github.com/aigarnetwork/aigar@v0.0.0-20191115204914-d59a6eb70f8e/core/vm/stack.go (about)

     1  //  Copyright 2018 The go-ethereum Authors
     2  //  Copyright 2019 The go-aigar Authors
     3  //  This file is part of the go-aigar library.
     4  //
     5  //  The go-aigar library is free software: you can redistribute it and/or modify
     6  //  it under the terms of the GNU Lesser General Public License as published by
     7  //  the Free Software Foundation, either version 3 of the License, or
     8  //  (at your option) any later version.
     9  //
    10  //  The go-aigar library is distributed in the hope that it will be useful,
    11  //  but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  //  GNU Lesser General Public License for more details.
    14  //
    15  //  You should have received a copy of the GNU Lesser General Public License
    16  //  along with the go-aigar library. If not, see <http://www.gnu.org/licenses/>.
    17  
    18  package vm
    19  
    20  import (
    21  	"fmt"
    22  	"math/big"
    23  )
    24  
    25  // Stack is an object for basic stack operations. Items popped to the stack are
    26  // expected to be changed and modified. stack does not take care of adding newly
    27  // initialised objects.
    28  type Stack struct {
    29  	data []*big.Int
    30  }
    31  
    32  func newstack() *Stack {
    33  	return &Stack{data: make([]*big.Int, 0, 1024)}
    34  }
    35  
    36  // Data returns the underlying big.Int array.
    37  func (st *Stack) Data() []*big.Int {
    38  	return st.data
    39  }
    40  
    41  func (st *Stack) push(d *big.Int) {
    42  	// NOTE push limit (1024) is checked in baseCheck
    43  	//stackItem := new(big.Int).Set(d)
    44  	//st.data = append(st.data, stackItem)
    45  	st.data = append(st.data, d)
    46  }
    47  func (st *Stack) pushN(ds ...*big.Int) {
    48  	st.data = append(st.data, ds...)
    49  }
    50  
    51  func (st *Stack) pop() (ret *big.Int) {
    52  	ret = st.data[len(st.data)-1]
    53  	st.data = st.data[:len(st.data)-1]
    54  	return
    55  }
    56  
    57  func (st *Stack) len() int {
    58  	return len(st.data)
    59  }
    60  
    61  func (st *Stack) swap(n int) {
    62  	st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
    63  }
    64  
    65  func (st *Stack) dup(pool *intPool, n int) {
    66  	st.push(pool.get().Set(st.data[st.len()-n]))
    67  }
    68  
    69  func (st *Stack) peek() *big.Int {
    70  	return st.data[st.len()-1]
    71  }
    72  
    73  // Back returns the n'th item in stack
    74  func (st *Stack) Back(n int) *big.Int {
    75  	return st.data[st.len()-n-1]
    76  }
    77  
    78  func (st *Stack) require(n int) error {
    79  	if st.len() < n {
    80  		return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
    81  	}
    82  	return nil
    83  }
    84  
    85  // Print dumps the content of the stack
    86  func (st *Stack) Print() {
    87  	fmt.Println("### stack ###")
    88  	if len(st.data) > 0 {
    89  		for i, val := range st.data {
    90  			fmt.Printf("%-3d  %v\n", i, val)
    91  		}
    92  	} else {
    93  		fmt.Println("-- empty --")
    94  	}
    95  	fmt.Println("#############")
    96  }