手把手教你玩eos：编写智能合约游戏——三连棋

文章由EOS节点EOSWing（柚翼）首发于eoswing.io博客，内容将不定期更新，仅供学习交流之用。

引言

0.1 教程概况

手把手教你学eos系列教程，从最基础开始，一步一步教你学会用eos。比如发代币，开发DAPP等等。

本文是第五篇,主要是如何使用eos智能合约编写一个游戏：三连棋。

0.2 学习内容

1.相关准备知识

2.编写智能合约

3.编译和运行智能合约

0.3 机器环境

cpu: 1核

内存: 2G

操作系统：CentOS 7.4 64位

服务器所在地：香港

推荐将服务器放在网络较为优质的环境，比如香港。不然会有很多配置依赖下载上的问题。

提示：以下命令行默认在root权限下执行。如遇权限问题，请在命令前加sudo。

相关准备知识

1.1 三连棋游戏规则

三连棋，又称“井字棋”，是棋类的一种，棋盘为九宫格，呈“井”字形，玩家双方各代表○或×，在棋盘上任意一方连成三个（横竖斜均可）就胜利了。

1.2 Multi-Index

Multi-Index是eosio上的数据库管理接口，通过eosio::multi_index智能合约能够写入、读取和修改eosio数据库的数据。

一个完整的multi_index表定义如下：

struct limit_order {

       uint64_t     id;

       uint128_t    price;

       uint64_t     expiration;

       account_name owner;



       auto primary_key() const { return id; }

       uint64_t get_expiration() const { return expiration; }

       uint128_t get_price() const { return price; }



       EOSLIB_SERIALIZE( limit_order, ( id )( price )( expiration )( owner ) )

};

1.3 建立项目框架

使用eosiocpp建立项目框架：

cd /contracts

eosiocpp -n tictactoe

cd tictactoe

命令行输出如下：

2 编写智能合约

2.1 编写hpp文件

引入标准库，编写基本结构

#include <eosiolib/eosio.hpp>

class tictactoe : public eosio::contract {

       public:

                  tictactoe( account_name self ):contract(self){}



       //...游戏数据定义...



       //...游戏命令定义...

};

游戏数据定义，参看1.2 Multi-Index。

struct game {

        static const uint16_t board_width = 3;

        static const uint16_t board_height = 3;

        game() { 

               initialize_board(); 

         }

         account_name   challenger; //挑战者

         account_name   host;       //主角

         account_name   turn; // 当前角色 host/challenger

         account_name   winner = N(none); // none/draw/name of host/name of challenger

         std::vector    board;



          // 初始化棋盘

          void initialize_board() {

              board = std::vector(board_width * board_height, 0);

           }



           // 初始化游戏

           voidreset_game() {

                initialize_board();

                turn = host;

                winner = N(none);

            }



            auto primary_key() const { return challenger; }

            EOSLIB_SERIALIZE( game, (challenger)(host)(turn)(winner)(board))

     };

typedef eosio::multi_index< N(games), game> games;

游戏命令定义

/// @abi action

  /// 创建新游戏

  void create(const account_name& challenger,const account_name& host);



   /// @abi action

   /// 重新开始游戏

   void restart(const account_name& challenger, const account_name& host,const account_name& by);



    /// @abi action

    /// 结束游戏

    void close(const account_name& challenger,const account_name& host);



     /// @abi action

     /// 下棋

     void move(const account_name& challenger,const account_name& host,const account_name& by,const uint16_t& row,const uint16_t& column);

hpp的完整源文件可以查看官方的github代码库:

https://github.com/EOSIO/eos/blob/master/contracts/tic_tac_toe/tic_tac_toe.hpp

本教程为避免代码文件冲突，仅修改tic_tac_toe为tictactoe

2.2 编写cpp文件

编写基本结构

#include "tictactoe.hpp"

using namespace eosio;

创建新游戏：

void tictactoe::create(const account_name& challenger, const account_name& host) {

        //验证主角签名

        require_auth(host);



         //验证主角和挑战者不是同一人

         eosio_assert(challenger != host, "challenger shouldn't be the same as host");



          //验证主角和挑战者当前没有游戏

         games existing_host_games(_self, host);

          auto itr = existing_host_games.find( challenger );

          eosio_assert(itr == existing_host_games.end(), "game already exists");



           //初始化游戏

           existing_host_games.emplace(host, [&]( auto& g ) {

               g.challenger = challenger;

               g.host = host;

               g.turn = host;

});

}

重新开始游戏：

void tictactoe::restart(const account_name& challenger, const account_name& host, const account_name& by) {

        //验证请求者签名

        require_auth(by);



         //验证这场游戏是否存在

         games existing_host_games(_self, host);

         auto itr = existing_host_games.find( challenger );

         eosio_assert(itr != existing_host_games.end(), "game doesn't exists");



          //验证请求者是不是主角或者挑战者

          eosio_assert(by == itr->host || by == itr->challenger, "this is not your game!");



          //重新开始游戏

          existing_host_games.modify(itr, itr->host, []( auto& g ) {

              g.reset_game();

           });

}

结束游戏：

void tictactoe::close(const account_name& challenger, const account_name& host) {

        //验证主角签名

        require_auth(host);



 //验证这场游戏是否存在

 games existing_host_games(_self, host);

 auto itr = existing_host_games.find( challenger );

 eosio_assert(itr != existing_host_games.end(), "game doesn't exists");



  //删除游戏

  existing_host_games.erase(itr);

}

下棋：

void tictactoe::move(const account_name& challenger, const account_name& host, const account_name& by, const uint16_t& row, const uint16_t& column ) {

  //验证请求者签名

  require_auth(by);



  //验证这场游戏是否存在

  games existing_host_games(_self, host);

  auto itr = existing_host_games.find( challenger );

  eosio_assert(itr != existing_host_games.end(), "game doesn't exists");



   //验证游戏没有结束

   eosio_assert(itr->winner == N(none), "the game has ended!");



   //验证请求者是不是主角或者挑战者

   eosio_assert(by == itr->host || by == itr->challenger, "this is not your game!");



   //验证是不是轮到请求者下棋

   eosio_assert(by == itr->turn, "it's not your turn yet!");





   //验证这一步棋子是不是下在空的棋盘格子

   //is_valid_movement方法提取出来，在后面单独写

   eosio_assert(is_valid_movement(row, column, itr->board), "not a valid movement!");



   //记录这一步下棋数据

   const uint8_t cell_value = itr->turn == itr->host ? 1 : 2;

   const auto turn = itr->turn == itr->host ? itr->challenger : itr->host;

   existing_host_games.modify(itr, itr->host, [&]( auto& g ) {

       g.board[row * tictactoe::game::board_width + column] = cell_value;

       g.turn = turn;

  //验证这一步棋，是不是赢了比赛

  //赢家验证get_winner方法提取出来，在后面单独写

       g.winner = get_winner(g);

 });

}

下棋步数有效验证方法is_valid_movement

bool is_empty_cell (const uint8_t& cell) {

  return cell == 0;

}

bool is_valid_movement (const uint16_t& row, const uint16_t& column, const vector<uint8_t>& board) {

  uint32_t movement_location = row * tictactoe::game::board_width + column;

  bool is_valid = movement_location < board.size() && is_empty_cell(board[movement_location]);

  return is_valid;

}

赢家验证

游戏规则：在横向、纵向和对角线任意一个方向上连线三点就赢得比赛。

account_name get_winner (const tictactoe::game& current_game) {

 auto& board = current_game.board;



 bool is_board_full = true;



  //采用&操作符来计算横向、纵向和对角线上的连线值。

  //3 == 0b11, 2 == 0b10, 1 = 0b01, 0 = 0b00

  vector consecutive_column(tictactoe::game::board_width, 3 );

  vector consecutive_row(tictactoe::game::board_height, 3 );

  uint32_t consecutive_diagonal_backslash = 3;

  uint32_t consecutive_diagonal_slash = 3;

  for (uint32_t i = 0; i < board.size(); i++) {

       is_board_full &= is_empty_cell(board[i]);

       uint16_t row = uint16_t(i / tictactoe::game::board_width);

       uint16_t column = uint16_t(i % tictactoe::game::board_width);



        //计算横向和纵向的连线值

        consecutive_row[column] = consecutive_row[column] & board[i]; 

        consecutive_column[row] = consecutive_column[row] & board[i];



        //计算对角线的连线值

        if (row == column) {

           consecutive_diagonal_backslash = consecutive_diagonal_backslash & board[i];

        }        

        if ( row + column == tictactoe::game::board_width - 1) {

           consecutive_diagonal_slash = consecutive_diagonal_slash & board[i]; 

        }

 }



 //检查所有横向、纵向和对角线的连线值并决定赢家

 vector aggregate = { consecutive_diagonal_backslash, consecutive_diagonal_slash };

 aggregate.insert(aggregate.end(), consecutive_column.begin(), consecutive_column.end());

 aggregate.insert(aggregate.end(), consecutive_row.begin(), consecutive_row.end());

 for (auto value: aggregate) {

     if (value == 1) {

         return current_game.host;

     } else if (value == 2) {

         return current_game.challenger;

     }

 }



 // 检查是否已有赢家，有就返回

 return is_board_full ? N(draw) : N(none);

}

cpp的完整源文件可以查看官方的github代码库:

https://github.com/EOSIO/eos/blob/master/contracts/tic_tac_toe/tic_tac_toe.cpp

本教程为避免代码文件冲突，仅修改tic_tac_toe为tictactoe

3 编译和运行智能合约

3.1 编译合约

eosiocpp -o tictactoe.wast tictactoe.cpp

eosiocpp -g tictactoe.abi tictactoe.cpp

命令行输出如下：

3.2 创建合约账户tttaccount

解锁xiao钱包，创建公钥-私钥对，导入公钥-私钥对到钱包，最后，用公钥创建tttaccount。

具体步骤不再赘述，不熟悉的可以翻看以前的教程。

tttaccount创建后命令行输出如下:

3.3 上传合同到账户

cleos set contract tttaccount /contracts/tictactoe -p tttaccount@active

命令行输出如下：

3.4 运行智能合约

创建游戏

cleos push action tttaccount create '{"challenger":"xiaoaccount", "host":"tttaccount"}' -p tttaccount@active

命令行输出如下：

下棋

cleos push action tttaccount move '{"challenger":"xiaoaccount", "host":"tttaccount", "by":"tttaccount", "row":0, "column":0}' --permission tttaccount@active

cleos push action tttaccount move '{"challenger":"xiaoaccount", "host":"tttaccount", "by":"xiaoaccount", "row":1, "column":1}' --permission xiaoaccount@active

命令行输出如下：