3.3 實現一種基於命令的語言

 

/* CLB.cpp 2011.1.18 本程序實現了一種最簡單的基於命令的語言 該語言有以下4種命令 PrintString "..." PrintStringLoop "..." number NewLine WaitForKeyPress 該程序通過讀取磁盤上，用該命令寫成的腳本，分析該語言，輸出對應的結果 //是遊戲腳本高級編程的第三章的第一個程序,我用c++將其重寫 //運行環境 vs2005 通過 運行結果: "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." 請按任意鍵繼續. . . */ #include<fstream> #include<iostream> #include<string> #include<vector> #include<cassert> #include"conio.h" using namespace std; #define COMMAND_PRINTSTRING "PrintString" #define COMMAND_PRINTSTRINGLOOP "PrintStringLoop" #define COMMAND_NEWLINE "NewLine" #define COMMAND_WAITFORKEYPRESS "WaitForKeyPress" //在內存中存放腳本 vector<string> script; /* 函數名:LoadScript 功能:讀入腳本 參數: fileName:文件名 */ void LoadScript(string fileName); /* 函數名:UnloadScript 功能:註銷腳本 */ void UnloadScript(); /* 函數名:RunScript 功能:運行腳本 */ void RunScript(); /* 函數名:GetCurrentScript 功能:得到當前行的腳本 參數: line:當前行號 返回值:當前行的腳本 */ string& GetCurrentScript(size_t line); /* 函數名:GetCommand 功能:得到當前行的腳本的命令 參數: currentScript:當前行的腳本 返回值:得到當前行的腳本的命令 */ string GetCommand(const string& currentScript); /* 函數名:GetIntParam 功能:得到當前行的腳本的int參數 參數: currentScript:當前行的腳本 返回值:得到當前行的腳本的int參數 */ int GetIntParam(const string& currentScript); /* 函數名:GetStringParam 功能:得到當前行的腳本的string參數 參數: currentScript:當前行的腳本 返回值:得到當前行的腳本的string參數 */ string GetStringParam(const string& currentScript); int main() { /* 本地文件cbl.txt PrintString "This is a command-based language." PrintString "Therefore,this is a command-based script." NewLine PrintString "...and it's really quite boring." NewLine PrintStringLoop "this string has been repeated four times." 4 NewLine PrintString "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"); //加載腳本 LoadScript(textName); //運行腳本 RunScript(); //卸載腳本 UnloadScript(); return 0; } void LoadScript(string fileName) { ifstream file; //打開文件 file.open(fileName.c_str()); if(!file) { cout<<"error: unable to open the file:" <<fileName<<endl; exit(-1); } //加載到內存中 while(!file.eof()) { string line; getline(file,line); script.push_back(line); } //垃圾回收 file.clear(); file.close(); } void UnloadScript() { //清空腳本 script.erase(script.begin(),script.end()); assert(script.empty()); } void RunScript() { //腳本行數 size_t scriptSize=script.size(); //循環運行每一條腳本 for(size_t line = 0;line !=scriptSize; ++line) { //得到當前腳本 string currentScript=GetCurrentScript(line); if(currentScript.size()<=3) continue; //得到當前腳本的命令 string command=GetCommand(currentScript); //根據命令不同,執行方式也不同 if(command==COMMAND_PRINTSTRING) { //得到string參數 string param=GetStringParam(currentScript); cout<<'/t'<<param<<endl; } else if(command == COMMAND_PRINTSTRINGLOOP) { //得到string參數 string param=GetStringParam(currentScript); //得到int參數 int loopNum=GetIntParam(currentScript); for(int i=0;i<loopNum;++i) cout<<'/t'<<param<<endl; } else if(command == COMMAND_NEWLINE) { cout<<endl; } else if(command == COMMAND_WAITFORKEYPRESS) { //_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(const string& currentScript) { string command(""); for(size_t i=0;currentScript[i]!=' ' && i!=currentScript.size();++i) command.push_back(currentScript[i]); return command; } int GetIntParam(const string& currentScript) { string loopNumString; for(size_t i=currentScript.find_last_of('"')+1;i!=currentScript.size();++i) { loopNumString.push_back(currentScript[i]); } int loopNum=atoi(loopNumString.c_str()); return loopNum; } string GetStringParam(const string& currentScript) { string param; for(size_t i=currentScript.find(' ')+1;i!=currentScript.find_last_of('"')+1;++i) { param.push_back(currentScript[i]); } return param; }