3.3 实现一种基于命令的语言(2)

经过修改:

 

1) 命令和参数之间由任意数量的空格和Tab建隔开

 

2) 支持简单的//注释符

 

代码如下

 

/*CLB.cpp2011.1.18本程序实现了一种最简单的基于命令的语言该语言有以下4种命令PrintString "..."PrintStringLoop "..." numberNewLineWaitForKeyPress该程序通过读取磁盘上，用该命令写成的脚本，分析该语言，输出对应的结果 //是游戏脚本高级编程的第三章的第一个程序,我用c++将其重写//运行环境 vs2005 通过运行结果: "This is a command-based language." "Therefore,this is a command-based script." "...and it's really quite boring." "this string has been repeated four times." "this string has been repeated four times." "this string has been repeated four times." "this string has been repeated four times." "Okay,press a key already and put us both out of our misery." "The new demo is cooler,I swear."请按任意键继续. . .*/#include<fstream>#include<iostream>#include<string>#include<vector>#include<cassert>#include"conio.h"#include<cctype>using namespace std;#define COMMAND_PRINTSTRING "PrintString"#define COMMAND_PRINTSTRINGLOOP "PrintStringLoop"#define COMMAND_NEWLINE "NewLine"#define COMMAND_WAITFORKEYPRESS "WaitForKeyPress"//在内存中存放脚本vector<string> script;/*函数名:LoadScript功能:读入脚本 参数:fileName:文件名*/void LoadScript(string fileName);/*函数名:UnloadScript功能:注销脚本 */void UnloadScript();/*函数名:RunScript功能:运行脚本 */void RunScript();/*函数名:GetCurrentScript功能:得到当前行的脚本 参数:line:当前行号返回值:当前行的脚本*/string& GetCurrentScript(size_t line);/*函数名:GetCommand功能:得到当前行的脚本的命令参数:currentScript:当前行的脚本返回值:得到当前行的脚本的命令*/string GetCommand( string& currentScript);/*函数名:GetIntParam功能:得到当前行的脚本的int参数参数:currentScript:当前行的脚本返回值:得到当前行的脚本的int参数*/int GetIntParam( string& currentScript);/*函数名:GetStringParam功能:得到当前行的脚本的string参数参数:currentScript:当前行的脚本返回值:得到当前行的脚本的string参数*/string GetStringParam( string& currentScript);/*函数名:DeleteSpaces功能:删除当前字符串最前面的任意数量的空格和Tab符号参数:str: 任意字符串*/void DeleteSpaces(string& str);int main(){/*本地文件cbl.txtPrintString "This is a command-based language."PrintString "Therefore,this is a command-based script."NewLinePrintString "...and it's really quite boring."NewLinePrintStringLoop "this string has been repeated four times." 4NewLinePrintString "Okay,press a key already and put us both out of our misery."PrintString "The new demo is cooler,I swear."WaitForKeyPress*/string textName("cbl.txt");//加载脚本LoadScript(textName);//运行脚本RunScript();//卸载脚本UnloadScript();return 0;}void DeleteSpaces(string& currentScript){//去掉空格和/twhile ( (currentScript[0]==' ') || (currentScript[0]=='/t')){if(currentScript[0]==' ')currentScript.erase(0,1);else currentScript.erase(0,4);}}void LoadScript(string fileName){ifstream file;//打开文件file.open(fileName.c_str());if(!file){cout<<"error: unable to open the file:"<<fileName<<endl;exit(-1);}//加载到内存中while(!file.eof()){string line;getline(file,line);DeleteSpaces(line);//判断简单注释符if((line[0] == '/' ) && (line[1]== '/' ))continue;script.push_back(line);}//垃圾回收file.clear();file.close();}void UnloadScript(){//清空脚本script.erase(script.begin(),script.end());assert(script.empty());}void RunScript(){//脚本行数size_t scriptSize=script.size();//循环运行每一条脚本for(size_t line = 0;line !=scriptSize; ++line){//得到当前脚本string currentScript=GetCurrentScript(line);if(currentScript.size()<=3)continue;//得到当前脚本的命令string command=GetCommand(currentScript);//根据命令不同,执行方式也不同if(command==COMMAND_PRINTSTRING){//得到string参数string param=GetStringParam(currentScript);assert(currentScript.empty());cout<<'/t'<<param<<endl;}else if(command == COMMAND_PRINTSTRINGLOOP){//得到string参数string param=GetStringParam(currentScript);//得到int参数int loopNum=GetIntParam(currentScript);assert(currentScript.empty());for(int i=0;i<loopNum;++i)cout<<'/t'<<param<<endl;}else if(command == COMMAND_NEWLINE){assert(currentScript.empty());cout<<endl;}else if(command == COMMAND_WAITFORKEYPRESS){assert(currentScript.empty());//_kbhit returns a nonzero value if a key has been pressed. Otherwise, it returns 0.while(!kbhit());}else{printf("/tError: Invalid command./n");break;}}}string & GetCurrentScript(size_t line){return script[line];}string GetCommand( string& currentScript){string command;for(size_t i=0;currentScript[i]!=' ' && i!=currentScript.size();++i)command.push_back(currentScript[i]);currentScript.erase(0,command.size());DeleteSpaces(currentScript);return command;}int GetIntParam( string& currentScript){string loopNumString;assert(isdigit(currentScript[0]));for(size_t i=0;i!=currentScript.size() && currentScript[i]!=' ' && currentScript[i]!='/t';++i){loopNumString.push_back(currentScript[i]);}int loopNum=atoi(loopNumString.c_str());currentScript.erase(0,loopNumString.size());DeleteSpaces(currentScript);return loopNum;}string GetStringParam( string& currentScript){int flag=0;//1表示有1个" 2表示有2个"string param;assert(currentScript[0]== '"');//第一个字符应该是"for(size_t i=currentScript.find('"'); i < currentScript.size();++i){param.push_back(currentScript[i]);if(currentScript[i] == '"')flag++;if(flag == 2)break;}currentScript.erase(0,param.size());DeleteSpaces(currentScript);return param;}