.get().Set(st.data[st.len()-n]))
    66  }
    67  
    68  func (st *Stack) peek() *big.Int {
    69  	return st.data[st.len()-1]
    70  }
    71  
    72  // Back returns the n'th item in stack
    73  func (st *Stack) Back(n int) *big.Int {
    74  	return st.data[st.len()-n-1]
    75  }
    76  
    77  func (st *Stack) require(n int) error {
    78  	if st.len() < n {
    79  		return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
    80  	}
    81  	return nil
    82  }
    83  
    84  func (st *Stack) Print() {
    85  	fmt.Println("### stack ###")
    86  	if len(st.data) > 0 {
    87  		for i, val := range st.data {
    88  			fmt.Printf("%-3d  %v\n", i, val)
    89  		}
    90  	} else {
    91  		fmt.Println("-- empty --")
    92  	}
    93  	fmt.Println("#############")
    94  }