github.com/4000d/go-ethereum@v1.8.2-0.20180223170251-423c8bb1d821/core/vm/stack.go (about)

     1  // Copyright 2014 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum 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 go-ethereum 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 go-ethereum 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  func (st *Stack) pushN(ds ...*big.Int) {
    46  	st.data = append(st.data, ds...)
    47  }
    48  
    49  func (st *Stack) pop() (ret *big.Int) {
    50  	ret = st.data[len(st.data)-1]
    51  	st.data = st.data[:len(st.data)-1]
    52  	return
    53  }
    54  
    55  func (st *Stack) len() int {
    56  	return len(st.data)
    57  }
    58  
    59  func (st *Stack) swap(n int) {
    60  	st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
    61  }
    62  
    63  func (st *Stack) dup(pool *intPool, n int) {
    64  	st.push(pool.get().Set(st.data[st.len()-n]))
    65  }
    66  
    67  func (st *Stack) peek() *big.Int {
    68  	return st.data[st.len()-1]
    69  }
    70  
    71  // Back returns the n'th item in stack
    72  func (st *Stack) Back(n int) *big.Int {
    73  	return st.data[st.len()-n-1]
    74  }
    75  
    76  func (st *Stack) require(n int) error {
    77  	if st.len() < n {
    78  		return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
    79  	}
    80  	return nil
    81  }
    82  
    83  func (st *Stack) Print() {
    84  	fmt.Println("### stack ###")
    85  	if len(st.data) > 0 {
    86  		for i, val := range st.data {
    87  			fmt.Printf("%-3d  %v\n", i, val)
    88  		}
    89  	} else {
    90  		fmt.Println("-- empty --")
    91  	}
    92  	fmt.Println("#############")
    93  }