LibDeque.sol

LibDeque提供了双端队列。用户也可以像用栈一样使用它。

使用方法

首先需要通过import引入LibDeque类库，然后通过”.”进行方法调用，如下为调用LibDeque方法的例子：

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);
    function f() public returns(bytes32, bytes32){
        _deque.offerFirst(bytes32(uint256(1)));
        _deque.offerLast(bytes32(uint256(2)));
        emit Log(_deque.getSize());//Should be 2
        bytes32 first =_deque.pollFirst();//Shoud be 0x1
        bytes32 last = _deque.pollLast();//Should be 0x2
        emit Log(_deque.getSize());//Should be empty
        return (first, last);
    }

}

API列表

编号	API	API描述
1	getSize(Deque storage self) internal view returns(uint256)	获取元素数
2	isEmpty(Deque storage self) internal view returns(bool)	判断是否为空
3	offerFirst(Deque storage self, bytes32 element) internal	将数据存入头部
4	offerLast(Deque storage self, bytes32 element) internal	将数据存入尾部
5	pollFirst(Deque storage self) internal returns(bytes32 ret)	取出头部元素
6	pollLast(Deque storage self) internal returns(bytes32 ret)	取出尾部元素
7	peekFirst(Deque storage self) internal view returns(bytes32 ret)	查看头部元素
8	peekLast(Deque storage self) internal view returns(bytes32 ret)	查看尾部元素
9	push(Deque storage self, bytes32 element) internal	入栈
10	pop(Deque storage self) internal returns(bytes32)	出栈

API详情

1. getSize 函数

查看元素数目

参数

• Deque：队列

返回值

• uint256： 元素数

实例

    uint256 size = _deque.getSize();

2. isEmpty 函数

查看是否为空

参数

• Deque：队列

返回值

• bool 是否为空

实例

    bool empty = _deque.isEmpty();

3. offerFirst 函数

从头部存入元素。

参数

• Deque：队列
• bytes32: 元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);

    function f() public{
        _deque.offerFirst(bytes32(uint256(1)));
        emit Log(_deque.getSize());//Should be 1
    }
}

4. offerLast 函数

从尾部存入元素。

参数

• Deque：队列
• bytes32: 元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);

    function f() public{
        _deque.offerLast(bytes32(uint256(2)));
        emit Log(_deque.getSize());//Should be 1
    }
}

5. pollFirst 函数

删除头部元素，并返回该元素。如果队列为空，则失败。

参数

• Deque：队列

返回值

• bytes32: 头部元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);
    function f() public returns(bytes32){
        _deque.offerFirst(bytes32(uint256(1)));
        _deque.offerLast(bytes32(uint256(2)));
        bytes32 r = _deque.pollFirst();//Should be 1
        emit Log(_deque.getSize());//Should be 1
        return (r);
    }
}

6. pollLast 函数

删除尾部元素，并返回该元素。如果队列为空，则失败。

参数

• Deque：队列

返回值

• bytes32: 尾部元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);
    function f() public returns(bytes32){
        _deque.offerFirst(bytes32(uint256(1)));
        _deque.offerLast(bytes32(uint256(2)));
        bytes32 r = _deque.pollLast();//Should be 2
        emit Log(_deque.getSize());//Should be 1
        return (r);
    }
}

7. peekFirst 函数

查看头部元素。如果队列为空，则失败。

参数

• Deque：队列

返回值

• bytes32: 头部元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);
    function f() public returns(bytes32){
        _deque.offerFirst(bytes32(uint256(1)));
        _deque.offerLast(bytes32(uint256(2)));
        bytes32 r = _deque.peekFirst();//Should be 1
        emit Log(_deque.getSize());//Should be 2
        return (r);
    }
}

8. peekLast 函数

查看尾部元素。如果队列为空，则失败。

参数

• Deque：队列

返回值

• bytes32: 尾部元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);
    function f() public returns(bytes32){
        _deque.offerFirst(bytes32(uint256(1)));
        _deque.offerLast(bytes32(uint256(2)));
        bytes32 r = _deque.peekLast();//Should be 2
        emit Log(_deque.getSize());//Should be 2
        return (r);
    }
}

9. push 函数

推入一个元素，就像使用栈一样。

参数

• Deque：队列
• bytes32: 元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);
    function f() public returns(bytes32){
        _deque.push(bytes32(uint256(1)));
        _deque.push(bytes32(uint256(2)));
        emit Log(_deque.getSize());//Should be 2
    }
}

10. pop 函数

弹出一个元素，就像栈一样。如果队列为空，则失败。

参数

• Deque：队列

返回值

• bytes32: 元素

实例

pragma solidity >=0.4.22 <0.7.0;

import "./LibDeque.sol";

contract Test{
    
    using LibDeque for LibDeque.Deque;
    
    LibDeque.Deque private _deque;
    
    event Log(uint size);
    function f() public returns(bytes32){
        _deque.push(bytes32(uint256(1)));
        _deque.push(bytes32(uint256(2)));
        bytes32 pop = _deque.pop();//Should be 2
        emit Log(_deque.getSize());//Should be 1
        return pop;
    }
}